NBS Special Publication 250

NBS Calibration Services

Users Guide 1986-88

U.S. Department of Commerce

National Bureau of Standards

NEW NBS PUB

AUG 2 7 '386

TO ORDER

PHONE 301/921-2805

NBS Calibration Services

Users Guide

1986-1988 Edition

George A. Uriano

Ernest L. Garner

R. Keith Kirby

William P. Reed, Editors

Office of Physical Measurement Services

National Bureau of Standards

Galthersburg, MD 20899

NBS Special Publication 250

Issued July, 1986

(Supersedes 1982 Edition)

U.S. Department of Commerce

Malcolm Baldrige, Secretary

National Bureau of Standards

Ernest Ambler, Director
National Bureau of Standards

Special Publication 250 - 1986 Edition Nat. Bur. Stand. (U.S.), Spec. Publ. 250, 1986 Ed.,

204 pages (July 1986)

CODEN: XNBSAV

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1986

For sale by the Superintendent of Documents,

U.S. Government Printing Office, Washington, DC 20402

U.S. Government Printing Office

Washington: 1986
Foreword

The NBS Calibration Service Users Guide provides detailed descriptions of the currently available NBS calibration services, special test services, and measurement assur- ance programs. This document is a revised edition of NBS Special Publication 250. It describes the NBS services available as of the second quarter of 1986 and reflects a number of important changes since the 1982 edition was published. A detailed description is given of each measurement service. A new numbering system is used to uniquely identify each of the services. Addendum I to this document is a cross- reference index that links the new NBS test numbers to those used previously to identify the services. Also cited are a large number of NBS technical experts (including

addresses and telephone numbers) who may be contacted for further information concerning services or measurement problems. Future editions will be published periodically as NBS services change.

This document also presents a detailed description of a number of Measurement Assurance Program (MAP) services. These are carefully designed quality control pro- grams for critical measurements that allow the user to achieve a high level of confidence that the measurements being made in the user's laboratory are consistent with

national standards and adequate for intended use. MAP services are available for some

basic measurement quantities (e.g., laser power and energy). New MAP services for luminous intensity of retroreflectors and spectral transmittance have been introduced

since the last edition of this document.

A Fee Schedule for the services described in this Users Guide is published every six months (April and October). It lists current prices for the services described here. NBS

will notify users of changes in services or proposed changes in services by means of

anftouncements in the semi-annual Fee Schedule. In addition, information about up- coming NBS Measurement Seminars is announced there. If you are not already on the

NBS physical measurement services mailing list and wish to be, fill in and return the

card below. It is important that you refer to the current issue of the Fee Schedule in order to have up-to-date information with respect to NBS points of contact. A companion document to this guide is NBS Special Publication 260, NBS Standard

Reference Materials Catalog. This document describes over 900 Standard Reference

Materials (SRMs) certified by NBS for use in industrial quality control, materials test- ing, environmental testing, and clinical testing applications. A copy of SP 260 may be

obtained by indicating interest on the mailing list card and returning it to NBS.

The Office of Physical Measurement Services welcomes suggestions on how this publication can be made more useful to those who rely on NBS physical measurement

services. Suggestions are also welcome concerning needs for new calibration services,

measurement assurance programs, or other measurement services. George A. Uriano, Director Ernest L. Gamer, Chief

Measurement Services Office of Physical Measurement Services

iii
Abstract

The National Bureau of Standards (NBS) Calibration Services Users Guide provides

detailed descriptions of currently available NBS calibration services, measurement as- surance programs, and special test services. The following measurement areas are covered: (1) dimensional, (2) mechanical including flow, acoustic, and ultrasonic, (3) ther- modynamic, (4) optical radiation, (5) ionizing radiation, and (6) electromagnetic

including dc, ac, rf, and microwave. A separate Fee Schedule is issued every six months, which provides current prices for the services offered, updates on points-ofcontact, and information on measurement seminars.

Key words: calibration; measurement assurance; measurement services; standards;

traceability.

iv
Acknowledgments

Many NBS staff members contributed to the development and preparation of this guide. Over 50 members of the NBS technical staff contributed data and information

that have been incorporated into the guide. Significant contributions were made by

John Mayo-Wells and Norman Belecki, who helped gather data for and review many

of the sections in Chapter VII on Electromagnetic Measurements. Peter de Bruyn

thoroughly reviewed the manuscript and made many suggestions for its improvement.

Julianne Chappell provided a number of excellent editorial suggestions and coordinated the preparation of the final document. We are deeply indebted to Margaret Musick, for an excellent job in typing what seemed like an endless number of drafts, and

to Verna Moore for considerable assistance in preparing the many drafts. We also are

grateful for the help of Marilyn Ugiansky and Ernie Kunz for contributions to the

graphic design and layout of the final document and to Nancy Gogniat and Use Put- man for typesetting the final draft. The Editors

V
List of Tables

Table Page

1. Piston Gage and Pressure Transducer Uncertainties 43

2. Thermometer Calibration Uncertainties 48

3. Calibration Uncertainties for Radionuclides Having Half-Lives

Greater than 15 Days 78

4. Calibration Uncertainties for Radionuclides Having Half-Lives Less than 15 Days 79

5. Specifications for Calibrations of Alpha-Particle-Emitting Samples 79

6. Specifications for Special Tests of Beta-Particle-Emitting

Solution Sources 80

7. X-Ray Beam-Quality Parameters 86

8. Calibration Uncertainties for DC Resistance Standards 96

9. Specifications and Estimated Uncertainties for Low-Frequency

TVC Services 117

10. Specifications and Estimated Uncertainties for High-Frequency

TVC Services 117

1 1 . Specifications and Estimated Uncertainties for Peak-to-Peak

Detector Services 118

12. Specifications and Estimated Uncertainties for RF

Micropotentiometer Calibrations 118

13. Specifications and Estimated Uncertainties for Data Converter

Calibrations 121

14. Available Values of the Parameters for Routine Wattmeter

and Watthour Meter Testing 136

15. Summary of NBS Standard Field Strength Facilifies 158

16. NBS Impulse Generator Spectrum Amplitude Measurement Service

Capabilities 160

17. Limits of Uncertainties for Calibration of Fast Repetitive

Baseband Pulse Parameters 161

vi
Ust of Figures

Figure Page

1 . Accuracy of Length Measurements at NBS 8

2. Precision of Angle Calibrations for Master

Angle Gage Blocks and Polygons 17

3. Uncertainty of NBS Measurements for Air

Flow Rate Standards 24

4. Uncertainty of NBS Measurements for Water

Flow Rate Standards 24

5. Uncertainty of NBS Measurements for Liquid

Hydrocarbon Flow Rate Standards 24

6. Accuracy of Airspeed Measurements for Calibration of Airspeed indicators 27

7. NBS Precision of Weighing for Mass Standards

Ranging from 10"* to 10"* Kilograms 29

8. Uncertainties of NBS Low Pressure and Vacuum Standards 45

9. Uncertainties for NBS Calibration of Temperature

Measuring Instruments 48

10. NBS Uncertainties for Measurement of Humidity

Standards with Atmospheric Air at Atmospheric Temperature 57

11. Uncertainties for NBS Spectral Radiance Calibrations 65

12. Uncertainties for NBS Spectral Irradiance Calibrations 66

13. Uncertainties of NBS DC Voltage Measurments 109

14. NBS Uncertainties for AC Voltage Measurements 113

15. Uncertainty for NBS Data Converter Test System

for Resolutions from 12-18 Bits 121

16. Estimated Total Uncertainties of the NBS Phase

Angle Calibration Standard 132

vii
Contents

Chapter 1—

Policies

A. Introduction 1 B. Questions and Inquiries 1 C. Fees 1 D. Types of Services 1 E. Criteria 2

F. Reports of Test Results 2

G. References to NBS in Advertisements 2 H. Traceability 2

I. Disclaimer 3

J. Ordering and Scheduling 3 K. Purchase Order 3 L. Shipping 4

M. Special Instructions for Foreign Customers 4

Chapter 2—

Dimensional Measurements

A. Length Measurements 7 100 IOC Gage Blocks

10020C Line Standards

10030C Surveying and Oil Gaging Tapes

10040S Special Tests of Surveying Leveling Rods

10050S Special Tests of Length Standards

10060S Special Tests of Sieves

10070M Measurement Assurance Program for Gage Blocks

B. Diameter Measurements 11 IIOIOS Special Tests for Plug Gages: External

Diameter Standards

11020C Measuring Wires for Threads and Gears

11030S Special Tests for Spherical Diameter Standards: Balls 11040S Special Tests for Internal Diameter Standards:

Ring Gages

1 1050S Special Tests of Length and Diameter

11060S Special Tests of End Standards

11070S Special Tests of Step Gages

11080S Special Tests of Thread Measuring Wires

C. Complex Dimensional Standards 13 120 IOC API Threaded Plug and Ring Gages

12020S Special Tests of Plain Conical Plug and Ring Gages

12030S Special Tests of Threaded Plug and Ring Gages

12040S Special Tests of Calipers and Gages

12050S Special Tests of Micrometer Screws and Dial

Micrometers

12060S Special Tests of Penetration Needles

12070S Special Tests of Two Dimensional Gages

viii
D. Optical Reference Planes & Roundness Standards 15 1301 OS Special Tests of Optical Reference Planes (Flats)

13020S Special Tests of Roundness

13030S Special Tests of Roundness Calibration Specimens

E. Angular Measurements 16 140 IOC Angle Gage Blocks

14020S Special Tests of Optical Polygons

14030S Special Tests of Rotary and Indexing Tables

14040S Special Tests of Wedges

14050S Special Tests of Autocollimators

14060S Special Tests of Angle Generators

F. Surface Texture 18 15010C Roughness Calibration Specimens

15020C Surface Roughness Comparison Specimens

15030C Step Height Measurements

G. Hydrometers 20

160 IOC Reference Standard Hydrometers

H. Volume and Density 20

170 IOC Volume Standards

17020S Special Tests of Volume Standards

17030S Special Tests of Density: Solids

17040S Special Tests of Density: Liquids

Chapter 3—

Mechanical Measurements

A. Flow Rate Measurements 23

180 IOC Single Turbine Meters

18020C Tandem Turbine Meters

18030C Flow Rate Meters (Direct Reading in Flow

Rate Units)

18040C Head Class Flow Measurement Devices

18050S Special Tests for Liquid and Gas Flow Rates

B. Flow Measurements at Cryogenic Temperatures 26

18800S Special Tests of Cryogenic Liquid Flow

C. Airspeed Measurements 27

190 IOC Pitot-Static Tubes

19020C Low Airspeed Measurements

19030S Special Tests for Airspeed Measurements

ix
D. Mass Standards 28

22010C-22030C. . .Weight Sets (1 mg to 30 kg)

22040C-22120C. . .Single Weights (1 mg to 30,000 kg)

22130C-22160C. . .Single Weight for Dead-Weight Pressure Testers

221 70S Special Mass Measurement Services

22180M Measurement Assurance Program for Mass

E. Force Measurements 33 23010C-23240C. . .Force Transducers (to 1,000,000 Ibf, 1 or 2 Modes)

23250C Force Transducers (over 1,000,000 IbO

23260S Special Tests of Force Transducers

23270S Pattern Evaluation Test of Load Cells in Compression

F. Vibration Measurements 35

24010C-24030C. . .Vibrations (Pickup Sensitivity, 2 to 10,000 Hz)

24040S Special Shock Measurement Services

24050S Special Tests of Pickup Sensitivity

24060S Special Vibration Tests

G. Acoustic Measurements 37

25010C-25020C. . .Pressure Response: WE Type 640AA

Microphones or Equivalent

25030C-25040C. . .Pressure Response: Tokyo Riko Type ECL

MR 112, or Equivalent Half-Inch Microphones

25050C Free-Field Response: Tokyo Riko Type ECL

MR 112, B&K Types 4133, 4134, 4165, 4166, or Equivalent Half-Inch Microphone

25060S Special Tests of Acoustic Devices

25070S Special Tests of Earphones

H. Ultrasonic Measurements 39

260 IOC Ultrasonic Transducer Power and Frequency

26020C Acoustic Emission Sensors

26030S Special Tests of Aluminum Reference Blocks

26050S Distance Amplitude Set 26070S Special Tests of Ultrasonic Transducer Power

Chapter 4—

Thermodynamic Quantities

A. Pressure Measurements 43

290 IOC Deadweight Piston Gages

29020C Controlled Clearance Piston Gages

29030C Pressure Gages and Transducers

29035C Mercurial Barometers and Manometers

29040S Special Tests of Pressure Gages

X
B. Vacuum and Low Pressure Measurements 45

30010C Absolute Low Pressure Gages

30020C Differential Low Pressure Gages

30030C High Vacuum Gages

30040S Special Tests of Low Pressure Gages

30050S Special Tests of Vacuum Gages

C. Laboratory Thermometers 47

31010C-31061C. . .Laboratory Thermometers

3I070C-31071C. . .Calorimetric Thermometers

31080C-31081C. . .Beckman Thermometers

31100S Special Tests of Liquid-in-Glass Thermometers

31 1 lOS-31 161S . . .Special Tests of Thermometers

31260S Special Thermometry Services by Prearrangement

D. Thermocouples, Thermocouple Materials, and 49

Pyrometer Indicators

32010C-32044C. . .Type S, R, B, E, J, K, N, and T, Measured with

Standard Thermocouples Covering 0-1750°C

32070C Thermocouple Materials Tests against Pt Standard with PRT (-100 to 300°C)

32090C Type S Measured with Freezing-Point Standards

(0-1450°C)

32100C Pyrometer Indicators (Portable Potentiometers,

First Dial or Range

321 10C-32147C. . .Thermocouple Materials Tested against PT

Standard with PRT-Varian Temperature

Ranges

321 SOS Special Tests of Thermocouples and Thermocouple

Materials

E. Resistance Thermometry 52

33010C-33020C. . .Long Stem Platinum Resistance Thermometers

33030C Calorimetric Type PRT (-50 to +150°C)

33040C-33050C. . .Capsule Type Platinum Resistance Thermometers

33060S Special Tests of Germanium Resistance

Thermometers

33100S Special Tests of Resistance Thermometers

33 11 OS Special Tests of Thermometric Fixed-Point

Devices

33120M Measurement Assurance Program for Temperature

xi
F. Radiation Thermometry 55

35010C-35040C. . .Optical Pyrometers

35050C-35060C. . .Ribbon Filament Lamps (800 to 2300°C)

35070S Special Tests of Radiation Pyrometers

G. Humidity Measurements 56

36010C-36020C. . .Dew-Point Hygrometers

36030C Electric Hygrometers

36040C Coulometric Hygrometers

36050C Aspirated Hygrometers

36060C Pneumatic Bridge Hygrometers

36070S Special Tests of Humidity

Chapter 5—

Optical Radiation i\1easurements

A. Photometric Measurements 59

37010C-37070C. . .Luminous Intensity Standard (100-lOOOW Frosted

Tungsten Lamp, 90-1400 candelas, 2700K and

2856K color temp.)

37080C Luminous Flux Standards (25W Vacuum Lamp)

37090C-37120C. . .Luminous Flux Standards (60-500W, Gas Filled

Lamps)

37130C Luminous Flux Standards (Miniature Lamps)

37I40C Airway Beacon Lamps

37170C Opal Glass Luminous Directional Transmittance

Standards

371 SOS Special Photometric Tests

B. Spectrophotometric Measurements 61 38010C-38040C. . .Spectral Transmittance Filters 38050C Wavelength Standards (Holmium Oxide Glass)

38060S Special Tests of Spectral Transmittance and

Reflectance

38070M-38074M. .Measurement Assurance Program for Retroreflectance

38080M Measurement Assurance Program for Transmittance

38090S Special Tests of Photographic Step Tablets

38100S Special Tests of Microcopy Resolution Test Charts

C. Radiometric Measurements 65

39010C-39030C. . .Spectral Radiance Ribbon Filament Lamps

39040C Spectral Irradiance Quartz-Halogen Lamps

(250-1600 nm)

39050C Spectral Irradiance Deuterium Lamps

(200-350 nm)

39060C Photodiode Spectral Response Rental Package

39070S Special Tests of Radiometric Sources

xii
D. Radiometric Standards in the Ultraviolet 68

40010S Special Test, Spectral Irradiance Standard, Argon

Mini-Arc

40020S Special Test, Spectral Radiance Standard, Argon

Mini-Arc

40030S Special Test, Spectral Irradiance Standard,

Deuterium Arc Lamp

40040S Special Test, Radiometric Devices in the Near and

Vacuum Ultraviolet

E. Optical Fiber Attenuation and Bandwidth 70

41010S Special Tests for Attenuation of

Telecommunication-Grade Multimode GradedIndex Optical Fibers at 850 and 1300 nm, by

Prearrangement

41020S Special Tests for Bandwidth of

Telecommunication-Grade Multimode

Graded-Index Optical Fiber Having an Operating Wavelength of 1300 nm, by

Prearrangement

F. Laser Power and Energy 72

420 lOS Special Tests of Laser Power and Energy, by

Prearrangement

42020M-42090M . .Measurement Assurance Programs for Laser

Power, Covering Wavelengths from 514.5 nm

to 10.6 jLtm for Various Power Levels

Chapter 6—

Ionizing Radiation Measurements

A. Radioactivity Sources 77

43010C-43020C. . .Gamma-Ray-Emitting Radionuclides in Solution

43030C-43050C. . .Alpha-Particle-Emitting Solid Sources

43060S-43070S . . .Special Tests of Beta-Particle-Emitting Solution

Sources

43090S Special Tests of Alpha-Particle-Emitting Solid

Sources

B. Neutron Sources and Dosimeters 81 44010C-44020C. . .Natural Standard Neutron Sources

44030S Special Tests of Activated Foil Irradiation with

Thermal Neutrons

44040S-44070S . . .Special Tests of Neutron Dosimeters

44080C Activated Foil Irradiation, Californium

Fission Neutrons

44090C Activated Foil Irradiation, Cavity Fission Source

44100S Special Tests of Neutron Sources and Dosimeters

xiii
C. Dosimetry of X Rays, Gamma Rays, and Electrons 85

CO Special Instructions for Using Electron and Photon Dosimetry Services

C.l X-Ray and Gamma-Ray Measurements

46010C-46011C. . .Radiation Detectors—Calibration/Correction Factor

46020C-46021C. . .Passive Dosimeters

46030S Special Tests of High-Gain Electrometers—Charge

Sensitivity

46040S Special Tests of X-Ray Penetrameters,

Ardran-Crookes-Type

46050S Special Tests of X-Ray and Gamma-Ray Measuring

Instruments C.2 Gamma-Ray and Beta-Particle Sources 470 IOC Gamma-Ray Sources

47030C Beta-Particle Sources Calibrated for Surface

Dose Rate

47040S Special Tests of Gamma-Ray and

Beta-Particle Sources

C.3 Dosimetry of High-Energy Electron Beams

480 IOC Irradiation of Ferrous-Ferric Dosimeters

48020S Special Tests of Electron-Beam Dosimeters

D. Dosimetry for High-Dose Applications 90

4901 OS Special Tests of Customer-Supplied Dosimeters

Irradiated with *°Co Gamma Rays

49020S-49030S . . .Dose Interpretation of NBS-Packaged Dosimeters

Irradiated by Customer

49040S-49041S . . .Special Tests of Dosimeters By Reading with

Spectrophotometer

49050S Special Measurement Services for Dosimeter

Response

Chapter 7—

Electromagnetic Measurements

A. Resistance Measurements

A. 1 DC Resistance Standards and Measurements 93

51100S Special Resistance Measurement Services by

Prearrangement

51110M Measurement Assurance Program Services for Resistance

51130C Standard Resistor, Thomas-Type, 1 £l 51131C Standard Resistor, Evanohm Wirewound

High-Precision, 10 kfl 51132C-51138C. . .Standard Resistors, Four-Terminal, 0.0001-100 H

51139C-51154C. . .Standard Resistors, 1 kfl-1 Til

51 160C-51 163C. . .Standard Resistors, for Current Measurements

(Shunts)

xiv
A.2 High-Voltage Standard Resistors 97

5 12 IOC High Voltage Standard Resistors

A. 3 High-Frequency Standard Resistors 98

51310C High-Frequency Standard Resistors,

Two-Terminal

A. 4 Special Tests of AC Resistors 99

51410S Special Tests of AC Resistors, by Prearrangement

B. Impedance Measurements

B. 1 Low-Frequency Capacitance and Inductance Measurements and Standards 100

5211 OS Special LF Impedance Measurements by

Prearrangement

52130C Standard Fixed, Fused Silica, Dielectric Capacitor

52140C Fixed Three-Terminal Standard Capacitors with

Coaxial Connectors, High-Accuracy

52150C Physical Tests to Qualify Three-Terminal Air

Capacitors for Measurement

52160C Fixed Three-Terminal Standard Capacitors with

Coaxial Connectors

52170C Two- or Three-Terminal Solid Dielectric Standard

Capacitors

52180C Fixed Inductors, Self or Mutual

B.2 High-Frequency Standard Capacitors and Inductors 103

52210C-5221 IC. . .Two-Terminal, Low-Loss, Standard Capacitors

52220C-52221C. . .Three-Terminal, Low-Loss, Standard Capacitors

52222C-52223C. . .Three-Terminal (MacLeod and Hanopol)

Capacitors

523 lOS Two-Terminal, High-Q Standard Inductors

B.3 Power Frequency Capacitors 105

52400C Power-Frequency Capacitors

B.4 Eddy-Current Conductivity 106

52610C Eddy-Current Conductivity Standards, 15-100%

lACS

B.5 Q Standards 107

52710C-52711C. . .Inductive Q-Standards

C. Voltage Measurements

C. 1 DC Voltage Measurements and Standards 108

531 lOS Special DC Voltage Measurements, by

Prearrangement

53120M Measurement Assurance Program for DC Voltage

53130C Saturated Standard Cells

53 HOC Pt. Resistance Thermometer Temp. Determination

for Standard Cell Calibration

XV
53150C Unsaturated Standard Cells

53160C Tests of Solid-State Voltage Reference Standards

C.2 Low-Frequency AC Voltmeters and Sources 112

53200S Special Tests of Low-Frequency AC Voltmeters

and Sources, by Prearrangement

C.3 AC-DC Thermal Voltage and Current Converters (to 1 MHz) 114

533 lOS Special AC-DC Measurement Services, by

Prearrangement

53340C-53343C. . .AC-DC Thermal Voltage and Current Converters

C.4 RF-DC Thermal Voltage and Current Converters (100 Hz-1 GHz) 116

53405S Special Tests of AC Thermal Current and Voltage

Converters, by Prearrangement

53410C-53415C. . .Low-Frequency TVC Calibrations

53420C-53421C. . .High-Frequency TVC Calibrations

53430S-53431S . . .Peak-tr-Peak Detector Calibrations

53440C-53445S . . .RF Micropotentiometer Calibrations

C. 5 Data Converters 119

53500S Special Data Converter Services by

Prearrangement

53510C A/D or D/A Converters, Linearity Errors, 10-Bit

Correction Coefficients, and Superposition Errors 53520C A/D or D/A Converters, Differential Linearity Errors 53530C A/D Converter, Equivalent RMS Input Noise

53540S A/D or D/A Converters, Offset and Gain Errors

Relative to Legal Volt

D. Precision Ratio Measurements

D.l Inductive Dividers 123

5411 OS Special Ratio Measurements and Tests of Inductive

Voltage Dividers, by Prearrangement

54120C-54131C. . .Inductive Voltage Dividers

D.2 Resistive Dividers 125

542 IOC Resistor and Resistive Dividers, Total Resistance or Voltage Ratio

D.3 Capacitive Dividers 127

5431 OS Capacitive Dividers

D.4 Mixed Dividers 128

5441 OS Pulse-Voltage-Measuring Systems Including

Kerr Cells

54420S X-Ray Unit, Voltage Dividers

D.5 Voltage and Current Transformers 129

54510C-54513C Voltage Transformers, Ratio and Phase Angle

54520C-54522C Current Transformers, Ratio and Phase Angle

54600S Special Tests of Dividers and Transformers, by

Prearrangement

xvi
E. Phase Angle Measurements

E.l Phase Angle Meters 132

551 lOS Special Tests of Phase Angle Meters, by Pre- arrangement

E.2 Very-High-Frequency Omnidirectional Range (VOR) Measurements 134

55210C-55211C. . .VOR Bearing-Angle Indicators

55220C-55221C. . .VOR Generators

55230S Special VOR Tests

F. Power and Energy Measurements, Low Frequency 136

561 lOS Special Tests of AC-DC Wattmeters by

Prearrangement

56120C Wattmeter Calibrations at Power Frequencies

56200C-56203C. . .Watthour Meters, Determination of Percentage

Registration at 60 Hz

562 lOM Measurement Assurance Program for Watthour

Meters

G. RF and Microwave Measurements

G.l Power Meters, RF and Microwave 139

61110S-61128S . . .Coaxial Power Meters, Combinations of Calibration

Factor, Effective Efficiency

Factor, and Reflection Coefficient

at Specified Frequencies in Range 0. 1 MHz

to 18 GHz

61 1308-61 1 5 5S . . .Rectangular-Waveguide Power Meters,

Combinations of Effective Efficiency,

Efficiency Factor and Reflection Coefficient

within Specified Frequency Bands Covering

2.6-96 GHz

61160S Measurement of Output of Power Reference in TE

Power Meters

61190S Special Microwave and RF Power Measurement

Services by Prearrangement

G.2 Attenuators, RF and Microwave 143

61210C Coaxial Fixed and Variable Attenuators, Measured

by ANA, 0.1 to 18 GHz

61211C Coaxial Fixed and Variable Attenuators, Measured

at 30 MHz

6121 5C Waveguide Circular (Below CutofO Piston

Attenuator, Coaxial Connector, Measured at 30 MHz

61220S Special Attenuation Measurements in Range 30 kHz

to 10 MHz, GR874 Connectors

61230C Variable Rectangular Waveguide Attenuators,

Attenuation Difference, WR28-WR284

Waveguide Bands

61240S Special Attenuation Measurements of Three-Port

and Two-Port Devices at 1.25 MHz

61250S Special Attenuation Measurements by

Prearrangement

xvii
G.3 Coaxial and Waveguide Terminations, Reflection Coefficient 146

61 3 IOC Complex Reflection Coefficient, Impedance, and

Voltage Standing Wave Ratio of Coaxial

Terminations by ANA, 0. 1 to 18 GHz

61320C Magnitude of Reflection Coefficient of Rectangular

Waveguide Reflectors (Mismatches) with

Standard Flange Connectors at Frequencies

within WR15-WR284 Waveguide Bands

61330C-61331S. . .Magnitude of Reflection Coefficient of Non-Reflecting Waveguide Ports and Matched Loads at Frequencies within WR15-WR284 Waveguide

Bands

G.4 Phase Shifters, RF and Microwave 148

6 14 IOC Coaxial Fixed and Variable Phase Shifters: Char icteristic Phase Shift Difference; Precision

Connectors; Measured at 30 MHz

61411C Coaxial Fixed and Variable Phase Shifters: Characteristic Phase Shift Difference; Precision

Connectors; Measured by ANA over 1-18 GHz,

Range 0-360°

61420C Variable Rectangular Waveguide Phase Shifters: Phase Shift Difference at Frequencies within

WR62-WR284 Waveguide Bands

61450S Special Tests of Phase Shifters, by Prearrangement

G.5 N-Port Scattering Measurements 150

61520S Linear, Reciprocal 2-Port Devices, 2-18 GHz

H. Noise Temperature Measurements 152

62020S Special Noise Temperature Measurements

(Electromagnetic), by Prearrangement

62100S-621 1 IS . . .Noise Temperature of Coaxial Noise

Generators, Type N Precision or 14 mm

Connectors, at 30 MHz or 60 MHz

62120S-62121S . . .Noise Temperature of Rectangular Waveguide

Noise Sources at Specified Frequencies within

WR62 and WR90 Waveguide Bands

62130S Noise Temperature of WRIO and WR15

Waveguide Noise Generators

62140S Special Services for Earth Terminals Used in Satellite Communications

L Electromagnetic Field-Strength and Antenna Measurements

/./ Microwave Antenna Parameter Measurements 154

63100S Gain and Polarization of Standard Antennas Using

Extrapolation Range

63200S Pattern, Gain, and Polarization of Arbitrary

Antennas Using Near-Field Scanning Techniques

63300S Special Test Service for Calibration of Probes

Used with Near-Field Scanning Techniques

63400S Special Consulting, Advisory, and Other Services

xviii
1.2 Electromagnetic Field-Strength Parameter Measurements 157

641008 Special Test Services for Antennas/Field Strength

Measurements, Using Transverse Electromagnetic Cell Method

64200S Special Test Service for Antennas/Field Strength

Measurements, Utilizing the Open Field

Method

64300S Special Test Service for Antennas/FieldStrength/Reflectivity Measurements, Utilizing

the Anechoic-Chamber Method

64400S Special Test Services for Electromagnetic

Interference

J. Pulse Waveform Measurements 159

65100S Impulse Generator Spectrum Amplitude (50 Ohm)

65200S Fast Repetitive Baseband Pulse Parameters

(50 Ohm)

65300S-63301S . . .Network Impulse Response of Coaxial Networks,

10 MHz to 10.0 GHz

65400S Pulse Time Delay Through Coaxial Transmission

Lines

Chapter 8—

Time and Frequency Measurements

A. Time and Frequency Dissemination 165

76100S Special Frequency Measurement Service

76110S Special Global Time Service

B. Oscillator Characterization 167

7710OC Precision Oscillator Frequency Calibration

771 IOC Characterization of Atomic Time and Frequency

Standards

77120C-77130C. . .Characterization of Precision Oscillators: Time

and Frequency Domain

77140S Special Time/Frequency Measurements

Addendum—Numerical Cross-Index

(Old vs. New Test Numbers) no

Alphabetical Cross-Index

178

xix
Chapter

A Introduction

B Questions and Inquiries

C Fees D Types of Services

E Criteria F Reports of Test Results G References to NBS in Advertisements

H Traceability

/ Disclaimer

J Ordering and Scheduling

K Purchase Order

L Shipping

M Special Instructions for Foreign

Customers
Policies

Introduction

The physical measurement services of

the National Bureau of Standards are designed to help the makers and users of precision instruments achieve the

highest possible levels of measure- ment quality and productivity. The

hundreds of individual services you

will find listed and described in this Users Guide constitute the highestorder calibration services available in the United States. They directly link a customer's precision equipment or

transfer standards to national measurement standards. These services are offered to public and private or- ganizations and individuals alike.

Questions and Inquiries

This Users Guide is designed to make

the task of selecting and ordering an

appropriate calibration service as quick and easy as possible. Nevertheless, questions will arise. When

they do, we urge you to call or write

for immediate clarification. Address

general questions and lengthy in- quiries to: Ernest Garner, Chief

Office of Physical Measurement

Services

National Bureau of Standards

Physics Building B362

Gaithersburg, MD 20899

(301) 921-2805.

If you have a technical question

concerning a specific service, contact

directly one of the NBS staff members responsible for that calibration

area. Consult the section of this guide

that describes the service in question

for names and addresses.

Fees

NBS recovers the cost of providing

calibration services by charging a fee for each calibration performed. These

fees range from a low of less than

$100 for calibration of a laboratory

thermometer to $50,000 or more for special tests of large microwave an- tenna systems.

PLEASE NOTE: The costs of ser- vices are not stated in this Users Guide. Instead, they are listed in a separate Fee Schedule, which is up- dated twice yearly to reflect changes

in prices and services. Request a free copy of the current Fee Schedule by

writing or calling the Office of Physical Measurement Services (see above

address) or the

Program Information Office

National Bureau of Standards

Boulder, CO 80303

(303) 497-3239.

Types of Services

You will find three types of physical

measurement services described in this guide: Calibration Services,

Special Tests, and Measurement

Assurance Programs.

Calibrations and Special Tests generally designate those NBS services

that check, adjust, or characterize

particular instruments, devices, and

sets of standards on a one-time-perrequest basis. The customer, in most

cases, ships an item requiring cali- bration to the appropriate NBS labo- ratory in Gaithersburg, MD, or Boulder, CO, as noted in this Users

Guide and in the separate Fee Schedule. The calibrated item is shipped

back to the customer, followed, under

separate cover, by a report of test procedures and results. Measurement Assurance Programs,

or MAPs, are quality control pro- grams for calibrating a customer's entire measurement system. In a typical

MAP, a stable artifact or set of

artifacts—called transfer standards

are first measured by NBS and sent to

1
a customer's laboratory for a series of

measurements. The transfer standards

are then returned to NBS for re- measurement, along with the participating laboratory's results. The

Bureau reports its comparative find- ings to the customer and, when necessary, offers guidance on how to achieve and maintain measurement

quality.

Successful use of an NBS MAP re- quires that the customer make periodic measurements of in-house check

standards to estimate the random er- ror and to ensure that the measure- ment process remains in a state of

statistical control. Unless a laboratory

has a measurement quality control

program to continously monitor its own measurement process parameters, there is little point in participating in a MAP.

PLEASE NOTE: NBS does not audit, regulate, or accredit metrology

laboratories as part of the MAP ser- vice. Whatever steps a participating

laboratory may take to improve its measurement process are undertaken

voluntarily.

E, Criteria

All the measurement services described in this guide meet rigorous

criteria for quality assurance. Calibration Services and MAPs satisfy the

most demanding and explicit requirements in that these services are carried out regularly under pre-established and well-defined conditions;

the measurement processes in- volved are well-characterized, stable,

and statistically controlled; and

quality-control procedures are welldefined and strictly followed. Fur- thermore, each Calibration Service or MAP is planned and documented to permit continuity of service over

time. A Special Test is so designated

for one or more of the following reasons: 1) the specific type of cali- bration is seldom requested, thus pre- cluding the maintenance of a reliable

statistical base for controlling the

measurement process, 2) the test re- quested is unique, or 3) the service is

still under development—meaning the

measurement or calibration methods

are still being perfected or all the

quality-control documentation has yet

to be completed.

F. Reports of Test Results

Reports on calibrations or other ser- vices are regarded as the property

of the customer. Copies are not supplied to other parties except as re- quired by federal law or requested in writing by the customer. The results of calibrations and tests performed by

NBS apply only to a particular instru- ment or standard at the time of test unless otherwise clearly stated.

G. References to NBS in

Advertisements

NBS test results or reports shall not be used to indicate or imply that the

National Bureau of Standards ap- proves, recommends, or endorses the

manufacturer, supplier, or user of any

instruments or standards or that NBS

in any way guarantees or predicts the

future performance of items after cali- bration or test. No reference shall be

made to NBS or to reports or results furnished by NBS in any advertising or sales promotions which would in- dicate or imply that NBS approves,

recommends, or endorses any proprietary product or proprietary material.

H. Traceability

Traceability is a term often used to designate a relationship between field measurements or instruments and

2
NBS measurements or national stan- dards. NBS does not define, deter- mine, regulate, or require traceability.

Moreover, the Bureau is not legally

required to comply with traceability

requirements of other federal agencies; nor do we state what must be

done to comply with another party's contract or regulation calling for such

traceability. However, NBS can and

does provide technical advice on how

to make measurements consistent

with national standards.

j Disclaimer

Commercial products—materials and

instruments—are identified in this document for the sole purpose of adequately describing experimental or

test procedures. In no event does

such identification imply recommendation or endorsement by the National Bureau of Standards of a particular product; nor does it imply that a named material or instrument is necessarily the best available for the

purpose it serves.

Ordering and Scheduling

Services are best arranged in ad- vance, beginning with a call or letter from the customer to an NBS staff member directly responsible for the

desired service. See the appropriate

technical section of this Users Guide

or the separate Fee Schedule to determine whom to call or write. This

advance communication can clear up

any questions you may have, clarify

the policies and procedures briefly

described here, and permit you to tentatively schedule a calibration

date. Following the initial communication, you will immediately need

to fill out and send in a purchase or- der and prepare and ship the item ac- cording to the procedures described

below. If a calibration must be scheduled far in advance, you may arrange

to delay shipment of the item until shortly before the scheduled date; you must however, submit the pur- chase order—complete with the name

and number of the desired service

before a firm calibration date can be

assigned. When NBS receives your

valid purchase order and assigns a firm service date, you will be notified

by mail to confirm the order.

PLEASE NOTE: Normal

turnaround time for NBS calibration

services varies greatly—from one week to three months—depending on

the type of service requested and

fluctuations in workload. Query and

schedule in advance to avoid

unnecessary delays.

Purchase Order

Send a purchase order to the address

listed in the appropriate technical sec- tion of this Users Guide, or in the

separate Fee Schedule, before you

ship an item for calibration. The pur- chase order must:

1) State both the name and number of the NBS service being

requested. FAILURE TO IN- CLUDE THE ORDER NUMBER WILL SERIOUSLY IMPEDE SCHEDULING AND

SERVICE.

2) Clearly identify the item(s) be- ing sent for calibration, including any serial number.

3) Give the name, address, and

telephone number of the re- questing company's pro- curement officer. 4) Give the name, address, and

telephone number of the re- questing company's technical

contact, if different from

above.

5) List separately the instructions

for return shipment, insurance,

mailing of the test report, and

billing. (Federal or state agency

requests for calibration services

should be accompanied by a document authorizing that the
cost of the service be billed to the agency.)

6) Clearly state any special or necessary conditions of test

such as operating frequency or temperature.

PLEASE NOTE: Receipt of orders

by NBS does not imply acceptance of

any provisions set forth in the order

that are contrary to the policy, practice, or regulations of the National

Bureau of Standards or the U.S. government. In general, NBS will not

sign any affidavits, acknowledgement

forms, or other documents that may

be required by company policy governing the procurement of goods and

services.

Shipping

Ship an instrument or standard to the

address to which you mailed your

purchase order. Adhere rigorously to the following procedures:

1) Ship only items in good repair.

Apparatus in disrepair will not be calibrated. If defects are found after calibration has be- gun, the procedure will be ter- minated, a report issued, and a charge levied for work completed.

2) Use strong, reusable packing

materials and containers

marked clearly and indelibly on

the outside with the requestor's name and address and the fol- lowing notation: REUSABLE

CONTAINER, DO NOT DESTROY.

3) Follow any special shipping

procedures given in the technical sections of this guide, in particular those sections covering radiation and dosimetry

measurements.

4) Insure the shipments to and

from NBS and clearly state the

method of return shipment.

NBS will not assume liability for loss or damage unless such

loss and damage result solely

from the negligence of NBS

personnel. If return shipment

by parcel post is requested or is suitable, NBS will prepay the return shipment but will not in- sure it. When no shipping or

insurance instructions are fur- nished, NBS will return the

shipment by common carrier, collect and uninsured.

PLEASE NOTE: Fees for NBS

services do not include shipping

costs. MSpecial Instructions for

r Foreign Customers

The National Bureau of Standards is authorized to provide measurement

services, including calibrations, for organizations or individuals located

outside the United States. NBS policy

requires a thorough review of each

request to determine if a comparable

service is available in the requestor's

country. Foreign customers must,

therefore, provide the following in- formation to the Office of Physical

Measurement Services (see address

under Section B):

1) If a national or official stan- dards laboratory in the country

of the requesting organization

is available and provides identi- cal or similar service to that re- quested from NBS, state why

NBS should provide the

service.

2) Provide a detailed description

of the instrument or standard

to be tested, particularly if it is not manufactured in the United

States.

3) Provide a detailed description

of the measurements that are needed or indicate the test or- der number as contained in this Users Guide or in the separate

Fee Schedule.

4) Provide a description of any

special requirements that might

affect the decision to provide

the service. For example, will there be a need for special ad4
justments, or will the length of

time in which the device is available for measurement be

restricted?

If the request for the measurement

service is accepted by NBS, the re- questing organization will be notified

of the cost of service and will be

given the identification of the NBS

laboratory that will perform the measurements. The requesting organization must then complete the following

steps:

1) Contact the NBS technical unit that will provide the service to determine the schedule.

2) Send a purchase order to the

Office of Physical Measurement Services. Complete addresses should be provided for returning the instrument and

for mailing the calibration or

test report. Send a check payable in U.S. dollars to the Office of Physical Measurement

Services for the full cost of the

service. The check must be

drawn on a U.S. bank. NBS

cannot begin the service until

full payment has been received.

3) Ship the instrument or standard

to the appropriate NBS technical unit. Air freight is most

satisfactory. You must pre- arrange shipment with a cus- toms broker for entry of the in- strument into the United States with prepaid transportation

from the port of entry. Entry

bond is required for instru- ments not manufactured in the

United States. If arrangements

are made with a broker in the

country of origin, that broker

should, in turn, have a U.S. customs broker in or near the

port of entry who will arrange

for the entry of the instrument

and its transportation to NBS.

Direct arrangements can be

made with customs brokers lo- cated in the Washington, DC/

Baltimore, Maryland metropolitan area or in the

Denver, Colorado, area, as appropriate. These brokers can

also arrange for transportation

to the port of exit after NBS

has completed the tests.

Members of the Measurement Services staff, clockwise from upper left: Joanne Marshall, computer

assistant; George Uriano, director. Measurement Services; Treva Siedling, administrative officer; Vickie Weedon, calibration assistant; Ernest Garner, chief, Office of Physical Measurement Services; Verna Moore and Margaret Mustek, secretaries.

5
Chapter

A Length Measurements

B Diameter Measurements

C Complex Dimensional Standards

D Optical Reference Planes &

Roundness Standards

E Angular Measurements

F Surface Texture G Hydrometers

H Volume and Density
Dimensional Measurements 10010C-10070M

Length Measurements

m Precision Engineering Division

Center for Manufacturing Engineering

Technical Contacts:

Theodore D. Grace Chaconas Linda Peake Ronald

Doiron lOOlOC lOOlOC Hartsock

10020C, Tel: 301/921-2216 Tel: 301/921-2216 10030C-10040C 10050S-10070M Tel: 301/921-2216

Tel: 301/921-2216

Mailing Address: A107 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items

100 IOC Gage Blocks

10020C Line Standards

10030C Surveying and Oil Gaging Tapes

10040S Special Tests of Surveying Leveling Rods

10050S Special Tests of Length Standards

10060S Special Tests of Sieves

10070M Measurement Assurance Program for Gage Blocks

Gage Blocks (lOOlOC)

This calibration service provides for measurement of the length of gage

blocks by either comparison to NBS

master gage blocks or by direct inter- ferometry. Generally, the length is transferred from known master blocks

by a systematic intercomparison pro- cedure using mechanical comparators.

Comparators with laser scales are also

available. All gage blocks submitted for test should be in substantially new block

condition and each block should be

marked with an identification number.

In shipping gage blocks, extreme care should be taken against both corrosion and damage by contact with

other gage blocks. All defining steel surfaces should be greased and blocks

padded with waxed paper or volatile

rust inhibitor treated paper. A

greased steel surface coming in contact with newspaper, wrapping paper

(unwaxed), or excelsior is likely to corrode. Sets of gage blocks should

have packing inside the case and the case should be bound shut, as the

clasps frequently open or break during shipment.

Square or rectangular blocks or

lengths up to 20 inches are routinely

calibrated and the lengths reported in English or metric units. For blocks

longer than 20 inches, the NBS technical contact should be consulted in advance to discuss alternative measurement techniques, approximate

costs, and scheduling.

The measurement uncertainty re- ported is the sum of the random error

in the measurement of the block un- der test and the estimated systematic

error in the measurement process. The process used to estimate this sys- tematic error is documented in publications referenced in this catalog. Although the uncertainty varies slightly

with each measurement, the variation

is usually small. A reasonable estimate

for the accuracy of the calibration is 2 microinches (0.05 micrometer) for blocks under 2 inches, and with accu- racy decreasing with length to 20 microinches for the 20-inch blocks.

Line Standards (10020C)

Line standards of 1 meter or less are measured on an instrument called a

line scale interferometer which is used to measure the distance between

suitable lines on a flat surface. The in- strument employs a fixed photoelectric microscope to determine the

position of the scale lines, a linearly

mobile carriage in the focal plane of

the microscope to carry the scales,

two interferometers (one commercial

unit and one NBS-made Michelson)

that can be used separately or in tan- dem to measure carriage displacement, and a temperature-controlled

housing enclosing the whole apparatus.The system is now highly auto- mated using a laboratory micro7
computer, NBS-developed optical

processing, and servo electronics.

With the microscope focused on the

scale zero line, a servo moves the car- riage until a null signal indicates the

line is centered in the microscopic

field. A stepping motor then drives

the carriage until the next line on the

scale is reached. Servoed line center- ing again takes place. The carriage is now moved precisely the distance between scale lines and the inter- ferometer has now measured this dis- tance in laser light wavelengths.

Proceeding down the scale in this manner results in the measurement of

the line spacings.

The maximum length of line stan- dards that can be measured is 1 meter, and the maximum width of any

part of the piece being calibrated can- not exceed 150 millimeters. The accu- racy of the calibration depends significantly on the shape and optical

properties of the line, the background, and the geometric flatness of

the artifact being calibrated. If the

lines have straight edges, are 2 to 10 micrometers wide, there is good contrast between the line and the background, and the reference surface of

the artifact is flat, then the accuracy

of the calibration will be near opti- mum. Uncertainties as low as 0.006

micrometer have been achieved on

short intervals and on 1 -meter lengths

uncertainties of 0. 1 micrometer can be

achieved. The current overall system

accuracy is limited by imprecise

knowledge of the refractive index of

air. Surveying and Oil Gaging Tapes

(10030C)

The calibration of surveying tapes

and oil gaging tapes is carried out in a laboratory that houses two permanent

working standards, a laser inter- ferometer and a 50-meter (200-foot)

stainless steel bench. Measurements

are performed for the most part using

a laser system that is referenced

against a cube-corner rectroreflector

attached to a microscope which is used manually for line location. The

laboratory is maintained at 20 °C, but

a control system can vary the chamber temperature from 15 to 40 °C for special tests. Calibration of tapes will normally be made with the tape un- der tension and supported on a

horizontal-flat surface. Unless otherwise requested, the total length and

each 15-meter or 50-foot subinterval

will be measured and reported. Each

interval calibrated on a surveying

tape will have computed lengths for two (single catenary), three, four, and

five equidistant points of support.

The laser standard is capable of cal- ibrating tapes with scribed graduations to an accuracy of 2 parts per

million (ppm). Calibrations made with

respect to the stainless steel tape

bench are normally reported to an ac- curacy of 10 ppm. An NBS serial number will be engraved on each cal- ibrated tape for identification. Figure 1 summarizes the accuracy

of length measurements at NBS. In- cluded are the NBS 5-meter bar, gage

Figure 1. Accuracy of Length Measurements at NBS

I 1 I I 1 I I I I I I 10"''10"M0^'^10"^10~''10~^10~^10"'10° 10' 10' 10' 10'

Length, inch

I I I I I I I I I I I i_

10"'10"''10"'10"^10'^10^'*10"'10^'10"M0° 10' 10'

Length, meter

8
10010C-10070M

block calibrations, end line standards,

and geodetic/steel tapes.

Special Tests of Surveying Leveling

Rods (10040S)

Leveling rods are currently calibrated

using two methods. One method in- volves the comparison of the rod to a 3-meter standard at the 1-, 2-, and

3-meter intervals. A second system

provides measurement at multiple in- tervals and automatic report generation. This automated system incorporates a 7-meter one-dimensional

measuring machine, a motorized carriage, a photoelectric microscope and

a helium-neon laser interferometer in- terfaced to a minicomputer. Measurements can be made on virtually

any type of linear scale or leveling

rod with scribed, engraved, or

painted graduations. The random er- ror of measuring high quality leveling

rods is plus or minus 6 micrometers

for new rods and plus or minus 12 micrometers for used rods at the one

standard deviation level. The systematic errors are largely unevaluated,

and to account for their existence the

total error being reported by NBS at present is plus or minus 50 micrometers for new rods. The length of inter- vals will be reported as measured at 20 °C unless otherwise requested. The

report can be supplied in either writ- ten or computer-readable form.

Special Tests of Length Standards

(10050S)

Includes linear thermal expansion of

gage blocks and line scales and radius

of gage-block comparator stylus tips.

Special Tests of Sieves (10060S)

To determine conformity to ASTM

Ell specifications.

Measurement Assurance Program for Gage Blocks (10070M)

The Measurement Assurance Pro- gram (MAP) for gage blocks is in- tended for laboratories that need to document, on a continuing basis, the

measurement uncertainty of their gage block calibration process. Check

standards, redundant measurements,

and statistical analyses form the basis for monitoring the in-house cali- bration process. Offset from the defined unit of length is determined

from the participant's measurements on transfer standards from NBS. Two

eighty-eight piece sets of steel gage

blocks, spanning the range from 0.100

to 4.0 inches, are available as transfer standards. Metric transfer standard

sets are also available. Detailed in- structions for participating in the pro- gram under three different options are provided in NBS Monograph 163. The three options allow for varying

degrees of rigor in operating a MAP,

and the choice of option depends on a number of factors including: 1. availability of master standards; 2. availability of time to operate the pro- gram; 3. equipment; and 4. accuracy

requirements. In principle, the participant can choose to operate the

MAP using any of the three options,

but only the second option is fully

supported by NBS. The three options

are briefly discussed below.

Option 1 is best suited for inter- ferometric measurement processes. One master set of steel blocks and 10

steel check standard blocks are pro- vided by the participant. The process

is monitored through the inclusion of

check standards in the calibration

workload at roughly equal size intervals. Transfer standards of the same

nominal size as the check standards

are provided by NBS. The analysis of

data is the responsibility of the participant.

Option 2 is intended for electro- mechanical comparators or inter- ferometers used as comparators. Two

9
master sets of steel gage blocks pro- vided by the participant are required.

Duplicate measurements are achieved

by comparing each test block with

each master block, and process control is maintained on the difference in observed length between master

blocks of the same nominal size. Two

sets of transfer standards are fur- nished by NBS, and complete data

analysis along with a report of test is also furnished.

Option 3 is intended for electro- mechanical comparators. Two master

sets of steel gage blocks provided by

the participant are required. Option 3

is a more complicated procedure than

Option 2 as it involves comparisons

among two test blocks and two master blocks of the same nominal size. Process control is maintained on the

difference in length between two

master blocks of the same nominal

size as calculated from the design.

Control is also maintained on process

variability as computed from each set of intercomparisons. Two sets of

transfer standards are furnished by

NBS. Data analysis is the re- sponsibility of the participant.

The purpose of the MAP is to maintain a continuous check on the

state of the calibration process

thereby guaranteeing that measurements are properly related to the

defined unit of length within the

stated uncertainty. This process implies that the daily calibration pro- cedure is identical to the MAP pro- cedure. Because considerable time

and effort may be required to implement a transition from single measurements to a MAP procedure and

to establish the database for the pro- gram, the prospective participant is

urged to weigh potential benefits of

the program against the investment of

time and effort before committing to

it.

References—Length Measurements

Interferometric Measurement of

Length Scales at the National Bureau

of Standards, J. S. Beers and K. B. Lee, Prec. Eng., 4, No. 4, 205 (Oct.

1982).

Measurement Assurance for Gage

Blocks, C. Croarkin, J. Beers, and C. Tucker, Natl. Bur. Stand. (U.S.),

Monogr. 163 (Feb. 1979).

Contact Deformation of Gage Block

Comparisons, J. S. Beers and J. E. Taylor, Natl. Bur. Stand. (U.S.),

Tech. Note 962 (May 1978).

Intercomparison Procedures for Gage

Blocks Using Electromechanical

Comparators, J. S. Beers and C. D.

Tucker, Natl. Bur. Stand. (U.S.), Int. Report, NBSIR 76-979 (Jan. 1976).

A Gage Block Measurement Process Using Single Wavelength Inter- ferometry, J. S. Beers, Natl. Bur. Stand. (U.S.), Monogr. 152 (Dec.

1975).

Measurement Assurance Program—

A

Case Study: Length Measurements.

Part 1 . Long Gage Blocks (5 in to 20

in), P. E. Pontius, Natl. Bur. Stand.

(U.S.), Mongr. 149 (Nov. 1975).

Preparations for Gage Block Comparison Measurements, C. D. Tucker,

Natl. Bur. Stand. (U.S.), Int. Report,

NBSIR 74-523 (July 1974).

Gage Block Flatness and Parallelism

Measurement, J. S. Beers and C. D.

Tucker, Natl. Bur. Stand. (U.S.), Int. Report, NBSIR 73-239 (Aug. 1973).

An Automatic Fringe Counting Inter- ferometer for Use in the Calibration

of Line Scales, H. D. Cook and L. A.

Marzetta, J. Res. Natl. Bur. Stand.

(U.S.), 65C, 129 (1961).

10
^

Diameter Measurements

w Precision Engineering Division

Center for Manufacturing Engineering

Technical Contacts:

William H. Jay H. Grace Chaconas

Gallagher, Jr. Zimmerman 11060S

IIOIOS, 11030C- 11020Cand Tel: 301/921-2216

11050S, 11070S 11080S

Tel: 301/921-2216 Tel: 301/921-2216

Mailing Address: A107 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items IIOIOS Special Tests for Plug Gages: External Diameter

Standards

1 1020C Measuring Wires for Threads and Gears 11030S Spherical Diameter Standards: Balls

11 040 S Special Tests for Internal Diameter Standards: Ring

Gages

1 1050S Special Tests of Length / Diameter

11060S Special Tests of End Standards

1 1070S Special Tests of Step Gages

11080S Special Tests of Thread Measuring Wires

General Information

For controlling dimensions in the

manufacture of all products, various

types of dimensional gages are used. The variety of such gages measured

includes cylindrical plug gages, ring gages, balls for diameter, and screw

thread gages. The diameter standards

and gages, with the exception of

thread and gear measuring wires, are

in general intended to be used as comparison masters.

Special Tests for Plug Gages: External

Diameter Standards (IIOIOS)

NBS will provide calibrations of external diameter standards by special

arrangement. Please consult with the technical contact listed above.

Measuring Wires for Threads and

Gears (11020C)

This service provides for measurement of the diameter of thread

and gear measuring wires by inter- comparison to NBS Master wires.

The diameter is transferred from

known Master wires using a systematized intercomparison sequence with

a mechanical comparator.

All measuring wires submitted for

test should be in substantially new

condition, each wire should be appropriately bottled, and the bottle should

be labeled with an identification number. In shipping thread wires, extreme

care should be taken to prevent corrosion; all wires should be properly

greased and their bottles rigidly contained inside an appropriate packing

case. Thread measuring wires for 60-degree and 29-degree threads are

tested for compliance with the latest specifications in commercial use. These wires, which are supplied in 3-wire sets, are calibrated and the

pitch diameter correction factor is computed for the average diameter

for three wires in the set. Gear measuring wires in the 1.92"/P, 1.728"/?,

1.68"/P, and 1.44"/P series supplied

in sets of two wires are tested for compliance with the latest specifications in commercial use and the mean

diameter reported. Accuracies are re- ported to a 3-sigma confidence level of 10 microinches for English wires

and 0.25 micrometer for metric wires.

Special Tests for Spherical Diameter

Standards: Balls (11030S)

Balls used in precision bearings and

master balls used as transfer diameter

1 1
standards are calibrated according to current commercial practice. The ball diameters reported are the un- deformed sizes as calculated with the

Hertz relations to maintain a consistency in reported sizes. Internal Diameter Standards: Ring

Gages (11040S)

NBS will provide calibrations of ring

gages by special arrangement. Please

consult with the technical contact

listed above.

Special Tests of Length and Diameter

(11050S)

NBS has a wide variety of state-of- the-art metrology equipment and can

provide services associated with di- mensional quality control as special

tests. A three-dimensional measuring

machine is available for calibration of

two- and three-dimensional ball

plates, two-dimensional grid plates,

and other artifacts of complex shape.

The machine has a working volume

of 48x24x12 inches and can detect a length difference of 0.013 micrometer

Reference to the international stan- dard of length is through inter- ferometers. Uncertainties in the cali- brations are variable. Spherical

diameter standards, such as balls used

in precision bearings and master balls used as transfer diameter standards, are calibrated using a laser-based mechanical comparator.

Special Tests of End Standards

(11060S)

Standards up to 20 feet in length,

having spherical, flat or pointed ends

can be measured; lengths are reported

with a 2.5 lb. measuring force unless

otherwise requested.

Special Tests of Step Gages (11070S)

Step gages having flat parallel faces can be measured in lengths up to one

meter.

Special Tests of Thread Measuring

Wires (11080S)

Wires for unusual thread sizes and for threads finer than 80 tpi are measured

in a manner consistent with current commercial practice.

References—Diameter Measurements

Federal Standard H-28, Screw

Thread Standards for Federal Services. English and metric versions.

These handbooks are available from

the General Services Administration

(GSA).

American National Standard B1.2,

Amer. Natl. Stand. Inst., New York.

Designs for the Calibration of Small

Groups of Standards in the Presence

of Instrumental Drift, J. M. Cameron

and G. E. Hieles, Natl. Bur. Stand.

(U.S.), Tech. Note 844 (Aug. 1974).

On the Measurement of Thread Measuring Wires, B. N. Norden, Natl. Bur. Stand. (U.S.), Report 10987 (Jan.

1973).

Measurements of Cylindrical Standards, R. C. Veale, Natl. Bur. Stand.

(U.S.), Int. Report, NBSIR 73-136

(1973).

On the Comparison of Cylinder in Contact with a Plane Surface, B. Norden, Natl. Bur. Stand. (U.S.), Int. Report, NBSIR 73-243 (1973).

1 2
12010C-12070S

C Complex Dimensional Standards

w Precision Engineering Division

Center for Manufacturing Engineering

Technical Contacts:

Edgar G. Erber William H. Ronald HarUock

12010C and Gallagher.Jr. 12060S 12070S 12020S-12050S Tel: 301/921-2216

Tel: 301/921-2216 Tel: 301/921-2216

Mailing Address: A107 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items 12010C API Threaded Plug and Ring Gages

12020S Special Tests of Plain Conical Plug and Ring Gages

12030S Special Tests of Threaded Plug and Ring Gages

12040S Special Tests of Calipers and Gages

12050S Special Tests of Micrometer Screws and Dial Micrometers

12060S Special Tests of Penetration Needles

12070S Special Tests of Two-Dimensional Gages

API Threaded Plug and Ring Gages

(12010C)

NBS provides calibration and certifi- cation services for API threaded plug

and ring gages, casing, tubing and

line pipe plug and ring gages as well

as sucker rod gages. NBS is the cus- todian of the American Petroleum Institute (API) Grand Master rotary

thread gages. These Grand Master

gages are maintained and have been

recalibrated at NBS for more than 40

years. They can be considered an in- ternational standard since all API Regional Master Gages throughout the

world are referenced to NBS. Foreign product manufacturers can have

their Reference Master Gages cali- brated and certified by NBS or by

one of the other national standard

laboratories listed below:

National Physical Laboratory,

Teddington, England

National Research Laboratory of

Metrology, Tokyo, Japan

National Standards Laboratory,

Chippendale, N.S.W., Australia

Physikalisch Technische Bundesanstalt, Braunschweig, Germany

Laboratoire National d'Essais, Paris

France

Instituto Nacional de Technologia

Industrial, San Martin, Argentina

As required, the API lab is temperature-controlled at 20 °C. Pa- rameters measured for plug gages are: length of plug, taper, pitch diameter,

major diameter, thread lead, lead and

following thread half-angles, and

depth of thread, pitch line width, and

radius of curvature. Parameters measured for ring gages

are: length of ring, taper, thread lead,

minor diameter, lead and following

thread half-angles, counter bore.

Brian Scace, calibrating American Petroleum Institute gage.

depth of thread, pitch line width,

radius of curvature, and standoff. These calibrations are based on a

three standard deviation confidence

level and are accurate to plus or mi- nus 0.0003 inch.

All gages received must be marked

with the API monogram and the API

registration number. If not so marked

13
the gages will be returned to the cus- tomer uncalibrated. Gages which

meet the specifications will be marked

as specified in the API Standards. All

thread gages must be submitted in sets of plug and ring. The name of

the gage owner should be given for inclusion in the Report of Calibration.

Special Tests of Plain Conical Plug

and Ring Gages (12020S)

NBS will provide special tests of

plain conical plug and ring gages by

special arrangement. Please consult

the technical contact listed above.

Special Tests of Threaded Plug and

Ring Gages (12030S)

NBS will provide special tests of

threaded plug and ring gages. Please

consult the technical contact listed above.

Special Tests of Calipers and Gages

(12040S)

Vernier calipers and similar gages can

be accepted for test. Special Tests of Micrometer Screws

and Dial Micrometers (12050S)

Standard procedures using gage

blocks for calibration of micrometers

are available in many standard documents such as U.S. Standard GGG-C1056. If necessary, however, NBS can

provide special tests on micrometer

screws and dial micrometers on re- quest.

Special Tests of Penetration Needles

(12060S)

Needles and cones are tested for compliance with ASTM specifications.

All devices must have individual

identification numbers.

Special Tests of Two-Dimensional

Gages (12070S)

NBS can provide special tests of twodimensional gages, ball plates or grid

plates, with dimensions up to 24

inches by 24 inches. The accuracy of

such calibrations depends substantially on the quality of the gage, but

accuracies of one micrometer or better are obtainable.

References—Complex Dimensional

Standards

On Characterizing Measuring Machine Geometry, R. J. Hocken and B. R. Borchardt, Natl. Bur. Stand.

(U.S.), Int. Report, NBSIR 79-1752

(1979).

Three-Dimensional Metrology, R. Hocken, J. Simpson, et al.. Annals of

the CIRP, 26-1 (1977).

Unified Three-Dimensional

Program—Two Useful NonContacting Probes, J. A. Simpson,

Natl. Bur. Stand. (U.S.), Report

10597 (1971).

1 4
Optical Reference Planes &

l^m Roundness Standards

Precision Engineering Division

Center for Manufacturing Engineering

Technical Contact:

Jay H. Zimmerman

Tel: 301/921-2216

Mailing Address: A107 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items 13010S Special Tests of Optical Reference Planes (Flats)

1 3020S Special Tests of Roundness

13030S Special Tests of Roundness Calibration Specimens

Special Tests of Optical Reference

Planes (13010S)

Optical reference planes are tested in- terferometrically, horizontally sup- ported with test surface supported on

three equally spaced pads located at 0.7 of the radius from the center. The

measurement is performed along two

marked diameters at 90° to each other

on each surface when each diameter

is parallel to two of the support pads.

Roundness Calibration Specimens and

Measurements; Special Tests of

Roundness (13020S and 13030S)

The deviation from roundness at eight or more positions around nominally round standards is determined.

The size of the calibration step or deviation from roundness on calibration

standards is determined. The departure from roundness of components and gages is measured and

the results are reported in graphical

form.

NBS will provide special tests of

roundness calibration specimens by

request. Consult with technical contact listed above.

References—Optical Reference Planes

The Calibration of an Optical Flat by

Interferometric Comparison to a Master Optical Flat, C. P. Reeve, Natl. Bur. Stand. (U.S.), Int. Report,

NBSIR 75-975 (Dec. 1975).

A Survey of the Stability of Optical

Flats, C. P. Reeve and R. C. Veale,

Natl. Bur. Stand. (U.S.), Int. Report,

NBSIR 73-232 (June 1973).

15
14010C-14060S

E Angular Measurements

r Precision Engineering Division

Center for Manufacturing Engineering

Technical Contact:

William H.

Gallagher, Jr. Tel: 301/921-2216

Mailing Address: A107 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items 14010C Angle Gage Blocks

14020S Special Tests of Optical Polygons

14030S Special Tests of Rotary and Indexing Tables

14040S Special Tests of Wedges

14050S Special Tests of Autocollimators

14060S Special Tests of Angle Generators

Angle Gage Blocks (14010C)

This service provides for the measurement of the angle of angle gage

blocks by direct comparison to NBS

master angle blocks using a dualautocollimator system. Current auto- collimators have resolution to 0.01 arc-second and electronic readout.

The blocks are enclosed in a special

chamber during intercomparison to minimize air currents, and the laboratory is maintained at 20 °C to within

plus or minus 0. 1 degree.

All angle gage blocks submitted for

test should be in substantially new

block condition and each block

should be marked with an identi- fication number. In shipping angle

blocks the same care as is exercised in gage block shipment should be used,

as the surfaces are subject to corrosion. All standard sizes of angle blocks can be calibrated in the NBS facilities. Blocks with angles ranging from

1 arc-second to 45 degrees are routinely handled; however, optical

squares and other standards can also be accommodated. Accuracy at the

3-sigma level is approximately 0.

arc-second; this value, however, varies with the condition of the gaging

surface on the standard.

Special Tests of Optical Polygons

(14020S)

The calibration of polygons is done

with autocollimation techniques. It consists of the determination of flat- ness of each face, variation of the angle between each face and the base

16
14010C-14060S

(where possible the polygon will be

adjusted for minimum variation), and

the angle between faces. Figure 2 summarizes the precision of angle cal- ibration for master angle gage blocks

and polygons.

Special Tests of Rotary and Indexing

Tables (14030S)

Instruments and tools used for the

precise measurement of angle, such as precision angular rotary and indexing

tables, autocollimating telescopes, or angle generating equipment, are cali- brated at specific angular settings.

Special Tests of Wedges (14040S)

Solid angle calipers and step mirrors

are calibrated by autocoUimation or

interferometric techniques as to the

angle between faces. Wedges are cali- brated by autocollimating or inter- ferometric techniques at a specified

wavelength for deviation angle. Mechanical angular references such as

Figure 2. Precision of Angle Calibrations for Master

Angle Gage Blocl<s and Polygons

10'

10"|-

10'

10'

10^

10^

10

1

Angular Measurement by

Direct Interferometry ^

Angle Gage Blocks by

Angular Subdivision ^

Polygons by Complete c, ^

Circular Closure ^ C'SP V- "

" w

"

c 12 10654

1= " 5^ 9, 45° 24

Direction of Constant

Angular Error Lines

I

. i I I. U.I ,_L. 10" 10"^ 10"

'Based on 3 standard

deviations. Systematic

errors may be of the same order of magni- tude as the precision

of detemnination10"

Degrees

1 2 3 5 10 20 50100

2 5 20 50 2 5 10 20 50

Seconds Minutes

cylindrical squares and machinist's squares are usually calibrated by mechanical techniques.

Special Tests of Autocollimators

(14050S)

Special tests of autocollimating tele- scopes may be made by special ar- rangement. Please consult the technical contact listed above.

Special Tests of Angle Generators

(14060S)

Precision equipment, including trans- ducers, are measured at specific angular settings.

References—Angular Measurements

The Calibration of Angle Blocks by

Intercomparison, C. P. Reeve, Natl. Bur. Stand. (U.S.), Int. Report,

NBSIR 80-1967 (1980).

The Calibration of Indexing Tables

by Subdivision, C. P. Reeve, Natl. Bur. Stand. (U.S.), Int. Report,

NBSIR 75-750 (July 1975).

A Survey of the Temporal Stability

of Angle Blocks, R. C. Veale and C.

P. Reeve. Natl. Bur. Stand. (U.S.),

Int. Report, NBSIR 74-601 (Nov.

1974).

17
15010C-15030C

V Surface Texture

m Precision Engineering Division

Center for Manufacturing Engineering

Technical Contacts:

Theodore V. Charles Giauque

Vorburger Tel: 301/921-2158

Tel: 301/921-2158

Mailing Address: A117 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items 15010C Roughness Calibration Specimens

15020C Surface Roughness Comparison Specimens

15030C Step Height Measurements

Roughness (15010C-15030C)

NBS provides measurement services

in three categories: instrument cali- bration specimens (with regular geometric profiles); roughness comparison (and other types of roughness

specimens); and step height speci- mens. The property of surface roughness

in the 10 /Ltm Ra range and below and

height up to 25 ^m are measured by means of a minicomputer/stylus in- strument system. Using an inter- ferometrically measured step, the sys- tem is calibrated at each value of

magnification employed during a measurement.

In measurements of roughness, sur- face profiles are taken according to American National Standard

B46. 1-1978 using a 0.76 mm cutoff

length, and a traversing length of 3.8 mm. A number of other statistical pa- rameters and functions may be calculated from the stored profile data in- cluding the rms roughness, average

slope, average wavelength, skewness,

amplitude density function, auto- correlation function, and power spectral density. In step height measurements, a

straight line is fitted by the method of

least squares to each side of the profile of the step and the height is cal- culated from the position of these two

lines. The NBS calibration uncertainty

for step height or Ra depends on a number of factors, the most important

being the step or Ra value itself. The

uncertainties range from approximately 0.3 /xm at a step height of 25

/Lim to 0.003 jLim at the smallest step

18
15010C-15030C

heights. Comparable uncertainties are achieved for measurements of Ra. References—Surface Texture

Sinusoidal Profile Precision Roughness Specimens, E. C. Teague, F. E.

Scire and T. V. Vorburger, Wear, 83, 61 (1982).

Three-Dimensional Stylus Profilometry, E. C. Teague, F. E. Scire,

S. M. Baker and S. W. Jensen, Wear,

83, 1 (1982).

FASTMENU: A set of FORTRAN

Programs for Analyzing Surface Texture, T. V. Vorburger, Natl. Bur. Stand. (U.S.), Int. Report, NBSIR

83-2703 (July 1982).

Optical Techniques for On-Line Measurement of Surface Topography, T. V. Vorburger and E. C. Teague,

Prec. Eng., 3, 611 (1981).

Uncertainties in Calibrating a Stylus

Type Surface Texture Measuring In- strument With an Interferometrically

Measured Step, E. C. Teague, Metrologia, 14, 39 (1979).

Measurements of Stylus Radii, T. V.

Vorburger, E. C. Teague, F. E. Scire

and F. W. Rasberry, Wear, 57, 39

(1979).

FAST Facility Available for Engineering Needs, T. V. Vorburger, E.

C. Teague and F. E. Scire,

Dimensions/NBS, 62, 18 (1978).

Evaluation, Revision and Application

of the NBS Stylus/Computer System

for the Measurement of Surface

Roughness, E. C. Teague, Natl. Bur. Stand. (U.S.), Tech. Note 902 (Apr.

1976).

Surface Finish Measurements: An

Overview, E. C. Teague, Soc. Manuf.

Eng., Tech. Pap. IQ75-137, 1 (1975).

The Measurement and Characterization of Surface Finish, R. D.

Young and E. C. Teague, Chapter 2

in Properties of Electrodeposits.

Their Measurement and Significance, R. Sard, H. Leidheiser, and F. Ogburn, Eds., 22, Electrochem. Soc,

Princeton, NJ (1975).

Precision Reference Specimens of

Surface Roughness: Some Characteristics of the Cali-Block, R. D. Young

and F. E. Scire, J. Res. Natl. Bur. Stand. (U.S.), 76C (Eng. and Instr.), Nos. 1 and 2, 21 (Jan.-June 1972).

19
16010C-17040S

G. Hydrometers

Chemical Process Metrology Division

Center for Chemical Engineering

Technical Contact:

John Houser

Tel:301/921-3681

Tel: 301/921-3281

Mailing Address: B312 Physics, National Bureau of Standards, Gaithersburg, MD 20899

Test No. Items 16010C Reference Standard Hydrometers

Reference Standard Hydrometers

(16010C)

Specific gravity hydrometers covering the range 0.62 to 3 g/cm' and

proof spirit hydrometers in the range

0 to 200 proof, which are designed

and used as reference standard hydrometers (used to test other hydrometers), normally are accepted for cali- bration. A limited number of other

types of reference standard hydrometers will be accepted for multipoint

calibration, subject to discussion. In- struments accepted must comply es- sentially with the requirements of

NBS Circular 555, "Testing of Hydrometers."

H. Volume and Density

Chemical Process Metrology Division

Center for Chemical Engineering

Technical Contact:

John Houser

Tel: 301/921-3681

Mailing Address: 105 Fluid Mechanics, National Bureau

of Standards, Gaithersburg, MD 20899

Test No. Items 17010C Volume Standards

17020S Special Tests of Volume Standards

17030S Special Tests of Density: Solids 17040S Special Tests of Density: Liquids

Volume Standards (17010C)

The procedure used for testing glass

volumetric apparatus is to weigh the

amount of distilled water contained

or delivered with reference to the

graduations marked on the instru- ment, the volume being computed

from the density of the water (for ta- bles see NBS Circular 19). The quality of the markings and the care exer- cised in reading or setting the liquid level are major factors in test cali- bration and usage. Normally the Bu20
17010C-17040S

reau will accept for calibration instru- ments that have volumes in the range

1 mL to 1 gal and which conform es- sentially to requirements contained in NBS Circular 602, "Testing of Glass

Volumetric Apparatus," Federal Pro- curement Specifications NNN-B00789 (Buret, straight, precision),

NNN-F-00289a (Pipet, volumetric),

NNN-P-0035a (Pipet measuring), or NNN-F-00289a (Flask, volumetric), if such instruments are to be used as ref- erence or transfer standards.

The usual calibration procedure for metal volumetric apparatus consists of

determining the value "to contain" or

"to deliver" by either gravimetric means or by the use of transfer stan- dards. Normally the Bureau will ac- cept for calibration instruments that have values in the range 1 gill to 1500

gal, which comply essentially with

the specifications contained in NBS

Monograph 62, "Testing of Volumetric Standards," and which are free from dents, bumps, or scratches. While it is preferred that the zero in- dex or the gage scale be adjusted and

scaled prior to calibration, these operations can be incorporated into the

calibration procedure if requested.

Slicker plate type standards should be

adjusted by the manufacturer.

Special Tests of Volume Standards

(17020S)

Special tests may be made of volume

standards by prearrangement with

NBS.

Special Tests of Density: Solids

(17030S)

NBS does not normally determine

density of solids for customers. However, special arrangements can be

made for customers to use the NBS

solid density measurement equipment

to make their own tests. The technical contact cited in this section

should be consulted concerning special arrangements for use of NBS

equipment.

Special Tests of Density: Liquids

(17040S)

NBS will accept requests for density

determinations of liquids if the need is critical. Limitations on the mass,

physical, dimensions, or volume of

the sample are available on request.

At NBS, liquid densities usually are determined by gravimetric, or weighing methods. Other methods are

available depending on the require- ments.

References—Volume and Density

Measurements

Reevaluation of the Densities of the

Four NBS Silicon Crystal Standards,

H. A. Bowman, R. M. Schoonover,

and C. L. Carroll, Int. Report,

NBSIR 75-768 (Aug. 1975).

The Utilization of Solid Objects as Reference Standards in Density Measurements, H. A. Bowman, R. M.

Schoonover, and C. L. Carroll, Metrologia 10, 117 (1974).

A Density Scale Based on Solid Objects, H. A. Bowman, R. M. Schoonover, and C. L. Carroll, J. Res. Natl. Bur. Stand. (U.S.), 78A, No. 1, 13 (Jan.-Feb. 1974).

Calibration of Small Volumetric Laboratory Glassware, J. Lembeck, Natl. Bur. Stand. (U.S.), Int. Report,

NBSIR 74-461 (Oct. 1974).

The Equivalence of Gravimetric and

Volumetric Test Measure Calibration, R. M. Schoonover, Natl. Bur. Stand.

(U.S.), Int. Report, NBSIR 74-454

(Feb. 1974).

Procedures for the Calibration of

Volumetric Test Measures, J. F. Houser, Natl. Bur. Stand. (U.S.), Int. Report, NBSIR 73-287 (Aug. 1973).

21
Chapter

A Flow Rate Measurements

B Flow Measurements at Cryogenic

Temperatures

C Airspeed Measurements

D Mass

E Force Measurements

F Vibration Measurements

G Acoustic Measurements

H Ultrasonic Measurements
Mechanical Measurements 18010C-18050S

^% Flow Rate Measurements

m Chemical Process Metrology Division

Center for Chemical Engineering

Technical Contacts:

Kenneth R. George E. Benson Mattingly

Tel: 301/921-3681 Tel: 301/921-3681

Mailing Address: 105 Fluid Mechanics, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items

180 IOC Single Turbine Meters

1 8020C Tandem Turbine Meters 18030C Flow Rate Meters (Direct Reading in Flow Rate Units)

18040C Head Class Flow Measurement Devices

18050S Special Tests for Liquid and Gas Flow Rates

Flow Meters (18010C-18040C)

NBS provides calibration services for

liquid flow meter systems which in- clude a flow meter and pertinent adjacent tubing, auxiliary measurement

instrumentation, and readout equip- ment. Flow meter systems having demonstrated precision and temporal sta- bility commensurate with the quality

of the calibrations are accepted for

calibration. Calibration tests usually

include five different flow rates, al- though additional rates can be in- cluded on request. At each flow rate, five determinations of meter indi- cation and flow rate are made; each

flow rate is tested two times. Meter systems submitted should

have connections for A/N flare fit- tings up to 2-in (5 cm) nominal di- ameters, or with connections for National Pipe Thread fittings up to 3-in (7.6 cm) nominal diameter. Larger

meters must terminate with ASA

150-lb steel flanges, or grooved-end

steel pipe compatible with Victaulic

couplings (for water meters), or with

adapters thereto: For air, flanges must

terminate with ASA 300-lb steel flanges except for laminar element

flowmeters operated near ambient

pressure levels. Connections other

than these should not be submitted

unless special arrangements have been

made in advance.

Meters must be submitted with

connections for A/N flange fittings

up to 3-in nominal diameters, or with

connections for National Pipe Thread

fittings up to 3-in nominal diameter.

For pipe sizes 4-in nominal diameter

and larger, meters must terminate

with ASA 150-steel flanges, or grooved-end steel pipe compatible

with Victaulic couplings (for water

meters), or with adapters thereto. Meters with connections other than these

should not be submitted unless special

arrangements have been made in ad- vance. Small Air Lab: Calibration of devices

in this laboratory covers the air flow

range up to approximately 100 stan- dard cubic feet per minute (SCFM).

The mass flow rate of gas passing

through a metering device during its calibration is determined from PVT

and transit time measurement of dis- placed volumes of gas. Two types of

displacers are used, bell gasometers

and mercury-sealed piston/cylinder

provers. Determination of the dis- placed volume in either case is based on diameter and stroke measurement.

Currently, these are done using fixed

switching positions of optical or mechanical switch mechanisms for eight

provers with volumes ranging from

200 cm' to 20 ft\ Measurements of

pressure are done using manometers

and barometers. Temperature measurements are made using contacting

techniques, i.e., thermocouples,

thermistors, etc. Large Air Flow Facility: The large air flow facility consists of a compressor

as the pressure source, a dryer, set- tling chamber, meter runs (2 to 8 inch

pipe sizes), and a collection tank.

23
18010C-18050S

Flow rates from 35 to 3000 SCFM

are attainable at pressures up to 90 psig. Calibration measurements are based upon the use of a set of working standards which are flow nozzles

operated under critical conditions,

i.e., at sonic velocity in the throat of

the nozzle. These provide an ex- tremely stable flow which is not influ- enced by variations in downstream

pressure and temperature conditions.

Determination of the mass flow rate through these nozzles is based upon

measured discharge coefficients. Measurement of the discharge coefficient for each nozzle over the range of

throat Reynolds numbers used has

been done in PVT experiments; in which the gas flowing through the

nozzle is diverted into the collection

tank of the facility for a measured pe- riod of time. Once the gas has been

collected, a PVT measurement is used

to determine the mass of gas in the

tank. This value of the mass of gas is used with the diversion time to comFigure 3. Uncertainty of NBS Measurements for Air Flow Rate Standards

03D.

CD 2. 10'

10-

Piston-Type & Bell-Type Provers

Sonic Nozzles

I I 1 I

0.01

T)

fD 0.10 o

(DD

03 1 .0 i 10"' 10° 10 10' 10^ 10' o3 ft^/min

I \

\ \ \

1 10"* 10"" 10"^ 10"' 10° 10

meter^/s Flow Rate

Figure 4. Uncertainty of NBS Measurements for Water

Flow Rate Standards

Dynamic Volumetric Present

S 10

0) 10

o

Dynamic Gravimetric

I L

^ Proposed

Static Gravimetric

0.01

o.iol

10" 10 10'

gal/min 10^

1 .0 10"

10" 10" —I r

10"" 10"

meter"/s Flow Rate

10"' 10°

pute the average mass flow rate through the nozzle. Figure 3 summarizes the NBS measurement uncertainty for air flow rate standards.

Water Flow Facility: The water flow

facility consists of reservoir, pumps,

meter runs and weigh tanks necessary

to make primary flow measurements.

Pipehne sizes up to 16 inches in di- ameter are available. The system

operates as a constant flow rate facil- ity using bypass and meter-run control valves to control the pressure and flow rate in the system. Diversion into the weigh tanks is accomplished with pneumatically driven

diverter valves fitted to each of the

four weighing systems used. Figure 4

summarizes the NBS measurement

uncertainty for water flow rate stan- dards.

Hydrocarbon Flow Facility: This fa- cility has the ability to handle a vari- ety of hydrocarbon liquids. The majority of the calibration requests

pertain to the use of a surrogate liquid for JP-4 and JP-5 jet fuels as the

liquid used in the calibration. The

flow rate range of this laboratory ex- tends from 0.01 to approximately 200

gallons per minute. Several types of

devices are calibrated, although tur- bine meters predominate. Figure 5

Figure 5. Uncertainty of NBS Measurements for Liquid

Hydrocarbon Flow Rate Standards „ Ib/hr g

1

CO 10' a

a>c

>. 10"

'cS

a>

nc 10'

Z)

10 10' 10" 10^ 10^ 10*^

1 1 1 Pre.c;ent1 1 Static Gravimetric Proposed ....

, Dynamic

Gravimetric

1 1 1

Dynamic

Volumetric

1 1 1

0.01

0.10

1.0 10"' 10" 10" 10 10'

gal/min

10"

r

10" 10" 10" 10"

kg/s

Flow Rate

10° 10 10'

24
summarizes the NBS measurement

uncertainty for liquid hydrocarbon

flow rate standards.

Special Tests for Liquid and Gas Flow

Rates (18050S)

Special tests for liquid and gas flow

rates can be arranged. Examples can

include "in-situ" calibration of flowmeter, proving other fluid measurement systems, etc. Details can be

obtained and arrangements made

through the technical contact listed at the beginning of this section. References—Flow Rate Measurements

A Laboratory Study of Turbine Meter Uncertainty, G. E. Mattingly, P. E. Pontius, H. H. Allion, and E. F. Moore, Natl. Bur. Stand. (U.S.),

Spec. Publ. 484 (Oct. 1977).

The National Measurement System

for Fluid Flow, W. C. Haight, P. S. Klebanoff, F. W. Ruegg, and G. Kulin, Natl. Bur. Stand. (U.S.), Int. Report, NBSIR 75-930 (Aug. 1976).

Introduction to Liquid Flow Metering and Calibration of Liquid Flowmeters, L. O. Olsen, Natl. Bur. Stand.

(U.S.), Tech. Note 831 (June 1974).

Flow Measurement: Procedures and

Facilities at the National Bureau of

Standards, F. W. Ruegg and M. R.

Shafer, (Proc. Symp. Flow Measurement, San Francisco, CA, Jan.

19-22, 1970). Chapter in ASHRAE

(Amer. Soc. Heat Refrig. Air-Cond.

Eng.), Bull. Flow Measurement Part

1, SF70-7, 1 (1972).

Gas Flow Measurement by Collection

Time and Density in a Constant Volume, L. Olsen and G. Baumgarten,

Symposium on Flow, Its Measurement and Control in Science and

Industry, ISA, 1, Part 3, 1287 (1972).

Evaluation of a Low Flow Generator

and Calibrator as a Flow Measurement Standard, G. Baumgarten,

Natl. Bur. Stand. (U.S.), Tech. Report 10921 (1972).

Practical Considerations for Gas

Flow Measurement, M. R. Schafer,

Jr. and D. W. Baker, Proc. 3rd Annual Prec. Meas. Assoc. Metrology

Conf., Natl. Bur. Stand., Gaithersburg, MD, June 17-18, 1970, 1, 187 Prec. Meas. Assoc., Burbank, CA

(1970).

Flow Measurement Engineering

Handbook, R. W. Miller, McGraw

Hill, New York (Jan. 1983).

Fundamentals of Flow Measurements,

J. P. DeCarlo, Instr. Soc. of America,

Research Triangle Park, NC (1984).

Liquid-Flowmeter Calibration Techniques, M. R. Shafer and F.W.

Ruegg, ASME Paper No. 57-A-70.

Performance Characteristics of Turbine Flowmeters, M. R. Shafer,

ASME Paper No. 61-WA-25.

25
18800S

J|7 Flow Measurements at Cryogenic

m^m Temperature

Chemical Engineering Science Division

Center for Chemical Engineering

Technical Contact:

James A. Edna M. Jones Brennan Administrative

Tel: 303/497-3611 and Logistics Tel:303/497-3753 Mailing Address: MC 773. 20, National Bureau of Stan

dards, 325 Broadway, Boulder, CO 80303

Test No. Items 18800S Special Tests of Cryogenic Liquid Flow

Special Tests of Cryogenic Liquid

Flow (18800S)

Limited measurement services are provided for cryogenic liquid flow.

Mass flow measurements are per- formed using liquid nitrogen flow

rates of 76 to 757 liters per minute.

References—Flow Measurements at Cryogenic Temperature

Cryogenic Fluids Density Reference

System: Provisional Accuracy State- ment (1980), J. D. Siegwarth and

J. K. LaBrecque, Natl. Bur. Stand.

(U.S.), Tech. Note 1041 (Apr. 1981).

LNG Materials and Fluids—A User's

Manual of Property Data in Graphic

Format, 1st Edition, D. B. Mann,

Ed.; Suppl. 1, D. E. Diller, Ed.,

Suppl. 2, N. A. Olien, Ed. (1980).

Progress Report on Cryogenic Flowmetering at the National Bureau of

Standards, J. A. Brennan, J. F. LaBrecque, and C. H. Kneebone, Proc.

1st Bienial Symp. Instrumentation in the Cryogenic Industry, Houston TX,

Oct. 11-14, 1976, 1, 621, Instr. Soc. of

America, Pittsburgh, PA (1976).

NBS-CGA Cryogenic Flow Measurement Program, J. A. Brennan, R. W. Stokes, C. H. Kneebone, and D.

B. Mann, (Proc. ISA Intl. Instrument. Automation Conf. and Exhibit, New

York, NY, Oct. 28-31, 1974), Paper in Adv. in Instrument. 29, 612.1 (Instr. Soc. of America, Pittsburgh, PA,

1974).

Cryogenic Flow Research Facility

Provisional Accuracy Statement,

J. W. Dean, J. A. Brennan, D. B. Mann, and C. H. Kneebone, Natl. Bur. Stand. (U.S.), Tech. Note 606

(July 1971).

Cryogenic Liquid-Measuring Devices,

Sec. 3.34, 3-57, in Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices, O. K. Warnlof, Ed.,

Natl. Bur. Stand. (U.S.), Handbook

44 (1986).

26
19010C-19030S

C Airspeed Measurements

w Chemical Process Metrology Division

Center for Chemical Engineering

Technical Contacts:

Norman E. George E. Mease Mattingly

Tel: 301/921-3684 Tel:301/921-3681

Mailing Address: 105 Fluid Mechanics, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items 19010C Pitot-Static Tubes (3 to 150 mph)

19020C Low Airspeed Instruments (15 to 2,000 fpm)

19030S Special Tests for Airspeed Instruments

Airspeed Instruments (19010C and

19020C)

Calibration of airspeed measuring devices is performed in the dual test section and low velocity wind tunnels. Elliptical-nose Pitot-static tubes

provide the basis of airspeed measurement in both tunnels. Low velocity airspeed measurements are based

upon laser velocimeter measurements

in the low speed wind tunnel. Calibration of the laser velocimeter is done using the Pitot-static tube at velocities which produce a sufficiently

large pressure in the tube that the uncertainty in the pressure measurement

does not propagate a large error into

the velocity determination. Extension

of the laser velocimeter to the low

velocity region, where the Pitot-static tube has large measurement errors due to the inability to accurately measure the extremely small pressures produced in the tube, allows considerably improved measurement uncertainty. Air density values in the tunnels are computed from pressure, temperature, and humidity measure- ments in the tunnel's settling

chamber.

Uncertainty levels for the range of

airspeed currently offered are shown

in Figure 6. Special Tests of Airspeed Instruments (19030S)

Special tests for airspeed instruments can be arranged. Examples include

"in-situ" calibration of air speed in- strumentation; proving other air speed measurement systems, etc. Details can be obtained and arrange- ments made through the technical contacts cited at the beginning of this section. References—Airspeed Measurement

Experimental Investigation of Drag

on a Compliant Surface, J. M. McMichael, P. S. Klebanoff, and N. E. Mease, Viscous Flow Drag Reduction, Gary R. Hough, Ed., Progress

in Astronautics and Aeronautics, 72

(1980).

A Low-Velocity Airflow Calibration

and Research Facility, L. P. Purtell and P. S. Klebanoff, Natl. Bur. Stand.

(U.S.), Tech. Note 989, (Mar. 1979).

Low-Velocity Performance of Anemometers, L. P. Purtell, Natl. Bur. Stand. (U.S.), NBSIR 79-1759 (May

1979).

Low-Velocity Performance of a Magnetic Pick-up Vane Anemometer, L.

P. Purtell, Natl. Bur. Stand. (U.S.),

NBSIR 79-1566 (Dec. 1978).

Low-Velocity Performance of a Ball Bearing Vane Anemometer, L. P. Purtell, Nafl. Bur. Stand. (U.S.),

NBSIR 78-1485 (June 1978).

Figure 6. Accuracy of Airspeed Measurements for Calibration of Airspeed Indicators

Miles per Hour

I . . ..I ,

. . I . . ..I ,

. . 1 , ,

. .1 , ,05 0.1 0.5 1.0 5.0 10 50

Meter/Second

27
22010C-22180M

Mass Standards

m Length and Mass Division

Center for Basic Standards

Technical Contact:

Jerry G. Keller

Tel: 301/921-3118

Mailing Address: B160 Physics, National Bureau of

Standards, Gaithersburg, MD 20899

Shipping Address: National Bureau of Standards, 1-270 at Quince Orchard Road, B33 Metrology, Gaithersburg,

MD 20899

Attn: J.G. Keller

Note: For weights larger than 50 lb (30 kg), contact J.G. Keller prior to shipment.

Test No. Items 220 IOC Weight Set (1 mg to 100 g)

22020C Weight Set (1 mg to 1 kg)

22030C Weight Set (2 to 30 kg)

22040C Single Weights (1 mg to 1 kg)

22050C Each additional weight

22060C Single Weights (2 kg to 30 kg)

22070C Each additional weight

22080C Single Weights (> 30 kg to 1200 kg, 2 double

substitution weighings)

22090C Each additional weight

22100C Single Weights (> 1200 kg to 30,000 kg)

221 IOC Single Weights (>30 kg to 1200 kg, calibrated in a weighing design)

22120C Each additional weight

22130C Single Weights for Dead Weight Pressure Testers (>13 lb) 22 HOC Each additional weight

22 1 50C Single Weights for Dead Weight Pressure Testers (<13 lb) 22160C Each additional weight

221 70S Special Mass Measurement Services

22180M Measurement Assurance Program for Mass

Mass (22010C-22120C)

NBS maintains the national standards

for mass in the form of the prototype

kilograms (K4 and K20) and provides

services to support the parts of the

national measurement system that rely

directly or indirectly on mass measurements. These services include the

calibration of suitable weight sets. A

calibration consists of establishing a mass value and the appropriate uncertainty for that value for each weight

which has been designated to be a reference standard. It is desirable, but

not necessary, that a weight meet the

adjustment tolerances established for Classes A, B, M, or S-1 prior to submission. Weights are available from

manufacturers, many of whom can di- rectly furnish documentation suitable for meeting quality assurance contracts and requirements.

For periodic recalibrations of refer- ence mass standards, the user need measure only differences between

weights or groups of weights within a

set and compare them with computed

differences. As long as the agreement

is within allowable limits, the values can be considered constant within the

precision of the comparison process. Mass standards which are submitted

to NBS for recalibration frequently

are tested in this manner. If these

tests indicate that no significant

changes have occurred, a continuation report so stating and re- ferring to the previous NBS Report

of Calibration will be issued. NBS calibrates individual weights

or sets in the range of 1 mg to 30 kg

or 1 lb to 50 lb in decimal subdivisions. If the weights are designated as reference standards, they

must be of design, material, and sur- face finish comparable to present

Classes A, B, M, S, or S-1. These in- clude ASTM Type I and II, grade S

and O, and OIML El, E2, and Fl.

NBS also calibrates large mass stan- dards (60 to 60,000 lbs) if the design,

material, and surface finish are compatible with the intended usage. For

these large mass standards, an adjustI ment with reference to a nominal or

28
22010C-22180M

desired value can be included as a

part of the calibration procedure.

The values of true mass (and an ap- parent mass correction) included in the report will be determined by us- ing computed volumes based on the

manufacturer's statement of density of

the material, or on the density computed from measured volumes, or, in the absence of this information, on es- timated densitj^ values. However, 1 kg mass standards fabricated from

stainless steel and of one-piece construction will have their density determined as part of a "first-time" cali- bration at NBS. The apparent mass

corrections are computed for 20 °C

with reference to Normal Brass (density 8.4 g/cm^ and volume coefficient

of expansion 0.000054/°C) and to

stainless steel (density 8.0 g/cm^ and

volume coefficient of expansion

0.000045/°C) in an ideal air density of

1.2 mg/cm^ Apparent mass corrections to any other basis can be fur- nished if requested. Typical uncertainties range from 50 parts per

billion at 1 kilogram up to 500 parts

per million at one milligram and 1 part per million for weights from 2 kilograms to 30 kilograms. Figure 7 shows the NBS precision of weighing

for mass standards over the range

10-* to 10') kilograms.

Single Weights for Dead-Weight Pressure Testers (22130C-22160C)

Weights less than six (6) pounds are determined by comparing them with

calibrated built-in-weights of appropriate analytical balances by the double substitution method. Weights

larger than six (6) pounds are compared to discrete standards by the

method of single transposition weighing.

Special Tests of Mass (22170S)

For tests not covered by the previous

descriptions, the NBS technical contact cited at the beginning of this sec- tion should be consulted to determine

whether a test can be performed and

to negotiate a price for the test. Measurement Assurance Program for Mass (22180M)

This service is most appropriate for primary calibration laboratories. Total

uncertainties ranging from a few parts

in 10^ to a few parts in 10^ for 1 kg

can be obtained. Unlike most other

NBS MAP services, the Mass MAP

Figure 7. NBS Precision of Weighing for Mass

Standards Ranging from 10~^ to W* Kilograms

- • Balances & Scales - .000001 %

^ Elastic Devices . • * . '' -.0001%

-.01%

- ' - 1 %

10"'° 10"" lO"*" 10"' 10"^ 1 10^ 10' 10^ Load in Kilograms

service does not involve the use of an NBS-owned transport standard that is shipped to participants for measurement. The transfer standards in the mass MAP are a set of mass stan- dards owned by the participant and

sent to NBS for calibration. These

standards are referred to as the "start- ing standards." In addition to the

starting standards, the mass MAP participant must also furnish a set of

much smaller weights called "sensitivity weights." The choice of both

the starting standards and the sensitivity weights will depend on the particular mass range of interest to the

participant; NBS staff can provide advice regarding suitable starting stan- dards and sensitivity weights for a

O 0) '^ c

> - 10' Q c

10^

-D $

29
particular range of mass weighings. In addition to the starting standards and

the sensitivity weights, the participating faciHty should have a working

set of weights known as the "test set" and a set of weights to be used as check standards. This set usually consists of weights in the range 1 to 1000 g. This service, like other NBS MAP

services, samples the participant's

measurement process and establishes

its uncertainty. Once the participant

has become well-established in the

Mass MAP, two options are possible:

a. NBS personnel do all of the

data analysis and record keeping for the participant and provide periodic

reports on the uncertainty of the participant's mass measurements.

b. The participant keeps all records and calculates the uncertainties of his measurements using

NBS methods and computer codes.

The implementation of the Mass

Measurement Assurance Program in

its most complete form typically pro- ceeds in four distinct phases which

may be abbreviated somewhat if the

participant already has a suitable mass measurement quality control system.

Phase I: Each new participant completes a questionnaire on equipment

and facilities and receives a written

description of the NBS process, methods and procedures to be used, an in- troduction to the interpretation of results, and information on the use of

these results in measurement decisions. At the participating laboratory,

the suitability of the weighing equipment is verified, the "starting stan- dards" selected or procured, and if the procedures are entirely new,

operators are trained. The starting

standards and sensitivity weights are

sent to NBS for calibration. If the

starting standards have a prior NBS

calibration history, those data are re- viewed, and if satisfactory, they are considered, along with the data from

the more recent determinations, in ar- riving at assigned values for the start- ing standards. NBS will recommend a weighing design to be used for cali- brating the test weight. This weighing

design prescribes the set of observations for intercomparing the test weights with known weights. NBS

will also supply data sheets that are used throughout the first three phases

of the program for recording data

taken using the design. The objective

of the first phase is to ensure that the

new participant is familiar with good

laboratory practices for high precision weighing. If the participating

laboratory has an established mass measurement capability and an exist- ing quality control procedure for mass measurements. Phase I is abbreviated considerably.

Phase II: The starting standards and

sensitivity weights are returned to the

participant and, following the pre- scribed procedures, measurements are made over a period of time by the

participant to verify that a state of

statistical control exists. The data

sheets are sent to NBS for review,

30
comments, and processing after each

measurement. If there are unanticipated problems, or the pro- cedure has not been followed exactly, more measurements may be required.

After three or more successful cali- brations in the user's facility, NBS an- alyzes the data to determine the val- ues of the check standards.

Phase III: A comprehensive report is issued by NBS which contains a re- view of the actions and decisions in each of the phases, control charts for the check standards to be used in the

participant's facility, and a comparison of the values assigned to the

starting standards by NBS and by the

participant. It is assumed at this point

that the participating facility is now

ready to extend the operation of the

MAP to its regular workload.

Phase IV: Having thus established

measurement comparability, the MAP

user can then, in principle, operate in- dependently of NBS. As long as there

is no indication of a loss of statistical control of the process, no further

checking with NBS should be necessary. Most participants request a re- check of the starting standards every

few years to ensure that no un- detected long-term drift has taken

place.

For work that differs from the items

normally calibrated by the participant, NBS can provide consulting

help and assistance such as might be

necessary to accommodate a greater

range of weights, calibrate pound

standards, and extend pound stan- dards to large weights normally asso- ciated with force measurement. Although the usual Mass MAP service

uses two one-kilogram masses as the

starting standards, the program is suf- ficiently flexible that the same methods can be used with other mass values.

References—Mass Measurements

Air Buoyancy Correction in HighAccuracy Weighing on Analytical

Balances, R. M. Schoonover and

F. E. Jones, Anal. Chem., 53, No. 6, 900 (May 1981).

National Bureau of Standards Mass

Calibration Computer Software,

R. N. Varner and R. C. Raybold,

Natl. Bur. Stand. (U.S.), Tech. Note

1127 (July 1980).

Quick and Accurate Density Deter- mination of Laboratory Weights,

R. M. Schoonover and R. S. Davis,

Proceedings of the 8th Conference of

IMEKO, Krakow, Poland (1980).

Precision Laboratory Standards of

Mass and Laboratory Weights. A re- print of NBS Circular 547, Section 1, T. W. Lashof and L. B. Macurdy,

August 1954, Natl. Bur. Stand. (U.S.),

Int. Report, NBSIR 78-1476 (Oct.

1978).

The National Measurement System

for Mass, Volume, and Density, P. E.

Pontius, J. R. Whetstone, and J. A.

Simpson, Natl. Bur. Stand. (U.S.), Int. Report, NBSIR 75-928 (May 1978).

Direct Determination of Air Density

in a Balance Through Artifacts Characterized in an Evacuated Weighing

Chamber, W. F. Koch, R. S. Davis,

31
22010C-22180M

and V. E. Bower, J. Res. Natl. Bur.

Stand. (U.S.), 83, No. 5, 407

(Sept.-Oct. 1978).

The Air Density Equation and the

Transfer of the Mass Unit, F. E. Jones, J. Res. Natl. Bur. Stand. (U.S.),

83, No. 5, 419 (Sept.-Oct. 1978).

Designs for the Calibration of Stan- dards of Mass, J. M. Cameron, M. C. Croarkin, and R. C. Raybold, Natl. Bur. Stand. (U.S.), Tech. Note 952

(June 1977).

The Air Density Equation and the

Transfer of the Mass Unit, F. E. Jones, Natl. Bur. Stand. (U.S.), Int. Report, NBSIR 77-1278 (July 1977).

Measurement Assurance, J. M. Cameron, Natl. Bur. Stand. (U.S.), Int Report, NBSIR 77-1240 (1977).

Surveillance Test Procedures, H. W.

Aimer, Natl. Bur. Stand. (U.S.), Int. Report, NBSIR 76-999 (Feb. 1976).

Mass and Mass Values, P. E. Pontius,

Natl. Bur. Stand. (U.S.), Monogr.

133, (Jan. 1974).

On Uncertainty in Mass Measurement, J. R. Donaldson, Natl. Bur.

Stand. (U.S.), Int. Report, NBSIR

73-151 (Mar. 1973).

Weight Cleaning Procedures, H. E. Aimer, Natl. Bur. Stand. (U.S.), Int. Report, NBSIR 74-443 (Nov. 1973).

Method of Calibrating Weights for Piston Gages, H. E. Aimer, Natl. Bur. Stand. (U.S.), Tech. Note 577

(May 1971).

Introduction to Intercomparison

Methods in Mass Measurement, H. E. Aimer, Natl. Bur. Stand (U.S.), Report 9487 (Feb. 1967).

Realistic Uncertainties and the Mass

Measurement Process, P. E. Pontius

and J. M. Cameron, Natl. Bur. Stand.

(U.S.), Monogr. 103 (Aug. 1967).

Measurement Philosophy of the Pilot Program for Mass Calibration, P. E.

Pontius, Natl. Bur. Stand. (U.S.),

Tech. Note 288 (May 1966).

A Primer for Mass Metrology, K. B. Jaeger and R. S. Davis, Natl. Bur.

Stand. (U.S.), Spec. Publ. 700-1 (Nov.

1984).

32
£ Force Measurements

r Automated Production Technology Division

Center for Manufacturing Engineering

Technical Contacts:

1

Richard A. Robert W.

Mitchell Peterson

Tel: 301/921-3884 Tel: 301/921-3884

Mailing Address: 221 Engineering Mechanics, National

Bureau of Standards, Gaithersburg, MD 20899

lest iNO. Items 23010C Force Transducers (to 25,000 Ibf, 1 mode)

23020C Extra observation

23030C Additional bridges

23040C Force Transducers (to 25,000 Ibf, 2 modes)

23050C Extra observation

23060C Additional bridges

23070C Force Transducers (25,001 to 112,000 Ibf, 1 mode)

23080C Extra observation

23090C Additional bridges

23100C Force Transducers (25,001 to 112,000 Ibf 2 modes)

23 HOC Extra observation

23120C Additional bridges

23130C Force Transducers (112,001 to 300,000 Ibf 1 mode)

23140C Extra observation

23150C Additional bridges

23160C Force Transducers (112,001 to 300,000 Ibf 2 modes)

23170C Extra observation

23180C Additional bridges

23190C Force Transducers (300,001 to 1,000,000 Ibf 1 mode)

23200C Extra observation

232 IOC Additional bridges

23220C Force Transducers (300,001 to 1,000,000 Ibf 2 modes)

23230C Extra observation

23240C Additional bridges

23250C Force Transducers (over 1,000,000 Ibf) 23260S Special Tests of Force Transducers

23270S Pattern Evaluation Test of Load Cells in Compression

Force Transducers (23010C-23250C)

NBS provides calibration services for force measuring devices by applying

known forces, either tension or compression, to the elastic device and

recording the sensed deformation.

Practically all of the devices cali- brated are either proving rings or

load cells. The deformation of proving rings is usually measured by means of a micrometer screw and vi- brating reed which are an integral

part of the device. Load cells, which

utilize strain gauge bridges, produce

an electrical output approximately

proportional to the applied force. The

calibration report describes the re- lationship between the applied force

and the measured deformation, in electrical or mechanical units. A load

cell can be calibrated using: (1) a readout device furnished by the cus- tomer (the load cell and the readout

device are calibrated as a system and

the calibration is only valid when

they are used together); or (2) instru- mentation furnished by NBS and the

data reported in terms of the ratio of

the output voltage to the DC excitation voltage (mVA^). In the latter case, the customer must possess the

necessary electrical instruments and

expertise to utilize the calibration results. Tension or compression calibrations

in the range of 10 pounds-force (Ibf) to 1,000,000 Ibf are performed using

deadweight machines. NBS has six such deadweight machines with max- imum capacities of 500; 6,100; 25,300;

112,000; 300,000; and 1,000,000 Ibf. The three larger machines allow the

force applied to the unit being cali- brated to be incremented or decremented without having to go to zero

33
load between force applications.

When using the three smaller machines it is necessary to go to zero

load before the load is changed. The

estimated uncertainty of the vertical

component of the applied force is 20

ppm.

Comparison calibrations in the

range of 1,000,000 Ibf to 12,000,000

Ibf in compression only are performed

in a universal testing machine. In this case, the system being calibrated is loaded in series with one or more

load cells that have been previously

calibrated in a deadweight machine.

Special Tests of Force Transducers

(23260S)

Temperature sensitivity, pressure sensitivity, eccentric-load sensitivity, and

creep tests of force transducers are measured. The ranges of test parameters and environmental conditions

may be limited by the characteristics

of the force transducer and the availability of special test fixtures. These

special tests should be discussed with

the designated NBS technical contact before the work is scheduled. Pattern Evaluation Test of Load Cells

in Compression (23270S)

Pattern evaluation tests of load cells are performed in compression, fol- lowing the procedures of OIML In- ternational Recommendation No. 60 over the loading ranges provided by

the NBS 112,000 Ibf, 300,000 Ibf, and

1,000,000 Ibf deadweight machines.

This test should be discussed with ap- propriate NBS staff before the work

is scheduled.

References—Force Measurements

Inherent Problems in Force Measurements, P. E. Pontius and

R. A. Mitchell, Exper. Mech., 22,

No. 3 (Mar. 1982).

Force Sensor-Machine Interaction, R. A. Mitchell and P. E. Pontius,

Proceedings of the 27th International

Instrumentation Symposium (ISA),

Indianapolis, IN, Instrumentation in the Aerospace Industry, 27, 225

(1981).

Characterizing the Creep Response of

Load Cells, R. A. Mitchell and S. M.

Baker, VDI-Berichte 312, 43 (1978).

Interlaboratory Comparison of Force

Calibrations Using ASTM Method

E74-74. Phase I., R. W. Peterson and

R. L. Bloss, Natl. Bur. Stand. (U.S.),

NBSIR 76-1145 (Aug. 1976).

A Study of the National Force Measurement System, D. E. Marlowe,

Natl. Bur. Stand. (U.S.), Int. Report,

NBSIR 75-929 (June 1975).

Universal Testing Machine of

12-Million-lbf Capacity at the National Bureau of Standards, A. F.

Kirstein, Natl. Bur. Stand. (U.S.),

Spec. Publ. 355 (Sept. 1971).

Studies of Calibration Procedures for Load Cells and Proving Rings as Weighing Devices, G. B. Anderson

and R. C. Raybold, Natl. Bur. Stand.

(U.S.), Tech. Note 436 (Jan. 1969).

Gravity Measurements and the Stan- dards Laboratory, D. R. Tate, Natl. Bur. Stand. (U.S.), Tech. Note 491

(Aug. 1969).

Absolute Value of g at the National

Bureau of Standards, D. R. Tate,

Natl. Bur. Stand. (U.S.), Monogr. 107

(June 1968).

Uncertainties Associated with Proving Ring Calibration, T. E. Hockersmith and H. H. Ku, Preprint No.

12.3-2-64: ISA Conference, Instr. Soc. of America, Res. Triangle Park, NC

(Oct. 1964).

Interlaboratory Comparison of Force

Calibrations Using ASTM Method

E74-74, R. W. Peterson, L. Jenkins,

and R. A. Mitchell, Natl. Bur. Stand.

(U.S.), Tech. Note 1211 (Apr. 1985).

Metrological Regulations for Load

Cells, OIML International Recommendation No. 60, Intl. Org. for Legal Metrol., Paris (Oct. 1984).

Progress in Force Measurement at NBS, R. A. Mitchell, Proc. 10th

Conf IMEKO TC-3 on Measurement

of Force and Mass, Kobe, Japan

(Sept. 1984).

34
Vibration Measurements

# m Automated Production Technology Division

Center for Manufacturing Engineering

Technical Contact:

Myroslav R. Serbyn

Tel: 301/921-3607

Mailing Address: A149 Sound, National Bureau of Standards, Gaithersburg, MD 20899

Test No. Items 24010C Vibrations (Pickup Sensitivity, 2 to 100 Hz)

24020C Vibrations (Pickup Sensitivity, 10 to 3,500 Hz)

24030C Vibrations (Pickup Sensitivity, 10 to 10,000 Hz)

24040S Special Shock Measurement Services

24050S Special Tests of Pickup Sensitivity

24060S Special Vibration Tests

Pickup Sensitivity (24010C-24030C)

NBS calibrations of vibration exciters

and pickups are performed by comparison with the response characteristics of NBS standards or by absolute

measurements. The measurement is the

transfer function of the instrument,

usually referred to as the sensitivity.

For a pickup it is the ratio of the

electrical output to a mechanical in- put. In the case of an accelerometer

the practice has been to express the

output in millivolts, and the input in units of g, the standard acceleration

of free fall. The acceleration sensitivity is then given in mV/g. Other

units are sometimes used; for example, the calibration of piezoelectric

and piezoresistive accelerometers

without signal conditioners is stated

in picocoulombs per g (pC/g).

The calibration of an accelerometer

is reported in tabular form as the sensitivity of the transducer at the dis- crete frequencies. Because sensitivity

is a phasor quantity, which may be

represented as a complex number, a complete calibration consists of a measurement of both magnitude and

phase of the sensitivity. Only the

magnitude of the sensitivity is usually

reported. However, the phase component can be furnished on request.

The NBS vibration standards have

been calibrated by reciprocity and in- terferometric techniques, two independent and absolute methods. Their

calibration is periodically checked us- ing both techniques. The use of these

standards in the calibration of stable transducers furnishes calibration data

with a typical uncertainty of from one to three percent depending on

the frequency range.

Special Shock Measurement Services

(24040S)

The shock facility provides a comparison calibration of accelerometers

by subjecting them to half-sinewave

pulses with peak amplitudes of 50 to 5000 g and pulse widths from 0.2 to 40 milliseconds. Both time and fre- quency domain measurements can be

performed.

Special Tests of Pickup Sensitivity

(24050S)

High accuracy measurements of

pickup sensitivity, magnitude only,

from 4 to 10 kHz and a peak acceler- ation of 10 g, normally requested

with test 24020C.

Special Vibration Tests (24060S)

Calibration of vibration and shock

measuring instruments to specifica35
tions different from those of the

above as well as other measurements

can be performed by prearrangement.

Consult with technical contact cited

at the beginning of this section.

References—Vibration Measurements

An Automated System for the Measurement of Pickup Sensitivity, B. F. Payne and M. R. Serbyn, NCSL 1983

Workshop and Symposium Proceedings, II-II.1-II-II.22 (July 1983).

The Application of Back-to-Back Accelerometers to Precision Vibration

Measurements, B. F. Payne, J. Res.

Natl. Bur. Stand. (U.S.), 88, No. 3, 171 (May-June 1983).

A Real-Time Active Vibration Controller, M. R. Serbyn and W. P. Penzes, ISA Transactions, 21, No. 3, 55

(1982).

Absolute-Calibration of Accelerometers at the National Bureau of

Standards, B. F. Payne and M. R. Serbyn, Proc. 10th Transducer Workshop: Telemetry Group, Inter-Range

Instrumentation Group, Range Commanders Council, June 12-14, 1979,

Colorado Springs, CO, 136 (1979).

Piezoelectric Accelerometer LowFrequency Response by Signal In- sertion Methods, R. S. Koyanagi and

J. D. Pollard, Natl. Bur. Stand.

(U.S.), Int. Report, NBSIR 74-597

(May 1975).

Shock Calibration of Accelerometers,

C. Federman, W. Walston, and J. Ramboz, Minutes of the 8th Trans- ducer Workshop: Telemetry Group,

Inter-Range Instrumentation Group,

Range Commanders Council, WrightPatterson AFB, OH (Apr. 1975).

Accelerometer Calibration at the National Bureau of Standards, B. F.

Payne, R. S. Koyanagi, C. Federman,

and E. Jones, 21st Intl. Instrument. Symp. ASD/TMD, May 19-21, 1975,

Philadelphia, PA, 1 (1975).

Development of a Low-FrequencyVibration Calibration System, R. S. Koyanagi, Exp. Mech., 15, 443 (Nov.

1975).

A Systematic Study of Vibration

Transfer Standards—Mounting Effects, R. S. Koyanagi, J. D. Pollard,

and J. D. Ramboz, Natl. Bur. Stand.

(U.S.), Int. Report, NBSIR 73-291

(Sept. 1973).

An Automated Precision Calibration

System for Accelerometers, B. F. Payne, Instrum. Soc. Am. 17th Natl. Aerospace Instrument. Symp., Instr. Soc. of America, Res. Triangle Park,

NC (May 1971).

Piezoelectric Shakers for WideFrequency Calibration of Vibration

Pickups, E. Jones, B. Yelon, and S. Edelman, J. Acoust. Soc. Am., 46,

No. 6, 1556 (June 1969).

Accelerometer Resonances Affecting

Vibration Measurement, E. T. Pierce,

O. W. Price, S. Edelman, and E.

Jones, J. Environ. Sci., 10, No. 6, 17 (Dec. 1967).

Improved Transfer Standard for Vibration Pickups, E. Jones, D. Lee,

and S. Edelman, J. Acoust. Soc. Am.,

41, No. 2, 354 (Feb. 1967).

Electrodynamic Vibration Standard

with a Ceramic Moving Element, T. Dimoff, J. Acoust. Soc. Am., 40, No.

3, 671 (Sept. 1966).

Calibration of Vibration Pickups at Large Amplitudes, E. Jones, S. Edelman, and K. S. Sizemore, J. Acoust.

Soc. Am., 33, No. 11, 1462 (Nov.

1961).

Calibration of Vibration Pickups by

the Reciprocity Method, S. Levy and

R. R. Bouche, J. Res. Natl. Bur.

Stand. (U.S.), 57, No. 4, 227 (Oct.

1956).

36

1
#' " Acoustic Measurements

Automated Production Technology Division

Center for Manufacturing Engineering

Technical Contact:

Victor Nedzelnitsky

Tel: 301/921-3607

Mailing Address: A149 Sound, National Bureau of Standards, Gaithersburg, MD 20899

Test No. Items 25010C Pressure Response: WE Type 640AA microphones or

equivalent (e.g., Tokyo Riko Type ECL MR103;

B&K Types 4144 or 4132 with DBOl 1 1 adapter). 50 to 10,000 Hz. 25020C Pressure Response: WE Type 640AA microphones or

equivalent (e.g., Tokyo Riko Type ECL MR103; B&K Type 4160; B&K Types 4144 or 4132 with

DBOl 11 adapter). 50 to 20,000 Hz. 25030C Pressure Response: Tokyo Riko Type ECL MRl 12, microphones. B&K Type 4134, or equivalent half- inch. 50 to 10,000 Hz. 25040C Pressure Response: Tokyo Riko Type ECL MRl 12, B&K Type 4134, or equivalent half-inch microphones. 50 to 20,000 Hz. 25050C Free-Field Response: Tokyo Riko Type ECL

MRl 12, B&K Types 4133, 4134, 4165, 4166, or equiv

alent half-inch microphones. 2,500 to 20,000 Hz. 25060S Special Tests of Acoustic Devices

25070S Special Tests of Earphones

Pressure and Free-Field Response of

Microphones (25010C-25050C)

Pressure calibrations are performed on type-L (one-inch microphones sat- isfying the requirements of American

National Standard SI. 12-1967

(R1977), Specifications for Laboratory Standard Microphones and its impending revision. The microphones

submitted for pressure calibration

must be suitable for use with the cali- brating couplers shown in figures 7 and 1 1 of the applicable American

National Standard SI. 10-1966

(R1976).

Pressure calibrations are reported

in terms of open-circuit voltage per

unit sound pressure applied uniformly

to the diaphragm. The open-circuit

voltage at the electrical terminals of a microphone may be influenced by

stray capacitance evident at these ter- minals. For type-L microphones,

these capacitances are defined by the

geometrical configuration of the

ground shield shown in figures 6 and

13 of SI. 10-1966 (R1976). If the

ground shield dimensions are not adhered to in making use of the re- sponse levels reported by NBS, errors may result. Pressure calibrations of

type-L microphones exhibit typical

uncertainties of approximately 0. 1 dB

or less at frequencies from 50 Hz to

8 kHz, 0.2 dB or less at frequencies

from 8 kHz to 20 kHz. Further infor- mation is contained in the references

for acoustic measurements.

Since American National Standards

Institute publications SI. 10-1966

(R1976) and SI. 12- 1967 (R1977) were

issued, certain types of half-inch di- ameter precision microphones have

attained widespread use. Therefore,

NBS has developed procedures for determining the pressure response

levels of half-inch microphones by

comparison with NBS type-L stan- dard microphones, which in turn are

calibrated periodically by the reci- procity technique. The technique

used, precautions to be observed, and

uncertainties of measurement are es- sentially the same as those given

above for one-inch microphones. Significant differences such as ground

shield configuration are described in the test report. Since several half-inch

laboratory standard microphones

have only been available for a rela- tively short time, their long-term sta- bility has yet to be determined.

The free-field response levels of

certain type-L microphones (e.g., Western Electric Type 640AA con- denser microphones) can be computed from pressure response levels reported by NBS. However, certain

37
precautions must be taken and there is some degradation in accuracy. Therefore, for the most demanding freefield measurement requirements, NBS

offers a calibration service for deter- mining the free-field response levels for half-inch microphones. The cali- brations are made at normal incidence over the frequency range of 2.5 kHz

to 20 kHz. They are reported in terms

of open-circuit voltage per unit sound

pressure of a plane progressive wave

whose direction of propagation is normal to the plane of the diaphragm.

The calibrations are performed in a well characterized anechoic chamber.

A typical uncertainty in this cali- bration is approximately 0.15 dB at each frequency within the range of

2.5 kHz to 20 kHz. Calibrations can be performed with or without protective grids on the microphone. For the

most precise free-field measurements,

the customer should contact the NBS

staff person cited at the beginning of

this section for recommendations

prior to submitting the microphone to NBS for calibration. Special Tests of Acoustic Devices

(25060S)

Acoustical measurement services are

available by special arrangement.

These services include extended fre- quency ranges, additional data points,

and calibration of certain pistonphones and acoustic calibrators. NBS has a large general purpose an- echoic chamber available for special

calibrations requiring such a facility.

The frequency-dependent and

position-dependent acoustical per- formance df this chamber, including

extremely low background noise, has

been carefully controlled during design and construction and is documented.

Special Tests of Earphones (25070S)

Earphones are tested on an NBS 9-A

Coupler from 125 to 8000 Hz.

References—Acoustic Measurements

Specifications for Laboratory Standard Microphones, American National Standards Institute, SI. 12-1967

(R1977), New York, N.Y.

Method for Calibration of Microphones, American National Standards

Institute, SI. 10-1966 (R1976), New

York, N.Y.

Calibrations of Microphones, Vibration Pickups, and Earphones,

R. K. Cook, S. Edelman, and

W. Koidan, J. Audio Eng. Soc, 13, No. 4 (Oct. 1965).

Method of Measurement of E/I in the

Reciprocity Calibration of Condenser

Microphones, W. Koidan, J. Acoust.

Soc. Am., 32, No. 5, 611 (May 1960).

Hydrogen Retention System for Pres- sure Calibration of Microphones in Small Couplers, W. Koidan, J. Acoust. Soc. Am., 35, No. 4, 614

(Apr. 1963).

Free-Field Correction for Condenser

Microphones, W. Koidan and D. S. Siegel, J. Acoust. Soc. Am., 36, No.

11, 2233 (Nov. 1964).

Calibration of Standard Condenser

Microphones: Coupler Versus Electrostatic Actuator, W. Koidan, J. Acoust. Soc. Am., 44, No. 5, 1451

(Nov. 1968).

Calibration of Laboratory Condenser

Microphones, V. Nedzelnitsky, E. Burnett, and W. Penzes, Proceedings

of the 10th Transducer Workshop,

Transducer Committee, Telemetry

Group, Range Commanders Council,

Colorado Springs, CO (June 1979).

Traceability of Acoustical Instrument

Calibration to the National Bureau of

Standards, V. Nedzelnitsky, Proc. INTER-NOISE 80, II, Dec. 8-10,

1980, Miami, FL, G. C, Maling, Jr., Ed., Poughkeepsie, NY: Noise Control Foundation, 1043 (1980).

Wedge Design for the National Bureau of Standards Anechoic Chamber, W. Koidan, G. R. Hruska, and

M. A. Pickett, J. Acoust. Soc. Am.,

52, No. 4 (Part 1), 1071 (1972).

Acoustical Properties of the National

Bureau of Standards Anechoic Chamber, W. Koidan and G. R. Hruska, J. Acoust. Soc. Am., 64, No. 2 (Aug.

1978).

38
LJ Ultrasonic Measurements

# #m Automated Production Technology Division

Center for Manufacturing Engineering

Technical Contact:

Gerald V.

Blessing

Tel: 301/921-3646

Mailing Address: A147 Sound, National Bureau of Standards, Gaithersburg, MD 20899

Test No. Items 260 IOC Ultrasonic Transducer Power and Frequency

26020C Acoustic Emission Sensors 26030S Special Tests of Area Amplitude of Aluminum

Reference Blocks—Set of Eight Blocks

26040S Each additional block/measurement

26050S Distance amplitude set 26060S Each additional block/measurement

26070S Special Tests of Ultrasonic Transducer Power

Ultrasonic Transducer Power and Fre- quency (260 IOC)

Measurements of total ultrasonic for- ward power radiated into a water

load are offered for the purpose of

characterizing ultrasonic systems and

transducers. Ultrasonic systems are characterized by measurement of out- put under operating conditions specified by the customer. Transducers for which the continuous-wave electrical input voltage can be accurately and

reproducibly measured are characterized by a radiation conductance determined from measurements of input

voltage and output power. A typical

calibration report for an ultrasonic

system provides the results of at least three measurements of output power

for each operating condition specified. Calibration reports for trans- ducers typically present a single value

of radiation conductance derived

from at least 15 measurements of output power spanning an appropriate

range of power. Resonance fre- quencies of transducers are deter- mined from the results of iterative spot-frequency relative measurements

of radiation conductance.

Continuous-wave ultrasonic power

is measured using a modulatedradiation force balance. Output power

is determined from the force required

to arrest the motion of a conical tar- get which diverts the output beam of

the transducer under test into a bank

of absorbers. Absolute power can

thus be measured at spot frequencies

between 1 and 20 MHz. The overall

uncertainty varies from 2.2% at 1 MHz to 7.6% at 20 MHz. These esfi- mates of uncertainty apply to measurements made at power levels ranging from a few milliwatts to a few watts; the minimum detectable

power is about 10 microwatts while

high-power measurements are limited

by the onset of cavitation in the water

load. Transducers of diameter no

greater than 45 mm can be tested in this apparatus.

Pulsed ultrasonic power is measured using a specially designed cal- orimeter. With pulsed excitation, only

ultrasonic systems comprising a trans- ducer and an electrical driver can be

tested. Transducers by themselves

cannot be independently characterized with pulsed drive waveforms

since the electrical input signals can- not at present be adequately measured

or characterized. Power levels ranging from 1 mW to several watts at frequencies between 1 and 15 MHz

can be measured with an overall uncertainty less than 7% + 0.2 mW.

Transducers with diameters as great

as 26 mm can be accommodated.

Measurements of continuous-wave

power are also possible with the cal- orimeter. The length of its response

time precludes swept-frequency tests. Acoustic Emission Sensors (26020C)

The NBS acoustic emission trans- ducer calibration provides the voltage

39
output of a transducer per unit of motion (displacement or velocity) of the

mounting surface as a function of fre- quency. The calibration is based upon

the normal component of motion

which would occur in the absence of

the transducer. The test method is as follows: a step function of "point"

force is generated on the surface of a

large steel block by breaking a glass

capillary. The transducer under test and the NBS standard capacitive

transducer are located on this same

surface and are equidistant from the

source. Both transducers experience

the motion of the seismic surface

pulse generated by the step function

force. The transient voltage outputs

from both transducers are recorded

and analyzed for frequency content. The frequency response of the trans- ducer under test is obtained by di- viding the spectral amplitude from it by that from the standard transducer,

frequency by frequency. The cali- bration is absolute, since the sensitivity of the standard transducer is known. The magnitude and phase of

the sensitivity of the transducer under

test are obtained at discrete fre- quencies, fn = 9765.625n (Hz), where

n= 1,2,3... The customer is provided

with the results in the form of graphs

of magnitude and phase. These are piecewise linear functions constructed

through the data points. Within the

valid range of 0. 1 to 1 MHz, the uncertainty is approximately 10%. At

the option of the customer, the results will be given with respect to normal

displacement of velocity of the

mounting surface, on a magnitude

scale or on a decibel scale. Special Tests of Aluminum Reference

Blocks (26030S-26040S)

The ultrasonic response of 7075 alu- minum alloy reference blocks of 0.50

inch and greater metal path distances

is determined relative to an NBS in- terim reference standard. The immersion, pulse-echo, longitudinal

wave, 5 MHz quartz transducer testing system defined in the ASTM

E-127 calibration document is used

with some procedural modifications. In the NBS-developed procedure, the

interim reference standards are cali- brated along with the customer's

blocks. System precision and stability over time are provided by the set of

check standard blocks with flat- bottom hole sizes of 3/64, 5/64, and

8/64 inch diameter. Standard deviation data, representing random er- rors associated with the NBS system,

are provided for the respective block

and hole sizes. The plus or minus two

standard deviation uncertainty levels range from about 3 to 10 percent of

block response, depending on the

block and hole sizes of the respective

check standards. A comparison of the customer's block value to the data

base of all blocks measured by NBS is also available. Response following the

procedures of the ASTM Recommended Practice E-127 can also be deter- mined. In addition, the response of some blocks with metal path distances

less than 0.50 inch can be obtained by

special arrangement.

Special Tests of Ultrasonic Transducer

Power (26070S)

This service includes consultation,

customized testing, and the lending of

air-backed transducers for the pur- pose of transferring power measurements. Quartz transducers characterized by radiation conductance and

thus suited for the reproduction of ar- bitrary power levels are available for frequencies of 2, 3, and 5 MHz and

can be specially calibrated for operation at odd overtones. Lithium nio- bate transducers with built-in cir- cuitry allowing the field user to reproduce prearranged power levels while measuring only dc voltage are

available for use at frequencies below

20 MHz approximated by odd multiples of 0.5 MHz.

References—Ultrasonic Measurement

An Assessment of Ultrasonic Refer- ence Block Calibration Methodology,

G. V. Blessing, Natl. Bur. Stand.

40
(U.S.), Int. Report, NBSIR 83-2710

(June 1983).

Standard Practice for Fabricating and

Checking Aluminum Alloy Ultrasonic

Standard Reference Blocks, E- 127-81,

in Annual Book of ASTM Standards,

Vol. 03.03, Philadelphia, PA, Amer.

Soc. for Testing and Materials (1982).

Acoustic Emission Transducer Calibration by Means of the Seismic Surface Pulse, F. R. Breckenridge, J. Acoust. Emission, 1, No. 2 (Apr.

1985).

Characterization and Calibration of

Acoustic Emission Sensors, N. N.

Hsu and F. R. Breckenridge, Matls.

Eval., 39, No. 1, 60 (Jan. 1981).

Surface-Wave Displacement: Absolute Measurements Using a Capacitive

Transducer, F. R. Breckenridge and

M. Greenspan, J. Acoust. Soc. Am.,

69, No. 4, 1177 (Apr. 1981).

Calibration and Sensor Activities,

D. G. Eitzen, F. R. Breckenridge,

R. B. Clough, E. R. Fuller, N. N.

Hsu, and J. A. Simmons, Chapter 2.0

in Fundamental Developments for Quantitative Acoustic Emission Measurements, EPRI NP-2089, Research

Project 608-1, Palo Alto, CA, Electric Power Research Institute, 2-1-2-52 (Oct. 1981).

Traceability of Acoustical Instrument

Calibration to the National Bureau of

Standards, V. Nedzelnitsky, Proc. INTER-NOISE 80, II, Dec. 8-10,

1980, Miami, FL, G. C, Maling, Jr., Ed., Poughkeepsie, NY; Noise Control Foundation, 1043 (1980).

Ultrasonic Transducer Characterization at the NBS, E. R. Miller and

D. G. Eitzen, IEEE Trans. Sonics

and Ultrasonics, SU-26, No. 1, 28

(Jan. 1979).

Recent Improvements to the ASTMType Ultrasonic Reference Block

System, D. J. Chwirut, Natl. Bur.

Stand. (U.S.), Int. Report, NBSIR

79-1742 (Feb. 1979).

The Evaluation of Search Units Used

for Ultrasonic Reference Block Calibrations, D. J. Chwirut and G. D.

Boswell, Natl. Bur. Stand. (U.S.), Int.

Report, NBSIR 78-1454 (Feb. 1978).

Ultrasonic Transducer Power Output

by Modulated Radiation Pressure, M.

Greenspan, F. R. Breckenridge, and

C. E. Tschiegg, J. Acoust. Soc. Am.,

63, No. 4, 1031 (Apr. 1978).

Ultrasonic Transducer Power Output

by Modulated Radiation Pressure (with details), M. Greenspan, F. R. Breckenridge, and C. E. Tschiegg,

Natl. Bur. Stand. (U.S.), Int. Report,

NBSIR 78-1520 (July 1978).

Improved Ultrasonic Standard Refer- ence Blocks, G. F. Sushinsky, D. G.

Eitzen, D. J. Chwirut, C. J. Bechtoldt, and A. W. Ruff, Natl. Bur.

Stand. (U.S.), Int. Report, NBSIR

76-984 (Nov. 1976).

Procedures for the Calibration of

ASTM E127-Type Ultrasonic Refer- ence Blocks, D. J. Chwirut, G. F. Sushinsky, and D. G. Eitzen, Natl. Bur. Stand. (U.S.), Tech. Note 924

(Sept. 1976).

Ultrasonic Calorimeter for Beam

Power Measurements from 1 to 15 Megahertz, T. L. Zapf, M. E. Harvey, N. T. Larsen, and R. E. Stoltenberg, 1976 Ultrasonics Symposium Proceedings, IEEE Cat. 76,

CH1120-ISU, Inst, for Electron, and

Electric. Engrs., New York, NY

(1976).

Ultrasonic Calorimeter for Beam

Power Measurements, T. L. Zapf, M.

E. Harvey, N. T. Larsen, and R. E.

Stoltenberg, Natl. Bur. Stand. (U.S.),

Tech. Note 686 (Sept. 1976).

Acoustic Emission: Some Applications of Lamb's Problem, F. R. Breckenridge, C. E. Tschiegg, and M.

Greenspan, J. Acoust. Soc. Am., 57, No. 3, 626 (Mar. 1975).

Calibration of Quartz Transducers as Ultrasonic Power Standards by an

Electrical Method, T. L. Zapf, 1974

Ultrasonics Symposium Proceedings,

IEEE Cat. 74, CH0896-ISU, Inst, for Electron, and Electric. Engrs., New

York, NY (1974).

41
Chapter

A Pressure Measurements

B Vacuum and Low Pressure Measurements

C Laboratory Thermometers

D Thermocouples, Thermocouple

Materials, and Pyrometer Indicators

E Resistance Thermometry

F Radiation Thermometry

G Humidity Measurements
Thermodynamb Quantities 29010C-29O4(JS

Pressure Measurements

m Temperature and Pressure Division

Center for Basic Standards

Technical Contact:

Bernard E. Welch

Tel: 301/921-2121

Mailing Address: A55 Metrology, National Bureau of Standards, Gaithersburg, MD 20899

Test No. Items 290 IOC Deadweight Piston Gages

29020C Controlled Clearance Piston Gages

29030C Pressure Gages and Transducers

29035C Mercurial Barometers and Manometers

29040S Special Tests of Pressure Gages

Piston Gages and Pressure Transducers (29010C-29035C)

The NBS provides measurement ser- vices for the calibration of piston

gages and transducers operating with

gas in the range of 1.4 kPa to 17 MPa

and with oil in the range of 700 kPa

to 400 MPa. Calibrations are done by

the cross-floating technique using

NBS piston gages. Uncertainties are shown in Table 1

.

Table 1: Gage and Pressure Measurement Uncertainties

Type of Instrument Range Uncertainty

Gas-operated PG 1.4 kPa to 17 MPa ±57 ppm

Oil-operated PG 700 kPa to 100 MPa ±63 ppm

100 MPa to 280 MPa ±60 to ±150 ppm

Oil-operated PG 40 to 400 MPa ±186 ppm

Special Tests of Pressure Gages

(29040S)

Special tests of pressure gages and

other pressure measuring devices can be performed on request.

References—Pressure Measurements

An Intercomparison of Pressure Stan- dards Between IMGC and NBS, J. C. Houck, G. F. Molinar, and R. Maghenzani, J. Res. Natl. Bur. Stand.

(U.S.), 88, 253 (1983).

An Intercomparison of Pressure Stan- dards Between LNE and NBS, R. G.

Driver, J. C. Houck and B. E. Welch,

J. Res. Natl. Bur. Stand. (U.S.), 86,

No. 3 (May-June 1981).

Absolute High Pressure Measurements, V. E. Bean, High Pressure Sci- ence and Technology, B. Vodar and

43
29010C-29040S

Greg Driver, calibrating deadweight tester.

Ph. Mardeau, Eds., 231, Pergamon

Press, Oxford, England (1980).

Piston Gages, P. L. M. Heydemann

and B. E. Welch, Chapter 4, Experimental Thermodynamics, Vol. II. Experimental Thermodynamics of NonReacting Fluids, B. Le Neindre and

B. Vodar, Eds., Part 3, 147, Butter- worth and Co., London (1975).

Reduction of Data for Piston Gage

Measurement, J. L. Cross, Natl. Bur.

Stand. (U.S.), Monogr. 65 (1963).

A Method to Determine the Pressure Dependent Distortion of a Simple

Piston Gage Based on Dimensional

Metrology, B. E. Welch and V. E. Bean, High Pres. Sci. and Tech., 22,

II, 261, C. Homan, R. K. MacCrone,

and E. Whalley, Eds., Elsevier Sci- ence Publishing Co., Inc., New York

(1984).

Effects of Viscosity, Temperature,

and Rate of Rotation on Pressure Generated by a Controlled-Clearance

Piston Gauge, J. K. N. Sharma, K. K.

Jain, V. E. Bean, B. E. Welch, and

R. J. Lazos, Rev. Sci. Instrum. 55,

563 (1984). Pressure and Temperature Measurements in the Annulus Between

the Piston and Cylinder of a Simple

Dead-Weight Piston Gauge, B. E.

Welch and V. E. Bean, Rev. Sci. In- strum. 55, 1901 (1984).

International Comparison in the Pres- sure Range 20-100 MPa Organized by

the High Pressure Working Group of

the Comite Consultatif pour la Masse,

J. C. Legras, V. E. Bean, J. Jager,

S. L. Lewis, and G. F. Molinar,

BIPM Internal Technical Report

84/2, Intl. Bur. of Weights and Meas.,

Paris (1984).

Note on the Results of the First Phase of an International Comparison

in the Pressure Range 20-100 MPa

Organized by the High Pressure Working Group of the Comite Consultatif pour la Masse, J. C. Lagras,

V. E. Bean, J. Jager, S. L. Lewis, and

G. F. Molinar, J. Phys. E: Sci. Instrum. 18, 361 (1985). Factors Affecting the Precision of

Gas Operated Piston Gages at the Part Per Million Level, B. E. Welch,

L. A. Guildner, and V. E. Bean,

Proc. 31st Intl. Instrum. Symp., San

Diego, CA, 9 (May 1985).

Elastic Distortion of Piston Gages,

J. Lazos-Martinez and V. E. Bean,

Proc. Xth Conf. of the Intl. Assoc.

for the Advanc. of High Pressure Sci. and Tech., Amsterdam (July 1985). Pressure Metrology: Primary Stan- dard Piston Gages, V. E. Bean, Proc. Xth Conf. of the Intl. Assoc. for the

Advanc. of High Pressure Sci. and

Tech., Amsterdam, (July 1985).

44
30010C-30050S

Vacuum and Low Pressure

Measurements

Temperature and Pressure Division

Center for Basic Standards

Technical Contacts:

Richard W. Shamll D. Wood

Hyland Tel:301/921-2121

Tel:301/921-2121 30030C, 30050S

30010C, 30020C,

30040S, 30050S

Mailing Address: A55 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items 30010C Absolute Low Pressure Gages

30020C Differential Low Pressure Gages

30030C High Vacuum Gages

30040S Special Tests of Low Pressure Gages

30050S Special Tests of Vacuum Gages

Low Pressure Gages (30010C and

30020C)

Absolute low pressure gages including capacitance diaphragm gages and

quartz spiral gages are calibrated

against the NBS Ultrasonic Inter- ferometer Manometer. This standard covers a range limited at the low end

by its 10 mPa instability and extending up to 1600 kPa (1200 Torr). The

uncertainty of the standard is 0.01%

of reading plus 10 mPa. This standard

is also used for the calibration of low

range differential gages, including ball gages. High Vacuum Gages (30030C)

A standard of the orifice flow type covers the range from 10"' to 10"* Pa

(10"^ to 10"* Torr) for most gases with an uncertainty of 1% between

10 ' and 10"^ Pa, increasing to 10%

at 10 *" Pa. Ion gages and spinning ro- tor or spinning ball gages are ac- cepted for calibration but all gages

must be bakeable to 250 °C and

should be welded to "Conflat" type

flanges. Standard procedure is to cali- brate the sensor and electronics as a package although ion gage controllers

that do not regulate the emission current or deliberately change it will not be accepted for calibration. An extra

fee will be charged for ion gage cali- bration below 10"'* Pa. For an additional fee NBS will pro- vide tabulated Bayard-Alpert gages

with tungsten filaments and 2.75 in.

Figure 8. Uncertainties of NBS Low Pressure and

Vacuum Standards

Log Pressure (Torr) -10 -8 -6 -4 -2 0 2 4

1 1 1 1 1 Ultra High

1 1 1 Atmospheric Vacuum Pressure

Ultrasonic

| \

^Manometers - ^.-^\ \

\ \

\ N _ \

Orifice Flow _ ' Standards ' V"\ Present Uncertainties Under Development

1 1 1 1 1

\\

\

\

\

1 1 1 -8 -6 -4 -2 0 2 4 6 Log Pressure (Pa)

"Conflat-type" flanges. These will be

calibrated with the user's electronics.

Special Tests of Gages (30040S and

30050S)

Instruments requiring special cali- bration procedures or prolonged test- ing can often be accommodated as a

special test. Consult with technical contact listed at the beginning of the

section. Figure 8 summarizes the uncertainties of the NBS low pressure and

45
30010C-30050S

vacuum standards. Dashed lines are

target uncertainties expected from new standards under development or improvements to existing standards.

References—Vacuum and Low

Pressure Measurements

Reliability of High Vacuum Measurements, C. R. Tilford, J. Vac. Sci. Technol., A1(2), 152 (Apr. -June

1983).

Calibration of Molecular Drag Vacuum Gages, K. E. McCulloh, J. Vac.

Sci. Technol. A 1(2) (Apr.-June 1983).

Performance Characteristics of a Broad Range Ionization Gage Tube,

C. R. Tilford, K. E. McCulloh and

H. S. Woong, J. Vac. Sci. Technol.,

20, 1140 (1982).

Ultrasonic Manometers for Low and

Medium Vacua Under Development

at NBS, P. L. M. Heydemann, C. R.

Tilford and R. W. Hyland, J. Vac.

Sci. Technol., 14, 597 (Jan.-Feb.

1977).

Zero Stability and Calibration Results

for a Group of Capacitance Diaphragm Gages, R. W. Hyland and

C. R. Tilford, J. Vac. Sci. Technol.,

A3, 1731 (1985).

Sensitivity of Hot Cathode Ionization

Gages, C. R. Tilford, J. Vac. Sci. Technol., A3, 546 (1985).

Long-Term Stability of Two Types

of Hot Cathode Ionization Gages, S. D. Wood and C. R. Tilford, J. Vac.

Sci. Technol., A3, 542 (1985).

Zero Stability of Spinning Rotor

Vacuum Gages, K. E. McCulloh, S. D. Wood, and C. R. Tilford, J. Vac.

Sci. Technol., A3, 1738 (1985).

pa „M

Sharrill Wood, calibrating spinning rotor vacuum gages.

46
31010C-31260S

C Laboratory Thermometers

V Temperature and Pressure Division

Center for Basic Standards

Technical Contact:

Jacquelyn A.Wise

Tel: 301/921-2087

Mailing Address: B128 Physics, National Bureau of Standards, Gaithersburg, MD 20899

Shipping Address: National Bureau of Standards, 1-270 at Quince Orchard Road, A242 Physics, Gaithersburg, MD

20899

Attn: J. Wise

Test No. Items Test No. Items 31010C Laboratory Thermometers (0 to 150 °C) (32 to 300 °F) 31110S Special Tests of Thermometers (0 to 150 °C)

31011C Each additional point (32 to 300 "F)

31020C Laboratory Thermometers (151 to 300 °C) 31111S Each additional point

(301 to 600 °F) 31 120s Special Tests of Thermometers (151 to 300 °C)

31021C Each additional point (301 to 600 "F)

31030C Laboratory Thermometers (301 to 538 °C) 31121S Each additional point

(601 to 1000 °F) 31130S Special Tests of Thermometers (301 to 538 °C)

31031C Each additional point (601 to 1000 °F)

31040C Laboratory Thermometers (—1 to — 1 10 °C) 31131S Each additional point

(31 to -166 °F) 31140S Special Tests of Thermometers (—1 to — 1 10 "C)

31041C Each additional point (31 to -166°F)

31050C Laboratory Thermometers (Liquid N2) 31141S Each additional point

(-196 °C or -320 "F) 31150S Special Tests of Thermometers (Liquid N2) ( — 196°C

31051C Each additional point or -320 °F)

31060C Laboratory Thermometers (Liquid O2) 31151S Each additional point

(-183 "C or -297 °F) 31160S Special Tests of Thermometers (Liquid O2) 31061C Each additional point (-183 °C or -297 °F)

31070C Calorimetric Thermometer 31161S Each additional point

31071C Each additional Calorimetric Thermometer 3 1200s Preliminary Exam or Ineligible Thermometer

31080C Beckmann Thermometer 31250S Additional copy of report

31081C Each additional Beckmann Thermometer 31260S Special Thermometry Services by Prearrangement

31100S Special Tests of Liquid-In-Glass Thermometers

Laboratory Thermometers

(31010C-31100S)

This service provides for the cali- bration of a variety of thermometers

covering the range from — 196 to + 538 °C (-320 to + 1000 °F).

Thermometers belonging to the

large and varied group, which may

47
31010C-31260S

be classed as laboratory or "chemical" therrnometers, are regularly ac- cepted. These are of the liquid-inglass type with either solid-stem or enclosed scale. Ordinary household

or meteorological thermometers will

not, in general, be accepted unless the

scale is graduated on the glass stem it- self and the thermometer can be

readily detached from its mounting

for insertion in a testing bath. Every

thermometer submitted must be

uniquely identified by a serial number

and must pass a preliminary examination for fineness and uniformity of

graduation; for cleanliness of the mercury and capillary bore; for freedom

from moisture, gas bubbles, and

cracks in the glass; for adequacy or omission of gas filling where needed;

for insufficient annealing; and for misnumbered graduations. When these or

other serious defects are found, the

thermometer is returned untested. The thermometers to be calibrated are placed in a constant temperature

bath along with the NBS primary

standard—a calibrated platinum re- sistance thermometer. The primary

standard maintains calibrations trace- able to the International Practical

Temperature Scale of 1968 (IPTS-68)

with an accuracy of ~ 5 mK at the

lower range and ~2 mK at the

higher range. (See Table 2).

Table 2: Thermometer Calibration Uncertainties

Type of Thermometer Range Uncertainty

(Total Immersion)

Mercury in-glass

(graduations:

0.1-0.2 "O

Mercury in-glass

(graduations:

1-2°C)

0 to 100 °C

0 to 300 °C

300 to 500 "C

Organic liquid-in-glass —200 toO°C

:0.03 to ±0.05 "C

:0.2 to ±0.3 °C

:0.5 to ±1.0°C

±0.2 to ±0.5 °C

Special Tests of Thermometers

(31110S-31161S)

Special tests may be conducted on

temperature measuring devices such

as industrial grade platinum resistance

thermometers, digital thermometers,

thermistors, etc. Laboratory personnel should be contacted before submitting items.

Figure 9 summarizes the relative

NBS uncertainties for different types

of temperature-measuring instruments

including thermometers, thermocouples, and pyrometers. See also fol- lowing sections.

References—Laboratory Thermometers

Liquid-in-Glass Thermometry, J. A.

Wise, Natl. Bur. Stand. (U.S.),

Monogr. 150, (Jan. 1976).

ASTM Standard El -85, Specification

for ASTM Thermometers, Annual

Book of ASTM Standards 14.01, 89,

Figure 9. Uncertainties for NBS Calibration of

Temperature Measuring Instruments

Uncertainty in NBS Calibrations

(Relative to IPTS-68 and EPT-76)

10°

10-'

tain 10-^

o

c

10"^

Z) 10-' ^°0

-IPTS-68- -EPT-76-

1.0

-J t 1 I H Hi 10 100

Temperature (K) 1000 10,000

Amer. Soc. for Test. and Matls., Phil. PA (1985).

ASTM Standard E77-84 Methods of

Verification and Calibration of

Liquid-in-Glass Thermometers, Annual Book of ASTM Standards 14.01,

150, Amer. Soc. for Test, and Matls.,

Phil., PA (1985).

48
32010C-32150S

D. Thermocouples, Thermocouple Materials,

and Pyrometer Indicators

Temperature and Pressure Division

Center for Basic Standards

Technical Contacts:

George W. Bums Margaret G.

Tel: 301/921-2069 Scroger

Tel: 301/921-2069

Mailing Address: B128 Physics, National Bureau of Standards, Gaithersburg, MD 20899

Shipping Address: National Bureau of Standards, 1-270 at Quince Orchard Road, B229 Physics, Gaithersburg, MD

20899

Attn: G. Bums or M. Scroger

George Bums, making reference junction connections in an ice bath, in preparation for thermocouple calibration.

Comparison Calibrations, Temperature Measured with Thermocouple:

Test No. ItemsTemp. Min. Est. TC Range Points Length Temp. Uncert. Type °C mm "C °C

32010C S 0-1450 1 ° interv. Table 700

32020C R 0-1450

32030C B 0-1750

32031C B 800-1750

700

1000

1000

0 to 1100 0.5 1450 2 0 to 1100 0.5 1450 2 0 to 600 (3fxV)

600 to 1100 0.5 1450 2 1750 3 800 to 1100 0.5 1450 2 1750 32040C E 0-1000 4 to 15 700

32041C J 0-760 4 to 15 700

32042C K 0-1100 4 to 15 700 32043C N 0-1100 4tol5 700

32044C T 0-400 4 to 15 700

32050C Comparison calibration, two point minimum, per

point, for all items above

3205 IC Comparison calibration, each additional point for above

32060C Each additional table of results at 1

° intervals, for Type S, R, or B

32070C Thermocouple materials tested against Pt standard, 4

to 15 points, 700 mm minimum lengths

Calibration at Metal Freezing Points. Minimum

Diameter 0.4 mm. Freezing Point Determination at Au, Ag, 630. 74 °C, and Zn

32090C S 0-1450 Table, 1

° interv. 1000 at freezing

and equations to points

generate table 0 to 1100

1450

0.2

0.3

3209 IC Type S, freezing point determination, per point, two

point minimum

32092C Type S, freezing point determination, each additional point for above

Calibration of Pyrometer Indicators 32100C Portable Potentiometer, first dial or range 32101C Portable Potentiometer, each additional dial or range

49
32010C-32150S

Comparison Calibrations, Temperature Measured with Thermocouple:

Test No. Items

Comparison Calibration of Thermocouples or Thermocouple Materials Tested Against Pt

Thermoelectric Standard, Temperature Measured

with Platinum Resistance Thermometer, Minimum

Length 36 Inches, Two Point Minimum

321 IOC* Range -110 to +300 "C and Liquid N2 (-196 °C) or - 166 to 600 °F and Liquid N2 (-320 °F) 321 1 IC* Each additional point for test 321 IOC

32120C* 301 to 538 "C or 601 to 1000 "F

32 121c* Each additional point for test 32120C

32 1 30C* Liquid O2 ( - 1 83 °C) or ( - 297 "F)

321 3 IC* Each additional point for test 321 30C

Table at one degree intervals for Type T thermocouple for any of the following options:

(The cost of the table will be in addition to the calibration per point covered under fee schedule items numbered 321 10C-32131C)

32141C* Option 1: Table from -190 to +300 °C (-310 to + 572 °F), calibration points at -183, -110, -50, + 100, +200, +300 °C. 32142C* Option 2: Table from -190 to +100 °C (-310 to + 212 °F), calibration points at -183, -110, -50, + 50, +100''C.

32143C* Option 3: Table from -110 to +300 "C (-166 to + 572 "F), calibration points at -110, -50, +100,

+ 200, +300 °C. 32144C* Option 4: Table from - 1 10 to +100 °C (- 166 to + 212 °F), calibration points at -110, -50, +50, + 100°C.

32145C* Option 5: Table 0 to 300 °C (32 to 572 °F), calibration points at +100, +200, +300 °C. 32146C* Option 6: Table from - 1 10 to 0 °C (- 166 to +32 °F), calibration points at — 1 10, —50 °C. 32147C* Option 7: Table from - 190 to 0 °C (-310 to + 32 °F), calibration points at -183, -110, -50 °C. 32150S Special Tests of Thermocouples and Thermocouple

Materials

* Jacquelyn Wise (Tel: 301/921-2087) is the technical contact for these

tests. See Section C of this chapter for her mailing and shipping addresses.

Thermocouples, Thermocouple

Materials, and Pyrometer

Indicators (32010C-32147C)

Calibration services for all commonly

used types of thermocouples are pro- vided by NBS from - 196 to 1750 "C

depending upon the wire or thermocouple type. The thermocouples are calibrated by one or a combination of

three general methods, depending on

the thermocouple type, the temperature range, and the accuracy re- quired. All three methods provide

traceability to the IPTS-68. In the

first method, thermocouples are cali- brated by comparison with a standard

thermocouple maintained at NBS. In the second method, thermocouples

are calibrated by comparison with a standard platinum resistance ther- mometer. In the third method, ther- mocouples are calibrated at three

defining temperatures on the IPTS

the freezing points of Zn, Ag, and

Au, as well as at 630.74 °C. Below

0 °C the thermocouple calibration is carried out in a cryostat, while above

0 °C stirred liquid baths, metal

freezing-point cells, and electric tubetype furnaces are employed for the

calibrations. Vacuum or inert gas fur- naces are also available for testing

thermocouples.

Only the bare wires are required to perform the thermocouple cali- brations. It is preferable not to send

insulating and protecting tubes as the

rate of breakage of these in shipment

is high. If the thermocouple is fur- nished mounted (as in a protection

50
tube assembly) a nominal charge will be made for dismantling the mounting

and the various parts will be returned

to the sender without reassembling

them. Thermocouple length requirements listed in the appendix are ex- clusive of lead wire. Lead wire need

not be sent with thermocouples. All

thermocouple calibration data fur- nished in reports will be on the basis

of a reference junction temperature of

0 °C or 32 °F. The calibration results will be given in degrees C or F, as re- quested by the customer. The cali- bration of a thermocouple will not be

undertaken if it will likely not yield

the specified accuracy or if it possesses such unusual characteristics as to prevent the carrying out of the cal- ibration or test at a reasonable cost. Only unused base-metal thermocouples and thermocouple materials

will be accepted for test. Special Tests of Thermocouples and

Thermocouple Materials (32150S)

For requirements not covered by cali- brations described above, special ar- rangements may be made by contacting one of the Temperature and

Pressure Division staff members identified at the beginning of this section.

References—Thermocouples

ASTM Standard E220-80, Standard

Method for Calibration of Thermocouples by Comparison Techniques,

Annual Book of ASTM Standards,

14.01, 255, Amer. Soc. for Test, and

Matls., Phil., PA (1983).

ASTM Standard E230-77,

Temperature-Electromotive Force

(EMF) Tables for Thermocouples,

Annual Book of ASTM Standards,

14.01, 271, Amer. Soc. for Test, and

Matls., Phil., PA (1983).

American National Standard, Temperature Measurement Thermocouples, ANSI-MC96. 1-1982, Instr. Soc. of Amer., Res. Triangle Park,

NC (1982).

Manual on the Use of Thermocouples

in Temperature Measurement, ASTM

STP 470B, Amer. Soc. for Test, and

Matls., Philadelphia, PA (1981).

Accurate Thermocouple Thermometry, L. A. Guildner and G. W. Burns,

High Temperatures—High Pressures,

11, 173 (1979).

International Electrotechnical Commission Standard, Thermocouples,

Part 1: Reference Tables, lEC Publication 584-1, Intl. Electrotech. Com.,

Geneva (1977).

Thermocouple Reference Tables

Based on the IPTS-68, R. L. Powell,

W. J. Hall, C. H. Hyink, Jr., L. L. Sparks, G. W. Burns, M. G. Scroger,

and H. H. Plumb, Natl. Bur. Stand.

(U.S.), Monogr. 125 (1974).

Methods of Testing Thermocouples

and Thermocouple Materials, W. F. Roeser and S. T. Lonbarger, Natl. Bur. Stand. (U.S.), Circular 590

(1958).

51
33010C-33120M

£ Resistance Thermometry

r Temperature and Pressure Division

Center for Basic Standards

Technical Contact:

William R. Bigge

Tel: 301/921-2757

Mailing Address: B128 Physics, National Bureau of

Standards, Gaithersburg, MD 20899

Shipping Address: National Bureau of Standards, 1-270 at Quince Orchard Road, B04 Physics, Gaithersburg, MD

20899

Attn: W. Bigge

Test No. Items 33010C Long Stem PRT (-50 °C to +500 or +630 °C)

33020C Long Stem PRT ( - 183 °C to +500 or +630 "C)

33030C Calorimetric Type PRT ( - 50 to + 1 50 °C)

33040C Capsule Type PRT (13 K to 600K)

33050C Capsule Type PRT ( - 183 °C to +300 °C)

33060S Special Tests of Germanium Resistance

Thermometers (2 to 20 K)

33070C Additional Copy of Table from Results of

33010C-33050C at Time of Test 33080C Additional Copy of Table from Results of

33010C-33050C at Later Date 33090C Minimum Charge for Unsuitable Thermometer

33100S Special Tests of Resistance Thermometers

331 lOS Special Tests of Thermometric Fixed-Point Devices

33120M Measurement Assurance Program for Temperature

Platinum Resistance Thermometers

(33010C-33050C)

NBS provides calibration services for standard platinum resistance ther- mometers (SPRTs) from 13.81 to 903

K. Both long-stem and capsule-type

SPRTs are calibrated, providing di- rect access to the IPTS-68. The re- producibility of the calibration measurements of SPRTs is better than

±0.3 mK and the accuracy of overall

calibration is ± 1 mK. The reproducibility of triple point of water cells used for calibration of SPRTs is ±50 jLiK or better while that for zinc

and tin freezing-point cells is ±0.1

mK. The precision of comparison cal- ibration of long-stem type SPRTs in terms of the reference standard

SPRTs at the oxygen boiling point

(-183 °C) is better than ±0.1 mK.

The stability of the reference SPRTs

in this temperature range is also about

±0.1 mK. The NBS temperature

scale in the range 1 3 to 90 K is based on stable reference standard SPRTs

of the capsule type and has a precision of about ±0.1 mK down to about 20 K. Below 20 K, the precision degrades to about ±0.3 mK as the SPRTs become less sensitive. To qualify for testing, either longstem or capsule platinum resistance

thermometers must meet two conditions. They must reasonably be ex- pected to meet the requirements of

the IPTS-68 for a standard inter- polating instrument (i.e., a four lead

resistor of high-purity platinum her- metically sealed in a protecting tube).

Second, they must be compatible

with the NBS highest-precision cali- bration equipment. It is important

that, insofar as possible, resistance

thermometers be protected from any

mechanical shock which will alter their calibration. To be shipped, the

thermometer must be softly supported

within a case but not be free to rattle. This necessitates the use of packing

material that does not become compacted. The thermometer case should

in turn be softly packed inside a shipping container. The outside shipping

container must be sufficiently rigid

and strong that it will not appreciably

deform under the treatment usually

52
33010C-33120M

given by shippers. Styrofoam is not

sufficiently rigid to be used as an outside container. Thermometers will not be returned in containers which are obviously unsuitable, such as those

closed by nailing. Suitable containers

will be provided, for a fee, when a thermometer shipping container is not

satisfactory for reuse. Special Tests of Germanium

Resistance Thermometers and

Thermometric Fixed Point Devices

(33060 S, 33100S, and 33110S)

Special tests of various resistance

thermometers and thermometric fixed

point devices may be made by pre- arrangement with the Temperature

and Pressure Division.

Measurement Assurance Program for Temperature (33120M)

The purpose of this MAP service is to assure the accuracy of the cali- bration of temperature standards

made by participating laboratories in the - 183 to +630 °C temperature

range when using platinum resistance

thermometry. Special arrangements

may be made if participants are inter- ested in only a portion of this temperature range. The MAP transport standard consists of a set of three commercial

glass-sheathed standard-type platinum

resistance thermometers (SPRTs)

packaged in a special shock-proof

shipping container (mechanical shock

or sudden temperature excursions

may result in shifts in calibration).

These SPRTs are used to assess both

the reproducibility and the accuracy

of calibrations performed by the participating laboratory.

MAP participants should use the

techniques in NBS Monograph 126

and the same fixed points as in the

NBS calibrations, or an SPRT pre- viously calibrated by NBS. In order

to achieve high accuracy, SPRTs

used as standards should be of the

matte-finish type to avoid systematic

errors arising from light pipe effects

in the glass sheath. The participant

must have a triple point cell and a calibrated resistance bridge.

After unpacking the transport stan- dard and inspecting it for damage the

participant should measure the re- sistance of the SPRTs at the triple

point of water using the triple-point

cell. A preliminary check of the re- sistances at the water triple point is used as a "go/no go" check to ensure

that the thermometers have not been

damaged in shipment.

These measurements are reported

by telephone to NBS; if the values

are consistent with the data taken by

NBS before shipment, the participant

should proceed with further measurements. Data are taken by NBS

and the participants at the fixed

points defined in the IPTS-68. NBS

provides a worksheet on which the

participant can record the data. The

participant then calculates the ther- mometer constants from the experimental data, records them, and pre- pares tables of resistance versus temperature.

The SPRTs are recalibrated upon

return to NBS and the data are compared to NBS's calibrations. NBS

provides a plot of the participating

laboratory's temperature deviation

from NBS values and a written analysis of the data including any perti- nent observations. In a typical transfer, the participant makes several

measurements over a period of two to three months. A typical turnaround

time from the date NBS receives the

participant's data until a test report is sent to the participant is three to four

weeks.

The best NBS SPRT calibrations

have precisions of about 0.1 to 0.2 mK. Sources of error that may contribute to the total uncertainty include

53
changes in the calibration of the measurement instruments, changes in the

SPRT itself, and uncertainty of the

degree of purity of the materials used

as fixed-point references (e.g., zinc).

As a result of quantifying these sources of error, NBS currently as- signs an uncertainty of 1 mK to the

values assigned to the MAP transport

standards. A standards laboratory

conscientiously participating in this MAP and having suitable equipment

should be able to closely approximate

this uncertainty figure. Participants in the temperature MAP have uncertainties that range from close to 1 mK

to hundredths of a kelvin.

No rigid recommendations can be

given concerning how often a participant should utilize the temperature

MAP service. Experience has indi- cated that when temperature measurements are in a state of statistical control using in-house check stan- dards and control charts to monitor

the process, the participant should be

able to go at least three years between transfers from NBS without

significantly degrading the confidence

in the correctness of the measurements.

References—Resistance Thermometry

Reproducibility of Some Triple Point

of Water Cells, G. T. Furukawa and

W. R. Bigge, Temperature, Its Measurement and Control in Science and

Industry, Vol. 5, 291, Amer. Inst. Phys., New York, NY (1982).

Standard Reference Materials: Application of Some Metal SRM's as Thermometric Fixed Points, G. T. Furukawa, J. L. Riddle, W. R. Bigge and

E. R. Pfeiffer, Natl. Bur. Stand.

(U.S.), Spec. Publ. 260-77 (Aug.

1982).

A Measurement Assurance ProgramThermometer Calibration, G. T. Furukawa and W. R. Bigge, in Testing

Laboratory Performance, Evaluation

and Accreditation, Natl. Bur. Stand.

(U.S.), Spec. Publ. 591, 137 (Aug.

1980).

Comparison of Freezing Temperature

of National Bureau of Standards

SRM-740 Zinc Standards, G. T. Fur- ukawa and J. L. Riddle, Comite Consultatif de Thermometrie, May 9-11,

1978, Sevres, France. The International Practical Temperature Scale of 1968 in the Region

90.188 K to 903.89 K as Maintained

at the National Bureau of Standards,

G. T. Furukawa, J. L. Riddle, and W.

R. Bigge, J. Res. Natl. Bur. Stand.

(U.S.), 80A, 477 (May-June 1976).

The International Practical Temperature Scale of 1968 in the Region

12.81 K to 90.188 K as Maintained at the National Bureau of Standards, G.

T. Furukawa, J. R. Riddle, and W. R. Bigge, J. Res. Natl. Bur. Stand.

(U.S.), 80A, 477 (May-June 1973).

Platinum Resistance Thermometry, J. L. Riddle, G. T. Furukawa, and H.

H. Plumb, Natl. Bur. Stand. (U.S.),

Monogr. 126 (Apr. 1973).

Investigation of Freezing Temperatures of National Bureau of Stan- dards Tin Standards, G. T. Fur- ukawa, J. L. Riddle and W. R. Bigge,

Vol. 4 of Temperature, Part 1, 247,

Instr. Soc. of Amer., Pittsburgh, PA

(1972).

54
35010C-35070S

F.

Radiation Thermometry

Radiometric Physics Division

Center for Radiation Research

Technical Contact:

Ronald L. Wilkinson

Tel: 301/921-3613

Mailing Address: A223 Physics, National Bureau of Standards, Gaithersburg, MD 20899

Test No. Items 35010C Optical Pyrometers (1 range between 800 to 2400 °C, 4 to 12 points)

35020C Optical Pyrometers (per range in addition up to 4200 °C)

35030C Additional interpolated values 35040C Optical Pyrometers (3 or fewer points, 800 to 4200 °C)

35050C Ribbon Filament Lamp (6 to 1 6 points, 800 to 2300 "C)

35060C Ribbon Filament Lamp (5 or fewer points, 800 to 2300 °C)

35070S Special Tests of Radiation Pyrometers

Optical Pyrometers and Ribbon

Filament Lamps (35010C-35060C)

These calibration services provide ac- cess to the IPTS-68 as realized by

NBS for the temperature range

800 °C to 4200 °C. High precision

monochromatic visual and automatic

optical pyrometers are calibrated in that temperature range. Uncertainties

in routine testing vary from ±3 °C at 1064 °C, and ±8 °C at 2800 °C, to ±30 °C at 4200 "C. Ribbon filament

lamps are calibrated using the NBS

photoelectric pyrometer, and reports

of brightness temperature at 655 nm

versus direct current are issued. Uncertainties in routine testing vary

from ±0.75 °C at 1064 °C to ±2 °C

at 2300 °C. The radiation thermometry portion

of IPTS-68 is defined in terms of a

fixed temperature for the freezing

point of gold (1064.43 °C) and the

Planck equation for the radiation of a blackbody source. In practice, temperature scales are realized by constructing a gold point blackbody and

a variable temperature blackbody,

and then measuring spectral radiance

ratio at a red wavelength (approximately 650 nm) in terms of the Planck

equation. Gold point blackbodies are reproducible to ±0.02 °C, but the

temperature assignment of the freez- ing point of gold is uncertain by

about ±0.5 °C. The spectral radiance

ratio measurements can be performed

with an uncertainty of 0.2 to .3%.

Higher accuracies than available in the routine tests described above can

be provided as special tests subject to the IPTS uncertainties noted. Calibrations at wavelengths other than

650 nm can be provided in the wavelength range 250 to 2500 nm subject

to an additional uncertainty due to the quality of the variable temperature blackbody.

Special Tests of Radiation Pyrometers

(35070S)

Calibrations at wavelengths other

than 650 nm can be provided in the

wavelength range 250 nm to 2500 nm

subject to an additional uncertainty

due to the quality of the variable temperature blackbody. Absorbing glass

55
filters used for range changing in optical pyrometers can also be cali- brated as special tests.

References—Radiation Thermometry

The International Practical Temperature Scale of 1968, Amended

Edition of 1975, Metrologia, 12, 7

(1976).

Corrections in Optical Pyrometry and

Photometry for the Refractive Index

of Air, W. R. Blevin, Metrologia, 8, 146 (1972).

Vacuum Tungsten Strip Lamps with

Improved Stability as Radiance Temperature Standards, T. J. Quinn and

R. D. Lee, 5th Symposium on Temperature, 395, Instr. Soc. Am., Res. Triangle Park, NC (1971).

High-Accuracy Spectral Radiance

Calibration of Tungsten-Strip Lamps,

H. J. Kostkowski, D. E. Erminy, and

A. E. Hattenburg, Adv. Geophys. 14, 111 (1970).

The NBS Photoelectric Pyrometer

and Its Use in Realizing the Inter- national Practical Temperature Scale

above 1063 "C, R. D. Lee, Metrologia, 2, No. 4, 150 (Oct. 1966).

Theory and Methods of Optical Pyrometry, H. J. Kostkowski and R. D.

Lee, Natl. Bur. Stand. (U.S.),

Monogr. 41 (Mar. 1962).

Humidity Measurements

Chemical Process Metrology Division

Center for Chemical Engineering

Technical Contact:

Saburo Hasegawa

Tel: 301/921-3748

Mailing Address: B312 Physics, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items 360 IOC Dew-Point Hygrometers (-1-25 to - 15 °C)

36020C Dew-Point Hygrometers (-70 to - 15 °C)

36030C Electric Hygrometers

36040C Coulometric Hygrometers

36050C Aspirated Hygrometers

36060C Pneumatic Bridge Hygrometers

36070S Special Tests of Humidity

Hygrometers (36010C-36060C)

NBS provides calibration services for

a wide variety of humidity-measuring

instruments. Calibrations are per- formed by subjecting the instrument

under test to atmospheres of known

moisture content produced by the

NBS two-pressure humidity generator. The instruments and ranges of

calibration are listed below:

A. Dew-Point Hygrometers cali- brated over the dew/frost range of

-80 to +80 °C.

B. Electric Hygrometers classified under this category are sensors which

56
36010C-36070S

sorb water vapor as a function of rel- ative humidity; associated with this sorption is a corresponding change in an electric parameter (that is, re- sistance, capacitance). The range of

calibration is 3 to 98 percent relative

humidity over the temperature range

-55 to +80 °C. C. Psychrometers are a wet-dry

bulb hygrometer (aspirated

psychrometers). The contact person

should be consulted for the special

features of the psychrometer which

are necessary before the instrument can be calibrated at NBS.

D. Coulometric Hygrometers are devices which electrolyze water into

gaseous oxygen and hydrogen by the

application of a voltage in excess of

the thermodynamic decomposition

voltage for water, and then measure

the electrolysis current. The range of

calibration is 1 to 31,000 ppm by vol- ume.

E. Pneumatic Bridge Hygrometers are instruments which measure the variation of the pressure drop across two combinations of nozzles, operating at critical flow, with a desiccant between one pair of nozzles. The range of calibration in mixing ratio (gram water vapor/gram

dry air) is 0.0005 to 0.015. Figure 10 illustrates typical NBS

uncertainties for measurement of humidity standards with atmospheric air at atmospheric pressure.

Special Tests of Humidity (36070S)

Tests such as response time, hysteresis, stability, can be provided upon

request.

References—Humidity Measurements

Vapor Pressure Formulation for Ice, A. Wexler, J. Res. Natl. Bur. Stand.

(U.S.), 81 A (Phys. and Chem.), No. 1, 5 (Jan.-Feb. 1977).

The NBS Two-Pressure Humidity

Generator, Mark 2, S. Hasegawa and

J. W. Little, J. Res. Natl. Bur. Stand.

(U.S.), 81 A (Phys. and Chem.), No .1, 81 (Jan.-Feb. 1977).

Vapor Pressure Formulation for Water in Range 0 to 100 °C. A revision,

A. Wexler, J. Res. Natl. Bur. Stand.

(U.S.), 80A (Phys. and Chem.), Nos.

5 and 6, 775 (Sept.-Dec. 1976).

A Correlation for the Second Inter- action Virial Coefficients and Enhancement Factors for Moist Air, R. W. Hyland, J. Res. Natl. Bur. Stand.

(U.S.), 79A (Phys. and Chem.), No. 4, 551 (July-Aug. 1975).

The NBS Standard Hygrometer, A.

Wexler and R. W. Hyland, Natl. Bur.

Stand. (U.S.), Monogr. 73 (May 1964).

Figure 1 0. NBS Uncertainties for Measurements of

(Humidity Standards with Atmospheric Air at Atmospheric

Temperature

1000

M 100

co

-70

Frost Point, °C Dew Point, °C

-50 -30 -10 10 30 50

10

T" I I III I I I r

' Gravimetric

Two-Pressure Generator

0.001 0.01 0.1 L_ 10

0,1

^1.o c

o

3.

10

100

100

Mlixing Ratio, g/kg

57
Chapter

A Photometric Measurements

B Spectrophotometric Measurements

C Radiometric Measurements

D Radiometric Standards in the

Ultraviolet E Optical Fiber Attenuation and

Bandwidth

F Laser Power and Energy
Optical Radiation Measurements

jt

3701OC-37180S

Photometric Measurements

r^m Radiometric Physics Division

Center for Radiation Research

Technical Contact:

Donald A. McSparron

Tel: 301/921-3613

Mailing Address: B306 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items Test No. Items

370 IOC Luminous Intensity Standard (100 W Frosted 37100C Luminous Flux Standard (100 W Gas-Filled Lamp

Tungsten Lamp, 90 candelas) about 1600 lumens)

37020C Luminous Intensity Standard (100 W Frosted 371 IOC Luminous Flux Standard (200 W Gas-Filled Lamp

Tungsten Lamp, color temp., 2700 K) about 3300 lumens)

37030C Luminous Intensity Standard (100 W Frosted 37120C Luminous Flux Standard (500 W Gas-Filled Lamp

Tungsten Lamp, color temp., 2856 K) about 10,000 lumens)

37040C Luminous Intensity Standard (500 W Frosted 37130C Luminous Flux Standard (Miniature Lamps 7 sizes Tungsten Lamp, 700 candelas) 6 to 400 lumens)

37050C Luminous Intensity Standard (500 W Frosted 37140C Airway Beacon Lamps for Color Temperature

Tungsten Lamp, color temp., 2856 K) (500 W, 1 point in range, 2000-3000 K)

37060C Luminous Intensity Standard (1000 W Frosted 37150C Each additional color temp.

Tungsten Lamp, 1400 candelas) 37160C Color temperature equation (4 points and

37070C Luminous Intensity Standard (10(X) W Frosted interpolation equation)

Tungsten Lamp, color temp., 2856 K) 37170C Opal Glass Luminous Directional Transmittance

37080C Luminous Flux Standard (25 W Vacuum Lamp about Standards

270 lumens) 371 80S Special Photometric Tests 37090C Luminous Flux Standard (60 W Gas-Filled Lamp

about 870 lumens)

General Information

Calibration services in this area pro- vide access to the photometric scales realized and maintained at NBS.

Lamp standards of luminous intensity,

luminous flux, and color temperature

as described below are calibrated on a routine basis. Luminous Intensity Standards

(37010C-37070Q

Luminous intensity standard lamps

supplied by NBS [100-W (90-140 cd),

59
5(X)-W (approximately 700 cd) and

1000-W (approximately 1400 cd)

tungsten filament lamps with C-13B

filaments in inside-frosted bulbs and

having medium bipost bases] are cali- brated at either a set current or a

specified color temperature in the

range 2700 to 3000 K. Approximate

uncertainties are 2 percent relative to the SI unit of luminous intensity and

1.5 percent relative to NBS standards.

Luminous Flux Standards

(37080C-37130C)

Luminous flux standards—lamps

(geometrically total) submitted by the customer. Vacuum tungsten lamps of

25 W and 60-, 100-, 200-, and 500-W

gas filled tungsten lamps are cali- brated. Lamps must be basf -up burning and rated at 120 V. Approximate

uncertainties are 2.5 percent relative to SI units and 1.5 percent relative to NBS standards. Luminous flux stan- dards for miniature lamps producing

6 to 400 Im are calibrated with uncertainties of 3 percent.

Airway Beacon Lamps

(37140C-37160C)

Color temperature standard lamps

supplied by NBS (airway beacon

500-W medium bipost lamps) are cali- brated for color temperature in the

range 2000 to 3000 K with an

uncertainty of 10 degrees.

Opal Glass Luminous Directional

Transmittance Standards (37170C)

Flashed opal glasses, 5 1 mm x 5 1 mm,

are calibrated for luminous directional

transmittance (exitant luminance per

incident illuminance). The glasses are masked with a diaphragm limiting the

useful area to a circle 1.9 cm in diameter.

Special Tests of Photometric Devices

(37180S)

Lamp standards of luminous intensity can be calibrated at any color temperature in the range 2000 K to 3200

K. Photometric values can be computed for special sources measured

spectrally on the Facility for Automatic Spectral Calibrations (FASCAL). See test 39070S for details. Reference—Photometric

Measurements

Photometric Calibration Procedures,

V. I. Burns and D. A. McSparron,

Natl. Bur. Stand., (U.S.), Tech. Note

594-3 (Nov. 1972).

60
Spectrophotometric Measurements

Radiometric Physics Division

Center for Radiation Research

Technical Contact:

Victor R. Weidner

Tel: 301/921-2453

Mailing Address: B306 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items 38010C Spectral Transmittance Filters (Cobalt Blue

Glass)

38020C Spectral Transmittance Filters (Copper Green

Glass)

38030C Spectral Transmittance Filters (Carbon Yellow

Glass)

38040C Spectral Transmittance Filters (Selenium

Orange Glass)

38050C Wavelength Standards (Holmium Oxide Glass)

38060S Special Tests of Spectral Transmittance and

Reflectance 38070M Measurement Assurance Program for Retroreflectance—Complete Package

3807 IM Retroreflectance MAP—Sheeting Standards or

Prismatic Standard with Colored Filters 38072M Retroreflectance MAP—Sheeting Standards

and Prismatic Standard Without Colored Filters 38073M Retroreflectance MAP—Sheeting Standards or

Prismatic Standard Without Colored Filters 38074M Retroreflectance MAP—Colored Filters Only

38080M Measurement Assurance Program for Transmittance

38090S Special Tests of Photographic Step Tablets 38100S Special Tests of Microcopy Resolution Test Charts

Spectral Transmittance Filters (38010C-38040Q

NBS supplies standards of spectral

transmittance for checking the photometric scale of spectrophotometers.

These are either 30 mm polished glass

disks or 5 1 mm polished glass squares, 2 to 3 mm thick, designated as cobalt

blue, copper green, carbon yellow,

and selenium orange (disks will be

supplied unless otherwise specified).

Information provided to the user in- cludes: values of transmittance at 25 °C at 10 nm intervals from 380 to 770 nm; the estimated uncertainty of

each value; and data as to the effect of temperature change on trans- mittance at each wavelength.

Wavelength Standards (38050Q

Holmium oxide glass standards are

also supplied for checking the ultra- violet and visible wavelength cali- brations of recording spec- trophotometers having a bandpass

less than 2 nm. These are made of

polished Coming 3130 glass, 51x51

mm, 2.5 mm thick. A table of wavelengths of minimum transmittance is provided in the report to the user. Special Tests of Spectral Transmittance and Reflectance (38060S)

Measurements of spectral trans- mittance can be made for the wavelength region 190 to 2500 nm. Measurements of absolute spectral

reflectance factors and of spectral

specular reflectance can be made for the wavelength region 250 to 2500 nm. However, arrangements for these

measurements on submitted specimens

61
must be made before shipment. The

decision as to whether or not to per- form the measurements and selection

of the instruments to be used will rest with NBS. Specimens not accepted

for measurement will be returned.

Accuracy and precision estimates will be given. Estimates will be dependent

upon the optical characteristics of the

submitted specimens.

Measurement Assurance Programs for Retroreflectance (38070M-38074M)

These Measurement Assurance Pro- grams (MAPs) verify, within certain

limits, how well a laboratory can measure coefficient of luminous in- tensity. The verification is accomplished by means of a MAP package.

The MAP package containf two

white bead sheeting retroreflectors, one colorless prismatic retroreflector,

and seven colored glass filters. The

elements in this package are measured

by NBS, then by the participating

laboratory, and finally by NBS. Quality control procedures are maintained

by using NBS master standards.

The use of three retroreflectors en- able determination of how well the

participant can measure coefficient of

luminous intensity for white or col- orless samples of three kinds of geometries. The luminous transmittance of

the seven colored glass filters can be

used as a diagnostic tool to check

measurements of coefficient of lumi- nous intensity of colored retroreflectors. This is accomplished by

checking the conformance of the

source-receiver combination to CIE

Illuminant A and photopic response

respectively.

The coefficient of luminous in- tensity of each of the bead sheeting

standards is measured at six combinations of observation and entrance angles. The coefficient of luminous in- tensity of the prismatic retroreflector

is measured at 18 combinations of en- trance and observation angles. The

luminous transmittance of the filters is provided only for the spectral conditions of source and receiver specified

above.

A general testing laboratory will probably need the service utilizing

the complete MAP package. However, some laboratories may be specialized. For this reason, we list five options that offer not only the complete package, but also some selected

components. These options are: A . Complete MAP package;

B. Sheeting standards or prismatic

standard with colored filters; C. Sheeting standards or prismatic

standard without colored filters; D. Sheeting standards and prismatic standard without colored fil- ters; and

E. Colored filters only.

Measurement of even the complete

MAP package achieves only part of

the goal of a MAP service. To fully

benefit from the MAP procedure, we

suggest that the participant have on

hand several check standards to be

measured while also measuring the

MAP package. These check standards can then be measured periodically to determine any gross error in measurement procedure, and a control

chart can be constructed. A control

chart is a plot of measurement result versus time, and normally the measurement process is considered to be

under control if measurements fall within ±3 standard deviations from

the mean. For retroreflectance measurements where geometric errors are

large, the standard deviation obtained

after changing geometrical parameters may be large compared with that

62
38010C-381(X)S

obtained from repeated measurements

without changing the apparatus.

Thus, the total variation for a given

instrument can be obtained only by

repetition over a period of time and

realignment of the experimental

apparatus.

The uncertainties of retro- reflectometer measurements have

three sources: uncertainties associated

with values assigned by NBS to the

MAP package, participant uncertainties, and uncertainties due to environment and sample interaction. Repeated measurements without

changing the apparatus show that the

NBS random error is small relative to the systematic errors. A large fraction

of the latter arise when the retro- reflector is rearranged and realigned

for making measurements with differ- ent measurement parameters.

Measurement Assurance Program for Transmittance (38080M)

The Transmittance Measurement Assurance Program (MAP) provides a means for a laboratory to assess the

accuracy of its spectral transmittance

measurement capabilities. A laboratory which participates in this pro- gram will be sent a package of trans- mittance filters, which have been

measured at NBS. These are to be

measured by the laboratory on its spectrophotometer(s) and returned,

together with the measurement results, to NBS. NBS will then re- measure the filters and send a final analysis of the result to the participating laboratory. The range of fil- ter measurements provided in the

MAP package permits an evaluation

of the accuracy of a laboratory's

spectral transmission measurements

and will often reveal the cause of any

systematic errors that exist. The contents of the MAP package

include seven neutral density filters with nominal transmittances ranging

from 0.2 to 0.001. The filters are

available in three sizes. The filter holders are 51x51 mm, 51x38 mm, or standard cuvette. In addition, the

package contains one didymium glass

filter that is to be used for wavelength scale calibration: several wavelengths of transmittance minima and

points of inflection have been measured by NBS for this filter. These

wavelengths have been shown to be

stable over long periods of time;

therefore, these didymium filters are not normally measured by NBS with

every use of the MAP package. The

didymium filter is useful for trian- gular bandpasses between 1.5 and

10.5 nm.

It is strongly suggested that the

participating laboratory acquire a set of check standards similar to the NBS

filters for maintaining a control chart

and measurement assurance.

Special Tests of Photographic Step

Tablets (38090S)

Special tests for transmission or re- flection optical density can be per- formed by prior arrangement. Tablets

submitted must be free of scratches,

fingerprints, abrasions, and foreign matter and must have steps of uni- form density. 45 °/0 ° absolute visual

reflection density is measured in ac- cordance with ANSI Standard

PH2. 17-1977. Special Tests of Microcopy Resolution Test Charts (38100S)

Tests charts conforming to ISO Stan- dard 3334, NMA Standard

MS 104- 1972, and MIL-M-9868D, can be tested by special arrangement.

References—Spectrophotometric

Measurements

White Opal Glass Diffuse Spectral

Reflectance Standards for the Visible

63
Spectrum (SRMs 2015 and 2016), V.

R. Weidner, Natl. Bur. Stand. (U.S.),

Spec. Publ. 260-82 (1983).

Extension of a Reference Spectrophotometer into the Near Infrared,

K. L. Eckerle, V. R. Weidner, J. J. Hsia, and Z. W. Chao, Natl. Bur. Stand. (U.S.), Tech. Note 1175 (Apr.

1983).

Measurement Assurance Program

Transmittance Standards for Spectrophotometric Linearity Testing:

Preparation and Calibration, K. L. Eckerle, V. R. Weidner, J. J. Hsia,

and K. Kafadar, J. Res. Natl. Bur.

Stand. (U.S.), 88(1), 25 (1983).

Second-Surface Mirror Standards of

Spectral Specular Reflectance (SRMs

2023, 2024, 2025), J. C. Richmo.id, J.

J. Hsia, V. R. Weidner, and D. B. Wilmering, Natl. Bur. Stand. (U.S.),

Spec. Publ. 260-79 (Oct. 1982).

Proposed Standards for the NBS Retroreflectance MAP, K. L. Eckerle

and J. J. Hsia, Color Res. and Appl.,

7(3), 235 (1982).

NBS 45 "/Normal Reflectometer for Absolute Reflectance Factors, J. J. Hsia and V. R. Weidner, Metrologia,

17, 97 (1981).

NBS Specular Reflectometer

Spectrophotometer, V. R. Weidner

and J. J. Hsia, Appl. Opt., 19, 1268

(Apr. 1980).

New Reference Retroreflectometer,

K. L. Eckerle, J. J. Hsia, V. R.

Weidner, and W. H. Venable, Jr., Appl. Opt., 19(8), 1253 (1980).

Photometry and Colorimetry of Retroreflection: State-of-Measurement

Accuracy Report, K. L. Eckerle,

Natl. Bur. Stand. (U.S.), Tech. Note

1125 (July 1980).

Inverse-Fourth Apparatus for Photometric Calibrations, D. A. Swyt and

J. G. LaRock, Rev. Sci. Instrum.,

49(8), 1083 (Aug. 1978).

Establishing a Scale of DirectionalHemispherical Reflectance Factor 1: The Van den Akker Method, W. H.

Venable, Jr., J. J. Hsia, and V. R. Weidner, J. Res. Natl. Bur. Stand.

(U.S.), 82, 1, 29 (July-Aug. 1977).

New Reference Spectrophotometer,

K. D. Mielenz, K. L. Eckerle, R. P. Madden, and J. Reader, Appl. Opt.,

12, 7, 1630 (July 1973).

Permanence of Glass Standards of

Spectral Transmittance, K. S. Gibson

and M. A. Belknap, J. Res. Natl. Bur.

Stand. (U.S.), 44, 463 (May 1950).

Basic Considerations of Densitometer

Adjustment and Calibration, R. E. Swing, Natl. Bur. Stand. (U.S.),

NBSIR 75-682 (Feb. 1975).

The Optics of Densitometry, R. E. Swing, Opt. Eng., 12, 6, 185

(Nov./Dec. 1973).

Basic Considerations of Densitometer

Adjustment and Calibration, R. E. Swing, Natl. Bur. Stand. (U.S.), Report 10970 (Dec. 1972).

64
39010C-39070S

C.

Radiometric Measurements

Radiometric Pliysics Division

Center for Radiation Research

Technical Contact:

John K. Jackson

Tel: 301/921-3613

Mailing Address: A221 Physics, National Bureau of Standards, Gaithersburg, MD 20899

Test No. Items

390 IOC Spectral Radiance Ribbon Filament Lamps (225

to 2400 nm)

39020C Spectral Radiance Ribbon Filament Lamps (225

to 800 nm)

39030C Spectral Radiance Ribbon Filament Lamps (650

to 2400 nm)

39040C Spectral Irradiance Quartz-Halogen Lamps (250

to 1600 nm)

39050C Spectral Irradiance Deuterium Lamps

(200-350 nm)

39060C Photodiode Spectral Response Rental Package

(DRIP)

39070S Special Tests of Radiometric Sources

Spectral Radiance Ribbon Filament

Lamps (39010C-39030C)

These spectral radiance standards are supplied by NBS. Tungsten, ribbon

filament lamps (30A/T24/13) are pro- vided as lamp standards of spectral

radiance. The lamps are calibrated at 34 wavelengths from 225 to 2400 nm,

with a target area 0.6 mm wide by 0.8 mm high. Radiance temperature

ranges from 2650 K at 225 nm, and

2475 K at 650 nm to 1610 K at 2400

nm, with corresponding uncertainties

of 3, 1, and 0.5%. See also related

tests 40010S-40040S, next section. Figure 1 1 summarizes the measurement uncertainty for NBS spectral radiance calibrations. Spectral Irradiance Lamps (39040C

and 39050C)

These spectral irradiance standards

are supplied by NBS. Lamp standards

of spectral irradiance are provided in two forms. Tungsten filament,

1000-watt quartz halogen type FEL

lamps are calibrated at 26 waveFigure 1 1 . Uncertainties for NBS Spectral Radiance

Calibrations

500

200 -

S 100

E

0.4 0.6 1 2 Wavelength in Micrometers

lengths in the range 250 to 1600 nm.

This will be extended shortly to 24(X) nm. At the working distance of 50

cm, the lamps produce 0.2 W/cm' at 250 nm, 220 W/cm^ at 900 nm, and

1 15 W/cm^ at 1600 nm, with corre- sponding uncertainties ranging from

2.5 to 1 percent. Deuterium lamp

65
standards of spectral irradiance are

also provided and are calibrated at 16 wavelengths from 200 to 350 nm. At

the working distance of 50 cm, the

spectral irradiance produced by the

lamp ranges from about 0.4 W/cm^ at 200 nm and 0.3 W/cm^ at 250 nm to 0.07 W/cm^ at 350 nm. The deuterium lamps are intended primarily

for the spectral region 200 to 250 nm. The approximate uncertainty relative to SI units is 6% at 200 nm and 3%

at 250 nm. The approximate uncertainty in relative spectral distribution

is 3%. It is strongly recommended

that the deuterium standards be compared to an FEL tungsten standard over the range 250 to 300 nm each

time the deuterium lamp is lighted to take advantage of the accuracy of the

relative spectral distribution. Figure 12 summarizes the measurement uncertainty for NBS spectral irradiance calibrations. Photodiode Spectral Response Package

(39060C)

Photodiode response packages can be

rented from NBS. Absolute spectral

responsivity calibrations can be obtained by leasing one of the NBS Detector Response Transfer and Inter- comparison Packages (DRIPs). This

is a well-characterized radiometer

that utilizes a silicon photodiode as the detector element. Its calibration is reported in units of A/W at a number

of wavelengths in the 250 to 1064 nm

range. A precision aperture is pro- vided for calibrations in units of A

cm^/W. The duration of the lease is sufficient to enable the transfer of the

calibration to a laboratory's own

in-house standards, and the per- formance of specific diagnostic tests to check the laboratory's capability to perform spectral response transfer measurements. At present, the DRIP

calibration is based on the self- calibrated silicon photodiode technique and electrical substitution radi- ometry using cw laser lines and

several atomic emission lines as monochromatic radiation sources for the characterization measurements.

The absolute spectral response is re- ported at 10 nm intervals from 250 to 960 nm, and at two discrete wavelengths outside this range (1014 and

1064 nm). The estimated uncertainty

ranges from 1 to 6%, depending on

the wavelength and the particular ra- diometers. The radiometers cover a range of detector current from 10"^

Figure 1 2. Uncertainties for NBS Spectral Irradiance

Calibrations

to

10' 1 1 I I I I I I I I I I i_J

0.1 0.2 0.4 0.6 1 2 4 6 Wavelength in Micrometers

to 10""* A. This corresponds to a radi- ant power range of about 1 nw to 1 mw.

Special Tests of Radiometric Sources

(39070S)

Spectroradiometric source caHbrations are performed on the Facility

for Automatic Spectral Calibrations

(FASCAL). This instrument has the

capability of performing spectral radi- ance measurements from 200 to 2500

nm, radiance temperatures from 1050

K to 2700 K, and adjustable spectral

bandpass down to 0. 1 nm. Spectral ir- radiance measurement capability from

200 to 2400 nm at flux levels down to

0. 1 W/cm' is also available. For both

spectral radiance and irradiance measurements a wide variety of sources

I 66
39010C-39070S

Jim Walker, aligning a lamp in the Facility for Automated Spectrometric Calibrations.

and measurement geometries are possible. Special tests utilizing the capabilities of PASCAL are occasionally

performed depending on the availability of the equipment and associated personnel.

References—Radiometric

Measurements

High-Accuracy Spectral Radiance

Calibration of Tungsten-Strip Lamps,

H. J. Kostkowski, D. E. Erminy, and

A. T. Hattenburg, Adv. Geophys.,

14, 111 (1970).

The 1973 NBS Scale of Spectral Irra- diance, R. D. Saunders and J. B. Shumaker, Natl. Bur. Stand. (U.S.),

Tech. Note 594-13 (1977).

Spectral Irradiance Standard for the

Ultraviolet: The Deuterium Lamp, R. D. Saunders, W. R. Ott, and J. M.

Bridges, Appl. Opt. 17, 593 (1978).

Silicon Photodiode Device with

100% External Quantum Efficiency, E. F. Zalewski and C. R. Duda,

Appl. Opt., 22, 2867 (1983).

Silicon Photodiode Absolute Spectral

Response—Self-Calibration Using a Filtered Tungsten Source, C. G.

Hughes, in, Appl. Opt., 21, 2129

(1982).

Silicon Photodiode Absolute Spectral

Response Self-Calibration, E. F. Zalewski and J. Geist, Appl. Opt., 19, 1214(1980).

Spectral Response Self-Calibration

and Interpolation of Silicon Photodiodes, J. Geist, E. F. Zalewski, and

A. R. Schaefer, Appl. Opt. 20, 3795

(1980).

The NBS Detector Response Transfer and Intercomparison Package:

The Instrumentation, M. A. Lind, E.

F. Zalewski, and J. B. Fowler, Natl. Bur. Stand. (U.S.), Tech. Note 950

(1977).

Spectral Radiometry: A New Approach Based on Electro-Optics, J. Geist, M. A. Lind, A. R. Schaefer,

and E. F. Zalewski, Natl. Bur. Stand.

(U.S.), Tech. Note 954 (1977).

Fundamental Principles of Absolute

Radiometry and the Philosophy of

this NBS Program (1968 to 1971), J. Geist, Natl. Bur. Stand. (U.S.), Tech.

Note 594-1 (1972).

67
40010S-40040S

D. Radiometric Standards in the Ultraviolet

Atomic and Plasma Radiation Division

Center for Radiation Research

Technical Contacts:

John M. Bridges

Tel: 301/921-2356

Jules Z. Klose

Tel: 301/921-2356

Mailing Address: A 167 Physics, National Bureau of Standards, Gaithersburg, MD 20899

Test No. Items 4001 OS Special Test, Spectral Irradiance Standard,

Argon Mini-Arc (140 to 330 nm)

40020S Special Test, Spectral Radiance Standard,

Argon Mini-Arc (115 to 330 nm)

40030S Special Test, Spectral Irradiance Standard,

Deuterium Arc Lamp (165 to 200 nm)

40040S Special Tests of Radiometric Devices in the Near and Vacuum Ultraviolet

Special Tests of Radiometric Stan- dards in the Ultraviolet

(40010S-40040S)

NBS maintains a collection of secondary standard sources such as argon

maxi-arcs, argon mini-arcs, and deuterium arc lamps in the near and vac- uum ultraviolet radiometric standards

program to provide calibrations for

user-supplied sources. The cali- brations of these sources are traceable

to a hydrogen arc whose radiance is calculable and which NBS maintains

as a primary standard. The collection

also includes tungsten strip lamps and

tungsten halogen lamps whose cali- brations are based on a blackbody

rather than a hydrogen arc. Customer-supplied sources are cali- brated in both radiance and irradiance

by comparing them with NBS sec- ondary standards.

Argon arcs are used to calibrate

other sources in the wavelength

range 115 nm to 330 nm for radiance

and 140 nm to 330 nm for irradiance.

The lower wavelength limit is deter- mined in radiance by the cutoff of the

magnesium fluoride windows used in the arcs and in irradiance by the de- crease in signal produced by the addition of a diffuser. Deuterium arc lamps are used in the range 165 nm to 200 nm, with the low wavelength

cutoff due to the onset of blended

molecular lines. The high wavelength

limit is the starting point of the range

of another calibration group at NBS.

(See tests 39010C-39050C, previous

section.) The tungsten lamps are used

at 250 nm and above, since their sig- nals are too weak at shorter wavelengths. It should be noted that the

wavelength range of the NBS arcs

partially overlaps the range of tungsten lamps, thus providing an independent check on calibrations. An argon mini-arc lamp supplied

by the customer is calibrated for spectral irradiance at 10 nm intervals in the wavelength region 140-300 nm.

68
40010S-40040S

Absolute values are obtained by comparison of the radiative output with

laboratory standards of both spectral

irradiance and spectral radiance. The

spectral irradiance measurement is made at a distance of 50 cm from the

field stop. Uncertainties are estimated

to be less than ±10 percent in the

wavelength region 140-200 nm and

within ±5 percent in the wavelength

region 200-330 nm. A measurement

of the spectral transmission of the

lamp window is included in order

that the calibration be independent of

possible window deterioration or damage.

The spectral radiance of argon

mini-arc radiation sources is deter- mined to within an uncertainty of less than 7 percent over the wavelength

range 140-330 nm and 20 percent over the wavelength range 115-140 nm. The calibrated area of the 4 mm

diameter radiation source is the central 0.3 mm diameter region. Typical

values of the spectral radiance are: at 250 nm, Lx = 30 mW cm"^ nm"' sr~'; and at 150 nm, Lx=3 mW cm"^ nm"'

sr"'. The transmission of the demountable lamp window and that of an additional MgF2 window are determined individually so that the user may check periodically for possible

long term variations.

The deuterium arc lamp is cali- brated at 10 wavelengths from 165 to 200 nm, at a distance of 50 cm, at a spectral irradiance of about

0.5 W/cm' at 165 nm, 0.3 W/cm^ at 170 nm, and 0.5 W/cm^ at 200 nm. The approximate uncertainty relative to SI units is estimated to be less than

10 percent. The lamp is normally supplied by NBS and requires 300 mA at about 100 V.

References—Vacuum Ultraviolet Radiometric Measurements

VUV Spectral Irradiance Calibrations: Method and Applications,

W. R. Ott, J. M. Bridges and J. Z. Klose, Opt. Lett., 5, 225 (1980).

Spectral Irradiance Standard for the

Ultraviolet: The Deuterium Lamp, R. D. Saunders, W. R. Ott, and J. M.

Bridges, Appl. Opt., 17, 593 (1978).

Spectral Radiance Calibrations Be- tween 165-300 nm: An Inter- laboratory Comparison, J. M.

Bridges, W. R. Ott, E. Pitz, A.

Schultz, D. Einfield, and D. Stuck,

Appl. Opt., 16, 1788 (1977).

VUV Radiometry. 3: The Argon

Mini-Arc as a New Secondary Stan- dard of Spectral Radiance, J. M.

Bridges and W. R. Ott, Appl. Opt.,

16, 367 (1977).

NBS UV Radiometric Standards, W.

R. Ott, Natl. Bur. Stand. (U.S.), Spec.

Publ. 456, 107 (1976).

69
41010S-41020S

E, Optical Fiber Attenuation and Bandwidth

Electromagnetic Technology Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

Robert L. Gallawa

Tel: 303/497-3761

Aaron A. Sanders

Tel: 303/497-5341 Edna M. Jones

Administrative and Logistics Tel:303/497-3753 Mailing Address: 724.02, National Bureau of Standards,

325 Broadway, Boulder, CO 80303

Test No. Items 41010S Special Tests for Attenuation of TelecommunicationGrade Multimode Graded-Index Optical Fibers at 850

and 1 300 nm, by Prearrangement

41020S Special Tests for Bandwidth of TelecommunicationGrade Multimode Graded-Index Optical Fiber

Having an Operating Wavelength of 1 300 nm, by

Prearrangement

Optical Fiber Attenuation

and Bandwidth—General

Information

The National Bureau of Standards has

been instrumental in the development

of test methods that are now accepted

by the U.S. optical fiber community.

Attenuation and bandwidth are two

of the most fundamental parameters

of interest in system design and ac- cordingly have been addressed first.

These special tests utilize a dedicated

set of instruments and ancillary equip- ment. Transfer standards are maintained at NBS for the express purpose

of serving industry in maintaining

precision and capability. The refer- ences collectively provide detailed in- formation on measurement pro- cedures and NBS capabilities.

The optical fiber services are based on the use of transfer standards in the

form of good-quality fibers of the ap- propriate type. The mode of operation is akin to that of a measurement

assurance program. The standards are characterized in the laboratories of

NBS and are available to the participant twice each year. The participant laboratory measures the loss or bandwidth, or both, in accordance

with the established standard pro- cedures provided or using its own

normal procedures. The data are then

sent to NBS, where they are analyzed

and a report prepared. The report

gives information on the precision of

the intercomparison and relates the

participant's data to data collected by

other participants (anonymously) and

by NBS. As appropriate, NBS may

act as consultant to the participating

laboratory to improve its precision.

Note: NBS plans to continue to offer an annual three-day short course on

optical fiber measurements, as long as there appears to be need for it. Special Test Measurements for Fiber

Attenuation (41010S)

The fiber attenuation measurement

special test is a new service supporting the measurement of total loss in telecommunication-grade multimode

graded-index optical fiber. Measurement procedures are based on re- cently established industry-approved

methods. This special test covers fiber

70
loss at wavelengths of 850 and 1300 nm.

Special Test Measurements for Fiber

Bandwidth (41020S)

The fiber bandwidth measurement

special test is a new service supporting the measurement of informationcarrying capacity of telecommunication-grade multimode graded-index

optical fiber. Measurement pro- cedures are based on methods ap- proved by the Electronic Industry

Association. This special test covers

the determination of bandwidth at the

operating wavelength of 1300 nm.

References—Optical Fiber Attenuation

and Bandwidth

Measurement Assurance, J. M. Cameron, Natl. Bur. Stand. (U.S.), Int. Report, NBSIR 77-1240 (April 1977).

An NBS Measurement Assurance

Program, A. A. Sanders and A. R. Cook, Proc. 1976 Electro-Optics Laser Conf. (1976).

Optical Fiber Characterization, Volume I, B. L. Danielson, G. W. Day,

D. L. Franzen, E. M. Kim, and M.

Young, Natl. Bur. Stand. (U.S.),

Spec. Publ. 637 (1982).

Optical Fiber Characterization, Volume II, G. E. Chamberlain, G. W.

Day, D. L. Franzen, R. L. Gallawa,

E. M. Kim, and M. Young, Natl. Bur. Stand. (U.S.), Spec. Publ. 637 (1983).

Technical Digest-Symposium on Optical Fiber Measurements, G. W.

Day, D. L. Franzen, Eds., Natl. Bur. Stand. (U.S.), Spec. Publ. 597 (1980).

Technical Digest- Symposium on Optical Fiber Measurements, D. L. Franzen, G. W. Day, and R. L. Gallawa, Eds., Natl. Bur. Stand. (U.S.),

Spec. Publ. 641 (1982).

Interlaboratory Measurement Comparison to Determine the Attenuation

and Bandwidth of Graded-Index Optical Fibers, D. L. Franzen, G. W.

Day, B. L. Danielson, G. E. Chamberlain, and E. M. Kim, Appl. Opt.

20, 2412 (1981).

Attenuation Measurements of Optical

Fiber Waveguides: An Inter- laboratory Comparison Among Manufacturers, G. W. Day and G. E. Chamberlain, Natl. Bur. Stand. (U.S.),

Int. Report, NBSIR 79-1608 (1979).

Standardizing Test Conditions for Characterizing Fibers, D. L. Franzen,

G. W. Day and R. L. Gallawa, Laser

Focus, 103 (Aug. 1982).

Optics and Lasers Including Fibers

and Integrated Optics, M. Young,

Springer-Verlag, New York (1984).

Measurement of Far-Field and NearField Radiation Patterns from Optical

Fibers, E. M. Kim and D. L. Franzen, Natl. Bur. Stand. (U.S.), Tech.

Note 1032 (1981).

On the Definition of Fiber Numerical

Aperature, R. L. Gallawa, ElectroOptical System Design, 46 (April

1982).

Optical Waveguide Communications

Glossary, A. G. Hanson, L. R. Bloom, A. H. Cherin, G. W. Day, R.

L. Gallawa, E. M. Gray, C. Kao, F.

P. Kapron, B. S. Kawasaki, P. Reitz,

and M. Young, Natl. Bur. Stand.

(U.S.), Handb. 140 (1982).

Measurement of Optical Fiber Attenuation: An NBS Special Test Service, R. L. Gallawa, G. E. Chamberlain,

G. W. Day, D. L. Franzen, and M.

Young, Natl. Bur. Stand. (U.S.), Int. Report, NBSIR 83-1691 (1984).

Technical Digest-Symposium on Optical Fiber Measurements, G. W. Day

and D. L. Franzen, Eds., Natl. Bur. Stand. (U.S.), Spec. Publ. 683 (1984).

71
42010S-42090M

IP Laser Power and Energy

Electromagnetic Technology Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

Thomas R. Scott Aaron A. Sanders Edna M. Jones

Tel:303/497-3651 TelJ03/497-5341 Administrative and Logistics Tel:303/497-3753 Mailing Address: 724.02, National Bureau of Standards,

325 Broadway, Boulder, CO 80303

Test No. Items 42010S Special Tests of Laser Power and Energy by

Prearrangement

42020M Measurement Assurance Program (MAP) for Laser Power; Wavelength: 514.5 nm; Power:

10 mW-6(X) mW

42030M MAP for Laser Power (632.8 nm; 1 mW)

42040M MAP for Laser Power (632.8 nm; 1 /xW, 30

fi,W, 100 fi-W) 42050M MAP for Laser Power (632.8 nm; For Any

2 Power Levels of 1 mW, 1 ^W, 30 jxW, 100 jnW,

where measurements are performed together)

42060M MAP for Laser Power (647.1 nm;

10 mW-200 mW)

42070M MAP for Laser Power (1.06 jum; 10 mW-1 W)

42080M MAP for Laser Energy (1.06 fxm; Qswitched, 100 mJ-10 J) 42090M MAP for Laser Power (10.6 /xm; 5-50 W)

Laser Power and Energy

General Information

The National Bureau of Standards develops and maintains the U.S. national

standards for measurement of laser power and energy. These standards

are realized in the form of three types

of isoperibol (constant temperature

environment) calorimeters. The cal- orimeters compare absorbed laser

radiation to an equivalent quantity of

electrical energy. NBS maintains

these calorimeters in three measurement systems so that other laser power or energy meters can be cali- brated against the national standards.

The calibration uncertainty ranges

from about 1 to 5 percent at the 99

percent level of confidence, depending on the power (or energy)

level and the wavelength at which

the calibration is performed.

Special Tests of Laser Power and Energy Meters by Prearrangement

(42010S)

Services include special calibrations

by prearrangement of laser power

and energy meters outside the formal

Measurement Assurance Programs

described below. Customer-owned in- struments are sent to NBS for measurement using one or more of the

NBS laser calibrating systems; the

customer receives a Report of Test. These special tests include special

Measurement Assurance Programs,

special calibration of instruments by means of 1.064-)xm laser pulses from

10 * to 10"'* watts peak power and

10"'* to 10 " joules, and the special

calibration of instruments by means of

10.6 \xm laser pulses at nanosecond

time scales using a TEA laser in the

energy range 10 mJ to 300 mJ.

Measurement Assurance Programs for Laser Power (42020M-42090M)

The laser power and energy measurement services include several advertised Measurement Assurance Pro- grams (MAPs). The laser MAPs are implemented by means of transfer standards which have been evaluated

and characterized relative to the national standards. The characteristics

of these transfer standards are well

understood, and their associated accuracies do not differ significantly from

those associated with direct comparisons to national standards. An

NBS-characterized transfer standard,

evaluated for the specific range of la- ser wavelength and power of interest (or energy, as appropriate to the situ- ation), is forwarded to each MAP

72
Commercial, electrically calibrated optical

participant twice per year. The participant is asked to calibrate the NBS

transfer standard in accordance with

the normal procedures in use at that laboratory, or in accordance with

procedures supplied by NBS with the

instrument.

NBS performs an analysis of the

data to provide an assessment of the

participant's measurement process for

laser power and energy. The resulting

report contains a scale factor that can be used to adjust values measured by

the participant to be consistent with

the national standards.

The participant is encouraged to make regular measurements on one or more in-house reference power meters or calorimeters (check standards)

in order to establish the random error and to provide assurance that the process is stable. Each of the three laser calibrating

systems used to support the NBS la- ser MAP service employs the two

calorimeter-beamsplitter configuration. All the significant parameters

for each calorimeter, including the

electrical calibration coefficient and

the absorption and window trans- mission for each laser wavelength bepower meter based on NBS design.

ing used, have been evaluated to re- late laser energy to electrical energy. The application of theory to the volt- age data (proportional to temperature) taken at equal time intervals

is accomplished by using a special

least squares computer program.

A properly designed and operated

calorimeter can make a valid comparison of energies independent of the

time (up to five minutes) required to put the energy into the calorimeter.

For instance, it is valid to compare

the energy in a pulse to continuous wave (cw) energy, applied over a five minute period, or to compare a laser pulse to an electrical input of 10 to 300 second duration.

Using a beamsplitter configuration,

energy measuring calorimeters can be

calibrated independently of laser stability, either with cw power or the

energy of single or multiple pulses. In

addition, if accurate timing and a sta- ble laser are employed, laser power

meters can also be calibrated.

Laser sources at NBS used with

these calorimeters are carbon dioxide, argon, krypton, helium-neon and

73
neodymium-doped YAG cw lasers,

and a pulsed YAG laser with a pulse

energy of about 0. 1 joule and a pulse

width of about 30 nanoseconds.

Since laser power and energy are highly-derived quantities, they are

subject to more sources of error than

are typically encountered in MAPs

for measurements closer to the base

SI units. Sources of error which must

be considered in laser power and en- ergy measurements include:

A . Beam size. The beam size should be small enough that the vari- ous instruments can capture the total beam, and large enough that the en- ergy density of the beam does not damage the surface of the absorber.

B. Beam alignment. Proper alignment ensures total beam capture and

avoids interference problems with re- flections. C. Window transmittance and

beam splitter ratio. These

wavelength-dependent ratio measurements must be determined for each laser wavelength of interest. D. Electrical measurements. To

relate the laser energy to base SI

units, time intervals, voltages and currents of the heater circuitry must be

measured accurately with respect to national standards.

E. Long term drifts in the parameters characterizing the measurement

system. Examples of parameters that may change with time are: electrical calibration coefficients; absorbing sur- face of the calorimeters; and window

transmittance.

Control charts for the beamsplitter

measurements with the two

calorimeter-beamsplitter configuration

are used at NBS to verify the stability

of the calibration systems.

References—Laser Power and Energy

An NBS Measurement Assurance

Program, A. A. Sanders and A. R.

Cook, Proc. Electro-Optics Laser

Conference (1976).

Theory of Isoperibol Calorimetry for Laser Power and Energy Measurement, E. D. West and K. L. Churney, J. Appl. Phys. 41, No. 6, 2705 (May 1970).

A Reference Calorimeter for Laser

Energy Measurement, E. D. West,

W. E. Case, A. L. Rasmussen, and L.

B. Schmidt, J. Res. Natl. Bur. Stand.

(U.S.), 76A, No. 1, 13 (Jan.-Feb.

1972).

Data Analysis for Isoperibol Laser

Calorimetry, E. D. West, Natl. Bur.

Stand. (U.S.), Tech. Note 396 (Feb.

1971).

Quality Assurance Program for the

NBS C, K and Q Laser Calibration

Systems, W. Case, Natl. Bur. Stand.

(U.S.), Int. Report, NBSIR 79-1619

(Aug. 1979).

Absolute Reference Calorimeter for Measuring High Power Laser Pulses,

D. L. Franzen and L. B. Schmidt,

Appl. Opt. 15, 3115 (Dec. 1976).

A System for Calibrating Laser

Power Meters for the Range 5-1000

W., E. D. West, and L. B. Schmidt,

Natl. Bur. Stand. (U.S.), Tech. Note

685 (May 1977).

Documentation of the NBS C, K and

Q Laser Calibration Systems, W. E. Case, Natl. Bur. Stand. (U.S.), Int. Report, NBSIR 82-1676 (Sept. 1982).

A System for Measuring Energy and

Peak Power of Low-Level 1.064-ju,m

Laser Pulses, A. A. Sanders and A.

L. Rasmussen, Natl. Bur. Stand.

(U.S.), Tech. Note 1058 (Oct. 1982).

A Calorimeter for Measuring HighEnergy Optical Pulses, P. A.

Simpson, E. G. Johnson, Jr., and S. M. Etzel, Natl. Bur. Stand. (U.S.),

Int. Report, NBSIR 84-3008 (Oct.

1984).

74
Apparatus for comparing customer's laser power meter (calorimeter) with NBS reference calorimeter.

75
Chapter

A Radioactivity Sources B Neutron Sources and Dosimeters

C Dosimetry of X Rays, Gamma Rays,

and Electrons D Dosimetry for High-Dose Applications
1 Ionizing Radiation Measurements 43010C-43090S

A Radioactivity Sources

Ionizing Radiation Division

Center for Radiation Research

Technical Contacts:

Jacqueline M. Pamela A. Hodge

Calhoun AdministratiTe

Tel: 301/921-2665 and Logistics TelJOl/921-2665 Mailing Address: C114 Radiation Physics, National Bureau of Standards, Gaithersburg, MD 20899

Test No. Items

430 IOC Gamma-Ray-Emitting Radionuclides in Solution

(Half Lives Greater Than 1 5 Days)

43020C Gamma-Ray-Emitting Radionuclides in Solution

(Half Lives Less Than 15 Days)

43030C Alpha-Particle-Emitting Solid Sources, NBS 2 na

proportional counter 43040C Alpha-Particle-Emitting Solid Sources, NBS 0.8 ira defined-solid-angle counter 43050C Alpha-Particle-Emitting Solid Sources, using both

counting systems

43060S Special Test of Beta-Particle-Emitting Solution Sources—Liquid Scintillation Counting

43070S Special Tests of Beta-Particle-Emitting Solution

Sources, Other Techniques

43090S Special Tests of Alpha-Particle-Emitting Solid Sources

Radioactivity Sources—General

Information (43010C-43090S)

The National Bureau of Standards of- fers calibration services for over 50

radionuclides. This service provides

calibrations which meet requirements

of industry, research, environmental

monitoring, and the life sciences. Radioactivity calibration services are

available for alpha-particle solid sources, beta-particle solutions, and

gamma-ray solutions. In order to offer such a broad

range of services, NBS must place

stringent limitations on the physical

and chemical form and activity range

of sources which can be accepted. To

insure that these specifications are un- derstood, it is essential that there be

good communication between the

technical user at the facility and those

at NBS. When planning to have a source calibrated the user should dis- cuss the following points with the

technical contact at NBS:

A. Type of calibration: Often, more than one type of calibration is available for a given source. A

cobalt-60 source, for example, may be

calibrated in terms of total activity or gamma-ray-emission rate. (Inquiries

regarding the calibration of radioactive sources for exposure rate should be directed to the Dosimetry

Group. See tests 47010C to 47040C.)

The total uncertainty in the cali- bration should also be discussed. B. General packaging and shipping requirements: Two general re- quirements apply to all sources submitted for calibration: (1) all shipments must conform to applicable

Nuclear Regulatory Commission

(NRC) and Department of Transportation (DOT) packaging and trans- port; and (2), source descriptions, in- cluding approximate activity, must be

provided in advance. The NBS

Health Physics Section must approve

in advance all proposed calibrations,

and sources may be refused if the

necessary information is not available. C. Reports of Calibration: A Report of Calibration is sent on completion of a radioactivity calibration

service. If the user has particular re- quirements for documentation of the

calibration, these should be discussed

with the technical contact at NBS before the services are performed.

D. Sample Preparation, Packaging and Shipping: All samples submitted for calibration must be chemically and physically stable. The

chemical form of solutions which are suggested for beta-particle emitters

and gamma-ray emitters are described

77
43010C-43090S

later in this document. A special lot of borosilicate-glass ampoules must be

used for gamma-ray emitters. Empty

ampoules are provided for this purpose. The volume of material in the

ampoule should be 5.0±0.2 ml.

Packaging for all sources must be

in compliance with DOT and NRC

regulations. Copies of regulations

may be obtained from Operations Division, Office of Hazardous Materials,

Department of Transportation, Washington, DC 20590. Postal regulations

prohibit mailing radioactive materials

which require a caution label under

DOT regulations.

Alpha-particle solid sources must

be supplied in special source holders

so designed that the active area is not touched by any material. For sources

to be measured in the 2 Tra counter

(calibration 43030C), the diameter of

the source must be less than 10 cm

and that of the active surface less than 9 cm. For the 0.8 Tra counter

(calibration 43040C), the maximum

diameter is 1.6 cm.

All sources arriving at NBS are checked by the Health Physics Section for radiation level and source in- tegrity. Sources should be shipped to the attention of the technical contact

at NBS, addressed as follows:

National Bureau of Standards

Attn: Jacqueline M. Calhoun

Health Physics (Radioactivity

Group)

Quince Orchard and Clopper

Roads

Gaithersburg, MD 20899

Gamma-Ray-Emitting Solution Sources

(43010C-43020C)

Tables 3 and 4 list 39 radionuclides,

solutions of which may be calibrated

in the National Bureau of Standards

"47r"7 ionization chamber. The

sources must be submitted flamesealed in the special ampoules pro- vided by NBS. The operation of this type of chamber is described in

NCRP Report 58, A Handbook of

Radioactivity Measurements Procedures, Section 4.4 "Ionization

Chambers", National Council on

Radiation Protection and Measurements Report, Mann, W.B. (Ed.),

Washington (1985).

Table 3: Calibration Uncertainties for Radionuclides

Having Half Lives Greater Than 15 Days (430 IOC)

Suggested Chemical Form'' Nominal Uncer.

Limits of Ion- Activity

Radio- ization-Chamber Range'*' nuclide Calibration'^' (MBq) Carrier Solution

1.6% 0.4-40 NaCl 1 JVl rH^l 0.8% 0.4-40 ScCl3 I M HCl

1.0% 2-60 CrCh u . J JVl rtv^i "*Mn 1.2% 2-60 MnCl2 1 ivi rii^i "Co 0.8% 2-60 C0CI2 1 MHCl

1.4% 0.4-40 FeCl3 1 MHCl

'^Co O.S% 0.4-40 C0CI2 1 MHCl

652n(d) 1.7% 2-60 ZnCh 1 MHCl

"Se 2.4% 2-60 H2Se03 1 M HNO3

2.0% 2-60 SrCl2 1 MHCl

SSy 0.7% 0.4-40 YCI3 1 MHCl

109(^j_109m^g(d) 1.7% 2-60 CdCl2 1.3 MHCl*

"°TMAg-"°Ag 0.9% 0.4-40 AgN03 1 N HNO3

"^Sn-"3'"In 3.0% 2-60 SnCl2 or 4 MHCl

SnCU

'"Ba 1.5% 2-60 BaCh 1 MHCl

'^*Cs 1.0% 2-60 CsCl 1 MHCl

1.5% 2-60 CsCl 1 MHCl

'^'Ce 1.0% 2-60 CeCh 1 MHCl

"•'Ce 2.0% 2-60 CeCl3 1 MHCl

'«Eu 1.6% 0.4-40 EuCh 1 MHCl

0.8% 0.4-40 EuCh 4 MHCl

'«Eu 1.5% 2-60 EuCh 4 MHCl

169Yb 2.5% 2-60 YbCh 0. 1 M HCl*

2.3% 2-60 KAu(CN)4 lOgL-' KCN*

203Hg

lOgL"' KCl*

1.4% 2-60 Hg(N03)2 0 . 1 M HNO3

1.1% 0.4-40 RaCl2 1.4 MHCl

' The total estimated uncertainty will depend upon the activity level and chemical form. The source activity should be in the indicated range when it arrives

at NBS. The calibration scheduling must be coordinated with the NBS

technical contact.

" This information is based in large part on the NBS Standard Refer- ence Materials for these radionuclides. For those radionuclides marked

with an asterisk, the carrier should be discussed with the NBS technical contact. The calibrations for ^'Zn and "^Cd-'°''"Ag are in terms of gamma-rayemission rate rather than activity.

78
Table 4: Calibration Uncertainties for Radionuclides

Having Half Lives Less Than 15 Days (43020C)

Suggested Chemical Fonn' Nominal Uncer.

Limits of Ion- Activity

Radio- ization-Chamber Range""

nuclide Calibration*'' (MBq) Carrier Solution

0.8% U.4—4U NaCl 1 MHCl

2.0% 2-60 KCl 1 MHCl

1.4% 0.4-40 GaCb 1 MHCl

"Mo-""Tc 1.6% 2-60 Molybdate 4 M HNO3

1.5% 2-60 No carrier Saline added/

'"In

pertechnetate

1.3% 2-60 InCl2 3 MHCl

123j 1.5% 2-60 KI, NazSOs 0.01 M LiOH*

1311 1.3% 2-60 KI, NaaSOs 0.01 M LiOH*

'^Ba-"«'La 3.4% 0.4-40 Ba(N03)2, 1 MHCl

La(N03)3

'"Hg 2.4% 2-60 Hg(N03)2 0 . 1 M HNO3

1.3% 2-60 KAu(CN)4 lOgL-'KCN*

10 gL"' KCl

1.9% 2-60 T(N03)3 0 . 9 M HNO3

203pi, 1.7% 2-60 PbCl2 0.5 MHCl

^ The total estimated uncertainty will depend upon the activity level and chemical form.

'' The source activity should be in the indicated range when it arrives

at NBS. The calibration scheduling must be coordinated with the NBS

technical contact.

' This information is based in large part on the NBS Standard Refer- ence Materials for these radionuclides. For those radionuclides marked

with an asterisk, the carrier should be discussed with the NBS technical contact.

Alpha-Particle-Emitting Solid Sources

(43030C-43050Q

Alpha-particle sources may be cali- brated using the National Bureau of

Standards Ina proportional counter, or the National Bureau of Standards

0.87ra defined-solid-angle counter. The former calibration is in terms of

alpha-particle-emission rate into In

steradians, while the latter is in terms of total activity. A more detailed

comparison of these counting systems

is given in NCRP Report 58 (Section

3.7). Backscattering corrections for a

variety of source-mount materials are

43010C-43090S

discussed in the references below.

The source thickness must be such

that more than 99.5 percent of the

emitted alpha particles have an en- ergy greater than 400 keV. Further

specifications for these calibration ser- vices are given in Table 5. Test 43050C includes calibration of the same source using both counting

systems.

Table 5: Specifications for Calibration of Alpha-ParticleEmitting Samples

Calibration Calibration 43030C 43040C

Counting System NBS Iva pro- NBS 0.87ra de- portional fmed-solid-angle counter counter

Sources Calibrated For: Alpha-particle- Total activity

emission

rate into 2tt steradians Nominal Uncertainty*"' 1.5% 1.0%

Activity Range 1.5 Bq to 1.9x10^ Bq to

1.1x10'* Bq 1.1x10'* Bq

Maximum Source 10 cm (9 cm for 1.6 cm

Diameter active surface)

" The total estimated uncertainty will depend upon the activity level and source geometry.

Special Tests of Beta-Particle-Emitting

Solution Sources (43060S and 43070S)

Beta-particle-emitting solutions that conform to the physical, chemical

and activity specifications for measurement are assayed by liquidscintillation counting. The specifications are shown in Table 6. Solutions

should be approximately 5 mL in vol79
43010C-43090S

ume and flame-sealed in glass vials or ampoules. The suggested radioactivity concentration range is 20 to 2000 kBq/g.

Table 6: Specifications for Special Tests of Beta-ParticleEmitting Solution Sources

Suggested Chemical

Composition"''

Radio- Nominal

nuclide Uncertainty""* Carrier Solution

1.0% H2O H2O

14^ 1.5% Na2C03 0.001 M NaOH

32p(c) 1.0% H3PO4 0.0034 M H3PO4

33p 1.0% H3PO4 0.0034 M H3PO4

1.0% Li2S04 0.1 MHCL

''CI 2.0% NaCl H2O

1.0% SrCl2 1 MHCl

90Sj._90y 1.0% SrCl2/YCl3 1 M HCl

90y 1.0% YCI3 1 MHCl

1.0% PmCl3 1 MHCl

2.0% T1(N03)3 1 M HNO3

' The total estimated uncertainty will depend upon the activity level and chemical form. The chemical composition is critical for these calibrations and should be discussed before sending the source.

" This calibration includes a half-life fit to determine the "P impurity.

Counting, W. B. Mann, Ed., Natl. Council Rad. Protect, and Meas.,

Wash., DC (1985).

Study of the Scattering Correction

for Thick Uranium-Oxide and Other

a-Particle Sources-I: Theoretical, L. L. Lucas and J. M. R. Hutchinson,

Int. J. Appl. Radiat. Isotopes, 27, 35

(1976).

Study of the Scattering Correction

for Thick Uranium-Oxide and Other

a-Particle Sources-II: Experimental,

J. M. R. Hutchinson, L. L. Lucas,

and P. A. Mullen, Int. J. Appl.

Radiat. Isotopes, 27, 43 (1976).

Backscattering of Alpha Particles

from Thick Metal Backings as a Function of Atomic Weight, J. M. R. Hutchinson, C. R. Naas, D. H.

Walker, and W. B. Mann, Int. J. Appl. Radiat. Isotopes, 19, 517 (1968).

An Experimental Study of the Backscattering of 5.3 MeV-Alpha Particles

from Platinum and Monel Metal, D.

H. Walker, Int. J. Appl. Radiat. Iso- topes, 16, 183 (1965).

No examination is made for beta- particle-emitting impurities, except in the case of phosphorus-32 where a

half-life fit is made. The sources will be examined for gamma-ray emitting

impurities.

Measurement of beta-particleemitting solutions by techniques other

than liquid-scintillation may be made

by special arrangement.

Special Alpha-Particle-Emitting Solid

Sources (43090S)

Special arrangements may be made

for measurements of solid alphaparticle-emitting sources with emission rates exceeding 1.1x10" Bq.

References—Radioactivity Sources

NCRP Report 58, A Handbook of

Radioactivity Measurements Procedures, Section 3.7-Alpha-Particle

80
B.

Neutron Sources and Dosimeters

Ionizing Radiation Division

Center for Radiation Research

Technical Contacts:

Robert B. Schwartz

Tel:301/921-2767

Tests 44010C44030S, 44100S

George P. Lomaze

Tel:301/921-2767

Tests 44080C- 44090S

E. Dale McGarry

TeI:301/921-2767

Tests 44040S44070S, 44100S Mailing Address: A155 Reactor, National Bureau of Stan

dards, Gaithersburg, MD 20899

Test No. Items 44010C

44020C

44030S

44040S

44050S

44060C

44070S

44080C

44090C

44100S

Natural Standard Neutron Sources (10^ to 10* n/s)

Natural Standard Neutron Sources (10* to 10'° n/s)

Activated Foil Irradiation with Thermal Neutrons

Special Tests of Neutron Dosimeters, Thermal Beam

Special Tests of Neutron Dosimeters, Filtered Beam

Calibrations of Neutron Dosimeters, Californium Sources

Special Tests of Neutron Dosimeters, Van de Graaff

Activated Foil Irradiation, Californium Fission Neutrons Activated Foil Irradiation, Cavity

Fission Source

Special Tests of Neutron Sources and Dosimeters

Natural Standard Neutron Sources

(44010C-44020C)

NBS provides calibration services for natural standard neutron sources and

neutron measuring devices such as ac- tivation foils. Neutron sources in the

range from 5 x 10' to 5 x 10' neutrons/second may be calibrated to an accuracy of about ± 1.2% (one

sigma) depending upon the amount

and knowledge of construction of

their encapsulations. Emission rates (neutrons/second) of neutron sources of unknown source strength are determined by the Manganous Sulfate

Bath Method. The neutron sources

are calibrated by comparing their

strengths to that of the NBS primary

standard source, a Ra-Be photo

neutron source known as NBS-1. The

comparison of the source strengths is made by activating a manganese sul- fate bath solution and continuously

counting the induced, saturated

manganese-56 radioactivity with a

scintillation counter. The present

emission rate of NBS-1, which is ab- solutely determined, is 1.246 x 10* n/s

with an assigned uncertainty of

± 0.85% (one sigma).

Activated Foil Irradiation with

Thermal Neutrons (44030S)

Materials dosimetry, such as that ac- complished for surveillance of fast neutron fluence seen by the pressure

vessel in an operating nuclear power

plant, depends upon correct assay of

the amount of isotopic radioactivity

induced in radiometric dosimeters,

such as foils or wires. For activation

foil irradiations, the following thermal

neutron sources are available: A. External Beam (Fully moderated): 4 x 10^ n/(cm^-s)

B. Cavity (Isotropic, Fully moderated): 2 x 10" n/(cm^-s)

C. Thermal Density Standard

(Undermoderated): 4000 n/cm^-s)

Special Tests and Calibrations of Neutron Dosimeters (44040S-44070S)

A wide variety of neutron radiation

detection instrumentation exists for the protection of personnel. NBS

maintains a correspondingly wide variety of neutron fields for both re- search and calibration in the area of

personnel dosimetry. A thermal neutron beam is available at the thermal

column of the NBS Research Reactor

(NBSR) which can provide dose

equivalent rates up to approximately

1 rem/hour over a 30-cm diameter

circle. Three monoenergetic epithermal neutron beams are available

81
at the NBSR to determine neutron re- sponse as a function of energy:

A. 2 KeV beam Dose Equiv.

rate = 8 mrem/hour

B. 24 KeV beam Dose Equiv.

rate= 15 mrem/hour

C. 144 KeV beam Dose Equiv.

rate = 1 20 mrem/hour

These epithermal neutron beams

give primarily neutron doses with the

gamma contributions being approximately 2 to 4 percent. The neutron

spectrum for a deuterium moderated

Cf-252 neutron source is available for calibration of personnel dosimetry in- struments. Available rates are 1 . 1 x

10^ n/(cm^-s) or equivalently 3.0 rem/

hour. Additionally, a pure Cf-252 fis- sion neutron spectrum is available

with rates of 1.3 x 10* n/(cm^-s) or

equivalently 1.6 rem/hour. A Van de

Graaff generator also provides neutrons in the energy range of 0.2-1.2

MeV with rates of 1.5 x 10^ n/cm'-s

(170 m rem/hr) and at 14 MeV: 60 n/

cm^-s (80 m rem/hr).

Calibrations of

Activated Foil Irradiations

(44080C-44090C)

NBS maintains Standard Fission Neutron Fields to supply calibration irra- diations and Certified Fluence Standards. The NBS Cf-252 Fission

Neutron Source (typical maximum

fluence 1.0 x 10'^ neutrons/cm^ in 24

hours) and the U-235 Cavity Fission

Neutron Source (typical maximum

fluence 3.3 x 10" neutrons/cm^ in 24

hours) provide standard neutron field spectra. Known fluences are based

upon known source strengths for the

californium sources. Special Tests of Neutron Sources and

Dosimeters (44100S)

Other tests of neutron sources and

dosimetry may be made by special ar- rangement with the Ionizing Radiation Division.

References—Neutron Sources and

Dosimeters

Fission Cross-Section Measurements

in Reactor Physics and Dosimetry

Benchmarks, J. A. Grundl and D. M.

Gilliam, ANS Trans., 44, 533 (June

1983).

Measurement of Neutrons Reflected

from the Surfaces of a Calibration

Room, C. M. Eisenhauer, R. B. Schwartz, and T. Johnson, Health Physics, 42, 489 (1982).

Integral Reaction Rate Measurements

in ^"Cf and "'U Fission Spectra, G.

P. Lamaze, E. D. McGarry, Proc. Conf. on Nucl. Data for Sci. and

Tech., Antwerp, Belgium (Sept.

1982).

Requirements for Reference Reactor

Pressure Vessel Surveillance Dosimetry to Benchmark Neutron Fields, E. D. McGarry, Proc. IAEA Advisory

Group Meeting on Nuclear Data for Radiation Damage Assessment and

Reactor Safety Aspects (Oct. 1981).

Measurements of the Average Activation Cross Section for the Reaction

*^Cu(n, a)^Ca in the Spontaneous Fis- sion Neutron Field of Californium252, C. Winkler, V. Spiegel, C. M.

Eisenhauer, D. L. Smith, Nucl. Sci. Eng., 78, 415 (Aug. 1981).

National Standards for Neutron Measurements, J. Grundl, Traceability for Ionizing Radiation Measurement

Symposium, Natl. Bur. Stand. (U.S.)

(May 1980).

"^U Cavity Fission Neutron Field

Calibration via the "^Cf Spontaneous

Fission Neutron Field, V. Spiegel, C.

M. Eisenhauer, D. M. Gilliam, J. A.

82
Grundl, E. D. McGarry, I. G. Schroder, W. E. Slater, and R. S. Schwartz, IAEA Consultant's Mtg. on Neutron Source Properties, Debrecen, Hungary (Mar. 1980).

The Design and Construction of a DaO-Moderated "^Cf Source for Calibrating Neutron Personnel Dosimeters Used at Nuclear Power Reactors, R. B. Schwartz and C. M.

Eisenhauer, U.S. Nucl. Reg. Com.

Doc, NUREG/CR-1204 (Jan. 1980).

Detailed Error Analysis of Average

Fission Cross-Section Measurements

in NBS Standard Neutron Fields, J. J. Wagschal, R. E. Maerker (ORNL),

and D. M. Gilliam (NBS), Trans. Am. Nucl. Soc, 33, 823 (Nov. 1979).

Dosimetry Results for BIG TEN and

Related Benchmarks, D. M. Gilliam,

J. A. Grundl, and C. E. Hansen,

Third ASTM-EURATOM Symposium on Reactor Dosimetry, Ispra,

Italy (Oct. 1979).

Benchmark Referencing of Neutron

Dosimetry Measurements, C. M.

Eisenhauer, J. A. Grundl, D. M. Gilliam, E. D. McGarry, and V. Speigel,

Third ASTM-EURATOM Symposium on Reactor Dosimetry, Ispra,

Italy (Oct. 1979). User's Manual—Neutron Calibration

Fields at NBS, J. E. Hoy and R. B. Schwartz, Dec. 8, 1976. Revised by

R. B. Schwartz (Jan. 1979).

Covariance of Fission-Integral Measurements at the NBS "^Cf and ISNF

Facilities and at the ORNL-PCA Facility, J. J. Wagschal, R. E. Maerker,

and D. M. Gilham, Third ASTMEURATOM Symposium on Reactor

Dosimetry, Ispra, Italy (Oct. 1979).

Neutronic Analysis of the NBS

Intermediate-Energy Standard Neutron Field (ISNF), P. D. Soran, R. J. Labauve, and E. C. George (LASL)

and C. M. Eisenhauer (NBS), Trans. Am. Nucl. Soc, 32 (June 1979).

Compendium of Benchmark and Test Region Neutron Fields for Pressure

Vessel Irradiation Surveillance; Stan- dard Neutron Spectra-Part I: "^Cf

Spontaneous Fission and Part II: "'U

Thermal-Neutron-Induced Fission,

Light-Water-Reactor, Pressure- Vessel-Surveillance Dosimetry

Progress Report. U.S. Nucl. Reg.

Com. Doc, NUREG/CR-0551 (Dec.

1978).

Reaction Rate Measurements and In- tegral Cross Sections Using the NBS

"^Cf Fission Neutron Indoor Irra- diation Facility, V. Spiegel, C. M.

Eisenhauer, and J. A. Grundl (NBS),

and G. C. Martin, Jr. (GE). Second

ASTM-EURATOM Symposium on

Reactor Dosimetry, Palo Alto, CA

(Oct. 1977). Also published as U.S. Nucl. Reg. Com. Doc, NUREG/

CP0004 (1978).

Utilization of Standard and Reference

Neutron Fields at NBS, C. M. Eisenhauer, D. M. Gilliam, J. A. Grundl,

and V. Spiegel. Second ASTM/

EURATOM Symp. on Reactor Dosimetry, Palo Alto, CA (Oct. 1977).

See also NUREG/CP0004 (1978).

A Califomium-252 Fission Spectrum

Irradiation Facility for Neutron Reaction Rate Measurements, J. A.

Grundl, V. Spiegel, C. M. Eisenhauer, H. T. Heaton, II, and D. M.

Gilliam (NBS), and J. Bigelow

(ORNL), Nucl. Tech., 32, 315 (Mar.

1977).

Fission Reaction Rate Standards and

Applications, J. Grundl and C. Eisenhauer, Int. Symp. on Neut. Stand, and

Applic, Gaithersburg, MD, Natl. Bur. Stand. (U.S.), Spec. Publ. 493

(Oct. 1977).

Integral Measurements Results in Standard Fields, D. M. Gilliam, Int. Symp. on Neut. Stand, and Applic,

83
Gaithersburg, MD, Natl. Bur. Stand.

(U.S.), Spec. Publ. 493 (Oct. 1977).

Neutron Transport Calculations for the Intermediate-Energy Standard

Neutron Field (ISNF), C. M. Eisenhauer and J. A. Grundl, Int. Symp.

on Neut. Stand, and Applic, Gaithersburg, MD, Natl. Bur. Stand.

(U.S.), Spec. Publ. 493 (Oct. 1977).

Calibration and Use of Filtered

Beams, R. B. Schwartz, Proc. Intl. Specialists Symp. on Neut. Stand, and

Applic, Gaithersburg, MD, Natl. Bur. Stand. (U.S.), Spec. Publ. 493,

250 (Oct. 1977).

Neutron Source Calibrations at NBS

for Calibration Checks of Neutron

Radiation Instruments, V. Spiegel, Proc. of Symp. on Meas. for the Safe

Use of Radiation, Natl. Bur. Stand.

(U.S.), Spec. Publ. 456, 87 (Nov.

1976).

Benchmark Neutron Fields for Reactor Dosimetry, J. A. Grundl and C.

M. Eisenhauer, IAEA Consultants'

Meeting on Integral Cross Section

Measurements in Standard Neutron

Fields for Reactor Neutron Dosimetry, Vienna (Nov. 1975-6).

The Effective Half-Life of

Californium-252, V. Spiegel, Jr., Nucl. Sci. and Eng., 53, 326 (1974).

Calibration of Thermal Neutron Absorption in Cylindrical and Spherical

Neutron Sources, V. Spiegel, Jr. and

W. M. Murphey, Metrologia, 7, 34

(Jan. 1971).

Review of Measurements of Absolute

Neutron Emission Rates and Spectra

from Neutron Sources, R. S. Caswell,

Neutron Sources and Applications, Proc. ANS Natl. Topical Meeting,

April 19-21, 1971, Augusta, GA,

CONF-71042, Vol. I, 1 (1971).

The Correction Factor for Fast Neutron Reactions on Sulphur and Oxygen in the Manganous-Sulfate-Bath

Calibration of Neutron Sources, W.

M. Murphey, Nucl. Instrum. Methods, 37, 13 (1965).

Recent Developments in Neutron

Source Standardization, R. S. Caswell, R. H. Noyce, S. B. Garfmkel

and E. R. Mosburg, Jr., Neutron Dosimetry II, 547, Intl. At. Energy

Agency, Vienna (1963).

Absolute Calibration of the National

Bureau of Standards Photoneutron

Source: III. Absorption in a Heavy

Water Solution of Manganous Sulfate, R. H. Noyce, E. R. Mosburg,

Jr., S. B. Garfmkel, and R. S. Caswell, J. Nucl. Eng., 17, No. 7, 313

(1963).

Absolute Calibration of the National

Bureau of Standards Photoneutron

Standard: II. Absorption in Manganese Sulfate, J. A. DeJuren and J. Chin, J. Res. Natl. Bur. Stand. (U.S.),

55, 311 (Dec. 1955).

Absolute Calibration of the National

Bureau of Standards Photoneutron

Standard: I., J. A. DeJuren, D. W.

Padgett, and L. F. Curtiss, J. Res.

Natl. Bur. Stand. (U.S.), 55, 63 (Aug.

1955).

Reproducibility of Photo-Neutron

Standards, L. F. Curtiss and A. Carson, Phys. Rev., 76, 1412 (1949).

84
Dosimetry of X Rays, Gamma Rays,

and Electrons

Ionizing Radiation Division

Center for Radiation Research

Technical Contacts:

Robert Loevinger

All Tests

Tel: 301/921-2364

Paul J. Lamperti

Tests 46010CTel: 301/921-2361

James T. Weaver

Tests 47010C- 47040S

Tel: 301/921-2361

Christopher G.

Soares

Tests 48010C- 48020S

Tel:301/921-2366

Mailing Address: C214 Radiation Physics, Center for Radiation Research, National Bureau of Standards,

Gaithersburg, MD 20899

Test No. Items

C.l X-Ray and Gamma-Ray Measuring Instruments 460IOC Radiation Detectors—Calibration/Correction

Factor, One Beam Quality (See Table 7) 460lie Each Additional Beam Quality or Condition

46020C Passive Dosimeters—Irradiation of Up to Six, One

Beam Quality at One Set-Up

4602 IC Up to Six Additional Dosimeters at Same Set-Up and

Beam Quality

46030S Special Tests of High-Gain Electrometers—Charge

Sensitivity, One Set of Switch Positions, with

46010C/46011C, by Previous Arrangement

46040S Special Tests of X-Ray Penetrameters, ArdranCrookes Type

46050S Special Tests of X-Ray and Gamma-Ray Measuring

Instruments

C.l Gamma-Ray and Beta-Particle Sources 47010C Gamma-Ray Sources—0.5 to 250 mg Ra; or ^Co,

'"Cs, '"I, or "^Ir, Having Exposure Rates 0.1 to 100 (|xR/s)ml

4701 IC Each Additional Gamma-Ray Source of Same Radionuclide 47030C Beta-Particle Sources Calibrated for Surface Dose

Rate

47040S Special Tests of Gamma-Ray and Beta-Particle Sources

C.3 Dosimetry of High-Energy Electron Beams

48010C Irradiation of Ferrous-Ferric Dosimeters—Three

Dosimeters (Two for Irradiation, One Control)

4801 IC Each Additional Dosimeter

48020S Special Tests of Electron-Beam Dosimeters

CO Special Instructions for Using

Electron and Photon Dosimetry Calibration and Test Services

(46010C-48020S)

The NBS dosimetry calibration and

test services for x rays, gamma rays, and electrons are performed in the Bureau's laboratories at Gaithersburg,

Maryland. Inquiries should be addressed to the appropriate technical contacts listed at the beginning of this section. The name and telephone

number of an individual who can an- swer technical questions that may

arise must be given in any inquiry, or- der, or shipment.

Upon receipt of a purchase order,

the Dosimetry Group assigns it a number. Calibrations are generally

performed in the sequence established

by those numbers, except when

greater efficiency can be achieved by

combining similar calibrations, or when work for a calibration laboratory is given a higher priority.

Arrangements for calibration must

be made in advance by letter or tele- phone, so that the instrument or source to be calibrated will not be

shipped to NBS until the time of its scheduled calibration approaches. In- quiry should be made as to scheduling and turn-around time.

Except for negligence by Bureau

personnel, the Bureau assumes no re- sponsibility for loss of or damage to the instruments or sources while in its possession. The risk should be covered by insurance.

The report of calibration or test will carry a Dosimetry Group number (e.g., DG 9876/85). Subsequent

reference to that calibration or test should cite the DG number.

C.l X-Ray and Gamma-Ray Measuring Instruments (46010C-46050S)

X-ray measuring instruments are cali- brated in terms of exposure by a substitution method in an x-ray beam at a point where the exposure rate has

been determined by means of a stan- dard free-air ionization chamber. In order to provide instrument cali- brations over a wide range of x-ray beam qualities, many combinations of

85
generating potential and filtration are

available. These are listed in Table 7 as

lightly (L), moderately (M), and heavily (H) filtered beams. Two beam qualities that do not fit into these cat- egories are considered as special (S)

qualitites, and two gamma-ray beams

are also available. The beam qualities

are identified by beam codes given in the first column. The calibration

beam qualities requested should be

appropriate to the instrument

submitted.

Table 7: X-Ray Beam-Quality Parameters

Beam

Code

Prev. Code Added Filter

Al (mm)Cu Sn (mm) (mm)

Pb

(mm)

Al (mm)

Cu

(mm)

Al Cu

LIO L-B 0. 0.029 79 TIC T 0. 0.050 74

T If* L-U U. U.U/ 1 10 U.ZOj U.ZZ DU L40 0.50 J 1 L50 0.639 0.75 58 L80 1.284 1.83 58 LlOO L-M 1 Q78 jy

M20 0.230 0.152 79 M30 L-G 0.50 0.36 64 M40 0.786 M50 L-I 1.021 1.02 0.032 66 62 M60 MFB 1.51 1.68 0.052 68 64 Mrvj J.U 5.0 0.20 72 55 M150 MFI 5.0 0.25 10.2 0.67 87 62 M200 4.1 1.12 14.9 1.69 95 69 M250 MFO 5.0 3.2 18.5 3.2 98 86 M300 4.0 6.5 22. 5.3 100 97

HIO 0.105 0.048 89 H15 0.500 0.152 87 H20 1.021 0.36 88 H30 4.13 1.23 0.038 93 94 H40 4.05 0.26 2.9 0.093 94 95 H50 HFC 4.0 0.10 4.2 0.142 92 90 H60 4.0 0.61 6.0 0.24 94 89 HlOO 4.0 5.2 13.5 1.14 100 94 H150 HFG 4.0 4.0 1.51 17.0 2.5 100 95 H200 HFI 4.0 0.60 4.16 0.77 19.8 4.1 100 99 H250 HFK 4.0 0.60 1.04 2.72 22 5.2 100 98 H300 4.1 3.0 5.0 23 6.2 99 98

S75 L-K 1.504 1.86 63 S60 MFC 4.0 2.8 0.089 75 70

137Cs Cs-137 10.8 60Co Co-60 14.9

Half-Value Homogeneity Effective Dis- Exposure Rate Layer Coefficient Energy tance Min. Max.

(keV) (cm) (mR/s) (R/s)

25 0.001 1.7 25 0.001 4.2 50 0.001 3.3 50 0.001 0.4 50 0.001 0.4 50 0.001 0.4 50 0.001 0.4 50 0.001 0.4

50 0.001 0.5 50 0.001 0.3 50 0.001 0.4 50 0.001 0.4

0.8 0.2

1.0 0.3

1.0 0.4

1.0 0.3

1.0 0.2

0.5 0.08

25 0.001 0.003 25 0.001 0.003 50 0.001 0.003 50 0.001 0.003 50 0.001 0.003

3846

80

120

166

211 252

662

1250

50

0.3

0.03 0.02

0.03 0.04

1.5

1.5

0.065

0.02 0.005 0.005 0.002 0.010

0.006

0.005 0.003

0.001 0.4

0.3 0.06

0.1 2.5 For the x-ray beam codes, the letter indicates light, moderate, heavy, and special filtration and the number

is the constant potential in kilovolts. The inherent filtration is approximately

1.0 mm Be for beam codes LIO-LIOO, M20-M50, H10-H40, and S75; and

3.0 mm Be for beam codes M60-M300, H50-H300, and S60. The half-value layers for '"Cs and "'Co are calculated. The homogeneity coefficient is taken as 100x(lst HVL)/(2nd HVL).

86
Gamma-ray measuring instruments

are calibrated in terms of exposure or absorbed dose at points in the col- limated cobalt-60 and cesium- 137

gamma-ray beams that have been

standardized by means of graphite

cavity chambers or a graphite cal- orimeter. Exposure rates and

absorbed-dose rates at the time of cal- ibration are computed from the origi- nal beam standardization data and ap- propriate decay corrections.

Ionization chambers submitted for an

exposure calibration should have suf- ficient wall thickness to provide elec- tron equilibrium for the gamma-ray

energy selected. Ionization chambers

submitted for an absorbed-dose cali- bration must be suitable for cali- bration in a phantom.

An ionization chamber and elec- trometer combination, with the elec- trometer marked in terms of exposure

or absorbed dose, is calibrated by

providing a dimensionless correction

factor for the electrometer scale. An

ionization chamber and electrometer

combination with the electrometer

marked in electrical units is calibrated

as follows: (1) the chamber is cali- brated in terms of exposure or absorbed dose per unit charge using an NBS electrometer, (2) the customer's

electrometer is checked for linearity

and charge measurement accuracy,

and (3) the combination of chamber

and electrometer is checked for consistency. An ionization chamber submitted without an electrometer is cali- brated in terms of exposure or absorbed dose per unit charge. Calibration can be based on measurements

for positive or negative polarizing potential, or on the mean of measurements for both potentials, as re- quested. The ratio of ionization currents for full and half polarizing

potentials and the corresponding ionization current, will be stated in the

calibration certificate. Ionization chambers are tested,

prior to calibration, for leakage, sta- bilization time, short-term stability.

recombination loss, and connection to the atmosphere. Chambers found unsuitable for calibration will be re- turned with a statement of the reason

for rejection. A charge may be made

for time incurred in the tests. Each instrument submitted to NBS

for dosimetry calibration or test must

be uniquely identified, usually by the

manufacturer's name, model number,

and instrument serial number. When

the serial number is lacking, an alter- native identifying mark should be

provided. If none is found, NBS will mark the piece with an identification

number. If the apparatus submitted

has been calibrated previously by

NBS, the serial number or identifying

mark should be given on the new or- der so that a continuing record of sta- bility can be maintained.

All shipments to NBS of instru- ments for dosimetry calibration must

be in reusable containers. Even if properly packed, there can be no as- surance that a calibrated instrument

has maintained its calibration during

shipment unless a method of verifying

instrument stability has been established. Measurement should be made

of the instrument response both before and after shipment, using a longlived radioactive source and a highly

reproducible measurement procedure.

A long-term record of instrument sta- bility using a suitable constancy check

procedure is the most effective

method for assuring the validity of the

instrument calibration. Irradiation of passive dosimeters,

for readout by the customer, is avail- able for the beam qualities listed in Table 7. These irradiations are generally in terms of exposure; for passive

dosimeters suitable for insertion in a

87
46010C-48020S

phantom, irradiation in terms of absorbed dose can be provided by

in-phantom irradiation using cobalt-60

gamma rays. X-ray penetrameters, of the

Ardran-Crookes type, can be caH- brated using constant x-ray generating

potentials up to 300 kV. These penetrameters are used for measurement

of the generating potential of diagnostic x-ray units.

C.2 Gamma-Ray and Beta-Particle

Sources (47010C-47040S)

Sources submitted to the Bureau for dosimetry calibration are subject to the following conditions:

A. Preparation: Sources submitted

for calibration must be sealed so that there can be no escape of any radioactive material, including any gaseous

decay products. The sources, shielding, and packaging must be free of

contamination. Contaminated or leak- ing sources cannot be measured and

may cause considerable loss of time

and damage to laboratory facilities. Sources must have been sealed for a

sufficient time to be substantially in radioactive equilibrium with their decay products when these contribute

to the emitted radiation. B. Packaging for shipment: Packages must be in compliance with the

regulations of the Department of

Transportation as specified in DOT

49CFR173.4- 173.478. Radionuclides

must be packaged as Limited Quantities (DOT 49CFR 173.421) or in Type A packages (DOT

49CFR173.412 and 173.433). Type A

packages must bear the appropriate

radioactive-hazard labels (DOT

49CFR 172.403). If the source is considered by the shipper to be in DOT

Special Form, a Special Form certifi- cate must be furnished to NBS in

strict compliance with DOT

49CFR 173.476. Copies of the codes

are available at the Government

Printing Office, Washington, DC

20402.

All shipments to NBS of gammaray and beta-particle sources must be

in reusable containers. A drawing

showing the source container and a

description of the method of source removal must be provided before the

shipment is received at NBS. Postal

regulations preclude shipment of dosimetry sources via the Postal Service.

If the nature of the shipment re- quires a Type B container subject to an NRC quality assurance program,

documentation must be supplied to NBS certifying that the use of the

container by NBS is part of the pro- gram of the shipper.

C. Possession of licensed materials: In submitting a source for calibration,

it is necessary for the submitter to

certify that he is duly authorized to possess the source under license by

the applicable authority. In the case of individuals residing in a State that has entered into agreement with the

Nuclear Regulatory Commission,

State regulations are applicable to all sources including radium. In the case of other individuals, NRC regulations

are applicable (radium is not licensed

by the NRC). This certification may

be by letter, by a suitable statement on the purchase order covering the

calibration fee, or by a clear copy of

the submitter's Possession License for the source. Calibration in terms of exposure

rate at 1 m is provided for gamma-ray

sources of cobalt-60, cesium- 137,

iridium-192, and iodine-125. Radium

is calibrated in terms of mass of

equivalent radium content measured

relative to the National Radium Stan- dard through comparison of the

gamma radiation from the specimen

and the standard; where the details of

encapsulation of the specimen are known, corrections can be made to obtain milligrams of radium content. Calibration in terms of absorbed-dose

rate is provided for suitable encapsulated beta-particle sources; the dose

88
rate to a low-atomic-number material

(graphite or plastic) is determined by

measurement with an extrapolation

chamber.

C.3 Dosimetry of High-Energy Elec- tron Beams (48010C-48020S)

Dosimeters are provided twice a year

to users requesting assistance with

absorbed-dose measurements in highenergy electron beams. The dosimeters consist of ferrous sulfate (Fricke) solution in radiation-resistant

silica-glass spectrophotometer cells. The user irradiates all but one of the

three furnished dosimeters to between

50 and 80 Gy (5000 and 8000 rad) to water at electron energies between 5 and 50 MeV, employing the irra- diation geometry (field size, phantom,

position of dosimeter in phantom)

given in the "Protocol for Dosimetry

of High-Energy Electrons," Physics

in Medicine and Biology 11, 505

(1966).

After irradiation, the dosimeters are returned to the Bureau for spec- trophotometric evaluation of the

ferric-ion concentration in terms of

absorbed dose in the phantom, using

the G-value given in the Protocol.

References—Dosimetry of X Rays,

Gamma Rays, and Electrons

C.l X- and Gamma-Ray Measuring

Instruments The Photon-Fluence Scaling The- orem for Compton-Scattered Radiation, J. S. Pruitt and R. Loevinger,

Med. Phys., 9, 176 (1982).

The Graphite Calorimeter as a Stan- dard of Absorbed Dose for Cobalt-60

Gamma Radiation, J. S. Pruitt, S. R. Domen, and R. Loevinger, J. Res.

Natl. Bur. Stand. (U.S.), 86, 495

(1981).

Uncertainty in the Delivery of Absorbed Dose, R. Loevinger and T. P. Loftus, Ionizing Radiation Metrology,

International Course at Varenna,

Italy, 1974, E. Casnati, Ed., G-6, 459,

Editrice Compositori, Bologna (1977).

Medical Dosimetry Standards Pro- gram of the National Bureau of Standards, R. Loevinger. Proc. Symp. on

Natl, and Intl. Standardization in Rad. Dosimetry, Atlanta, GA, Dec.

5-9, 1977, Intl. Atomic Energy

Agency, Vienna (1978). (This article provides references for earlier publications on NBS exposure and

absorbed-dose standards.)

Exposure Spectra from the NBS

Vertical-Beam ^Co Gamma-Ray

Source, M. Ehrlich and C. G. Soares,

Natl. Bur. Stand. (U.S.), Int. Report,

NBSIR 76-1117 (1976).

Spectrometry of a '^Co Gamma-Ray

Beam Used for Instrument Calibration, M. Ehrlich, S. M. Seltzer, M.

J. Bielefeld, and J. I. Trombka, Metrologia, 12, 169 (1976).

C.2 Gamma-Ray and Beta-Particle Sources Standardization of Iridium- 192

Gamma-Ray Sources in Terms of Exposure, T. P. Loftus, J. Res. Natl. Bur. Stand. (U.S.), 85, 19 (1980).

Medical Dosimetry Standards Pro- gram of the National Bureau of Standards, R. Loevinger. Proc. Symp. on

Natl, and Intl. Standardization in Rad. Dosimetry, Atlanta, GA, Dec.

5-9, 1977, Intl. Atomic Energy

Agency, Vienna, 1978. (This article provides references for earlier publications on NBS exposure and

absorbed-dose standards.)

Exposure Standardization of

Iodine- 125 Seeds Used for Brachytherapy, T. P. Loftus, J. Res. Natl. Bur. Stand. (U.S.), 89, 295 (1984).

C.3 Dosimetry of High-Energy

Electron Beams

Uniformity of High-Energy ElectronBeam Calibrations, M. Ehrlich and P.

J. Lamperti, Phys. Med. Biol. 14, 305

(1969).

Proposed National Bureau of Stan- dards Program for the Calibration of Instruments Used in High-Energy

Electron and X-Ray Beams, M. Ehrlich, Ann. N.Y. Acad. Sci. 161, 139

(1969).

89
49010S-49050S

Dosimetry for High-Dose Applications

m Ionizing Radiation Division

Center for Radiation Research

Technical Contacts:

William L. Jimmy C. McLaughlin Humphreys

Tel: 301/921-2201 Tel: 301/921-2201

Mailing Address: C216 Radiation Physics, National Bureau of Standards, Gaithersburg, MD 20899

Test No. Items 4901 OS Special Tests of Customer-Supplied Dosimeters

Irradiated with ^Co Gamma Rays

49020S Dose Interpretation of NBS-Packaged Dosimeters

Irradiated by Customer

49030S Dose Interpretation of Each NBS-Supplied

Dosimeter Package in Addition to those Supplied

Under 49020S

49040S Special Tests of Dosimeters by Reading with

Spectrophotometer, Optical Density at One to Five

Wavelengths (Each Dosimeter)

4904 IS Spectrophotometric Readings of Dosimeters,

Ultra-Violet and Visible Spectrum Scan (Each

Dosimeter)

49050S Special Measurement Services for Dosimeter

Response

Special Tests of Dosimeters

(49010S-49050S)

The following dosimetry services are

for individual users of intense radi- ation fields, in particular, large

gamma-ray sources and electron

accelerators up to approximately

10 MeV. These services include the

administering of known doses of

photons to customer-supplied

dosimeters; supplying calibrated

secondary-standard transfer dosimeters to customers for irra- diation and subsequent readout and

dose interpretation; and special measurement services such as the deter- mination of temperature dependence,

dose-rate dependency or reproducibility of dosimeter response, and measurement of detailed dose distribu- tions in specific irradiation geometries

and in selected absorbing materials.

These dose distribution measurements

can include dose profiles in heteroge- nous absorbers and at surfaces and in- terfaces of different substances. Such

information is important in research

leading to the commissioning of a

radiation process, and in measurement

assurance that provides quality control of a given radiation treatment.

Special Tests of Dosimeters Irradiated

with *°Co Gamma Rays (49010S)

Irradiation tests are available for customer-supplied dosimeters (such as solid radiochromic or liquid chemical

types) or test samples that are sent to NBS, where they are packaged in ap- propriate conditions of electron equilibrium. They are then irradiated in the NBS standard cobalt-60 cali- bration facility to specific agreedupon absorbed dose values in the

90
49010S-49050S

nominal "high-dose" ranges of 10-10* grays (10^-10* rads). The dosimeters

may either be read and evaluated by

NBS or sent back to the customer for analysis and evaluation. Dosimeters

should not exceed dimensions of 1 cm

X 2 cm X 5 cm.

Special Tests of Radiochromic

Dosimeters (49020S and 49030S)

NBS can provide sets of calibrated

radiochromic dosimeters packaged in appropriate equilibrium material, such

as polystyrene or aluminum. The

sealed, packaged dosimeters are sent to the customer for irradiation to nominal agreed-upon absorbed dose

levels in a prescribed geometrical ar- rangement. The unopened packaged

dosimeters are then returned to NBS

to be read and evaluated. The ab- sorbed dose range that is suitable for use with the radiochromic dosimeters

is 1 to 50 kGy (0.1 to 5 Mrad) in water, silicon, aluminum, graphite, or

certain plastics.

Special Tests of Dosimeters:

Spectrophotometric Reading

(49040S-49041S)

Dosimeters may be read at several

specific ultraviolet or visible optical

wavelengths or as a spectral scan over an appropriate wavelength re- gion of interest. Special Measurement Services for Dosimeter Response (49050S)

Tests of dosimeter response, such as temperature dependence, dose rate dependence, and dose distributions in

specific irradiation geometries, can be

provided as special measurement ser- vices.

References—High Dose Dosimetry

A National Standardization Pro- gramme for High-Dose Measurements, W. L. McLaughlin, Technical Report No. 205, 17, Intl. Atomic Energy Agency, Vienna

(1981).

Dosimetry for Industrial Radiation

Processing, W. L. McLaughlin, J. C. Humphreys, and A. Miller, Natl. Bur. Stand. (U.S.), Spec. Publ. 609 (1981).

Dye Film Dosimetry for Radiation

Processing, J. C. Humphreys and W.

L. McLaughlin, IEEE Trans. Nucl.

Sci., NS-28, 2, 1797 (Apr. 1981).

The Measurement of Absorbed Dose

and Dose Gradients, W. L. McLaughlin, Radiat. Phys. Chem.,

15, 9 (1980).

Dosimetry Standards for Industrial

Radiation Processing, W. L. McLaughlin, National and Inter- national Standardization of Radiation

Dosimetry, 1, Intl. At. Energy

Agency, Vienna (1978).

91
Chapter

A Resistance Measurements

B Impedance Measurements

C Voltage Measurements

D Precision Ratio Measurements

E Vhase Angle Measurements

F Power and Energy Measurements

G Microwave Measurements

H Noise Tfemperature Measurements

/ Electromagnetic Field-Strength and

Antenna Measurements

J Pulse Waveform Measurements
Electromagnetic Measurements 5I100S-51163C

Resistance Measurements

^1'A.I DC Resistance Standards and

Measurements

Electricity Division

Center for Basic Standards

Technical Contacts:

Ronald F. Norman B. Avis R. Wise

Dziuba Belecki Administrative

Tel: 301/921-2715 Tel: 301/921-2715 and Logistics

Tel: 301/921-2715

Mailing Address: B146 Metrology, National Bureau of Standards, Gaithersburg, MD 20899

Test No. Items SHOOS special Resistance Measurement Services by

Prearrangement

511 lOM Measurement Assurance Program Services for Resistance

51130C Standard Resistor, Thomas-Type 1 ft 51131C Standard Resistor, Evanohm Wirewound High

Precision, 10 kft 51132C Standard Resistor, Four-Terminal 0.0001 ft 51133C Standard Resistor, Four-Terminal 0.001 ft 51134C Standard Resistor, Four-Terminal 0.01 ft 51135C Standard Resistor, Four-Terminal 0.1 ft 51136C Standard Resistor, Four-Terminal 1 ft 51137C Standard Resistor, Four-Terminal, 10 ft 51 BSC Standard Resistor, Four-Terminal, 100 ft 51139C Standard Resistor, 1 kft

5 1 140C Standard Resistor, 10 kft 51141C Standard Resistor, 100 kft 51142C Standard Resistor, 1 Mft

51143C Standard Resistor, 10 Mft

5 1 144C Additional Voltage

51145C Standard Resistor, 100 Mft

Special DC Resistance Measurements

by Prearrangement (51100S)

Testing or evaluation of prototype re- sistance standards or measuring in- struments; unique resistance measurements; and other calibration

services not specified below, such as the determination of the pressure coTest No. Items

5 1 1 46C Additional Voltage

51147C Standard Resistor, 1 Gft

5 1 1 48C Additional Voltage

51149C Standard Resistor, 10 Gft

5 1 1 50C Additional Voltage

5 1 1 5 1 C Standard Resistor, 1 00 Gft

5 1 1 52C Additional Voltage

51153C Standard Resistor, 1 Tft

5 1 1 54C Additional Voltage

51160C Standard Resistor for Current Measurements

(Shunts), One Range, One Current Not to Exceed 300 A (May & Nov.)

51161C Standard Resistor for Current Measurements

(Shunts), One Range, One Current Between 300 A

and 1000 A (May & Nov.)

51162C Standard Resistor for Current Measurements

(Shunts), Additional Range of a Multi-Range Resistor (May & Nov.)

51163C Standard Resistor for Current Measurements

(Shunts), Additional Determination at Another

Current Level (May and Nov.)

efficient of Thomas-type resistors, the

determination of the temperature coefficient of standard resistors, and the

calibration of resistance standards in

oil at temperatures other than 25 °C, are carried out under this test number. Such measurements are made at the discretion of the NBS technical

93
staff in a manner specifically agreed

upon by the customer and the expert

involved. Testing of component re- sistors will only be considered under

the rare circumstance that the behavior of the resistors has been observed

to approximate that of state-of-the-art standards under the same conditions.

Measurement Assurance Program

Services for Resistance (51110M)

Resistance MAP transfers are generally carried out at the 1 ohm and 10

kilohm levels. Four wellcharacterized commerical standard

resistors are used as transport stan- dards. The suggested measurement

schedule at the client laboratory consists of measurements on each trans- port resistor 3 times a wee': for a pe- riod of 4-6 weeks, depending upon

the settling time of the resistors due

to transportation effects. Participation in this program is generally not advisable unless one is required to support resistance measurements at or near state-of-the-art accuracies and is willing to adopt a system for the continuous surveillance

of standards during the intervals between NBS MAP transfers. A successful transfer requires a considerable amount of data collection and

a willingness to become involved in the data analysis process. Data supplied in the course of routine NBS

calibrations suffice for normal measurement requirements of standards

laboratories if proper methods are used by the laboratory to quantify the

additional uncertainties caused by

transportation and the laboratory's

own measurement process. Special Standard Resistors 1 H and

10 kCl (51130C and 51131Q

Thomas-type 1 ohm resistors or their equivalent are calibrated directly

against the NBS 1 ohm reference

group that is used to maintain the U.S. legal ohm. Special 10 kilohm

standard resistors designed for air or

011 use are calibrated directly against'

the NBS 10 kilohm working stan- dards. The special 10 kilohm standard

resistors (Evanohm wirewound highprecision or equivalent) are characterized by resistance corrections within

10 ppm of nominal value, temperature

coefficients of 0± 1 ppm/°C at the

operating temperature, and drift rates of < 1 ppm/year.

The customer resistors are accli- matized in their respective test environments for approximately one week

prior to their calibration. Measurement parameters of temperature

and current level are as follows:

Resistor Medium Temperature Current la oil 25.00±0.003''C 100 mA

lOkfl oil 25.00±0.0rC 1mA

10 kn air 23.0±1.0''C 1mA

The temperature of the customer re- sistor at the time of the measurement

94
51100S-51163C

is given in the report of calibration. Since the Thomas-type resistor exhibits a significant pressure coefficient, the barometric pressure at the

time of the measurement is also re- ported for the 1 ohm standards. Uncertainties are based upon (1) the ran- dom behavior of the measurement

process as characterized by data from

a large population of individual cali- brations, and (2) an estimate of the

systematic errors. Uncertainties are

listed in Table 8 at the end of this section. Standard Resistors 10 "-lO* il (51132C-51142Q

Standard resistors with nominal decade values in the range between 10"'* and 10^ ohm are calibrated by comparison with NBS working standards. In general, these standards are characterized by (1) resistance corrections

within 500 ppm of nominal value, (2)

temperature coefficients of < 10 ppm/

°C at the temperature of use, and (3)

drift rates of < 5 ppm/year. Normally,

standard resistors are measured in an

oil bath maintained at 25.0+0.05 °C,

and at a power level of <0.1 W. Resistors in temperature-controlled en- closures with fixed terminations are

also accepted for calibration. At the

levels of accuracy involved, four- terminal measurements are required

for resistors whose nominal value is 100 ohms or less. Uncertainties are based upon (1) the random behavior

of the measurement process as characterized by data from a large population of individual calibrations, and

(2) an estimate of the systematic errors. Uncertainties are given in Table

8 at the end of this section. High-Valued Standard Resistors: lO'-lO'' SI (51143C-51154C)

High-value standard resistors in the

range between 10^ and 10'^ ohms are

calibrated in an air bath maintained at a temperature of 23.0±0.5 °C and at a

relative humidity of 35 ±5%. Customer resistors are compared 1 : 1 with

NBS working standards of the same

nominal value up to and including the

10'" ohms level. Above 10'° ohms,

10:1 and 100:1 ratio techniques are employed. The maximum test voltage

is 500 volts for resistors < 10'° ohms

and 1000 volts for resistors > 10'° ohms. Uncertainties depend upon the

stability and performance of the specific resistor involved, and are given

at the end of this section. Only re- sistors that are mounted in a shielded

enclosure with a permanent identi- fying number and have suitable terminations are accepted for calibration. The resistance of thin-film, highvalued resistance standards is fre- quently highly voltage dependent.

Hence, the magnitude of the test volt- age should be specified by the cus- tomer when a resistor is submitted for

calibration. The temperature, relative

95
51100S-51163C

humidity, and test voltage of the resistor are given in the report of caHbration.

High-Current Standard Resistors

Shunts (51160C-51163O

Four-terminal standard resistors for use in the precise measurement of

high direct currents (shunts) are cali- brated by NBS only during May and

November of the calendar year. Arrangements should be made with

NBS prior to submitting a resistor for

calibration. Normally only resistors of

0.04% accuracy or better are cali- brated. The maximum test current

available is 1000 amperes. The uncertainty of measurement depends

largely upon the performance of the

customer resistor involved.

Table 8: Calibration Uncertainties for DC Resistance

Standards

Test Nominal Terminal Maximum Uncertainty

Number Resistance (ohms) Couiection Power (mw) ppm

51130C 1 (Thomas) 4 10 0.08 51131C 10" (Special) 5 50 1 51132C 10 " 4 100 20 51133C 10-^ 4 100 12 51134C 10-2 4 100 7 51135C 10-' 4 100 5 51136C 1 4 100 3 51137C 10 4 100 4 51138C 10^ 2 100 4 51139C 10^ 2 100 5 51140C 10" 2 100 7 51141C 10' 2 100 10 51142C 10* 2 100 15 51143C 10' 3

* 50-2000

51145C 10' 3

* 100-2000

51147C 10' 3

* 2000

51149C 10'° 3

* 2000

51151C 10" 3

* 2000

51153C 10'^ 3

* 2000

* Resistors at this level are tested at customer-specified voltages up to 1 k V.

References—DC Resistance

A Test of the Quantum Hall Effect as a Resistance Standard, M. E. Cage,

R. F. Dziuba, and B. F. Field, IEEE

Trans. Instrum. Meas., IM-34, 301

(1985).

Automated NBS 1-Ohm Measurement

System, K. R. Baker and R. F. Dziuba, IEEE Trans. Instrum. Meas.,

IM-32, 154 (1982).

Determination of the Fine-Structure

Constant Using GaAs-Al, Ga(i_x) as Heterostructures, D. C. Tusui, A. C.

Gossard, B. F. Field, M. E. Cage, and

R. F. Dziuba, Phys. Rev. Lett., 48, 3 (1982).

Measurement of the Quantized Hall

Steps in Silicon at the PPM Level, R.

J. Wagner, C. F. Lavin, M. E. Cage,

R. F. Dziuba, and B. F. Field, Surf.

Sci., 113, 10 (1982).

An Integrated System for the Precision Calibration of Four-Terminal

Standard Resistors, T. E. Wells and

E. F. Gard, IEEE Trans. Instrum. Meas., IM-20, 253 (Nov. 1971).

Calibration Procedures for Direct

Current Apparatus, P. Brooks, Natl. Bur. Stand. (U.S.), Monogr. 39 (Mar.

1962).

Measurement of Multimegohm Resistors, A. H. Scott, J. Res. Natl. Bur.

Stand. (U.S.), 50, No. 3 (Mar. 1953).

Precision Resistors and Their Measurement, J. L. Thomas, Natl. Bur.

Stand. (U.S.), Circular 470 (Oct.

1948).

Methods, Apparatus, and Procedures

for the Comparison of Precision Stan- dard Resistors, F. Wenner, J. Res.

Natl. Bur. Stand. (U.S.), 25, Res. Paper RP1323 (Aug. 1940).

96
Resistance Measurements

r^m A.2 High-Voltage Standard Resistors

Electrosystems Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

Martin Misaldan Robert E.

Tel: 301/921-3121 Hebner, Jr. Tel: 301/921-3121

Mailing Address: B344 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Shipping Address: National Bureau of Standards 1-270 at Quince Orchard Road, Gaithersburg, MD 20899

[Attn: M. Misakian, Bid. 220, Room B344]

Test No. Items 51210C High-Voltage Standard Resistors

High-Voltage Resistors (51210Q

A routine calibration service is maintained for resistors designed for dc

high-voltage applications. This ser- vice is for nearly corona-free resistors designed for dc operation between 10 kV and 150 kV.

Resistors can be hand-carried or shipped to NBS. If they are shipped,

they should be packaged in sturdy re- usable containers. The design of many

high voltage resistors makes them

vulnerable to shear-type forces, so provisions should be made to minimize the likelihood of damage due to such forces when the device is in the

shipping container.

References—High-Voltage Standard

Resistors

Special Shielded Resistor for HighVoltage Measurements, J. H. Park, J. Res., Natl. Bur. Stand., 66C, No. 1, 1924 (Jan.-Mar. 1962).

High Voltage Divider and Resistor

Calibrations, M. Misakian, NBS Tech.

Note 1215 (July 1985).

NBS reference high-voltage resistor

(large object; for size comparison,

low-voltage resistor at left).

97
51310C

A

Resistance Measurements

A,3 High-Frequency Standard Resistors

Electromagnetic Fields Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

Cletus A. Hoer

Tel: 303/497-3705 Raymond N. Jones

Tel: 303/497-3609

Edna M. Jones

Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Bureau of Standards, 325 Broadway, Boulder, CO 80303

Test No. Items

5 13 IOC High-Frequency Standard Resistors; Two-Terminal

High-Frequency Standard Resistors

(513I0C)

The overall frequency range covered

is 10 kHz to 250 MHz. The range of

resistance that can be calibrated depends on the measurement frequency,

as follows:

Frequency Range

10 kHz-2 MHz

2MHz-10MHz

10 MHz-100 MHz

100 MHz-250 MHz

Resistance Range

0.1 nto 1 Ma

50 n to 1 Ma

20 n to 50 ka

20 fl to 20 kn

Measurement uncertainties are given

in the reference; the minimum uncertainty provided is ±0.1 percent.

Reports of Calibration or Tests for

resistors will include the inductance

or capacitance associated with the resistor. Equivalent series values are normally given for inductive resistors and equivalent parallel values for ca- pacitive resistors.

References—High-Frequency Standard

Resistors

The Measurement of Lumped Parameter Impedance: A Metrology Guide,

R. N. Jones, Nat. Bur. Stand. (U.S.),

Monogr. 141, (June 1974).

Impedance of Lumped Circuits, L. E. Huntley, and R. N. Jones, Proc. IEEE, 55(6), 900 (June 1967).

98
A

Resistance Measurements ' A.4 AC Resistors

Electrosystems Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

Barry A. Bell

Tel: 301/921-2727

Tel: 301/921-2727

Mailing Address: B162 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

ratings not to exceed 50A. The values

for the ac resistance and phase angle

(or time constant) can be reported for frequencies between 50 Hz and 10 kHz. To be accepted for test, resistors must have phase angles no greater

than 0.01 radian at all requested test frequencies.

The service is being offered on a

trial basis under Special Test Procedures. The fee for this service will be based on the actual cost. Prior ar- rangements are essential. References—AC Resistors

An Audio Frequency Four-Terminal

Resistance Bridge, T. M. Souders,

IEEE Trans. Instrum. Meas., IM-23,

No. 4, 342 (Dec. 1974).

Test No. Items 51410S Special Tests of AC Resistors by Prearrangement

Special Tests of AC Resistors (51410S)

Properly designed four-terminal ac

resistors in the range of 0. 1 ohm to 0.001 ohm can be measured at current

99
52110S-52181C

Impedance Measurements (Except Resistors)

mt^m B. 1 Low-Frequency Capacitance and

Inductance

Measurements and Standards

Electricity Division

Center for Basic Standards

Technical Contacts:

Norman B. George M. Free Avis R. Wise

Belecki Tel: 301/921-2715 Administrative

Tel: 301/921-2715 and Logistics

Tel: 301/921-2715

Mailing Address: B146 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items 52110S Special LF Impedance Measurements by

Prearrangement

52130C Standard Fixed, Fused-Silica Dielectric Capacitor

(10 and 100 pF at 100, 400, or 1000 Hz)

52131C Additional Frequency Points 52140C Fixed Three-Terminal, High-Precision Standard

Capacitor With Coaxial Connectors (1 frequency,

high accuracy under controlled conditions, 100, 400, or 1000 Hz)

52141C Additional Frequency Points 52150C Physical Tests to Qualify Three-Terminal Air

Capacitor for Measurement under 52140C

52160C Fixed Three-Terminal Standard Capacitor with

Coaxial Connectors (1 frequency, laboratory

conditions, 100, 400, or 1000 Hz)

52161C Additional Frequencies

52170C Two or Three-Terminal Solid Dielectric Standard

Capacitor (66-2/3, 100, 400, 1000, or 10,000 Hz)

52171C Additional Frequencies

52180C Fixed Inductor, Self or Mutual (100, 400, 1000, or

10,000 Hz)

52181C Additional Points

Low-Frequency Capacitance and In- ductance Measurements and Standards

(52110S-52181C)

These services cover the calibration

of standard capacitors and inductors

in the audio-frequency range. Stan- dard capacitors having fused-silica (10

and 100 pF), air (0.001 to 1000 ^iF),

and silvered-mica (1 to 1000 HF) di- electrics can be measured at fre- quencies between 66-2/3 and 10,000

Hz. Air-core standard inductors having nominal values between 0.01 mH

and 10 H can be measured at the same frequencies.

Calibration services for some types

of capacitance standards at fre- quencies as low as 1 kHz can be pro- vided by the NBS Boulder Laboratory provided the accuracy

requirement does not exceed ±0.01

percent. In some circumstances, this can eliminate the necessity of sending

a standard to both Gaithersburg and

Boulder Laboratories for a complete

calibration. See also tests 52210C-52310C for calibration ser- vices for capacitors at higher fre- quencies. For additional details please

inquire at NBS/Boulder: Telephone

(303) 497-3609.

Special LF Impedance Measurements

by Prearrangement (52110S)

This service provides for the testing or evaluation of prototype impedance

standards or measurement instrumentation at the state-of-the-art, and other

impedance measurements (such as the

calibration of decade or variable ca- pacitance standards), at the discretion

of NBS technical experts. Component

capacitors, inductors, and resistors are not considered for test by the NBS

unless their performance approximates that of the best available stan- dards. Even under those conditions,

only limited testing will be done to ascertain the possible use of the components in precision measurement applications.

Standard Fixed, Fused-Silica

Dielectric Capacitors

(52130C-52131C)

Fused-silica dielectric standard capacitors are generally submitted in temperature-controlled ovens due to

their 10-ppm/degree temperature coefficient. Because of the magnitude of

the temperature coefficient, it is rec100
ommended that a calibrated temperature sensor be permanently

mounted in the oven and thus in- cluded for the calibration. For baths not so equipped, the temperature is measured in terms of the International

Practical Temperature Scale of 1968

as amended in 1975 [Metrologia 12, 7 (1976)] using a standard platinum re- sistance thermometer.

Calibrations are carried out at 100,

400, or 1000 Hertz, or any combination of these chosen by the client. A

minimum of eight measurements are made over a two-week or longer period, comparing the test capacitor di- rectly with an NBS fused-silica stan- dard at 10 pF. The number of

readings taken depends on the sta- bility of the temperature controller in the oven containing the test capacitors and can be as high as fourteen.

The averages of the measured values

of capacitance and temperature are reported. The uncertainty of the re- ported capacitance value depends on

the stability of the temperature as well as on the performance of the ca- pacitance standard itself. Because the

temperature coefficients of individual

standards are not known quantitatively, the results are not temperature corrected. Despite these factors, the uncertainty can be as low as

0.1 ppm.

Fused-silica dielectric standards not submitted in their own temperaturecontrolled oven are calibrated in stirred oil at a temperature of 25 °C.

If they are supplied with built-in sensors, the sensors and the bath temperature are both measured.

Standard Capacitors (52140C-52171Q

The following guidelines apply to the

calibration of standard capacitors at NBS.

Calibrations are ordinarily per- formed at a normal laboratory ambient temperature of 23±1 °C except

for high stability gas dielectric capacitors. These are placed in a highly in- sulated chamber for 48 hours to achieve temperature stability during

calibration. The calibration temperature of about 23 °C is reported to

within ±0.1 °C. Relative humidity is maintained at 50 percent or less in all cases. Precision three-terminal gas di- electric capacitors, such as ESI

Model SCIOOO and GENRAD Model

1404, have been found to be variously

affected by mechanical shock and ori- entation. Accordingly, two types of

calibrations are offered. The higher

accuracy calibration (52140C) re- quires a qualification test (52150C) to determine the effect on capacitance of

various impacts and changes in orientation. Results of this test are coupled

with the random error of the precision calibration which follows to provide a definitive accuracy for the

process. For the lower accuracy test (52160C), a similar calibration, albeit with reduced resolution, is per- formed, but no physical testing is per- formed. The assigned uncertainty is fixed and has been deduced from an

analysis of data taken from tests on a

large population of standard capacitors. The frequencies available for ca- pacitance calibrations depend upon

the type of capacitor and its connectors. In general, capacitors with

coaxial connectors can be calibrated

at 100, 400, and 1000 Hz. Capacitors

with binding posts or banana plugs can be calibrated at 66-2/3, 100, 400,

1000 and 10,000 Hz.

The capacitance value given is the

equivalent parallel capacitance. In

general, an accurate determination of

the equivalent parallel conductance

with high accuracy is not feasible. However, for solid dielectric capacitors an approximate value is given

without charge.

The uncertainty stated in the report

of calibration is determined in part by

the accuracy of the Bureau's measurements and in part by the characteristics of the capacitor itself. The

uncertainty is sufficiently broad to al- low for variations in the stray capaci- tance at the connectors, variations in temperature of a few degrees Celsius,

considerable variation in relative humidity and atmospheric pressure, and

101
frequency deviations of a few percent

from the stated test conditions. Over

the above frequency range, and in the

capacitance range from 0.001 to 100 ju,F, the uncertainty usually lies in the range 0.002 to 0.5 percent.

Capacitors requiring terminal plugs

(banana plugs) for parallel connection

should be sent to NBS, together with

the plugs that will be used with the

capacitor after calibration. If such a capacitor arrives without plugs, the

NBS must attach plugs temporarily in order to calibrate the capacitor. The

plugs used by the Bureau are GENRAD Type 274-P. If, after calibration

with these plugs, the capacitor is used

with plugs of even slightly different

length and base, the capacitance can

differ significantly from that reported.

Unless otherwise requested, the measured value reported by NBS is the

capacitance added when the standard

is plugged directly into the binding

posts of the NBS bridge. For twoterminal GENRAD capacitors Type

1401, Type 509, and Type 1409

(when used as a two-terminal capacitor), a capacitance increase ranging

from 0.01 to 0.04 pF has been found

for different plugs. No significant

change in conductance has been

found in either the two-terminal or

three-terminal value. The importance

of terminal connection methods be- comes extremely critical when capacitance values of 0.01 fxF or less are being measured. Improved accuracy

in two-terminal measurement can be

realized if standards are provided

with precision coaxial connectors.

In the case of direct or three- terminal capacitance standards, the

connectors are assumed to be coaxial. While the connectors available for

this purpose are adequate, it should

be noted that changes or instabilities in the impedance of the shield or guard connection of a three-terminal

capacitor can change the capacitance

significantly.

Unless otherwise specified in the customer's purchase order, capacitors

with solid dielectric—except fusedsilica capacitors,—will be calibrated

as two-terminal capacitors (measurement of "grounded" capacitance, case connected to low terminal).

Standard Inductors, Self or Mutual

(52180C-52181Q

Standard inductors for use in ac

bridges are tested at a room temperature of 23 °C and a relative humidity of 50 percent or less. Measurements at 10,000 Hz are limited to standard inductors of 0. 1 H or less. Most inductors used at 60 Hz can be

tested at 100 Hz since the variation of

inductance with frequency in this range is usually negligible. A metalencased standard is calibrated with

the case connected to the "low" ter- minal of the inductor unless other

conditions are specified.

References—Low-Frequency Capacitance and Inductance Standards

Testing to Quantify the Effects of

Handling of Gas Dielectric Standard

Capacitors, C. R. Levy, Natl. Bur.

Stand. (U.S.), Tech. Note 1161

(1982).

Transportable 1000 pF Standard, G.

M. Free and J. J. Morrow, Natl. Bur.

Stand. (U.S.), Tech. Note 1162

(1982).

New Measurements of the Absolute

Farad and Ohm, R. D. Cutkosky,

IEEE Trans. Instrum. Meas., IM-23,

No. 4, 305 (Dec. 1974).

Applications of Coaxial Chokes to AC Bridge Circuits, D. N. Homan, J. Res. Natl. Bur. Stand. (U.S.), 72C,

No. 2 (June 1968).

Improved Ten-Picofarad Fused Silica Dielectric Capacitor, R. D. Cutkosky

and H. L. Lee, J. Res. Natl. Bur. Stand. (U.S.), 69C, No. 3, 173 (Sept.

1965).

Calibration of Inductance Standards

in the Maxwell-Wein Bridge Circuit, T. L. Zapf, J. Res. Natl. Bur. Stand.

(U.S.), 65C, No. 3 (Sept. 1961).

Capacitance Bridge—NBS Type 2, R. D. Cutkosky, Natl. Bur. Stand. (U.S.),

Report 7103 (Mar. 1961).

102
52210S-52310S

B.

Impedance Measurements (Except Resistors)

B.2 High-Frequency Standard Capacitors

and Inductors

Electromagnetic Fields Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

Sr.

Raymond N.

Jones

Tel: 303/497-3609

Cletus A. Hoer

Tel: 303/497-3705 Edna M. Jones

Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Bureau of Standards, 325 Broadway, Boulder, CO 80303

Test No. Items

522 lOS Two-Terminal, Low-Loss Standard Capacitors

10 kHz to 250 MHz; 1 pF to 1 ju.F 5221 IC Two-Terminal, Low-Loss Standard Capacitors,

(High Accuracy)— 1 MHz; 50, 100, 200, 500 and lOOOpF

52220C Three-Terminal, Low-Loss Standard Capacitors

100 kHz, 465 kHz, 1 MHz; 10"^ pF to 10^ pF

5222 IC Three-Terminal, Low-Loss Standard Capacitors

(High Accuracy)— 100 kHz, 465 kHz, 1 MHz; 10 ^

10-', 1, 10, 10^ and 10^ pF

52222C Three-Terminal (MacLeod and Hanopol) Capacitors465 kHz; 0.001 to lOpF

52223C Auxiliary Unit for 52222C

523 lOS Two-Terminal, High-Q Standard Inductors (10- VH to 1 H)

High-Frequency Standard Capacitors

and Inductors (52210S-52310S)

Services provided in this category

(and also test nos. 5 13 IOC and

52700C) are for passive devices over

the frequency range from 10 kHz to 250 MHz. Highest accuracy is obtained only for standards equipped

with precision coaxial connectors. Standards submitted for calibration

should be in good repair and, except

for very minor cleaning of connector

surfaces, should require no pre- calibration maintenance. NBS does

not provide repair services so that items received that require mainte- nance will be returned to the sender

and a handling fee will be charged.

Calibration services for some types

of capacitance standards at fre- quencies as low as 1 kHz can be pro- vided by the NBS Boulder Laboratory provided the accuracy

requirement does not exceed ±0.01

percent. In some circumstances this can eliminate the necessity of sending

a standard to both the Gaithersburg

and Boulder Laboratories for a complete calibration. For additional details please consult with the technical contact listed at the beginning of this section. Calibration service for measuring

instruments such as bridges or meters

is not provided. The accuracy of

these instruments should be verified

by the owner through the use of sta- ble standards especially selected for particular values and frequencies ap- propriate to the instrument in question. All calibrations are performed un- der typical ambient laboratory conditions of 23 °C, and an atmospheric

pressure of approximately

8.4±0.2X 10' Pa at Boulder, Colorado. Services at ambient conditions

outside these limits are not provided.

Also, the power applied to any device being calibrated does not exceed

1 W. Additional information per- taining to immittance (impedance and

admittance) measurement and stan- dards is contained in the references. Two-Terminal, Low-Loss, Standard

Capacitors (52210C-52211Q

In the frequency range from 10 kHz

to 250 MHz, capacitance calibrations to a minimum uncertainty of ±0.1

103
percent are available from 1 pF to 1 jxF depending upon frequency. The

upper capacitance limit for calibration

decreases as the frequency increases

and is 50 pF at 5 MHz and above.

At 1 MHz a special high accuracy

service is available for capacitors

with nominal values of 50, 100, 200,

500, and 1000 pF provided they are equipped with 14 mm coaxial connectors. Reports of calibration for capacitors normally do not give conductance values. This is because capacitors of standard quality, especially

those with air-dielectric, have con- ductance values too small to be measured accurately at the present state- of-the-art. A technique for extrapolating the 1 kHz values of capacitance standards

to high frequencies is described by R. N. Jones (see references). This refer- ence describes a technique for obtaining a high frequency value of a ca- pacitor equipped with an unshielded

(banana plug) connector. The measurement technique yields effective

capacitance values at high frequencies

using the capacitance value at 1 kHz

and the residual series inductance.

The same technique, with some modifications, is usable for three-terminal

and four-terminal pair capacitors. It is emphasized that these extrapolation

procedures are only usable for air di- electric capacitors or capacitors with

insulating materials whose dielectric constant does not change with fre- quency.

Three-Terminal, Low-Loss, Standard

Capacitors (52220C-52221C)

Fixed value reference standards are maintained by NBS for values of 10, 100, and 1000 pF. High quality threeterminal air dielectric capacitance

standards should have low residual

series inductance (<0.1 jiiH). This being the case, it may be assumed that to an accuracy of ±0.10 percent, the

capacitances of standards of 1 pF or

less with air dielectric is the same at 1 MHz as it is at 1 kHz. Thus, it is un- necessary to have capacitors smaller

than 10 pF calibrated at 1 MHz.

Two-Terminal, High-Q, Standard

Inductors (523 ICS)

In the frequency range from 10 kHz

to 250 MHz, inductance calibrations to a minimum uncertainty of ±0.1

percent are available from 0.01 jliH to

1 H. The upper inductance limit for calibration decreases as the frequency

increases and is 1 jliH at 250 MHz. In the Report of Calibration, the re- sistance of the inductor is also given.

Service is available only for aircore

inductors or inductors whose value is independent of current.

References—High Frequency Standard

Capacitors and Inductors

The Measurements of Lumped Pa- rameter Impedance: A Metrology

Guide, R. N. Jones, Natl. Bur. Stand.

(U.S.), Monogr. 141 (June 1974).

Impedance of Lumped Circuits, L. E. Huntley, R. N. Jones, Proc. IEEE

55(6), 900 (June 1967).

A Technique for Extrapolating the 1 kc Values of Secondary Capacitance

Standards to Higher Frequencies, R. N. Jones, Natl. Bur. Stand. (U.S.),

Tech. Note 201 (Nov. 1963).

A Precision High Frequency Calibration Facility for Coaxial Capacitance Standards, R. N. Jones and

L. E. Huntley, Natl. Bur. Stand.

(U.S.), Tech. Note 386 (Mar. 1970).

Evaluation of Three-Terminal and

Four-Terminal Pair Capacitors at High Frequencies, R. N. Jones, Natl. Bur. Stand. (U.S.), Tech. Note 1024

(Sept. 1980).

104
P

Impedance Measurements (Except Resistors)

' B.3 Power-Frequency Capacitors

Electrosystems Division

I Center for Electronics and Electrical

I Engineering

Technical Contacts:

William E. Robert E. Anderson Hebner, Jr. Tel: 301/921-3121 Tel: 301/921-3121

Mailing Address: B344 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Shipping Address: National Bureau of Standards 1-270 at Quince Orchard Road, Gaithersburg, MD 20899

[Attn: W. E. Anderson, Bid. 202, Room 167]

Test No. Items 52400C Power-Frequency Capacitors

Power-Frequency Capacitors (52400Q

A calibration service is maintained for capacitors designed for 60-Hz operation, especially at voltages above 100

V. Typical uncertainties for a cali- bration are ± 100 ppm of the capacitance, and ± 1 % of the dissipation

factor ±1 X 10"'. Routine calibrations are limited to devices with a dissi- pation factor of 0.01 1 or smaller and

which are operated at sufficient volt- age that at least 40 fiA pass through

the device under test. The high power limit for routine

tests is 10 kVA. Some capability to perform tests outside of these limits exists and NBS should be contacted

to discuss special arrangements for such tests. References—Power-Frequency

Capacitors

A Wide Range High-Voltage Capacitance Bridge With One ppm Accuracy, O. Petersons, and W. E. Anderson, IEEE Trans. Instrum. Meas.

24, 4, 336 (Dec. 1975).

An International Comparison of

High-Voltage Capacitor Calibrations,

W. E. Anderson, R. S. Davis, O. Petersons, and W. J. M. Moore, IEEE

Trans. Power Appar. Syst., 97, 4, 1217 (July 1978).

105
526 IOC

B. Impedance Measurements (Except Resistors)

B.4 Eddy-Current Conductivity Standards

Electricity Division

Center for Basic Standards

Technical Contacts:

George M. Free Avis R. Wise

Tel: 301/921-2715 Administrative and Logistics

Tel: 301/921-2715

Mailing Address: B146 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items 526 IOC Eddy-Current Conductivity Standards; 15-100% I ACS

Eddy-Current Conductivity Standards;

15% to 100% lACS (52610C)

Electrical conductivity standards for calibrating eddy-current conductivity

instruments in the range 15-100%

lACS (International Annealed Copper Standard) are calibrated in the

Electricity Division. Customer stan- dards are calibrated on a variable fre- quency eddy-current bridge using a

coil with a mean diameter of 0.4 cm.

Standards are measured in a fre- quency range of 10 kHz to 100 kHz,

depending on the electrical conductivity value of the standards. Customer standards are compared with

NBS standards while submerged in an

oil bath which maintains a nominal

temperature of 20.00 "C. The electrical conductivity of the NBS stan- dards is based on a dc measurement

of electrical conductivity. Customer

standards are checked for uniformity

of electrical conductivity over the

surface to be calibrated. The conductivity reported is that measured at the center of this surface. Standards to be tested must be of

non-magnetic materials and must have

a surface geometry such that the dis- tance from the center of the standards

to the closest edge is at least 2.2 cm

and no greater than 3.8 cm. The sample must be free of scratches, grooves, etc. Special arrangements can be

made for calibrating standards at user-specified frequencies for those

eddy-current systems that function at a fixed frequency. The user-specified

frequency should be less than 100

kHz.

The minimum uncertainty of the

calibrated value is ±0.15% of the

stated value. This uncertainty consists

of components from the dc deter- mination of the NBS standards, errors

in the transfer of value from the NBS

standards to customer standards, and

errors due to offset from the nominal

temperature of 20.00 °C.

Charles Levy, conducting electrical conductivity

measurements of non-ferrous standards.

106
52710C-52711C

B.

Impedance Measurements (Except Resistors) ' B.5 Q-Standards

Electromagnetic Fields Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

Raymond N.

Jones

Tel:303/497-3609

Cletus A. Hoer

Tel: 303/497-3705 Edna M. Jones

Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Bureau of Standards, 325 Broadway, Boulder, CO 80303

Test No. Items

527 IOC Inductive Q-Standards; 50 kHz-45 MHz, 0.25 fi,H to 25 mH

5271 IC Each Additional Frequency for 52710S

Q-Standards (52710C-52711C)

Standards for Q-measurements are maintained at NBS. These are high-Q

inductors equipped with banana plug

connectors at a spacing of 1 inch on

centers. These standards have in- ductance values of 0.25, 2.5, 25, 250,

2500, and 25,000 fiH, and effective Qvalues from 100 to approximately 600. These serve as working standards for calibration of Q-standards of a similar type. Calibration frequencies range

from 50 kHz to 45 MHz. The cali- bration report includes effective reso- nating capacitance and effective Q.

Uncertainties are of the order of ±0.2

percent for capacitance and 2 percent

for Q. Provisions are made for cali- brating each Q-standard at three fre- quencies; however, adequate assur- ance of stability is usually provided

by recalibrating only at the center frequency.

Estimated limits of uncertainty are based upon a statistical analysis of

previously obtained calibration data. These uncertainties are believed to result solely from sources of random er- ror as opposed to known systematic

errors.

References—Q Standards

Standards for the Calibration of QMeters, 50 kHz to 45 MHz, R. N. Jones, J. Res. Natl. Bur. Stand. (U.S.),

58C No. 4, 243 (Oct.-Dec. 1964).

107
53110S-53190S

C Voltage Measurements

^ C.I DC Voltage Measurements and

Standards

Electricity Division

Center for Basic Standards

Technical Contacts:

June E. Sims Bruce F. Field Norman B. Avis R. Wise

Tel:301/921-3806 Tel:301/921-380(i Belecki Administrative

Tel: 301/921-2715 and Logistics

Tel: 301/921-2715

Mailing Address: B146 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items

531 lOS Special DC Voltage Measurements by

Prearrangement

53120M Measurement Assurance Program for DC Voltage

53130C First Saturated Standard Cell in a Group

53 1 3 IC Each Additional Cell 53140C Platinum Resistance Thermometer Temperature

Determination for Standard Cell Calibration 53150C Unsaturated Standard Cells 53160C Tests of Solid State Voltage Reference Standard

(1 Output, 1-10 V)

53161C Each Additional Output

531 SOS Special Handling (Equipment Pickup or Delivery)

531 90S Special Handling (Cleaning, Minor Repair, Return

Service Charge)

General Information—DC Voltage

Measurement Standards

The service described in this section

provides for the calibration of stan- dards of direct voltage, saturated and

unsaturated standard cells, and solid

state standards, and for dc voltage

MAP services at the 1.02 volt level. The U.S. Legal Volt is maintained by

monitoring the emfs of a group of

saturated standard cells in an oven on

a monthly basis using the ac Jo- sephson effect and a specialized measuring system to perform the required

scaling (from about 10 mV to 1.02 V). Customer cells are calibrated by

measuring the difference between

their emfs and those of working

groups of standard cells using lowlevel potentiometers and nanovoltmeters or precision digital volt- meters. Figure 13 summarizes the uncertainty of NBS dc voltage measurements for the primary standards,

standard cells, and Zener diodes.

Special DC Voltage Measurements by

Prearrangement (53110S)

The evaluation, testing, or calibration

of prototype dc voltage standards and

measuring apparatus or unique volt- age measurements are provided for in

this service. These measurements are performed only when deemed reasonable by the appropriate technical staff and serving the best long-term inter- ests of the client, the measurement

community, and NBS.

Measurement Assurance Program

Service (53120M)

This MAP service provides a measurement of the error of dc voltage

measurements in the customer laboratory at the 1.02-volt level, the uncertainty of the results, and an updated

assigned value for the client's refer- ence standards. A transport standard,

which consists of a standard cell en- closure containing four saturated stan- dard cells, maintaining constant temperature via line and battery power,

and packaged for shipment by air, is used. It is calibrated by NBS, the cus- tomer laboratory, and again by NBS

to obtain the required data. The trans- port standards are capable of per- forming at the 0.2 to 0.3 ppm level of

reproducibility under these conditions. The measurement uncertainty

achieved in this service contains primarily random errors. The major

components of random error can be

attributed to: A. Day-to-day fluctuations in temperature-corrected cell emfs

108
53110S-53190S

caused by temperature-hysteresis ef- fects;

B. The finite resolution of the

measurement apparatus at both the

cHent laboratory and at NBS;

C. Thermal emfs, unstable with

time, which occur in the measuring

circuit due to room temperature

changes and drafts; D. Temperature coefficients of

the enclosures as a whole, not compensated for by temperature corrections;

E. Lack of resolution or in- stability of the apparatus used to monitor the cell temperatures;

F. Slow changes in temperature

gradients or enclosure temperatures

possibly due to atmospheric "pumping" of cool air into the enclosures, or vibration effects on the control cir- cuitry;

G. Controller instability caused

by power-line noise; H. Effects of electrostatic or elec- tromagnetic pick-up on the measuring

system;

I. Detector drift; and

J. Momentary upsets in cell emfs caused by small electrical currents passing through the cells. The experimental design described

for making the intercomparison measurements removes the effects of av- erage "left-right" or offset errors. One potentially significant source of

error not corrected for or quantified

in the MAP service is that caused by

scale-factor errors in the instrumentation used to measure the differences

between cell emfs. An error from

this source can be eliminated by using

calibrated instruments and applying

the appropriate calibration corrections to the results. A method for quantifying scale-factor errors can be

provided to MAP service users by

NBS on request.

The transport standard is normally

kept in the client's laboratory for

about four weeks, as eight to twelve

measurement sets are generally re- quired. Data analysis and issuance of

the test report by the NBS takes four

to five weeks following the return of

the transfer standards.

If the participating laboratory has a quality instrument that has been accurately calibrated and also has quality

standards, the uncertainty of a single transfer of the unit of voltage using

NBS transport standards is generally

of the order of 0.5 ppm or better. The

best achievable long-term uncertainty,

Figure 13. Uncertainties of NBS DC Voltage

Measurements

10' -

10^

-Primary Cells

Zener

Diodes /

Standard

Cells

10° 10' DC Voltage

resulting from five or more transfers over an extended time, is of the order

of 0.2-0.3 ppm.

In this service, the NBS provides

detailed instructions for carrying out

the transfer and making the required

measurements. The participant must

have in-house standards and instru- mentation capable of sustained per- formance at the 0. 1 ppm level. When

a new participant (or group of participants) expresses a desire to use the

109
voltage MAP service, NBS requests

that a complete description of the

participant's measurement system, in- cluding instruments, standards, wires,

switches, and their use, be sent to the

NBS technical staff. This description

enables NBS personnel to assist in re- solving measurement problems by

telephone.

NBS now requires evidence, in the

form of control charts, of the exis- tance of a formal quality-control pro- gram in the laboratory as a prerequisite to participation in the service.

This requirement has been established

to enable problems to be addressed in advance of the transfer and to reduce

delays in returning the standards to NBS.

Saturated Standard Cells (53130C-53140C)

Routine calibrations of saturated stan- dard cells involve the following considerations: A. Saturated standard cells of the

unshippable type should always be

transported by messenger because

such cells should never be tipped

from an upright position by more

than 45 ° in any direction. Unshippable saturated cells contained in portable, temperature-regulated en- closures should also be transported by

messenger and with the enclosure ac- tivated or under power, if possible. B. Saturated standard cells of the

shippable type housed in portable

thermoregulated enclosures should be

packed carefully and shipped under

power if possible. Any liquid-in-glass

thermometer mounted in such a device should be removed and provided

with additional rigid packing for protection against breakage. Enclosures

having a nominal cell temperature of

28 °C or lower should not be trans- ported during the summer due to the

danger of overheating. Enclosures

should not be energized by using the ac power mains while they are in shipping containers as heat from the

transformer will cause them to go

over-temperature.

C. Saturated standard cells, which

are maintained continuously at their

nominal temperature of use during

shipment, will (workload permitting)

undergo test starting one week after receipt for a period not to exceed

four weeks, unless other arrangements

are made. If such cells perform abnormally, the owner will be notified. Arrangements for further testing may

be made at that time if desired. Cells

will be returned as soon as possible

after calibration. D. Saturated cells arriving at a temperature other than their nominal

temperature of use will be brought to

their use temperature as soon as possible after receipt. Starting one month

after they are initially brought to use temperature, weekly readings will be

taken to observe the stability of the

cells. When the cells stabilize, 10

daily readings will be taken and aver- aged to assign values to them. This

process will not exceed 90 days with- out special arrangements being made.

E. For an additional fee, the temperature of air bath enclosures for saturated standard cells will be deter- mined using a calibrated NBS platinum resistance thermomenter (test 53140C). Daily readings are taken and

reported. The reported cell emfs are assumed to correspond to the mean of

the temperatures measured on the same days as the emf readings were

taken. The client must understand

that, when this is done, the uncertainties of the reported emfs include

the emf equivalent of the uncertainty

of the measured temperatures in terms of the International Practical Temperature Scale of 1968 as amended in 1975 [Metrologia 12,7 (1976)]. Moreover, estimates of the uncertainties of

any voltage measurements made by

the client using these cells as a refer- ence must include corresponding uncertainties of his own temperature

measurements.

F. NBS accepts cells used in oil baths for calibration in NBS oil baths

maintained at 28 and 30 °C. Cells used

in oil baths operating at other nominal temperatures can best be cali- brated using transport standards as in

11 0
53110S-53190S

the MAP service. (See 53120M

above.)

Calibration uncertainties generally

range from 0.3 to 0.75 ppm. The

stated uncertainties are those of the

NBS measured average values, i.e., they do not reflect long-term behavior of the cells, transporation effects, etc. Unsaturated Standard Cells (53150Q

Unsaturated cells require approximately three weeks for a complete

calibration. The emfs of such cells are read daily for a minimum period

of ten days. These cells are compared

with NBS saturated cells using a precision digital voltmeter to measure

the difference emf directly. The cali- bration uncertainty is 0.005% of the

measured voltage unless the cell is abnormal. If the measured emf fluctu- ates unduly or is unusually low, or if the cell behaves abnormally, the re- port of calibration will reflect these

circumstances. Unsaturated cells are not likely to be injured by normal

transportation (mail or express) if they are packed carefully. Because of

the possible hazard from freezing,

shipment during extremely cold

weather should be avoided.

Solid-State Voltage Reference

Standards (53160Cand 53161C)

Solid-state voltage standards with

outputs in the range from one to ten

volts are calibrated using a self- calibrating automated system which

scales to any multiple up to ten of

1.018 volts from the emf of a working

group of NBS saturated standard

cells. It then measures the difference

between the emf of the standard un- der test and the emf of its own output

closest to that being measured and

computes the emf of the test unit. Measurements are taken daily for twelve to fifteen working days and

the mean value of the results re- ported. If the standard being cali- brated has internal batteries, the measurements are generally taken with it disconnected from the mains to avoid

possible ground loop, common mode,

or mains noise problems. Sufficient

time is allowed for stabilization after disconnection from the mains.

Because of the limited battery life of many commercial standards, special shipping arrangements are advisable and can be made by contacting

the Electricity Division.

Many solid-state standards have

multiple outputs; the outputs to be

calibrated should be specified on the

shipping papers as well as on the pur- chase order to facilitate testing.

Voltmeter calibrators, multirange

instruments with up to eight decimal

digits of adjustability, are not considered by the NBS to be standards and

are not to be submitted for calibration

under this test category. Likewise,

NBS will not accept component

solid-state devices for routine cali- bration. New, state-of-the-art devices

and instruments may be accepted for

test under special circumstances (see

test 53110S) at the discretion of NBS

technical staff. References—Voltage Measurements

and Standards

Volt Transfer Program Instructions,

NBS Internal Document, Unpublished, Revised (1983).

A High-Resolution Prototype System

for Automatic Measurement of Stan- dard Cell Voltages, D. W. Braudaway and R. E. Kleinmann, IEEE

Trans. lustrum. Meas., IM-23, 282

(1974).

Volt Maintenance at NBS via 2e/h: A

New Definition of the NBS VoU, B. F. Field, T. F. Finnegan, and J. Toots, Metrolgia, 9, 155 (1973).

Designs for Surveillance of the Volt

Maintained by a Small Group of

Saturated Standard Cells, W. G.

Eicke and J. M. Cameron, Natl. Bur. Stand. (U.S.), Tech. Note 430 (Oct.

1967).

Standard Cells—Their Construction,

Maintenance and Characteristics, W.

J. Hamer, Natl. Bur. Stand. (U.S.),

Monogr. 84 (Jan. 1965).

A Sub-PPM Automated One-To-Ten

Volt Measuring System, B. F. Field,

IEEE Trans. lustrum. Meas., IM-34,

327 (1985).

111
532008

C.

Voltage Measurements

C.2 Low-Frequency AC Voltmeters and

Sources

Electrosystems Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

Howard K. Barry A. Bell Schoenwetter Tel: 301/921-2727

Tel: 301/921-2727

Mailing Address: B162 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items 53200S Special Tests of Low-Frequency AC Voltmeters and

Sources—0.1 Hz to 10 Hz, 0.5 mV to 7 V, by

Prearrangement

Special Tests of Low-Frequency AC

Voltmeters and Sources by

Prearrangement (53200S)

NBS offers a calibration service for ac voltage standards and rms volt- meters in the 0.1 Hz to 10 Hz range. This service is provided by means of an "AC Voltmeter/Calibrator,"

which is an NBS-developed instru- ment containing a high resolution rms

digital voltmeter and both ac (sinewave) and dc voltage calibrators. Calibrations are performed on rms- responding ac voltmeters using the ac

voltage calibrator of the AC

Voltmeter/Calibrator. AC voltmeters can be calibrated at frequencies of 10,

5, 2, 1, 0.5, 0.2, and 0.1 Hz at any

voltage level between 0.5 mV and 7

V. The total uncertainty of a cali- bration is ±(€c + €r), where is the

uncertainty of the ac voltage cali- brator voltage and is the imprecision of the calibration process. The estimated uncertainty of the ac voltage calibrator is ±0.020 percent.

The imprecision for a_given cali- bration point is ts/VN, where t is Student's t for the selected confidence

level, s is the standard deviation for a measurement, and N is the number of

measurements (test runs) used to obtain the mean values of the measured

quantities (voltmeter readings).

Unless otherwise requested by the

customer, a single uncertainty of cali- bration will be given for the corrections to the calibration points,

based on a confidence level of 0.98

and the largest standard deviation en- countered. It is expected that the

value of N, requested by the cus- tomer, will generally be 3, 4, or 5. Assuming a selected confidence level of 0.98, values of t corresponding to N equal 3, 4, and 5 are approximately

7.0, 4.5, and 3.7, respectively.

Typical NBS uncertainties of ac

voltage measurements for calibration

of ac voltmeters (0.1-10 Hz) and

ac/dc difference (20 kHz-1 MHz) are shown in Figure 14. Voltage calibrations are performed on precision ac sources using the ac

voltage calibrator and rms voltmeter

of the AC Voltmeter/Calibrator. The

rms voltmeter is used as a transfer voltmeter to compare the voltages (of

the same nominal level) from the test unit and the ac calibrator. Voltage

calibrations can be made at any fre- quency in the 10 Hz to 0.1 Hz range

and are usually made near the full- scale level of the voltmeter ranges (2,

5, 10, 20, 50 mV, and 0.1, 0.2, 0.5, 1, 2, 5 V). For each calibration point,

the rms voltmeter (DVM) is used to compare the voltage Vj from the

standard under test with the voltage

Vc of the same nominal level from

the ac voltage calibrator, choosing

the calibrator frequency closest to

112
that of the voltage being measured.

After the test runs are made, the av- erage (Vc-Vt) is calculated for each

calibration point, yielding corrections

to the nominal voltage values of the

test unit. If the uncertainty of the calibrator

voltage and the uncertainty caused by

the DVM frequency response are denoted by Cc and e^, respectively, the

total uncertainty of a calibration point

is given by ±(€c + €m + ts/'\/N), where

s is the standard deviation of a (Vc-Vt) comparison and N is the

number of comparisons (test runs). If the frequencies of the voltages being

compared are within 5 percent of

Figure 14. NBS Uncertainties for AC Voltage

Measurements

10"

10' -

r 10'

COa.

(0c

o

c

10^

10^

10'

10°

20 KHz

AC Voltmeters 0.1-10 Hz AC/DC Difference

1 MHz

±_ 10" 10" 10° AC Voltage

10-^

each other, is 7 ppm. If the fre- quency difference is larger, the worst

case value of 40 ppm, is used. The

value assigned to is 200 ppm

(0.02%). However, if the highest cali- bration accuracy is required by the

customer, €c can be decreased to 125

ppm by a special calibration of the

NBS instrument.

If the voltage standard has inherently stable voltage with respect to

frequency, a frequency response (rela- tive voltage) calibration may be preferable to a conventional voltage cali- bration. The user then establishes the

voltage levels by calibrating the volt- age at 10 Hz. Since the rms voltmeter

has a frequency response that is flat to within ±40 ppm, it is used to determine the frequency response of

voltage sources. Frequency response

calibrations can be made at any fre- quency in the 10 Hz to 0.1 Hz range

and are usually made near the full- scale level of the DVM ranges (2, 5, 10, 20, 50 mV, and 0.1, 0.2, 0.5, 1, 2,

5, 10 V). These calibrations are made

using the DVM to compare test unit voltages of frequency f with the 10 Hz value. After N comparisons, the

average quantities (V^Vio) are computed for each test frequency, yielding the frequency response. The uncertainty of these calibration points is ± (Cm + ts/VN), where is 40 ppm,

and s is the standard deviation of a comparison.

For test requirements not covered

by the above, contact the Electrosystems Division to make special ar- rangements.

References—Low-Frequency AC

Voltmeters and Sources

An RMS Digital Voltmeter/

Calibrator for Very Low Frequencies, H. K. Schoenwetter, IEEE

Trans. Instrum. Meas., IM-27, No. 3, 259 (Sept. 1978).

AC Voltage Calibrations for the 0.

1

Hz to 10 Hz Frequency Range, H. K.

Schoenwetter, Natl. Bur. Stand.

(U.S.), Tech. Note 1182 (Sept. 83). (This reference provides a complete

description of this calibration ser- vice.)

11 3
53310S-53343C

aVoltage Measurements

C.3 AC-DC Thermal Voltage and Current

Converters (To 1 MHz)

Electricity Division

Center for Basic Standards

Technical Contacts:

Joseph R. Kinard

Tel: 301/921-2715 Norman B.

Belecki

Tel: 301/921-2715

Avis R. Wise

Administrative and Logistics

Tel: 301/921-2715

Mailing Address: B146 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items

533 lOS Special AC-DC Measurement Services by

Prearrangement

53340C AC-DC Thermal Voltage and Current Converters

(1 voltage, 1 frequency up to 50 kHz)

53341C AC-DC Thermal Voltage and Current Converters

(1 voltage, 1 frequency-50 kHz to 1 MHz)

53342C Additional Determination at 1 Frequency (20-50 kHz)

53343C Additional Determination at 1 Frequency

(from 50 kHz-1 MHz and from 10 kHz-50 kHz for 1000 Volt Range)

General Information—Thermal

Voltage and Current Converters

Thermal voltage and current converters are now being calibrated on a scheduled basis. To arrange scheduling, contact A. R. Wise at the tele- phone no. /address cited above. Send

in the equipment only as scheduled to avoid a long turnaround time at NBS.

Calibration services for wide fre- quency range thermal voltage converters, such as John Fluke Model

A55 or HP 11000 series, have been

extended in the NBS Boulder Laboratory to cover frequencies down to

100 Hz with uncertainties as low as 0.05% (see tests 53405S-53420C).

This means thermal generators of this type can be completely calibrated at NBS Boulder if the 0.05% uncertainty is acceptable. Calibration re- quiring uncertainties less than 0.05%

in the range below 1 MHz continue

to be done in NBS Gaithersburg

(53310S-53343C).

Special AC-DC Measurement Services

by Prearrangement (533 lOS)

This service provides for the measurement or evaluation of prototype

ac voltage or current standards,

sources, or measurement instrumentation, and for other measurements of

alternating voltage, alternating current, or ac-dc difference not provided

for below, at the discretion of NBS

technical experts. Components used

for ac-dc conversions will generally not be tested unless they show promise of standards-like behavior. Even

then, such components will only be

tested in very limited numbers to ex- plore their possible use for precision

measurements.

AC-DC Thermal Voltage and Current

Converters (Up to 1 MHz)

(53340C-53343C)

This service covers the calibration of

thermal voltage and current converters, ac shunts, and primary ther- moelements covering the ranges 2 Hz

to 1 MHz, 1 mA to 20 A, and 0.5 to 1000 V. These are used to make measurements of alternating current and

voltage in terms of direct current standards of voltage and resistance

and are calibrated at NBS by comparison with similar NBS devices. Ordinarily only ac-dc transfer standards

and thermal converters of 0.05 per- cent or better rated accuracy are ac- cepted for test. AC-DC difference

tests consist of determinations of the

differences between the current or

voltage, required to give the same re- sponse (output) of the transfer stan- dard for alternating current and for the average of the two directions of

114
53310S-53343C

direct current. Tests are recommended at rated voltage or current on

each range up to the highest fre- quency of interest. For 1000 V

ranges, a second test at 600 V is rec- ommended because these ranges may

be affected by self-heating. In addition to the high-frequency tests, an

ac-dc difference test (ordinarily at 20

Hz) is recommended for one range, to verify the low-frequency accuracy.

Thermoelements have a lowfrequency limit, below which they

fail to integrate properly. The ac-dc

difference may approach 0.02 percent

at frequencies ranging from about 5 Hz for most low-range thermoelements to about 60 Hz for some

thermoelements with ratings above 1 A. This low-frequency ac-dc differ- ence is the same for all ranges of a multirange converter in which a sin- gle thermoelement is used with shunts or multipliers. For convenience, usually a low-voltage or current range is chosen for the test. Unless the test points have been firmly established in prior practice, the user is strongly advised to contact the appropriate NBS

Cliff Childers, carrying out AC-DC difference calibrations.

technical staff prior to submission of

the standards to NBS for calibration. References—AC-DC Thermal Converters (To 1 MHz)

A Dual-Channel Automated Comparator for AC-DC Difference Measurements, E. S. Williams and J. R. Kinard, IEEE Trans. Instrum. Meas.,

IM-34, No. 2, 290 (June 1985).

An Investigation of the Uncertainty

of the NBS Thermal Voltage and

Current Converters, F. L. Hermach,

Natl. Bur. Stand. (U.S.), Int. Report,

NBSIR 84-2903 (April 1985).

The Practical Uses of AC-DC Transfer Instruments, E. S. Williams, Natl. Bur. Stand. (U.S.), Tech. Note 1166

(Nov. 1982).

A Thermoelement Comparator for Automatic AC-DC Difference Measurements, E. S. Williams, IEEE

Trans. Instrum. Meas. IM-29, No. 4, 405 (Dec. 1980).

An Investigation of Multijunction

Thermal Converters, F. L. Hermach

and D. R. Flach, IEEE Trans. In- strum. Meas., IM-25, No. 4, 524 (Dec.

1976).

Thermal Voltage Converters and

Comparators for Accurate AC Voltage Measurements, E. S. Williams, J. Res. Natl. Bur. Stand. (U.S.), 75C

(Dec. 1971).

Thermal Voltage Converters for Accurate Voltage Measurements to 30

Megacycles Per Second, F. L. Hermach and E. S. Williams, Trans. AIEE (Communica. Elect.) 79, 1, 200

(July 1960).

Thermal Converters on AC-DC

Transfer Standards for Current and

Voltage Measurements at Audio Frequencies, F. L. Hermach, J. Res.

Natl. Bur. Stand. (U.S.), 48, 121

(1952).

115
53405S-53445S

aVoltage Measurements

C.4 RF-DC Thermal Voltage and Current

Converters (100 Hz-1 GHz)

Electromagnetic Fields Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

'sk «t; W

Gregorio Rebuldela

Tel: 303/497-3561

Cletus A. Hoer

Tel: 303/497-3705 Edna M. Jones

Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Bureau of Standards, 325 Broadway, Boulder CO 80303

Test No. Items 53405S Special Tests of AC Thermal Current and Voltage

Converters by Prearrangement

534 IOC Low Frequency TVC Calibration at One Frequency

Selected from Those Given in Table 9 at Rated

Voltage in the Range 0.1 -50V.

5341 IC Additional Frequency Selected from Table 9 for Same TVC as in 534 IOC

53412C Same as 5 34 IOC, Except Customer Designates a Single Frequency (in Same Frequency Range)

other than those given in Table 9 5341 3C Low Frequency TVC Calibration at One Frequency

Selected From Those Given in Table 9 at Rated

Voltage in the Range 50-200 V

534 14C Additional Frequency Selected from Table 9 for Same TVC as in 534 13C

53415C Same as 53413C, Except Customer Designates a Single Frequency (in Same Frequency Range)

other than those given in Table 9

Test No. Items 53420C High Frequency TVC Calibration at One Frequency

Selected from Those Given in Table 10 at Rated

Voltage in the Range 0.1-7.5 V

5342 IC Additional Frequency Selected from Table 10 for Same TVC as in 53420C

53430S Peak-to-Peak Detector Calibration at One Frequency

Selected from Those Given in Table 11 at 1.2 V

Applied RF Voltage

5343 IS Additional Frequency for Peak-to-Peak Detector in Test 53430S

53440C RF Micropotentiometer Calibration for Percent RF-DC Difference, at any Single Frequency Within

0.05-900 MHz and at Rated Voltage (Range

1-100,000 /xV)

53441C Additional Frequency Selected for RF

Micropotentiometer Calibrated in 53430C

53445S Special Calibration of RF Micropotentiometer

(Output Voltage Range, 200 to 200,000 juiV at Frequency Range, 0.05 to 1000 MHz) with Reduced

Limits of Uncertainty

General Information—RF-DC Thermal

Voltage and Current Converters, 100

Hz to 1 GHz (53405S-53455S)

Services are available for four types

of electromagnetic voltage measuring

devices: (1) Thermal Voltage Converters (TVCs), (2) Peak-to-Peak Detectors, (3) Voltage Comparators, and

(4) rf Micropotentiometers.

Many years of experience in calibration of micropots and TVCs have

shown that these are very stable devices even for periods of up to 10

years. Thus, in most cases, a 2-year or

longer recalibration cycle is recom- mended. An exception might be the

micropots which operate below

lOOjLtV.

Assurance of device stability can be

obtained by intercomparison of mi116
53405S-53445S

cropots or TVCs with others which

are adjacent in voltage. For example,

a 0.3 to 1 V TVC can be compared

with a 1 to 3 V TVC at 1 V, etc. Calibrations requiring uncertainties

less than 0.05% below 1 MHz are performed in NBS Gaithersburg. See

tests 53310S-53343C.

Rf Voltage Comparators (53405S)

Special tests are performed on rf volt- age comparators using TVCs and micropotentiometers from 100 kHz to 1 GHz at voltages ranging from 10 mV

to 20 V. Several calibration options

are available to the customer. Therefore, consultation by telephone or

written correspondence is suggested

before the comparator is submitted

for calibration. Thermal Voltage Converters

(53410C-53421C)

The thermal voltage converter (TVC)

category also includes other devices

using thermal detectors such as Rawson rf voltmeters, thermal transfer standards, rf voltage standards, and

ac-dc transfer standards.

Most converters have rf-dc differ- ences within ±0.01 percent of zero at

1 MHz and below. All converters having previous calibration history

that are submitted for recalibration

should be evaluated at 1 MHz and results compared to prior data. If the

difference is negligible, no further cal- ibrations are usually necessary below

1 MHz.

The quantity measured by this cali- bration service is the rf-dc difference,

defined as the percentage difference

between the rf and dc voltages re- quired to produce the same thermocouple output, e.g.,

rf-dc difference(%)

=^

^^~

j

X 100.

Services available for low-frequency

TVCs without a built-in "T" connector are given in Table 9. For highfrequency TVCs with a built-in "T"

connector, the services available are given in Table 10. Calibrations above

100 MHz are performed only on the

new high frequency thermal voltage converters with a "T" connector in- corporated in the converter housing.

The measurement reference plane is at the Type "N" male output connector.

Table 9: Specifications and Estimated Uncertainties for Low-Frequency TVC Services

Recommended

Frequencies

RF Voltage

Range

(V)

Estimated

Limits of Uncertainty*

(±%)

0.1,0.3, 1, 3, 10, 30, 100, and 300

kHz; 1 MHz

0.1 to 200 0.05

3 and 10 MHz 0.1 to 200 0.1 30 MHz 0.1 to 200 0.2 100 MHz 0.1 to 200 1.0 *No rf-dc differences greater than ±20 percent will be reported. This normally limits the calibrations to 100 MHz and below.

Table 10: Specifications and Estimated Uncertainties for High-Frequency TVC Services

RF Voltage Estimated

Frequency Range Limits of Uncertainty*

(MHz) (V) (±%)

10 0.1 to 7.5 0.1 30 0.1 to 7.5 0.2

100, 200, 300, 400 0.1 to 7.5 1 500, 600, 700 0.1 to 7.5 1 800, 900, 1000 0.1 to 7.5 1 *No rf-dc differences greater than ±20 percent will be reported.

Peak-to-Peak Detectors (53430S)

Measurements on peak-to-peak detectors are performed from 100 kHz

to 500 MHz and are referenced to the center of a GR 874 "T" connector. A

50 kHz ac signal is applied instead of

dc. The services available are specified in Table 1 1. RF Micropotentiometers

(53440C-53445S)

Radio frequency micropotentiometers

are usually calibrated at their nominal

rated output voltages. Frequencies

117
53405S-53445S

Table 11: Specifications and Estimated Uncertainties for Peak-to-Peak Detector Services

Applied RF Voltage Estimated Limits

Frequency for "0" Detector Output of Uncertainty

(MHz) (Vp-p) (%)

0.1,0.3,1.0 1.2

3, 10 1.2 30 1.2 50 1.2 100,200,300,400,500 1.2

0.15 0.20

0.30

0.60

1.10

suggested for a normal calibration are

5, 100, 300, 400, 500, 700, and 900

MHz. Special arrangements may be

made for calibrations up to 1000 MHz

with reduced limits of uncertainty.

Radio frequency micropotentiometers having resistive ele- ments greater than 10 milliohms in combination with thermoelement

housings between 5 and 100 mA, usually have rf-dc differences within ± 1 percent at 5 MHz. Since the rf-dc dif- ference approaches zero below 5 MHz, calibrations at 50 kHz and 5 MHz would suffice to determine in- terpolated points of interest between

50 kHz and 5 MHz, with no appreciable loss of accuracy. Estimated uncertainties are shown in Table 12. An rf-dc difference of about ±5

percent at 1 MHz usually results from

a combination using a 1 milliohm ele- ment with thermoelement housings

between 5 and 100 mA. Interpolation

below 1 MHz is not recommended in

this case. The rf-dc difference is defined as the percentage difference between the

rf and dc voltages required to pro- duce the same thermocouple output,

with the resistive elements terminated

in 50 ohms, e.g..

rf-dc difference(%) = xioo.

As a special service, rf micropotentiometers with output voltage

greater than 200 fxV can be calibrated

from 0.05 to 1000 MHz, with reduced

limits of uncertainty varying from

±0.2% to ±2%. This uncertainty is dependent on frequency, output level and the rf-dc difference vs frequency

response. For further details, consult

with the technical contact cited at the

beginning of this section.

Table 12: Specifications and Estimated Uncertainties for RF Micropotentiometer Calibrations

Any Frequency

Within Band

(MHz)

RF Voltage

Range

(]LlV)

Estimated

Limits of Uncertainty*

(+%)

0.05 to 100

100 to 500

500 to 900

1 to 100,000

1 to 100,000

1 to 100,000

*For rf-dc differences greater than ±20 percent, estimated limits of uncertainty are larger than those Hsted.

References—RF-DC Voltage and

Current Converters (100 Hz-1 GHz)

NBS RF Voltage Comparator, L. D.

Driver, F. X. Ries, G. Rebuldela,

Natl. Bur. Stand. (U.S.), Int. Report,

NBSIR 78-871, (Dec. 1978).

Thermal Voltage Converters for Accurate Voltage Measurements to 30

Megacycles Per Second, F. L. Hermach and E. S. Williams, Trans. AIEE, Pt. 1, Commun. Elect., 72, 200

(July 1960).

Thermal Converters as AC-DC

Transfer Standards for Current and

Voltage Measurements at Audio Frequencies, F. L. Hermach, J. Res.

Natl. Bur. Stand. (U.S.), 48, 121

(1952).

Accurate Radio Frequency Microvoltages, M. C. Selby, Trans. AIEE,

Pt. 1, Commun. Elect., 72, 158 (May

1953).

High Frequency Microvolt Measurements, F. X. Ries, G. Rubuldela,

ISA Proc, 18, 1, 37.2.63, Instrum. Soc. of America, Res. Triangle, NC

(Sept. 1963).

118
53500S-5354OS

C.

Voltage Measurements

C.5 Data Converters

Electrosystems Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

Barry A. Bell

Tel: 301/921-2727

Tel: 301/921-2727

Mailing Address: B162 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items 53500S Special Data Converter Services by Prearrangement

535 IOC A/D or D/A Converter, Linearity Errors at 1024

Points, 10-Bit Correction Coefficients, and Superposition Errors 53520C A/D or D/A Converter, Differential Linearity Errors at 2(N-1) Points (N = No. of Bits) 53530C A/D Converter, Equivalent RMS Input Noise

53540S A/D or D/A Converter, Offset and Gain Errors

Relative to U.S. Legal Volt

Data Converters (53500S-53540S)

NBS maintains a calibration service

for static testing of high resolution

(12-18 bit) analog-to-digital (ADC)

and digital-to-analog (DAC) converters. Routine measurements, for which calibration reports are issued, are made of the static parameters

listed below. However, NBS has re- cently developed the capability to measure the dynamic response of

ADCs to well-defined, programmable

input voltage steps characteristic of

typical input signals. These dynamic

measurements can be made as a special test. Until further analysis of sys- tematic and random errors of the test procedure is completed and until additional operating experience is obtained, the customer will receive the

test results with appropriate error

analysis, but no calibration report will be issued. There is no standard data-converter

terminology, but NBS uses the fol- lowing definitions of parameters to describe its calibration service: A. Linearity Error: The differ- ence between the actual and ideal levels of the static input/output characteristic after corrections have been

made for offset and gain errors. B. Differential Linearity Error: The difference between the actual and the ideal separation between

adjacent levels. C. Offset Error: The difference

between the actual and the ideal levels, measured at the most negative

level of the input/output characteristic. Due to practical considerations,

this definition is modified to the 2nd

most negative level, (i.e., with the

least significant bit (LSB) on).

D. Gain Error: The difference

between actual and ideal levels, measured at the most positive level of the

input/output characteristic, after cor- rection for offset error. Again, in practice, a defining level is chosen

slightly below the one stated here. E. Equivalent RMS Input

Noise: The rms value of the effective

internal noise of an ADC, referred to

its input terminals. In these definitions, the specified

levels for DACs are taken to be the

discrete output levels, and for ADCs

the analog input levels at which the

digital output transitions between adjacent codes occur. In this latter case, the transition levels are defined by

the upper digital code of the transi- tion in question.

The principal error parameters are

usually those of linearity and differ- ential linearity. Nevertheless, gain and

offset errors may also be measured

when appropriate, and the equivalent

119
53500S-53540S

rms input noise of ADCs can be measured as well, provided it has approximately a Gaussian distribution. Determination of monotonicity in DACs

and missing codes in ADCs is not

generally performed since these tests require excessive measurement time

for high-resolution converters. These

characteristics can often be inferred,

however, from the available linearity data. Sensitivity of the various parameters to changes in temperature and

power supply voltage, for example, is also not generally determined.

Description of Static Tests: A. Linearity: For the linearity test,

all 1024 digital codeword combinations of the 10 most significant bits are measured. Errors contrbuted by

the remaining, less significant bits are generally insignificant, a premise

which is tested during the calibration process. The data are numerically

processed to determine the maximum,

minimum, and rms errors of the 1024

tested codes, and to determine, on a least-squares basis, individual cor- rection coefficients for the ten most

significant bits. The residuals from the

computation of correction coefficients are a direct measure of the converter's superposition errors. These

are computed as well.

B. Differential Linearity: Differential linearity errors are measured at 2(N-1) major codeword

transitions, for an N-bit converter.

C. Offset & Gain: In general, converter offset and gain measurements are not required, since it is common practice to provide adjustable trimmer circuits, which are periodically set to suit individual system

requirements. However, accurate

voltage measurements directly trace- able to legal standards can be pro- vided if required. Offset and gain er- rors are measured directly by setting

the test converter to the designated

code and measuring the input (or output) voltage by direct comparison

with a transfer standard calibrated by

NBS.

D. RMS Input Noise: The equivalent rms input noise of ADCs can be

measured either as an average value over the entire full-scale range of the

converter, or as a function of co- deword, at 64 randomly selected

points. The measurement technique

relies upon the assumptions that the

noise has a Gaussian distribution, and

that at a given sampling rate, successive values are uncorrected. The validity of these assumptions is tested prior to performing the measurements.

E. Specification for Test Converters: To be compatible with the

NBS data converter test set, test units must conform to the following general specifications:

1. Nominal resolution from 12 to 18 bits,

2. Conversion rate of at least 10

kHz,

3. Binary coding format, including

binary sign-magnitude, offset bi- nary, 2's complement, I's complement, and complemented versions of these,

4. TTL compatibility,

5. Voltage ranges of 0-5 V, ±5 V;

0-10 V, ±10 V,

6. Maximum error, including offset and gain, not to exceed 500 ppm.

Systematic Uncertainties:

The estimated limits of the systematic

uncertainties in measuring the various

converter error parameters are summarized in Table 13 for a ±10 V

range. Random errors of the measurement process necessarily include

random variations in the test converter and are, therefore, individually

evaluated for each test. Nevertheless,

measurements on very stable (check

standard) converters indicate the ran- dom errors contributed by the test set

itself are substantially less than the re- spective systematic uncertainties

listed in the table. Figure 15 shows

120
5350(JS-5354fJS

the estimated systematic uncertainty

of the NBS data converter test system

for resolutions from 12 to 18 bits. Dynamic Tests of ADCs:

Dynamic errors in ADCs are defined

as any deviations from the static transfer characteristic resulting from

Figure 1 5. Uncertainty for NBS Data Converter Test System for Resolutions from 12-18 Bits

10^

10'

10^

Integral Linearity Error

Differential Linearity Error

12 13 14 15 16

Resolution in Bits

1 7 18

prior exercise, (i.e., previous changes

in input). The test converter is exercised with stepped input changes typi- cal of the conditions of actual use. The dynamic errors are measured in terms of the changes in the test converter's code transition levels re- sulting from prior exercise. A more

complete description of the dynamic

testing now provided for ADCs on a Special Test basis is provided in Souders et al., "An Automated Test Set

for the Dynamic Characterization of

A/D Converters" (see references).

Preparation of Test Boards:

In general, the customer is re- sponsibile for mounting the integrated

circuit, hybrid, or modular test converters on suitable test boards, and

for providing all required trimmer

circuits, voltage references, input or output amplifiers, recommended

power supply decoupling capacitors,

and connectors for interfacing to the

input/output lines. Fully self- contained converters need only be fit- ted with the necessary interfacing connectors. In so doing, the customer

gains significant performance advantages while at the same time saving

the additional fee that would otherwise be charged by NBS for per- forming this service. Highperformance converters are often

susceptible to small changes in grounding, routing of dynamic signal

lines, capacitive loading, etc. Particularly with ADCs, signal dynamics are

Table 13: Specifications and Estimated Uncertainties for Data Converter Calibrations

Parameter

Estimated Systematic Uncertainty

DACs ADCs

Linearity Error

Differential Linearity Error

Offset Error'"' Gain Error'"' RMS Input

Noise"''

2.7 ppm

3.2 ppm

3 ppm

6 ppm

+0.04 LSB + 0.04 LSB

4.7 ppm

5.2 ppm + 0.16 LSB + 0.16 LSB

3 ppm +0.07 LSB

6 ppm +0.13 LSB

-100%; +(20%+10

fiV) Noise introduced

by the Test Set is approximately

30 nV/(Hz)'^- in a

1 MHz bandwidth

(a) Measured upon special request only, if no adjustable trimmers are provided for these parameters.

(b) Since the effective bandwidth of the test converter is generally un- known, the noise contribution from the test set cannot be determined.

Therefore, only an upper limit can be accurately placed on the noise measurements.

quite important, even for static test- ing, because the converter itself al- ways operates at high speeds. When

mounted by the customer, the test converter and its support circuitry can be laid out to simulate more clo- sely the way it will be used, according to the specific manufacturer's rec- ommendations. Therefore, the test results should more closely describe

the converter's in situ performance.

Detailed type and wiring requirements for the interfacing connectors

are available upon request.

121
Michael Souders, working on development of NBS system for characterizing

analog-to-digital and digital-to-analog data converters.

References—Data Converters

A Calibration Service for Analog-toDigital and Digital-to-Analog Converters, T. M. Souders, D. R. Flach,

and B. A. Bell, Natl. Bur. Stand.

(U.S.), Tech. Note 1145, (July 1981).

(Provides a complete description of

the calibration service.)

A 20-Bit + Sign Relay Switched D/

A Converter, T. M. Souders and D.

R. Flach, Natl. Bur. Stand. (U.S.),

Tech. Note 1105, (Oct. 1979). (Describes the reference standard used in the calibration service.)

A Technique for Measuring the

Equivalent RMS Input Noise of A/D

Converters, T. M. Souders and J. A.

Lechner, IEEE Trans. Instrum. Meas., IM-29, No. 4, 251 (Dec. 1980).

A High-Speed Low-Noise 18-Bit

Digital-to-Analog Converter, H. K.

Schoenwetter, IEEE Trans. Instrum. Meas., IM-27, No. 4, 413 (Dec. 1978).

An Automated Test Set for the Dynamic Characterization of A/D Converters, T. M. Souders, D. R. Flach,

and T. C. Wong, IEEE Trans. In- strum. Meas., IM-32, No. 1, 180 (Mar.

1983).

122
54110S-54131C

D.

Precision Ratio Measurements

D. 1 Inductive Dividers

Electricity Division

Center for Basic Standards

Technical Contacts:

George M. Free

Tel: 301/921-2715 Norman B. Belecki

Tel: 301/921-2715

Avis R. Wise

Administrative

Logistics

Tel: 301/921-2715

Mailing Address: B146 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items 54110S Special Ratio Measurements and Tests of Inductive

Voltage Dividers by Prearrangement

54120C Inductive Voltage Dividers—(Single Frequency,

Voltage to be Specified, Each Setting of 3 Most

Significant Dials) 5412 IC Additional Frequency Points 54130C Inductive Voltage Dividers—(Single Frequency,

Voltage to be Specified, Each Setting of Most

Significant Dial Only)

541 3 IC Additional Frequency Points

Special Ratio Measurements and Tests of Inductive Voltage Dividers by

Prearrangement (541 lOS)

This service category provides for the measurement and/or evaluation of

prototype ratio devices and inductive

voltage dividers based on new principles, and for unique ratio measurements at the highest accuracy levels, such as the determination of the

ratios of Hamon resistance transfer devices or Silsbee-type voltage ratio standards. Such measurements are un- dertaken at the discretion of NBS

technical staff and oniy when the

need for them can be clearly demonstrated. Inductive Voltage Dividers

(54120C-54131C)

Inductive voltage dividers (decade

transformer dividers) are accepted for calibration only at 400, 1000, and

10,000 Hz. The largest contribution to

instability in undamaged inductive

123

voltage dividers is wear or dirt in the

decade switches. Variable contact re- sistance in these switches sometimes

affects the stability of voltage-ratio

measurements to a significant extent but is most evident by its effect on

the phase angle. When a decade in- ductive voltage divider exhibits large

changes in phase angle for repeated

measurements after the switches have

been disturbed, the divider should no

longer be considered satisfactory for use as a voltage-ratio reference stan- dard. Inductive voltage dividers that use pushbutton switching or incorporate a resistive divider as a fine adjustment usually are not accepted for calibration. Corrections to the separate decades of an inductive divider,

in general, cannot be simply combined. However, the correction to a

step setting of one of the higher decades usually is independent of the

settings of the lower decades. The ef- fects of stray impedances must be

corrected by connecting the case to the divider at one point, and unless otherwise specified, the case will be

connected to one of the common ter- minals. Decade inductive voltage di- viders are calibrated at NBS at room

temperature (22 to 24 °C) by a comparison method, using a two-stage,

three-decade transformer of known

ratios.

References—Inductive Dividers

American National Standard for Decade Transformer Dividers (Voltage

Type), ANSI ClOO, 1-1972 Amer.

Natl. Stand. Inst., New York (Jan.

1972).

Instructions for the Use of the NBS

Reference Inductive Divider, Wilbur

C. Sze, Natl. Bur. Stand. Int. Report,

Unpublished (1970). (Available from

NBS).

Two-Stage, Guarded Inductive Voltage Divider for Use at 100 kHz, D.

H. Hamon and T. L. Zaf, ISA Transactions, 9, 3 Instrum. Soc. of America, Res. Triangle Park, NC (1970).

Comparator for Calibration of In- ductive Voltage Dividers from 1 to 10 kHz, W. C. Sze, ISA Transactions,

6, 4 Instrum. Soc. of America, Res.

Triangle, NC (1967).
us Department of Commerce

National Bureau of Standards

Standard

Reference

Materials

For Use In Calibrating or Checking Instruments Used in the Determination of:

• Chemical Composition

• Crystal Structure

• Electrical Properties

• Metallurgical Properties

• Optical Properties

• Partical Size • pH

• Temperature

• Thermal Properties

• And Others

Office of Standard Reference

Materials National Bureau of Standards Room B3 1 1 Chemistry BIdg. Gaithersburg, MD 20899 301—921-2045
542 IOC

D. Precision Ratio Measurements

D.2 Resistive Dividers

Electi'osystems Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

Martin Misakian Robert E.

Tel: 301/921-3121 Hebner, Jr. Tel: 301/921-3121

Mailing Address: B344 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Shipping Address: National Bureau of Standards, 1-270 at Quince Orchard Road, Gaithersburg, MD 20899

[Attn: M. Misakian, Bid. 220, Room B351]

Test No. Items

542 IOC Resistor and Resistive Dividers, Total Resistance or Voltage Ratio, Two Direct Voltage Levels Between

10 kVand 150 kV

Resistor and Resistive Dividers

(54210Q

A calibration service is maintained at NBS to specify the dc voltage ratio of resistive dividers. The routine cali- bration service is available for applied

voltages from 10 kV to 150 kV. The

calibrations are performed with a measurement system which has an uncertainty of ±0.01% of the voltage

ratio. To assure adequate sensitivity

at the lowest applied voltage levels,

calibrations are performed routinely

only on dividers with ratios of

100,000:1 or smaller. The routine cali- bration service is also restricted to di- viders with a low-resistance element

of 10,000 ohms or less. Resistive dividers are acceptable

for calibration only if they are nearly corona free at the rated operating

voltage and are designed to have

small temperature and voltage coefficients. Specifically, a device is not

generally suitable for calibration by

NBS if these coefficients produce a change in the ratio of ±0.1% over

the normal range of operating volt- ages. At a given voltage, dividers

should not exhibit instabilities in their ratio value in excess of 0.005 percent.

NBS staff can provide some assis- tance in the identification of other

calibration laboratories capable of

certifying the response of less accurate dividers.

Resistive dividers of sufficient quality to be considered as transfer stan- dards are calibrated at 60 Hz for applied voltages between 10 kV and 100

kV rms. High voltage dividers may

perform satisfactorily as standards un- der dc voltages but do not perform

well enough to be considered as stan- dards when excited by 60-Hz volt- ages. The design of an ac divider re- quires special features, beyond those

of a dc divider. In particular, ac di- viders designed to be used as transfer standards may have to be equipped

with external shielding to minimize

the effects of capacitive coupling to surrounding objects.

If the device is not properly

shielded, the effects of proximity to surrounding objects and pickup from

high-voltage conductors can intro- duce large uncertainties into the measured value of the divider ratio. In such cases, the measurement of the

ratio for one configuration would not

necessarily be valid for another configuration. Consequently, a meaningful calibration of the device is diffi- cult or impossible.

Therefore, we recommended that the following two preliminary proximity tests be performed before an ac

125
divider is submitted for test to deter- mine the suitability of the device as a

transfer standard. The divider should

be placed about 2.0 m from a vertical

ground plane as measured from the center of the device. The divider

should then be energized to some safe voltage level and the divider ratio should be measured. The measurement should then be repeated

with the vertical ground plane (or di- vider) moved into a position 1.2 m

from the center of the divider. If the

divider ratio, at the same applied high

voltage, changes by 0. 1 percent or more, the device has excessive capacitive coupling and is not suitable as a

transfer standard.

To test for pickup, remove the

high-voltage connection to he top of

the divider and then connect the top

of the divider to ground with a thin

wire. Measure the output voltage of

the divider under these conditions

both with and without the highvoltage source energized. If the re- sulting change in the output voltage

exceeds 0. 1 percent of the expected

output voltage when the high voltage

is connected to the divider, then

again there is excessive coupling indi- cating that the device is not suitable

as a transfer standard.

Whenever a high-voltage ac di- vider is sent to NBS, it will first be

subjected to tests like those described

above. If such tests show variations in the measured ratio of more than 0.

percent for either proximity or

pickup, then no further tests will be

performed and the device will be re- turned. The customer will be charged

for the cost of these tests. The NBS calibration of voltage

transformers at 60 Hz is generally more accurate than its calibration of

dividers at the same frequency.

Therefore, customers having a re- quirement for a calibrated divider

may find it advantageous to use a voltage transformer as the transfer standard and to use that transformer

to calibrate the divider in their own

facilities. Dividers can be hand-carried or shipped to NBS. Shipped dividers

should be packaged in sturdy reusable

containers. The design of many high

voltage dividers makes them vulnerable to shear-type forces, so provisions should be made to minimize

the likelihood of damage due to such

forces when the device is in the shipping container.

Resistive divider ratios are also determined under pulsed high-voltage

conditions. Determinations employ

special-design pulse dividers and cali- brated Kerr cells as reference stan- dards. A variety of pulses may be applied to simulate the conditions under

which the divider will be used. Calibrations are made at selected voltage

intervals from 20 kV to 300 kV as re- quested and up to 500 kV with certain pulse shapes. The typical uncertainty is ±3% of the voltage ratio although smaller uncertainties can occasionally be reported as a special

test.Routine tests are carried out for voltages between 10 kV and 200 kV

and are performed with a measurement system having an uncertainty of 0.05% in the determination

of the ratio and ±0.5 milliradian in the determination of the phase angle.

References—Resistive Dividers

Evaluation of a Multimegavolt Impulse Measurement System, R. E. Hebner, D. L. Hillhouse, and R. A.

Bullock, Natl. Bur. Stand. (U.S.), Int. Report, NBSIR 79-1933 (Nov. 1979).

Calibration of High-Voltage Pulse

Measurement Systems Based on the

Kerr Effect, Natl. Bur. Stand. (U.S.),

Int. Report, NBSIR 77-1317 (Sept.

1977).

Special Shielded Resistor for HighVoltage Measurements, J. H. Park, J. Res. Natl. Bur. Stand. (U.S.), 66C,

No. 1, 19 (Jan.-Mar. 1962).

126
Precision Ratio Measurements

m D.3 Capacitive Dividers

Electrosystems Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

William E. Robert E. Anderson Hebner, Jr. Tel:301/921-3121 Tel: 301/921-3121

Mailing Address: B344 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Shipping Address: National Bureau of Standards, 1-270 at Quince Orchard Road, Gaithersburg, MD 20899

[Attn: W. E. Anderson, Bid. 202, Room 167]

Test No. Items

543 lOS Capacitive Dividers

Capacitive Dividers (54310S)

Capacitive divider ratios are deter- mined under both pulsed high-voltage

and ac conditions. Determinations un- der high-voltage pulse conditions employ special-design pulse dividers and

calibrated Kerr cells as reference

standards. A variety of pulses may be

applied to simulate the conditions un- der which the divider will be used. Calibrations are made at selected

voltage intervals from 20 kV to 300

kV as requested and up to 500 kV

with certain pulse shapes. The typical

uncertainty is ±3% of the voltage ratio although smaller uncertainties can

occasionally be reported as a special

test.Determinations at 60 Hz ac employ

the same equipment used for the cali- bration of ac resistive dividers (see

542 IOC). The same limitations pertain

to shielding (proximity and pickup ef- fects). The NBS measurement system

imposes a negligible burden on the di- vider if its output voltage is 100 volts or less. Otherwise, the burden is equivalent to a 1000 picofarad capacitor.

References—Capacitive Dividers

Evaluation of a Multimegavolt Impulse Measurement System, R. E. Hebner, D. L. Hillhouse, and R. A.

Bullock, Natl. Bur. Stand. (U.S.), Int. Report, NBSIR 79-1933 (Nov. 1979).

Calibration of High-Voltage Pulse

Measurement Systems Based on the

Kerr Effect, Natl. Bur. Stand. (U.S.),

Int. Report, NBSIR 77-1317 (Sept.

1977).

Special Shielded Resistor for HighVoltage Measurements, J. H. Park, J. Res. Natl. Bur. Stand. (U.S.), 66C,

No. 1, 19 (Jan.-Mar. 1962).

High Voltage Divider and Resistor

Calibrations, M. Misakian, Natl. Bur. Stand. (U.S.), Tech. Note 1215 (July

1985).

127
54410S-54420S

Precision Ratio Measurements ' D,4 Mixed Dividers

Electrosystems Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

Ronald H. McKnight Robert E.

Tel: 301/921-3121 Hebner, Jr. Tel: 301/921-3121

Mailing Address: B344 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items

5441 OS Pulse-Voltage-Measuring Systems, Including Kerr

Cells 54420S X-Ray Unit, Voltage Dividers (Two dividers in same

container)

Mixed Dividers (54410S and 54420S)

A mixed divider is one constructed of

resistors and capacitors. Ratios of

mixed-voltage dividers are deter- mined under pulsed high-voltage conditions. Determinations employ

special-design pulse dividers and cali- brated Kerr cells as reference stan- dards. A variety of pulses may be applied to simulate the conditions under

which the divider will be used. Calibrations are made at selected voltage

intervals from 20 kV to 300 kV as re- quested and up to 500 kV with certain pulse shapes. The typical uncertainty is ±3% of the voltage ratio although smaller uncertainties can occasionally be reported as a special

test.A special set of tests has been developed to evaluate the mixed di- viders used to measure the voltage

pulses in diagnostic x-ray units. These

tests involve measurement of the vari- ation of the ratio with a change in the

frequency of the applied voltage in the frequency range from dc to 10,000 Hz; a determination of the ratio under direct voltage at 25 kV; a measurement of any voltage induced

variation of the ratio in the voltage

range from 20 to 70 kV. If the device

under test is designed to operate continuously under full rated voltage,

this last test is performed at three dc

voltages between 20 and 70 kV. For

devices that cannot operate continuously, a preselected number of

half cycles of 60-Hz voltage with

peak voltage ranging from 20 to 70

kV are applied.

Routine tests are performed with

an uncertainty of ±0.1% of the indi- cated value of the dc ratio at 25 kV,

and an uncertainty of ± 1 % of the in- dicated value of the frequency dependence. Generally the ratio varies

by less than ± 1 % as the applied volt- age is varied over the full range. This calibration service was developed to assist in compliance with the

U. S. Food and Drug Administration's regulations on good manufacturing practice for medical devices

(Federal Register, Vol. 43, 31508,

1978).

References—Mixed Dividers

X-CAL—A Calibration System for Electrical Measurement Devices Used

With Diagnostic X-Ray Units, R. H.

McKnight and R. E. Hebner, Natl. Bur. Stand. (U.S.), Int. Report, NBSIR 79-2072, (June 1980).

Evaluation of a Multimegavolt Impulse Measurement System, R. E. Hebner, D. L. Hillhouse, and R. A.

Bullock, Natl. Bur. Stand. (U.S.), Int. Report, NBSIR 79-1933, (Nov. 1979).

Calibration of High-Voltage Pulse

Measurement Systems Based on the

Kerr Effect, Natl. Bur. Stand. (U.S.),

Int. Report, NBSIR 77-1317, (Sept.

1977).

Special Shielded Resistor for HighVoltage Measurements, J. H. Park, J. Res. Natl. Bur. Stand. (U.S.), 66C,

No. 1, 19 (Jan.-Mar. 1962).

128
54510C-546O0S

Precision Ratio Measurements ' D.5 Voltage and Current Transformers

Electrosystems Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

William E. Anderson

(Voltage Transformers)

Tel: 301/921-3121

John D. Ramboz

(Current Transformers)

Tel: 301/921-3121

Mailing Address: B344 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Shipping Addresses: National Bureau of Standards, 1-270

at Quince Orchard Road, Gaithersburg, MD 20899

For 54510C-54513C:

[Attn: W. E. Anderson, Bid. 202, Room 167]

For 54520C-54522C:

[Attn: J.D. Ramboz, Bid. 220, Room B165]

Test No. Items

545 IOC Voltage Transformer, Ratio & Phase Angle, at 60 Hz

on 1 Range, 1 Secondary Voltage, 1 Burden Primary

Vn„s<150 kV

5451 IC Same as 545 IOC, Additional Similar Transformer at Same Time

545 12C Same as 545 IOC and 545 UC, Additional Burden or Range

545 1 3C Same as 545 1 OC-545 1 2C, at Each Additional

Secondary Voltage

54520C Current Transformer, Ratio & Phase Angle, 1 Range

at 1 Frequency and 1 Burden, Secondary Currents 0.5,

1, 2, 3, 4, 5 A, Primary Current Not Over 8000 A

5452 IC Current Transformer, Ratio & Phase, 1 Secondary

Current, Additional Combination of Range,

Frequency, and Burden, Primary Current Not Over

8000 A

54522C Current Transformer, Ratio & Phase at Each

Additional Secondary Current, Same Combination of

Range, Frequency, and Burden as 54520C or 5452 IC

54600S Special Tests of Dividers and Transformers by

Prearrangement

Voltage Transformers

(54510C-54513C)

NBS provides routine services for the

measurement of complex voltage ratios (magnitude and phase angle) of

transformers for primary voltages up

to 1 50 kV and for secondary voltages

above 50 V, subject to some constraints as to the maximum physical

size of the device. Results of these

routine tests are reported with an uncertainty of ±0.03% for ratio and 0.3 mrad (1 mrad = 3.438 min) for phase

angle. If the test conditions and the

device under test warrant, special

tests with smaller uncertainties can be

performed. These special tests may

require an extra fee. The customer must specify the sec- ondary voltage and the secondary

burden for each transformer or for each range of a multirange trans- former. Ambiguity can be avoided if the impedance and power factor, or

the resistance and reactance are specified rather than the volt-ampere rat- ing of each burden. The customer

should note that the NBS calibration

system represents a minimum burden

of 1000 pF for routine calibrations. The customer should give some care

to the specification of a burden recognizing that the use of the transformer

with a burden different from that used in the calibration can result in significant error. Calibrations of voltage transformers

are performed routinely only at 60

Hz. Measurements are made with one

side of both the primary and secondary windings connected to ground.

NBS does have some capability to perform measurements at voltages,

frequencies, and burdens outside of

129
the ranges described above. Calibrations can occasionally be provided

at these nonroutine test points as a

special test for an increased fee. Current Transformers

(54520C-54522Q

Normally NBS calibrates only current transformers of high quality for use as reference standards. The NBS equipment is designed to test current trans- formers with a rated secondary current of 5 A, with test points chosen to be one or more of the following values: 0.5, 1, 2, 3, 4, 5 A.

Routine tests are carried out at 50,

60 and 400 Hz. For measurements at 50 or 60 Hz, the results are generally

reported with an uncertainty of

±0.01% in ratio and ± 100 fxrad in phase angle. For measurements at 400

Hz, the reported uncertainty is ±0.03% in ratio and ±300 /xrad in phase angle.

The customer must specify the test frequency, the secondary currents,

and the secondary burdens for each

transformer or for each range of a multirange transformer. Current

transformers should be tested with

burdens equivalent to those which are imposed when the device is used as a

transfer standard. Routine calibration

using the burdens specified in the

American National Standards Insti- tute (ANSI) Standard C-57.13 is not recommended unless these burdens

are subsequently used in the cus- tomer's factory or laboratory. Large

errors can result if the values of ratio and phase angle obtained with an ANSI recommended burden are used

for the transformer when it is con- nected to a different burden.

Preferably the burden should be

specified in terms of the measured re- sistance and inductance. These values

should include the effects of the leads

used to make a connection to the

transformer secondary. An alternative, which is sometimes feasible, is to submit the transformer together with

its normal leads and connected burden for calibration as a unit. If neither

of the above are possible, the burden

may be stated in terms of the volt- ampere product and the power factor

of the secondary circuit at the test frequency. For reference, it should be

noted that the test equipment regularly used at NBS represents a minimum test burden of about 0.03 ohms

with an inductance of about 10 /ih. Because of contact resistance and

current rectification, loose or dirty

primary and secondary terminations

130
may affect the measurement results. These surfaces should be clean when

the transformer is shipped to NBS to minimize this source of error. Unless otherwise specified, current transformers are demagnetized prior

to calibration. If it is desired to have

a transformer tested as submitted

(without demagnetization), this equipment should be stated on the pur- chase order and NBS staff should be

informed by telephone before the

transformer is shipped.

Many current transformers are not designed to be used as transfer stan- dards and most of these do not re- quire calibration at NBS. The NBS

staff can provide some assistance in the assessment of the appropriateness

of the device for NBS calibration and

in the identification of alternative cal- ibration sources. If NBS is required to perform laboratory measurements to determine whether or not a particular

device can be calibrated, a charge for the cost of these measurements will be made.

Special Tests of Dividers and

Transformers (54600S)

The Electrosystems Division maintains an active program of research

and development in the area of electrical measurements at high voltage

levels. For this reason, NBS often is able to provide measurement support

for high voltage devices other than

those listed above in this section. Special tests will generally be conducted

by NBS, if the following criteria are met:A. The requested tests are fully

developed and documented.

B. There is a significant technical or economic justification for traceability of the test on the item to national standards. C. There has not been a routine or recurrent need for the test.

References—Voltage and Current

Transformers

A Wide Range High-Voltage Capacitance Bridge With One ppm Accuracy, O. Petersons and W. E. Anderson, IEEE Trans. lustrum. Meas.,

IM-24, No. 4, 336 (Dec. 1975).

An Electronic Ratio Error Set for Current Transformer Calibrations, R.

L. Kahler, IEEE Trans. Instrum. Meas., IM-28, No. 2, 162 (June 1979).

A Wide Range Current Comparator

System for Calibrating Current

Transformers, T. M. Souders, IEEE

Trans. Power Appar. Syst. PAS-90

No. 1, 318 (Jan.-Feb. 1971).

Wide-Band Two-Stage Current

Transformers of High Accuracy, T. M. Souders, IEEE Trans. Instrum. Meas. IM-21, No. 4, 340 (Nov. 1972).

131
55110S

Phase Angle Measurements

E. 1 Phase Angle Meters

Electrosystems Diyision

Center for Electronics and Electrical

Engineering

Technical Contacts:

Raymond S. Turgel

Tel: 301/921-2727

Barry A. Bell

Tel: inxmx-nii

Mailing Address: B162 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Test No. Items

551 lOS Special Tests of Phase Angle Meters, by

Prearrangement

Special Tests of Phase Angle Meters,

by Prearrangement (55110S)

NBS has recently developed a capability for characterizing audio fre- quency phase meters over a fre- quency range of 1 Hz to 50 kHz. The

standard used is a microcomputerbased system that synthesizes two si- nusoidal voltages by means of digital

techniques. The two signals are dis- placed relative to one another by a

precisely known phase angle. Phase

angles can be set with a resolution of

0.002 degree up to 5 kHz and 0.005

degree above 5 kHz. The amplitude

of the two output signals can be varied independently from 0.5 volt to 100 volts rms. At power frequencies, one of the inputs can be a current

from 0.5 to 5 amperes. The uncertainty in setting the standard is less than ±0.01 degree below 5 kHz and

increases to ±0.04 degree at 50 kHz

if the two output signals have the same amplitude. For unequal outputs,

this uncertainty increases to ±0.015

degree and ±0.090 degree re- spectively, if the amplitude ratio is less than 10:1. Although the accuracy of the phase

angle standard does not rely on the

stability of the frequency, the generated output, which can be varied in

Figure 1 6. Estimated Total Uncertainties of the NBS

Phase Angle Calibration Standard

0.100 — 0.080

-a 0.060

ro 0.040

=> 0.020-

0.000

Amplitude Ratio 10:1

0.002 5 10 15

Output Frequency (KHz)

50

Steps of 1 Hz, is locked to a crystal

controlled frequency synthesizer.

Figure 16 shows a plot of the total estimated uncertainty of the NBS

Phase Angle Calibration Standard as a function of frequency for two limiting amplitude ratios. This service is being offered on a

trial basis under NBS Special Test

procedures. If sufficient interest is shown, NBS will consider upgrading

this trial service to full "Calibration

Service" status. Special requirements

for this service are as follows:

A. The voltage inputs of phase

meter to be tested must have impedances such that the current is limited

to a few milliamperes at any applied

voltage requested. Current inputs

132
5511 OS

must have impedances low enough so

that the compUance voltage does not exceed 2 volts. B. NBS will test the instrument in the as-received condition, without

making any zero or gain adjustments.

C. In some cases, the response of

phase meters involves significant time

constants; therefore, readings will be

taken 30 seconds after the setting of

the standard.

D. For given voltage and fre- quency settings, at least three readings will be taken at each specified

phase angle. The order of readings

will be randomized.

E. The experimental data are fit- ted to a mathematical model from

which the phase meter response can be predicted. From the closeness of

fit to the model, it can be determined

whether observed deviations from the

predicted values are significant. F. Each phase meter will be operated under power for at least 2 hours

before test data are taken. G. Meters that are not in operating condition upon receipt at NBS

will be returned to the owner without

repairs.

The fee for this service will be

based on the actual cost. Prior ar- rangements are essential.

References—Phase Angle Meters

High-Precision Audio-Frequency

Phase Calibration Standard, R. S. Turgel and N. M. Oldham, IEEE

Trans. Instrum. Meas., Vol. IM-27,

No. 4, 460 (Dec. 1978).

NBS Phase Angle Calibration Stan- dard, R. S. Turgel, N. M. Oldham, G.

N. Stenbakken, and T. H. Kibalo,

Natl. Bur. Stand. (U.S.), Tech. Note

1144, (July 1981).

A Power Factor Standard Using Digital Waveform Generation, N. M.

Oldham and R. S. Turgel, IEEE

Trans. Power Appar. Syst., PAS- 100,

No. 11, 4435 (Nov. 1981).

NBS 50 kHz Phase Angle Calibration

Standard, R. S. Turgel, Natl. Bur. Stand. (U.S.), Tech. Note 1220 (in

press).

IR-100 winner Raymond Turgel with his NBS phase-angle standard.

133
55210C-55230S

£ Phase Angle Measurements

' E.2 Very-High-Frequency Omnidirectional

Range (VOR) Measurements

Electromagnetic Fields Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

Neil T. Larsen Qetus A. Hoer Edna M. Jones

Tel: 303/497-3711 Tel: 303/497-3705 Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Bureau of Standards, 325 Broadway, Boulder, CO 80303

Test No. Items 552 IOC VOR Bearing-Angle Indicators, 12 Bearing Angles

Over the Range 0 to 330 Degrees

5521 IC Calibration of VOR Bearing-Angle Indicator at Each

Additional Angle

55220C VOR Generators, 12 Bearing-Angle Equivalent

Signals Over the Range 0 to 330 Degrees

5522 IC Calibration of VOR Generator at Each Additional

Angle

55230S Special VOR Tests VOR Measurements—General

Information

The NBS calibration services for VOR air navigation signals is described in detail in the April 1985

NBS Technical Note 1069, "VOR

Calibration Services" by N. T. Larsen, et al. Two services are offered to support

the calibration of VOR (Very-highfrequency Omnidirectional Range) in- struments. NBS has designed and

built a standard VOR audio generator, used to calibrate unknown VOR

bearing-angle indicators, and a stan- dard VOR bearing-angle indicator,

used to calibrate unknown audio generators. Direct generation or measurement of standard VOR rf signals

is not a part of the service.

Quality control of the NBS stan- dards is accomplished by using each

to measure the other. As a result of

these measurements, the uncertainty

of a calibration of either a generator or a bearing-angle indicator is given

by the following statement, which is part of the calibration report:

"The assigned values of VOR

phase angles are the nominal bearings

from 0 to 360 degrees in increments

of 0.01 degrees. The overall uncertainty of these values has been esti- mated from test data at bearings from

0 degrees to 360 degrees at 30 degree

increments. Thus, each of the nominal

bearings has been assigned a provisional overall uncertainty of ±

0.0028 degrees, based on estimated

bounds of ± 0.0022 degrees on the

systematic error and a computed stan- dard error of 0.0002 degrees."

VOR Bearing-Angle Indicators

(55210C and 552110

An unknown bearing-angle indicator

is calibrated by connecting its input

to the output of the NBS standard

generator. The generator provides a composite audio signal that is the sum

of two signals, each 1 volt rms (±

134
5521OC-55230S

1%) in amplitude. The first signal is a 30 Hz sinusoid, and represents the

variable phase signal recovered from

the VHF carrier. The second is the

frequency-modulated 9960 Hz subcarrier. NBS will calibrate at any set of 12 bearing-angles specified by the

customer (if not specified, at 30 degree intervals over the inclusive

range 0 to 330 degrees).

VOR Generators (55220C and 55221Q

Only certain commercial VOR generators are suitable for calibration. They should provide a composite au- dio signal of nominally 1 volt rms, per tone. They must have a short- term phase jitter of less than 10 nsec. The modulation index for the 9960

Hz subcarrier must be equal to 16 ±1%. Most commercial generators

do not meet these requirements and

can best be calibrated by submitting a bearing-angle indicator for calibration

instead. This can then be used to

transfer the NBS calibration to the

unknown generator with some loss of

accuracy. An uncertainty statement

for this transfer has not been developed due to lack of history. NBS will calibrate at any set of 12 bearingangle equivalent signals corresponding to bearing-angles specified by the

customer (if not specified, at 30 degree intervals over the inclusive

range 0 to 330 degrees).

Special VOR Tests (55230S)

The NBS standard bearing-angle indi- cator lends itself to the measurement

of audio frequency periodic waveforms through the use of sampling

techniques and time series analysis. It has been used for the accurate measurement of phase angles between

two sinusoids. Special tests of this na- ture may be provided by pre- arrangement. The uncertainty depends upon the frequency; at 30 Hz it is about 0.0006 degrees (3 standard

deviations).

References—VOR Measurements

VOR Calibration Services, N. T. Larsen, D. F. Vecchia, and G. R. Sugar,

Natl. Bur. Stand. (U.S.), Tech. Note

1069, (April 1985).

Fourier Transformation of the Nonlinear VOR Model to Approximate

Linear Form, D. F. Vecchia, Natl. Bur. Stand. (U.S.), Tech. Note 1021,

(June 1980).

135
56110S-562I0M

Power and Energy Measurements,

t m Low-Frequency

Electrosystems Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

Elizabeth A. Robert E. Matthews Hebner, Jr. Tel: 301/921-3121 Tel: 301/921-3121

Mailing Address: B344 Metrology, National Bureau of

Standards, Gaithersburg, MD 20899

Shipping Address: National Bureau of Standards, 1-270 at Quince Orchard Road, Gaithersburg, MD 20899

[Attn: E. A. Matthews, Bid. 220, Room B165]

Test No. Items

561 1 OS Special Tests of AC-DC Wattmeters by

Prearrangement

56120C Wattmeter Calibrations at Power-Frequencies

56200C Watthour Meter, Initial Two Determinations of

Percentage Registration at 60 Hz

5620 IC Each Additional Determination of Percentage

Registration of Same Meter at 60 Hz

56202C Initial Two Determinations of Percentage

Registration of One or Two Meters Run

Simultaneously with the First (56200C)

56203C Each Additional Determination of Percentage

Registration of One or Two Meters Run as in 56202C

562 lOM Measurement Assurance Program for Watthour

Meters

and does not knowingly begin tests of

faulty meters. The test conditions must be specified by the customer. These include

the current and voltage ranges to be

tested, the frequency, the applied

voltages, the applied currents, and the

power factors. Values of these parameters which are available for routine

testing are summarized in Table 14.

Table 14: Available Values of the Parameters for Routine Wattmeter and Watthour Meter Testing

Parameter Available Values

Voltage (V) 110 220 440

115 230 460

120* 240* 480

125 250 500

130 260 520

Current (A) 0.50 2.50 7.50 25.00

0.75 3.00 10.00 30.00

1.25 3.75 12.50 37.50

1.50 4.00 15.00 40.00

2.00 5.00* 20.00 50.00

Power Factor l.O* 0.5* lagging

0.5* leading

Frequency (Hz) 60* 50

* Available values for Measurement Assurance Program (MAP) measurements

If necessary, measurements can sometimes be made at other values of

these parameters. These would, however, be considered special tests. Separate, specific arrangements and a higher fee will be charged than for a routine calibration. Unless otherwise specified, the duration of a test run on a wattmeter is of approximately 100 seconds. For a watthour meter, the test run duration

is approximately 100 seconds for unity power factor and approximately

200 seconds duration for 0.5 power

factor. Prior to the calibration, the

meters are energized for between one and four hours at rated voltage and

current on one range. A calibration

consists of at least two sets of meaPower and Energy Measurements,

Low-Frequency (56110S-56210M)

Only portable standard wattmeters

and watthour meters (rotating stan- dards and electronic types) are ac- cepted for test. If necessary the meters should be cleaned or adjusted by

the customer before they are shipped

to NBS. NBS does not adjust meters

136
56110S-56210M

surements taken over a minimum period of two days.

For wattmeters, the values of the

reported corrections (in watts) generally have uncertainties of ±0.05% of

the full scale range in volt-amperes.

For watthour meters, the reported

values of the percentage registration

generally have uncertainties of

±0.05% of the indicated value. Special, higher accuracy tests can be ar- ranged for an additional fee. The uncertainties for power or energy

measurements in these special tests may be as low as ±0.01% if the

short-term standard deviation of the

device under test is appropriately

small. Wattmeter calibrations at other

than power frequencies are considered Special Tests and must be ar- ranged on an individual basis. The

following limitations apply:

A. Instruments must have separate voltage and current input terminals. B. The instrument must have a

self-contained power indicator, or provide a direct current signal which

is proportional to power, or provide an output frequency (TTL compatible) which is proportional to the

power.

C. Measurements are generally

limited to sinusoidal signals at fre- quencies between dc and 100 kHz.

Signal levels should not exceed 240

volts and 5 amperes.

D. Instruments will be tested in the as-received condition, and test uncertainties will be based in part on the

performance of the instrument during

the test. The Measurement Assurance Pro- gram for electric energy is designed

to evaluate the performance of en- ergy measuring systems at the cus- tomers laboratory. An NBS-owned,

transport standard watthour meter of

known stability is measured by NBS.

It is then shipped to and measured by

the customer, and then shipped back

to NBS. NBS analyzes the data and

provides a report to the customer in- dicating the total uncertainty of his measurement. This procedure enables customer's standards to be measured

relative to NBS standards without the

downtime encountered when the cus- tomer's standards are shipped to and

calibrated by NBS. In addition, and more important to those who cali- brate standard watthour meters, the

NBS MAP standard can be used by

customers to evaluate their measurement process in a convenient and

cost-effective way.

The uncertainty of a MAP includes

the effects of the long-term and short- term instabilities of the NBS cali- bration system, the customer's cali- bration system, and the transport

Customer's typical watthour meter. NBS provides reference measurements

supporting metering of over $140 billion dollars worth of electricity each year.

137
56110S-56210M

standard. Typically, the uncertainty

in a well-controlled comparison

ranges between ± 0.03% and ±

0.05%.

The Electrosystems Division of the

Center for Electronics and Electrical

Engineering maintains an active pro- gram of research and development in the area of electric power and energy

measurements. For this reason, this

Foreground: NBS reference wattmeters, watthour

meters. Background: NBS electrical power and energy

measurement system.

often enables NBS to provide measurement support for watt and watt- hour meters beyond that listed in this section. Special tests will generally be

conducted when the following conditions prevail:

A. The requested tests are fully

developed and documented.

B. There is a significant technical or economic justification for traceability of the test on the item to national standards.

C. There has not been a routine or recurrent need for the test.

References—Power and Energy

Measurements, Low Frequency

A Calibration Service for Wattmeters

and Watthour Meters, J. D. Ramboz

and R. C. McAuliff, Natl. Bur. Stand.

(U.S.), Tech. Note 1179, (July 1983).

A Measurement Assurance Program

for Electric Energy, N. M. Oldham,

Natl. Bur. Stand. (U.S.), Tech. Note

930, (Sept. 1976).

Sampling Techniques for Electric

Power Measurement, R. S. Turgel,

Natl. Bur. Stand. (U.S.), Tech. Note

870, (June 1975).

Transfer of the Kilowatthour, S. R. Houghton, IEEE Trans. Power Appar. Syst. PAS-94, No. 4, 1232 (JulyAug. 1975).

A Current Comparator System to Establish the Unit of Electrical

Energy at 60 Hz, K. J. Lentner,

IEEE Trans. lustrum. Meas. IM-23,

No. 4, 334 (Dec. 1974).

A Wideband Sampling Wattmeter,

G. N. Stenbakken, IEEE Trans. Power Apparatus and Systems,

PAS- 103, No. 10, 2919 (Oct. 1984).

NBS Wideband Sampling Wattmeter,

G. N. Stenbakken, O. B. Laug, A. G.

Perry, B. A. Bell, and T. H. Kibalo,

Natl. Bur. Stand. (U.S.), Tech. Note

1221 (in press).

138
61110S-61190S

#' ~ Microwave Measurements

G. 1 Power Meters, RF and Microwave

Electromagnetic Fields Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

Leon F. Manly P. Cletus A. Hoer Edna M. Jones

Saulsbery Weidman Tel: 303/497-3705 AdministratiTe

Tel: 303/497-3970 Tel: 303/497-3210 and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Bureau of Standards, 325 Broadway, Boulder, CO 80303

Test No. Items 61110S Effective Efficiency and Reflection Coefficient of Coaxial Power Meters at Specified Frequency in Range 0.1 to 10 MHz

61 1 1 IS Each Additional Frequency for 61 llOS

61120S Calibration Factor, Effective Efficiency, Efficiency Factor and Reflection Coefficient of Coaxial Power

Meters at 10, 50, and 100 MHz

61121S Calibration Factor, Effective Efficiency, Efficiency Factor and Reflection Coefficient of Coaxial Power

Meters at 100, 500, and 1000 MHz

61122S Calibration Factor, Effective Efficiency, Efficiency Factor and Reflection Coefflcient of Coaxial Power

Meters at 10, 50, 100, 500, and 1000 MHz

61123S Effective Efficiency, Efficiency Factor and

Reflection Coefficient of Coaxial Power Meters at 50-MHz Intervals Within 1-2 GHz

61124S Effective Efficiency, Efficiency Factor and

Reflection Coefficient of Coaxial Power Meters at 100-MHz Intervals Within 2-4 GHz

61125S Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Coaxial Power Meters at 200-MHz Intervals Within 4-8 GHz

61126S Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Coaxial Power Meters at 200-MHz Intervals in the Range 8-12.4 GHz

61127S Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Coaxial Power Meters at 250-MHz Intervals in the Range 12.4-18 GHz

Test No. Items 61128S Effective Efficiency, Efficency Factor, and

Reflection Coefficient of Coaxial Power Meters at 1-GHz Intervals in the Range 1-18 GHz

611 BOS Effective Efficiency and Reflection Coefficient for Rectangular-Waveguide Power Meters at a Specified

Frequency Within WR28 or WR42

61131S Each Additional Frequency for 61130S

61140S Effective Efficiency, Efficiency Factor and

Reflection Coefficient of Rectangular-Waveguide

Power Meters at 6 Frequencies (2.6, 2.85, 3.0, 3.25, 3.55, and 3.95 GHz) Within 2.6-4 GHz (WR284)

61141S Effective Efficiency, Efficiency Factor and

Reflection Coefficient of Rectangular-Waveguide

Power Meters at 100-MHz Intervals Within 4.0-5.8 GHz (WR187)

61142S Effective Efficiency, Efficiency Factor and

Reflection Coefficient of Rectangular-Waveguide

Power Meters at 100-MHz Intervals Within 5.8-8.0 GHz (WR137)

61143S Effective Efficiency, Efficiency Factor and

Reflection Coefficient of Rectangular-Waveguide

Power Meters at 200-MHz Intervals Within 7.0-10.0 GHz (WR112)

61144S Effective Efficiency, Efficiency Factor and

Reflection Coefficient of Rectangular-Waveguide

Power Meters at 200-MHz Intervals Within 8.2-12.4 GHz (WR90)

61145S Effective Efficiency, Efficiency Factor and

Reflection Coefficient of Rectangular-Waveguide

Power Meters at 250-MHz Intervals Within 10.0-15.0 GHz (WR75)

61146S Effective Efficiency, Efficiency Factor and

Reflection Coefficient of Rectangular-Waveguide

Power Meters at 250-MHz Intervals Within 12.4-18.0 GHz (WR62)

61147S Effective Efficiency, Efficiency Factor and

Reflection Coefficient of Rectangular-Waveguide

Power Meters at a Specified Frequency Within

18-26.5 GHz (WR42)

61148S Effective Efficiency, Efficiency Factor and

Reflection Coefficient of Rectangular-Waveguide

Power Meters at a Specified Frequency Within

26.5-40 GHz (WR28)

611 SOS Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Rectangular-Waveguide

Power Meters at a Specified Frequency Within 50-70

GHz (WR15)

61155S Effective Efficiency, Efficiency Factor and

Reflection Coefficient of Rectangular-Waveguide

Power Meters of Specified Frequency Within 94-96

GHz (WRIO)

611 60S Measurement of Output of Power Reference in TE

Power Meters

61 190S Special Microwave and RF Power Measurement

Services by Prearrangement

139
61110S-61190S

Power Meters, RF and Microwave

(61110S-61190S)

The principal emphasis is on those

caUbrations and other tests requiring

such accuracy as can be obtained

only by direct comparison with NBS

standards. However, in order to maintain efficient utilization of specialized equipment and skilled personnel, when workload permits NBS

may calibrate devices requiring lesser accuracy but suitable for working

standards in a plant or laboratory.

Also, upon request, special measurements may be made. Inquiries

should describe clearly the measurement desired and indicate the sci- entific or economic basis for the re- quirement.

Thermistor-type bolometer units

have shown adequate stability over

long periods of time (approximately

10 yr.) and warrant long recalibration

intervals. Two- or three-year re- calibration intervals are recommended once the stability of a bolometer

unit has been verified. Thermoelectric

power-meter sensor units are cali- barated at a nominal level of 10 mW.

No linearity checks are performed.

Assistance is available for applying

published, technically valid measurement techniques in lieu of pre- viously available NBS calibration ser- vices for coaxial and waveguide

calorimeters, power meters, and bolometer coupler units. The attainable

limits of measurement uncertainty us- ing these techniques are comparable

to those of the previously available

calibration services for these devices.

The calibration reports give the

amplitude of the reflection coefficient

and either the effective efficiency, ef- ficiency factor, or the calibration fac- tor depending on the type of sensor and frequency range.

Definitions:

Calibration results are reported in the

following units: Effective Efficiency Tje The effective efficiency rje is the

ratio of the bolometrically substi- tuted dc power in the bolometer

unit to the net cw rf microwave

power absorbed by the bolometer unit. Bolometrically Substituted dc

Power

The bolometrically substituted dc

power is the change in dc (or au- dio frequency) bias power re- quired to maintain the resistance

of the bolometer element at a constant value following the application of rf or microwave

power.

Calibration Factor, Kb

The calibration factor is the ratio of the bolometrically substituted

dc power in the bolometer unit to the cw rf microwave power

incident upon the bolometer unit. KB =T,e(l-|r|^).

Efficiency Factor

TE sensor-power meter units: Efficiency factor (mWA'^) is the ratio of the net rf microwave

power absorbed by the sensor head to the dc voltage at the

recorder output of the meter on

the 10 mW range. Reflection Coefficient Amplitude,

|r|

The reflection coefficient amplitude is the ratio of the reflected wave voltage amplitude to the

incident wave voltage amplitude.

The reflection coefficient amplitude is included in the Report of

Calibration for all power measurements. All calibrations are performed under typical ambient

laboratory conditions at 23 °C,

and an atmospheric pressure of

approximately 8.4±0.2xlO'* Pa at Boulder, Colorado. Services at ambient conditions other than

these are not provided. Also, the

power applied to any device being calibrated does not exceed 10 mW.

Coaxial Power Meters and

Sensors (61110S-61127S)

Only bolometer units designed

for low frequency operation wUl

be calibrated below 100 MHz.

Most TE sensor units can be cali- brated below 100 MHz.

140
61110S-61190S

the unit being calibrated such as connector type, reflection coefficient, and

repeatability.

Waveguide Power Meters and Sensors

(61130S-61155S)

Measurements of effective efficiency,

efficiency factor and reflection coeffi- cient are made for various waveguide

sizes as follows:

Specify frequency in range 0.

1

to 10 MHz for special low fre- quency bolometer units (Test No.

61 1 lis). Values for rje and | T

|

are calculated from voltage and

resistance measurements.

i7e=(Pdc)/(Prf), where

Prf=V^/Rp, where Rp is the parallel equivalent resistance and Pdc

is the bolometrically substituted

dc power in the bolometer. The

uncertainty in measuring rje is ±0.3 percent.

Measurements are made at the

following frequencies:

Range Frequency or Interval

10-100 MHz

100-1000 MHz

1-2 GHz

2-4 GHz

4-8 GHz

8-12.4 GHz

12.4-18 GHz

10, 50, & 100 MHz

100, 500, & 1000 MHz

50 MHz intervals 100 MHz intervals 200 MHz intervals 200 MHz intervals 250 MHz intervals

Frequency

Wave- Range

guide (GHz)

WR284 2.6-4.0

WR187 4.0-5.8 WR137 5.8-8.0 WR112 7.0-10.0 WR90 8.2-12.4 WR75 10.0-15.0 WR62 12.4-18.0 WR42 18-26 WR28 26.5-40 WR22 33-50

WR19 40-60

WR15 50-70

WRIO 94-96

Measurement

Frequency or

Intervsd

6 frequencies: 2.6, 2.85, 3.0, 3.25,

3.55, 3.95 GHz

100 MHz intervals 100 MHz intervals 200 MHz intervals 200 MHz intervals 250 MHz intervals 250 MHz intervals Specify frequency

Specify frequency

Not Available

Not Available

Specify frequency

Specify frequency

Measurement of the output power

from the reference port on TE power

meters can also be made.

The estimated limits of uncertainty

in effective efficiency and calibration

factor will vary from approximately

±0.5 to 1.5 percent depending on the

frequency and the characteristics of

Effective efficiency is measured for bolometer units only. Efficiency fac- tor is measured for TE sensor-power

meter units only. The estimated limits

141
of uncertainty in effective efficiency

will vary from 1 to 3 percent depending on the frequency and the

characteristics of the unit being cali- brated.

References—Power Meters, RF and

Microwave

A Refined X-Band Microwave Microcalorimeter, G. Engen, J. Res., Natl. Bur. Stand. (U.S.), 63C, 77

(1959).

WR-15 Microwave Calorimeter and

Bolometer Unit, M. Harvey, Natl. Bur. Stand. (U.S.), Tech. Note 618

(May 1972).

WR-10 Millimeter Wave Microcalorimeter, M. Weidman, and P. Hudson, Natl. Bur. Stand. (U.S.),

Tech. Note 1044 (June 1981).

A Bolometer Mount Efficiency Measurement Technique, G. Engen, J. Res. Natl. Bur. Stand. (U.S.), 65C,

113 (Apr.-June 1961).

A Transfer Instrument for the Inter- comparison of Microwave Power

Meters, G. Engen, IRE Trans. In- strum. Meas. 19, 202 (Sept. 1960).

A Semiautomated Six-Port for Measuring Millimeter-Wave Power and

Complex Reflection Coefficient, M.

Weidman, IEEE Trans. Micro. Theory Tech. MTT-25, 12 (Dec. 1977).

Performance Characteristics of an Automated Broad-Band Bolometer

Unit Calibration System, E. Komarek,

IEEE Trans. Micro. Theory Tech.

MTT-25, 12 (Dec. 1977).

Application of an Arbitrary Six-Port

Junction to Power Measurement

Problems, G. Engen, and C. Hoer,

IEEE Trans. Instrum. Meas. IM-21,

470 (Nov. 1972).

Accurate Microwave High Power

Measurements Using a Cascaded

Coupler Method, K. E. Bramall, J.

Res. Natl. Bur. Stand. (U.S.), 75C,

Nos. 3 and 4, 185 (July-Dec. 1971).

Bolometric Microwave Power Calibration Techniques at the National

Bureau of Standards, R. F. Desch,

and R. E. Larson, IEEE Trans. In- strum. Meas. IM-12, 1 (June 1963).

A Method of Determining the Mismatch Correction in Microwave

Power Measurements, G. Engen,

IEEE Trans. Instrum. Meas. IM-17, 4

(December 1968).

Theory of UHF and Microwave

Measurements Using the Power

Equation Concept, G. Engen, Natl. Bur. Stand. (U.S.), Tech. Note 637

(AprU 1973).

Microcalorimeter reference for microwave-power

measurement.

142
aMicrowave Measurements

G,2 Attenuators, RF and Microwave

Electromagnetic Fields Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

LeonF.

Saulsbery

Tel: 303/497-3970

Cletus A. Hoer

Tel: 303/497-3705 Edna M. Jones

Administration and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Bureau of Standards, 325 Broadway, Boulder, CO 80303

Test No. Items 61210C Coaxial Fixed and Variable Attenuators Measured by

ANA, Frequency Range 0. 1 to 18 GHz, Attenuation

0 to 60 dB

61211C Coaxial Fixed and Variable Attenuators, Measured at 30 MHz, Attenuation 0 to 120 dB

61215C Waveguide Circular (Below Cutoff) (Piston)

Attenuator, Coaxial Connector, Measured at 30 MHz,

Attentuation 0-140 dB (Total Insertion Loss)

61220S Special Attenuation Measurements in Range 30 kHz

to 10 MHz, GR 874 Connectors, 0-10 dB

61230C Variable Rectangular Waveguide Attenuators, Attenuation Difference, Specify Frequencies for Waveguide Sizes, WR28, WR42, WR62, WR90,

WR137, WR187, WR284, 0-50 dB

61240S Special Attenuation Measurements of Three-Port and

Two-Port Devices at 1.25 MHz, 0-6 dB

61250S Special Attenuation Measurements by

Prearrangement

Attenuators, RF and Microwave

(61210C-61250S)

Specific attenuation measurements

currently available are listed below.

Measurements not listed may possibly

be provided (61250S) if sufficient ad- vance notice is given and resources

permit. The cost of such services

must be negotiated and will, in general, be higher than other established

services. Consultation by telephone or

written correspondence is suggested.

Often a measurement technique can be suggested that will permit the cus- tomer to perform his calibrations in- house with appropriate reference to other NBS supported standards.

Fixed and Variable Coaxial

Attenuators (61210C and 61211Q

Coaxial fixed and variable attenuators are measured on the NBS modified

automatic network analyzer (ANA)

over the frequency range 0. 1 to 18 GHz.

All measurements are made by the

substitution method, which requires

that the connectors used be asexual or

that the attenuator have a male connector at one port and a female at the

other. If an adapter is required to comply with the foregoing, it must be

supplied with the attenuator. The

combination will be calibrated as one

unit. In addition to measurements per- formed on the ANA, measurements at a fixed frequency of 30 MHz are

available referenced to the NBS

waveguide below cutoff standard at

this frequency.

Coaxial attenuators are normally

measured in a system having a characteristic impedance of 50 ohms. Limits of uncertainty depend upon the

VSWR of the individual attenuator,

143
quality of the attenuator and connectors, and the magnitude of the at- tenuation. Typical systematic uncertainties range from 0.03 to 0.05 dB/10

dB of attenuation up to 60 dB.

Waveguide Circular Piston Attenuator Measurements at 30 MHz (61215C)

Incremental attenuation is the change

in attenuation of an adjustable attenu- ator between a reference setting (usually zero) and any other setting. The

same restraints on system conditions

apply as for attenuation. The term

"differential attenuation" is sometimes

applied to this case and usually refers to two non-zero settings.

Measurements on waveguidebelow-cutoff (piston) attenuators are performed at 30 MHz. These attenuators are normally quite stable and

seldom need recalibration unless damaged or mechanically worn. Since

any laboratory can perform independent checks to determine continuing

repeatability and linearity of attenuation, we do not recommend periodic

NBS recalibrations. This recommendation is also made because more

damage can be suffered in transit than

in daily use. In any measurement, the

maximum power delivered to the test attenuator will not exceed 400 mW. If the attenuator cannot tolerate this power level, some reduction of measurement range will be required.

Piston attenuators are normally cal- ibrated in a system having a characteristic impedance of 50 ohms. Since

only measurements of incremental at- tenuation are made on this type of at- tenuator. Type BNC, C, TNC, and

similar connectors are acceptable, but

precision connectors are preferred to reduce leakage. Limits of uncertainty

depend upon the quality of the atten- uator and connectors, as well as upon

the VSWR of the attenuator, and the

magnitude of attenuation. Typical sys- tematic uncertainties range from 0.()03 to 0.005 dB/10 dB of attenuation. Total insertion loss must be less than 140

dB.

Special Attenuation Measurements

below 10 MHz (61220S)

Special tests may be performed over

the frequency range 30 kHz to 10

MHz using the voltage ratio measurement technique. These tests are

limited to attenuators with GR 874

connectors and to 10 dB maximum.

Rectangular Waveguide Variable Attenuators (61230Q

Variable waveguide (usually rotary

vane) attenuators are calibrated by

the IF- substitution technique refer- enced to 30 MHz, direct rf substi- tution, or on the NBS modified ANA,

as appropriate. Service is available for frequencies corresponding to waveguide sizes WR28, WR42, WR62,

WR90, WR137, WR187, and WR284.

Requested measurements should be

for a minimum number of settings at a

single band-center frequency and be

sufficient to determine the characteristics of the device. Previously cali- brated units should not be re- submitted unless tests performed by

the user indicate a shift in values. The uncertainty is a function of resettability, internal leakage, and quality of flanges. Except for measurements made on the NBS modified

ANA, the uncertainty is also a function of the VSWR of the waveguide

ports. Devices submitted should be in the best possible condition to justify

calibration and insure long-term sta- bility of measured values. Typical sys- tematic uncertainties range from 0.03

to 0.05 dB/10 dB of attenuation up to 50 dB.

Special Attenuation Measurements at 1.25 MHz (61240S)

A provisional service is now available

for attenuation measurements of special three-port devices at 1.25 MHz.

144
A measurement system has been developed to measure the change in the

ratio I S21/S31 1 of special stable twoposition three- port devices, sometimes called voltage doublers, at 1.25 MHz. The device must have an input

for a 1.25 MHz source (port 1), a ref- erence output (port 3), and an output

(port 2) with a level switchable to two different values. The two levels of the bi-level output have a nominal

ratio of 6.0206 dB.

If Pri is the reference power level when the bi-level output is at level 1 (Pbi), and Pr2 is the reference power

level when the bi-level output is at level 2 (Pba), then parameter measured

is given by the following equation:

10Log,o(|j|)-10Log,o(^)dB

^Pr2

where the subscripts (1), and (2) refer to the switch positions 1 and 2, re- spectively. The above is equivalent to

10 log,

S2.(l)/S3l(l)

S2,(2)/S3,(2)

The loads presented to the two out- puts are 50 ohms. The device must al- low the signal input to be of such

strength that the bi-level output is at least 10 mW in the high level position. The total uncertainty of the measurement system in measuring a 6 dB

change in attenuation is estimated to have a systematic error no greater

than 5 juB, and random error of about

3 fiB, where 1 fiB = 10"' dB or about 2.3 ppm of the power ratio. Two-port step attenuators having a nominal change in attenuation of 6 dB

can also be measured by this system

at 1.25 MHz.

References—Attenuators, RF and

Microwave

Application of Waveguide and Circuit Theory to the Development of

Accurate Microwave Measurement

Methods and Standards, R. W.

Beatty, Natl. Bur. Stand. (U.S.),

Monogr. 137 (Aug. 1973).

Basic Theory of Waveguide Junctions

and Introductory Microwave Net- work Analysis, D. M. Kearns and R. W. Beatty, Intl. Ser. of Mongr. in Electromag. Waves, 13, 59, Per- gammon Press, New York, NY

(1967).

The Six-Port Reflectometer: An Alternative Network Analyzer, G. F. Engen, IEEE Trans. Micr. Theory

Tech., MTT-25, 1075 (Dec. 1977).

A Network Analyzer Incorporating

Two Six-Port Reflectometers, C. A.

Hoer, IEEE Trans. Micr. Theory

Tech., MTT-25, 1070 (Dec. 1977).

"Thru-Reflect-Line": An Improved

Technique for Calibrating the Dual

Six-Port Automatic Network Analyzer, G. F. Engen and C. A. Hoer,

IEEE Trans. Micr. Theory Tech.,

MTT-27, 987 (Dec. 1979).

Effects of Connectors and Adapters on Accurate Attenuation Measurements at Microwave Frequencies, R. W. Beatty, IEEE Trans. Instrum.,

IM-13, 272 (Dec. 1984).

Insertion Loss Concepts, R. W.

Beatty, Proc. IEEE 55, 6, 663 (June

1964).

RF Attenuation, D. Russell, Proc. IEEE 55, 6, 942 (June 1967).

Specifications and Test Methods for Fixed and Variable Attenuators, dc to 40 GHz IEEE Standard 474 (1973).

145
61310C-61331S

Microwave Measurements

G.3 Coaxial and Waveguide Terminations,

Reflection Coefficients

Electromagnetic Fields Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

Leon F. Cletus A. Hoer Edna M. Jones

Saulsbery Tel: 303/497-3705 Administrative

Tel: 303/497-3970 and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723. 10, National Bureau of Standards, 325 Broadway, Boulder, CO 80303

Test No. Items

61 3 IOC Complex Reflection Coefficient, Impedance, and

Voltage Standing Wave Ratio of Coaxial

Terminations by ANA Within 0.1 to 18 GHz, T: 0.01 to 0.6, Z: 12.5—200a

61320C Magnitude of Reflection Coeflicient of Rectangular

Waveguide Reflectors (Mismatches) with Standard

Flange Connectors, Specify Frequency for Waveguide Sizes WR28, WR42, WR62, WR90,

WR137, WR187, and WR284, T: 0.025 to 0.2 6 1 330C Magnitude of Reflection Coefficient of Nonreflecting

Waveguide Ports and Matched Loads, Specify

Frequency for Waveguide Sizes WR42, WR62,

WR90, WR137, WR187, T: 0.0001 to 0.025 61331S Same as 61330C; Special Services for WR15, WR28,

WR284 Only on Critical Need Basis

Coaxial and Waveguide Terminations,

Reflection Coefficient

(61310C-61331S)

Services provided in this category are

for passive devices over the fre- quency range from 10 MHz to 95

GHz. Available calibration fre- quencies are listed in the test descriptions. Highest accuracy is obtained

only for standards equipped with precision coaxial connectors or waveguide flanges. Standards submitted for calibration should be in good repair

and, except for very minor cleaning

of connector surfaces, should require no recalibration maintenance. NBS

does not provide repair services. Items received requiring maintenance

will be returned to the sender and a handling fee will be charged.

Coaxial Terminations (61310Q

Services are available for complex impedance, reflection coefficient, and

voltage standing wave ratio (VSWR).

Measurements on coaxial devices in the frequency range 0.1 to 18 GHz

are made on the NBS modified Automatic Network Analyzer (ANA) for r in the range 0.01 to 0.6 and Z in the range 12.5 to 200 ohms. The cali- bration services usually apply to determining the reflection coefficient or VSWR of standard terminations and

mismatches. Typical uncertainties are ± 0.005 to 0.01 in reflection coefficient. Waveguide Terminations

(61320C-61331S)

Waveguide terminations are measured

in a reflectometer system relative to a

146
61310C-61331S

quarter-guide wavelength short cir- cuit and a precision transmission Une. Some measurements in waveguide

bands below 18 GHz can be per- formed on the NBS modified ANA

while all of those above 18 GHz are performed on manual fixed- fre- quency systems. (See test descriptions

above.) Typical uncertainties are ±(0.001 +0.0035r).

Waveguide terminations are usually

quite stable and need not be re- submitted unless tests performed by

the user indicate a shift in values. The

terminations must be fitted with stan- dard waveguide flange connectors. The faces of these flanges should be

machined flat and smooth and should

not contain protrusions or indentations. Considerable care must be ex- ercised in keeping the mating connector flange surfaces smooth and

clean. Accurate alignment of the inte- rior surfaces of the joining waveguides at the flange junction also is very important. The back of the

flange which makes contact with the

connecting bolts should be nominally

flat and free of soft materials including paint. The connecting holes of the

flange should be symmetrically and

accurately aligned to the rectangular

waveguide opening. These pre- cautions must be observed when us- ing a waveguide termination in a precision measurement system.

Assigned limits of uncertainty depend upon the quality of the flanges

as well as the numerical value of re- flection coefficient magnitude. Systematic errors assigned by NBS vary

with waveguide size and depend on

the absolute dimensions of the precision transmission lines.

References—Coaxial and Waveguide

Terminations, Reflection Coefficients

An NBS-Developed Automatic Net- work Analyzer, W. Little, et al.

,

Conf. on Prec. Electromag. Meas.,

Boulder, CO., Digest, 130 (June

1976).

A Guide to the Use of the Modified

Reflectometer Technique of VSWR

Measurement, W. J. Anson, J. Res.

Natl. Bur. Stand. (U.S.), 65C, 4, 217

(Oct.-Dec. 1961). (The measurement

technique utilized in reflection measurements is described in this paper.)

Millimeter Attenuation and Reflection Coefficient Measurement System,

B. C. Yates and W. Larson, Natl. Bur. Stand. (U.S.), Tech. Note 619

(1972).

147
61410C-61450S

G. Microwaye Measurements

G.4 Phase Shifters, RF and Microwaye

Electromagnetic Fields Diyision

Center for Electronics and Electrical

Engineering

Technical Contacts:

Leon F. Saulsbery

Tel: 303/497-3970

Qehis A. Hoer

Tel: 303/497-3705 Edna M. Jones

Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723. 10, National Bureau of Standards, 325 Broadway, Boulder, CO 80303

Test No. Items

6 14 IOC Coaxial Fixed and Variable Phase Shifters; Characteristic Phase Shift Difference; Precision Connectors; Measured at 30 MHz, Range 0-360 °

6141 IC Coaxial Fixed and Variable Phase Shifters; Characteristic Phase Shift Difference;

Precision Connectors; Measurement by ANA over

1-18 GHz, Range 0-360° 61420C Variable Rectangular Waveguide Phase Shifters; Phase Shift Difference; VSWR < 1.4; Specify

Frequencies for Waveguide Sizes WR62, WR90,

WR137, WR187, WR284, Range 0-720° 61450S Special Tests of Phase Shifters by Prearrangement

Phase Shifters, RF and Microwave

(61410C-61450S)

The specific phase shift services listed below are available on a limited basis

depending on other demands and staff

availability. Measurements not listed may possibly be provided if sufficient advance notice is given. The cost of

such services must be negotiated and

will, in general, be higher than the es- tablished phase shift services. Consultation by telephone or written corre- spondence is suggested. Often a measurement technique can be sug- gested that will permit the customer

to perform calibrations in-house with

appropriate reference to other NBSsupported standards.

Coaxial Phase Shifters (61410C and

61411Q

Fixed and variable coaxial two-ports

are measured on the NBS modified

Automatic Network Analyzer (ANA)

over the frequency range 0.1 to 18 GHz. In addition, measurements can be performed with reference to a precision variable air line at 30 MHz. Because of the specialized nature of

coaxial phase shifting components,

prior discussions should be held with

NBS staff before submission of any

devices to NBS. Items to be cali- brated must be fitted with connectors

having a known plane of reference

such as sexless precision connectors, or Type N connectors meeting Mil.

Std. C39012. The phase angle measured is ^'-|-360n where n is an in- teger. The value of n is not deter- mined.

Limits of uncertainty are: Frequency Range Uncertainty 30 MHz

0.1-18 GHz

360°

-360° 0.1-0.5°

0.5°

These limits of uncertainty are the sums of systematic and random er1

148
61410C-61450S

rors. The values are dependent upon

the particular standard under cali- bration. The VSWR of the device

and the quality of the connectors will contribute to the calibration uncertainties. Phase Shifters (61420C)

For a rectangular waveguide, the

measurement services are limited to phase shift difference at frequencies

below 18 GHz. Measurements are made on continuously variable waveguide phase shifters with the zero

value of the scale as the normal refer- ence position. Since 360 mechanical

degrees of rotation represent 720 electrical degrees, attention should be

given to the relationship between dial indication and actual mechanical position of the rotating vane assembly.

The uncertainty is approximately

the same as for coaxial devices.

References—Phase Shifters, RF and

Microwave

UHF and Microwave Phase Shift

Measurements, D. A. Ellerbach, Proc. IEEE 55, 6, 960 (June 1967).

New generation of reference

microwave measurements: NBS

duai six-port automatic networl<

analyzer covering frequency range

of 100 kHz-1 GHz. Two sets of

six ports—one on des/f at left and

one on console at right—are needed to cover this frequency

range.

149
61520S

Microwave Measurements

G.5 N-Port Scattering Measurements

Electromagnetic Fields Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

Leon F. Oetus A. Hoer Edna M. Jones

Saulsbery Tel: 303/497-3705 Administrative

Tel: 303/497-3970 and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Bureau of Standards, 325 Broadway, Boulder, CO 80303

Test No. Items 61520S Linear, Reciprocal 2-Port Devices, 2-18 GHz

Scattering Parameters of Linear

N-Port Devices—General

Information

The signal levels at the ports of a lin- ear network having N-ports is dependent on the impedances or loads

presented to each of the N-ports. For

example, the power at a load con- nected to a source of given level through an attenuator is not only dependent on the properties of the at- tenuator but on the generator and

load impedances as well. In this ex- ample, insertion loss, as defined by

the IEEE Dictionary of Electrical

and Electronics Terms, is the ratio of

the power in the load before insertion

of the attenuator to that after in- sertion. Insertion loss, as given in this general definition, is a very poor measure of the property of the attenuator

as it is generator and load dependent.

To alleviate this problem, the parameters of the N-port network are measured when the ports are presented

with reflectionless terminations. With

such terminations, the network is said to be measured under matched conditions. A particularly useful description of

N-port networks at higher frequencies

where reflections are of importance in systems is the scattering of S- parameter description. It is couched

150
in terms of the incident and reflected waves at each of the N-ports. The S- parameters have magnitude and phase

and are defined as: g

emergent wave at port i

'J "~ incident wave at port j for i. j = 1, 2 ... N, where all ports

other than the input port j are terminated with non-reflecting (matched)

terminations. Thus, for a two-port at- tenuator, I S21 1 Ms the insertion loss and the argument of S21 is the in- sertion phase shift from port 1 to port

2 under matched conditions. Sn and

S22 are the respective reflection coefficients at ports 1 and 2; again, under

matched conditions.

For a one-port, there is only a sin- gle S-parameter, Sn, where S,i is the

reflection coefficient, F. The S-parameter fully describes the

network (as a black box) since, given

the S- parameters, one can completely

determine the relative signal re- lationships at the ports for any set of

terminations presented to the ports be

they matched or not. Linear, Reciprocal 2-Port Devices

(61520S)

Presently, routine calibrations are provided only for linear, reciprocal, one- port and two-port networks and

then only over limited frequency

(2-18 GHz) and parameter ranges. NBS plans to greatly extend the cov- erage in the near future by providing

all S-parameter measurements at most

frequencies from 100 kHz to 100

GHz, and for |S|2| up to approximately 60 dB using 6-port ANA's.

References—Scattering Parameters of

Linear N-Port Devices

The Six-Port Reflectometer: An Alternative Network Analyzer, G. F. Engen, IEEE Trans. Micr. Theory

Tech., MTT-25, 1075 (Dec. 1977).

A Network Analyzer Incorporating

Two Six-Port Reflectometers, C. A.

Hoer, IEEE Trans. Micr. Theory

Tech., MTT-25, 1070 (Dec. 1977).

"Thru-Reflect-Line": An Improved

Technique for Calibrating the Dual

Six-Port Automatic Network Analyzer, G. F. Engen, and C. A. Hoer,

IEEE Trans. Micr. Theory Tech.,

MTT-27, 987 (Dec. 1979).

151
62020S-62140S

LJ Noise Temperature Measurements nm Electromagnetic Fields Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

Sunchana Perera William C. Edna M. Jones

Tel: 303/497-3546 Daywitt Administrative

Tel: 303/497-3720 and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Bureau of Standards, 325 Broadway, Boulder, CO 80303

Test No. Items 62020S Special Noise Temperature Measurements

(Electromagnetic) by Prearrangement

62100S Noise Temperature of Coaxial Noise Generator, Type

N Precision or 14 mm Connectors, at 30 MHz or 60 MHz; VSWR <1.2, Temperature: 77 K-15,000 K,

ENR <17 dB

62101S Each Additional 62100S Item Tested at Same

Frequency

621 ICS Noise Temperature of Coaxial Noise

Generator, Type N Precision, 14 mm, APC 7 or APC

3.5 Connector; Continuous Frequencies 2.0-4.0 GHz,

Reflection Coefficient <0. 1, Temperature:

77 K-15,000 K, ENR < 17 dB

621 1 IS Each Additional 621 1 OS Item Tested at Same

Frequency

62120S Noise Temperature of Rectangular

Waveguide Noise Sources at Specific Frequencies in WR62 (12.4, 13.5, 14.0, 15.0, 16.0, 16.5, 17.0, 18.0 GHz) and WR90 (8.2, 9.0, 9.5, 9.8, 10.0, 10.5, 11.2,

11.8, 12.4 GHz); Reflection Coefficient <0.09,

Temperature: 9,000 K-13,000 K, ENR <16.5 dB

62 12 IS Each Additional 62120S Item Tested at Same

Frequency

62130S Noise Temperature of WRIO (77 K-15,000 K) and

WR15 (700 K-15,000 K) Waveguide Noise

Generators at Specific Frequencies

62140S Special Services for Earth Terminals Used in Satellite Communications

Noise Temperature Measurements

Electromagnetic (62020S)

Special test services for the measurement of electromagnetic noise are offered in limited frequency coverage

from 30 MHz to 94 GHz and include

measurements through adaptors and

out-of-range noise temperatures. The

type of service offered is determined

by the frequency. In some frequency

regions, only spot frequency measurements are available. However, some gaps in the frequency coverage

exist. Depending on the frequency

coverage available, noise sources submitted for measurement will be compared, via one of three different types

of radiometers, against a hot or cold

primary reference standard or a transfer standard. Since there are limitations which are a function of the

noise standards and radiometer available, the customer should check with

the technical contact listed at the beginning of this section before submitting a device for measurement.

Noise Sources and Generators

(62100S-62130S)

Noise temperature measurements are

available on single-port, coaxial, and

rectangular waveguide noise sources under conditions of continuous, un- modulated operation. Precision coaxial connectors or clean, smooth, and

flat standard EIA waveguide flanges are required. Complete operating in- structions and special electronic connectors should be supplied, and perti- nent operating conditions (voltages,

circuits, etc.) specified for the noise source to be measured. Devices submitted that are not of sufficient quality or not mechanically compatible

with the measuring system will be re- jected and an appropriate fee charged. Availability of measure- ments at specific frequencies and for various connector types are specified

above. Generally, an attempt is being

made to expand services to include more types of precision connectors

and waveguide sizes. However, the cost of measurements requiring the

152
use of adaptors as part of the measurement process can be substantially

greater than the cost of measurements on sources with connectors mating di- rectly to the measurement system.

Furthermore, measurement results on

devices submitted with adaptors at- tached may apply only to the source/

adaptor combination.

The limits of uncertainty vary with

noise temperature, reflection coefficient, and source and connector stability, but typically lie between 1%

and 3% of the noise temperature.

Earth Terminals for Satellite Communications (62140S)

Measurement and consultation ser- vices are available on a limited and

special basis for characterizing the

noise properties of earth terminals.

Quantities such as G/T (gain to sys- tem noise temperature ratio) and sys- tem noise temperature are available. Special arrangements need to be

made for these services.

References—Noise Temperature

Measurements

Noise Standards, Measurements, and

Receiver Noise Definitions, C. K. S. Miller, W. C. Daywitt, and M. G.

Arthur, IEEE Proc. 55, 6, 865 (June

1967). (This reference describes noise

standards, basic principles of noise

measurements, and concepts of noise

factor and noise temperature.)

Measurement of Effective Temperature in Microwave Noise

Sources, J. S. Wells, W. C. Daywitt,

and C. K. S. Miller, IEEE Trans. lu- strum. Meas., IM-13, 1, 17 (Mar.

1964). (This reference describes the

method of measurement and error

analysis).

A Coaxial Noise Standard for the

1 GHz to 12.4 GHz Frequency

Range, W. C. Daywitt, NBS Tech.

Note 1074 (Mar. 1984).

The NBS WR62 and WR90 Refer- ence Noise Standards, C. K. S. Miller

and W. C. Daywitt, NBSIR 84-3005

(May 1984).

The NBS Switching Radiometers,

C. J. S. Miller and W. C. Daywitt,

NBSIR 84-3004 (May 1984).

WR15 Thermal Noise Standard,

W. C. Daywitt, W. J. Foote, and

E. Campbell, NBS Tech. Note 615

(Mar. 1972).

Design and Error Analysis for the

WRIO Thermal Noise Standard,

W. C. Daywitt, NBS Tech. Note

1071 (Dec. 1983).

A Derivation for the Noise Temperature of Horn-Type Noise Standards, W. C. Daywitt, Metrologia 21,

127 (Sept. 1985).

Precision Measurement of Antenna

System Noise Using Radio Stars, D.

F. Wait, IEEE Trans. Instrum. Meas.,

IM-32, 1 (Mar. 1983).

153
63100S-63400S

/Electromagnetic Field Strength and Antenna

f Measurements

/. / Microwave Antenna Parameter

Measurements

Electromagnetic Fields Division

Center for Electronics and Electrical

Engineering

Tedinical Contacts:

Allen C. Newell Carl F. .\ndrew G. Repjar Edna M. Jones

(631CN3S-63400S1 Snibenrauch l632O0Sl AdmimstratiTe

Tel: 303 49''-3"43 (63100S1 Tel:303 49'-5'a3 and Logistics

Tel: 303 49-'-39:^ TeJ: 3J3 49--3^53 Mailing Address: M.C. 723.10. National Bureau of Standards. 325 Broadway. Boulder. CO S0303

Shipping Address: Room 1300. Bldg. 24, National Bureau

of Standards. 325 Broadway. Boulder. CO 80303

Test No. Items

C)3100S Gain and Polarization Calibrations of Standard Antennas Using Extrapolation Range

6320OS Measurement of Pattern. Gain and Polarization of

Arbitrary .Antennas Using Near-Field Scanning

Techniques

63300S Special Test Serxices for Calibration of Probes Used

with Near-Field Scaiming Facilities 634O0S Special Consulting. Ad%-isory. and Other Services

Antenna Parameter

Measurements

(Microwave)—General

Information

Accurate measurements of antenna

gain, pattern, and polarization are generally ax ailable from about 750

MHz to about "5 GHz. Howe\"er. be- cause the measirrement accuracy, capability, and cost depend on the fre- quency, type and size of antenna, and

the parameters to be measured, a particular measurement service must be

negotiated in advance. Antennas sub- mitted for evaluation should be mechanically and electrically stable in order to retain a calibration for a sig- nificant length of time. Antennas with

either coaxial or waveguide connectors can be measured: however, if coaxial connectors are employed,

they should be precision connectors

to minimize uncertainties due to a lack of connector repeatability. In

particular, the use of SMA connectors is strongly discouraged be- cause of poor coimector repeatability.

The following methods and facilities are used for these measurements.

Gain and Polarization Calibrations

of Standard Antennas Using

Extrapolation Range (63200S)

This calibration ser\ice is otTered primarily for determining the absolute

on-axis gain and polarization of stan- dard gain horns which, in turn, are used as reference standards in deter- mining the gain and polarization of

other antennas by the gain comparison technique. In the extrapolation method, three anteimas are nor- mally utilized and three pairv\ise

combinations are defined. The re- ceived signal transmitted between

each pair of antennas is measured as a function of the separation distance be- tween the antennas. The antennas need not be identical, and no assumptions concerning the polarization are

required. The method is not well

suited for panem measurements, but

is the most accurate technique known

for absolute gain and polarization

measurements. Above 1 GHz. the ac- curacies are t>'pically zbO. 10 dB for gain measurements, and ±0.05 dB/dB

for polarization axial ratio measurements. There are antenna size limitations associated with existing

154
63IOf)S-634(X)S

NBS extrapolation ranges. These limitations depend on the type of antenna, the frequency, and the desired

measurements and accuracies. Therefore, negotiations must be conducted

prior to submitting antennas for cali- bration to ascertain whether all re- quirements can be met. Measurement of Pattern Gain, and

Polarization of Arbitrary Antennas Using Near-Field Scanning Techniques

(63200S).

With this technique, gain, pattern,

and polarization parameters are calculated from near-field amplitude and

phase measurements taken over a sur- face close to the test antenna. The absolute gain can be determined to within about 0.15 dB, the polarization

axial ratio to within about 0.10 dB/

dB, and side lobe levels can be obtained down to —50 or —60 dB. The

exact uncertainties in these parameters will depend on such factors as the frequency, type and size of antenna. Antennas with apertures up to

about 3.5 meters in diameter can be

managed. Measurements can be made

from about 750 MHz to about 75

GHz. Measurements are most com- monly made over a plane surface in front of the antenna being evaluated,

but the capability also exists for measuring over a cylindrical surface sur- rounding the antenna when it is advantageous to do so. Calibrated

probes are normally required for these measurements. These near-field scanning measurements are offered as a special-test service because nearly

every measurement is unique and it is difficult to build up a statistical his- tory as required for a regular cali- bration service. Special-Test Service for Calibrating

Probes Used with Near-Field Scanning

Facilities (63300S)

This special-test service is available to support those organizations that have

established their own near-field measurement facilities and need to characterize the probes used in per- forming the near-field measurements.

In order to achieve accurate results with either the planar, cylindrical, or

spherical near-field method, the trans- mitting or receiving properties of the

probe must be known. With this in- formation, the measured data can be

corrected for the non-ideal pattern

and polarization properties of the

probe. Probes are characterized by a

NBS Near-Field Scanning Antenna Range. The well- characterized probe rides on a dual-carriage system

covering a plane. The carriage that moves left and right

appears as a large vertical rectangle with a slot in the

long direction (background). The dark-appearing

material absorbs microwave energy and prevents

unwanted reflections. The antenna under test is a

simple conical antenna.

155
three-step process: (1) The on-axis

gain and polarization properties are measured using the extrapolation

technique described above; (2) the

far-field amplitude and phase patterns are measured for two nominally or- thogonal polarizations of the incident

field; and (3) the on-axis and pattern

data are combined to obtain the probe

correction coefficients at the desired

lattice points on the measurement sur- face as specified by the customer. The

final output consists of a computer

tape containing the measured far-field patterns and the calculated probe coefficients. Typical types of probes are open-ended waveguides and small

horns. Both linearly and circularly

polarized probes can be evaluated.

Special Consulting, Advisory, and

Other Services (63400S)

A variety of special consultation and

advisory services related to the measurements described above are avail- able upon request. These services are offered to disseminate NBS technologies and to assist other or- ganizations in establishing their own

measurement facilities and capabilities. Included are cooperative measurement programs. A customer actually participates directly in the

measurement of his device in order to become familiar with the measurement methods and assist in the

analysis of the results. This is a useful approach when one is attempting to

establish a new measurement capability that is related to or based upon

NBS measurement techniques.

References—Microwave Antenna

Parameter Measurements

Accurate Measurement of Antenna

Gain and Polarization at Reduced

Distances by an Extrapolation Technique, A. C. Newell, R. C. Baird, and

P. F. Wacker, IEEE Trans. Antennas

Propagat. AP-21, 4, 418 (July 1973).

Determination of Both Polarization

and Power Gain of Antennas by a Generalized 3-Antenna Measurement

Method, A. C. Newell and D. M.

Kerns, Electronics Letters, 7, 7, 68

(Feb. 1971).

Correction of Near-Field Antenna

Measurements Made With an Arbitrary but Known Measuring Antenna,

D. M. Kerns, Electronics Letters 6, 11, 346 (May 1970).

New Method of Gain Measurement

Using Two Identical Antennas, D. M.

Kerns, Electronics Letters 6, 11, 348

(May 1970).

Plane-Wave Scattering-Matrix Theory of Antennas and AntennaAntenna Interactions: Formulation

and Applications, D. M. Kerns, J. Res. Natl. Bur. Stand. (U.S.), 80B, 1, 5051 (Jan.-Mar. 1976).

Plane-Wave Scattering-Matrix Theory of Antennas and AntennaAntenna Interactions, D. M. Kerns,

Natl. Bur. Stand. (U.S.), Monograph

162 (June 1981).

Upper-Bound Errors in Far-Field Antenna Parameters Determined from

Planar Near- Field Measurements, A.

D. Yaghjian, Natl. Bur. Stand. (U.S.),

Tech. Note 667 (Oct. 1975).

156
J Electromagnetic Field Strength and Antenna

a Measurements

L2 Field Strength Parameter Measurements

Electromagnetic Fields Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

Jose E. Cruz Ezra B. Larsen Motohisa Kanda Edna M. Jones

Tel: 303/497-3763 Tel: 303/497-3540 Tel: 303/497-5320 Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Bureau of Standards, 325 Broadway, Boulder, CO 80303

Test No. Items 64100S Special-Test Service for Antenna/Field Strength

Measurements, Using the Transverse Electromagnetic

(TEM) Cell Method, (10 kHz-300 MHz)

64200S Special-Test Service for Antennas/Field Strength

Measurements, Utilizing the Open-Field Method

64300S Special-Test Service for Antennas/Field Strength

Reflectivity Measurements, Utilizing the Anechoic-Chamber Method

64400S Special-Test Service for Electromagnetic

Interference

Special-Test Service for Antennas/

Field Strength Measurements, Utilizing the Transverse Electromagnetic (TEM)

Cell Method (64100S)

Standard electromagnetic fields are generated in TEM cells and used to calibrate electrically small antennas

and antenna systems used for electro- magnetic field probes in the fre- quency range 10 kHz to 300 MHz.

Special-Test Service for Antennas/

Field Strength Measurements, Utilizing the Open Field Method (64200S)

These measurements include cali- bration of antenna factor and gain of antennas used in conjunction with

field strength meters, and of electrically small antennas used in electro- magnetic field probes. The following

methods and facilities are used for these measurements:

A. Dipoles, log-periodic and

other antennas (25 to 1000 MHz) are used to generate electromagnetic

fields which are used for calibrating

various antennas and electromagnetic

field probes. The field strength is es- tablished using the standard receiving antenna method.

B. Monopoles (30 to 300 MHz)

are used to generate standard electric

fields for calibrating antennas and

electromagnetic field probes. C. Loop antennas (14 kHz to 50

MHz) are used to generate standard

magnetic fields for calibrating loop

antennas used in conjunction with

field strength meters.

Special-Test Service for Antennas/

Field Strength/Reflectivity

Measurements, Utilizing the Anechoic-Chamber Method (64d00S)

A. Open-ended waveguides (200

to 450 MHz) are used to generate

standard electromagnetic fields for

1 57
64100S-64400S

calibrating antennas and electro- magnetic field probes.

B. Pyramidal horns (0.45 to 18 GHz) are used to generate standard

electromagnetic fields for calibrating antennas and electromagnetic field probes, and for measuring reflectivity

of materials.

Table 15 summarizes the field parameters, frequency ranges, and radi- ating antenna sources for the various

NBS field strength measurement

facilities.

Table 15: Summary of NBS Standard Field Strength

Facilities

Type of Radiating

Field Measurement Frequency Antenna

Parameter Facility Range Source H Wood 14 kHz to Loop (20 cm)

building 50 MHz

E (vertical) Open site 30 kHz to Short

(ground screen) 30 MHz Monopole

E (vertical) Open site 30 to Quarter wave

(ground screen) 300 MHz length

monopole

E (horizontal) Open site 25 to Dipole, log- 1000 MHz periodic antenna, etc. Power Density Anechoic 200 to Open-end

chamber 450 MHz waveguide

Power Density Anechoic 0.45 to Pyramidal

chamber 18 GHz horn

Material re- Anechoic 0.45 to Pyramidal

flectivity chamber 18 GHz horn

Special-Test Services for Electromagnetic Interference (64400S)

This service includes evaluating

equipment used for measuring the

electromagnetic environment, per- forming radiated-field susceptibility

(immunity) and emission testing, and

performing conducted interference

testing. In special cases, measurements will be made to evaluate

facilities used to perform electro- magnetic interference tests (susceptibility, emission, or conducted)

and to evaluate localized electro- magnetic environments.

References—Electromagnetic Field

Strength Parameter Measurements

Methodology for Standard Electromagnetic Field Mesurements, N. S. Nahman, M. Kanda, E. B. Larsen,

and M. L. Crawford, IEEE Trans.

Instrum. Meas. IM-34, 4 (Dec. 1985)

A Review of Electromagnetic

Compatibility/Interference Measurement Methodologies, M. T. Ma,

M. Kanda, M. L. Crawford, and E.

B. Larsen, Proc. IEEE, 73, 3, 388

(Mar. 1985).

158
65100S-65400S

J.

Pulse Waveform Measurements

Electromagnetic Fields Division

Center for Electronics and Electrical

Engineering

Technical Contacts:

William L. Gans

Tel: 303/497-3538 Ramon C. BairdTel: 303/497-3301 Edna M. Jones

Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Bureau of Standards, 325 Broadway, Boulder, CO 80303

Test No. Items 65100S Impulse Generator Spectrum Amplitude (50 Ohm)

65200S Fast Repetitive Broadband Pulse Parameters

(50 Ohm)

65300S Network Impulse Response (Frequency Domain

Parameter S21) of Coaxial Networks, 10 MHz to 10.0 GHz, 0 to ± 40 dB

6530 IS Additional 65300S Item Tested at Same

Time as First 65400S Pulse Time Delay Through Coaxial Transmission

Lines

Pulse Waveform

Measurements—General

Information

NBS offers special test services for a number of baseband pulse parameters.

These are broken down into four cat- egories; impulse generator spectrum

amplitude, fast repetitive baseband

pulse parameters, network impulse re- sponse, and pulse time delay. All of

these special test services are per- formed on the NBS Automatic Pulse

Measurement System (APMS) consisting of a sampling oscilloscope inter- faced to a minicomputer. In addition,

all of these special tests are performed

at cost. References pertaining to these

four services are located at the end of

this section. Impulse Generator Spectrum

Amplitude, 50 Ohms (65100S)

In response to calibration needs from

the electromagnetic interference

(EMI) community, NBS has developed a special test service to calibrate

the broadband spectrum amplitude

output from impulse generators. Such

a generator can then be used as a

transfer standard of broadband impulsive noise for field calibration of

spectrum analyzers and field intensity

Electrical Pulse Inputs Oscilloscopes, Etc.

t I

Operator

Minicomputer

System

-^Output

Waveforms

Correl, Funct. Complex Spectra

t \ Optical Pulse Inputs Streak Camera, Etc.

meters. The NBS special test service uses the time domain measurement/

frequency domain deconvolution

computational method for calibration

of impulse generators. A wideband

(dc-18 GHz) sampling oscilloscope is

159
used to measure the time domain

waveform from the impulse generator. A dedicated minicomputer then

computes the spectrum ampUtude,

S(f), versus frequency using the fast Fourier transform (FFT). NBS will provide 50 to 100 data points over a wide frequency range for a single fee. NBS impulse generator spectrum

amplitude measurement service capabilities shown in Table 16.

Table 16: NBS Impulse Generator Spectrum Amplitude

Measurement Service Capabilities

Parameter Limits Notes

Maximum impulse

amplitude without

attenuators Maximum impulse

amplitude with

external attenuators Spectrum amplitude

S(f) uncertainty

Frequency range Frequency spacing

Frequency uncertainty

Load impedance

Load impedance

uncertainty

Trigger pulse

amplitude

Trigger pulse

transition duration

Trigger to impulse

delay

Trigger to impulse

jitter

:600mV 1,2,3

±1.2 kV 3,4

- 1 5 dBjaV/MHz < [S(f) 5, 6, 7 -So]< + 5dBjLiV/MHz

Nominally f< 1 GHz,

±0.6 dB 5,

1 GHz<f<4GHz,

±1.2 dB 6,7

4 GHz <f< 10 GHz,

±2.0 dB 8&9

5 MHz to 10 GHz 5, 6, 7 & 10 Af= 5, 10,20,50, or

100 MHz 5,10

of the order of ±1% 7 50.011 Nominally ±0. 1 Jl at dc 8, 1

VSWR < 1.3 up to 10 GHz

> 100 mV 12

<5ns 12

75 ns<ti< 100 ns 12

<20ps 12

Notes: 1. The impulse generator is characterized by its impulse output waveform into 50 ohms of peak amplitude (Vpk), 50 percent level duration (r), and low frequency spectrum amplitude (So~2Vpi(T).

2. Impulse generator with an adjustable amplitude impulse out- put will be calibrated with the generator adjusted to give a peak ampli- tude in the range of 200 to 400 mV.

3. Impulse generators with fixed outputs greater than ±400

mV must have the impulse attenuated to the 200-400 mV level by 50-ohm wideband coaxial attenuators.

4. Either customer supplied or NBS attenuators may be used.

5. Depends upon actual generator characteristics.

6. Data will not be given in the first spectrum null or at fre- quencies above. Typically 100 data points are supplied.

7. Subject to revision.

8. Only for impulse ampHtudes less than ±400 mV.

9. If external attenuators and/or a 6 dB tee and delay line are used then the uncertainty associated with the attenuator calibration is added to these values.

10. Lower frequencies (<5 MHz) are available as a special test.

1 1 . Depends upon input impedance of external attenuators when

used.

12. If the impulse generator does not supply a trigger output or

if the trigger output does not have the proper characteristics then a 6 dB tee and a delay line will be used to provide a suitable trigger pulse.

160
Fast Repetitive Baseband Pulse

Parameters, 50 Ohms (65200S)

NBS offers a special test service for selected pulse parameters. These pa- rameters are measured with the NBS

Automatic Pulse Measurement System (APMS), which consists of a cali- brated wideband (nominally dc-18

GHz) equivalent-time sampling oscil- loscope custom interfaced to a dedicated minicomputer system. The pa- rameters, ranges, and estimated

uncertainty limits for this service are

listed in Table 17.

Table 17: Limits of Uncertainty for Calibration of Fast

Repetitive Baseband Pulse Parameters

Parameter Range

Typical

Limits of Uncertainty*

Pulse Baseline (0% level) ± 500 mV ±(l% + 3mV)

Pulse Topline (100% level) ± 500 mV ±(l%-F3mV)

Pulse Amplitude ± 500 mV ±(l% + 3mV)

Pulse OvershootAJndershoot ±500 mV ±(l% + 3mV)

Pulse First Transition Duration (Rise Time) 10 ps-100 ns ±(l% + 5ps)

Pulse Second Transition Duration (Fall Time) lOps-lOOns ±(l%-h5ps)

Pulse Duration (Between

50% levels) 10 ps-100 ns ±(l% + 5ps)

* Smaller limits of uncertainty are achievable in some cases.

651005-654005

Restrictions: 1. Customer's device

must generate a repetitive pulse with

repetition rate between 100 Hz and 1 GHz.

2. Customer's device

must have a 50 ohms nominal output

impedance.

3. Customer's device

should have a precision coaxial out- put connector, e.g., SMA, APC-7, or Type "N".

4. Pulse topline is only

measured for "step-like" pulses.

5. Pulse second transi- tion duration and pulse duration are only measured for "impulse-like"

pulses.

6. Pulse overshoot/

undershoot is estimated as a percent

of pulse amplitude.

This measurement service includes

the previously offered measurement

service referred to in prior editions of

NBS pulse rise-time reference for 100 ps. The small unit produces a pulse which is filtered by the liquid delay line

in the standard.

161
the NBS SP250 Appendix as "LowPass Filter Transition Duration."

Measurements of other pulse pa- rameters or parameter ranges may be

provided by special arrangement.

Consulting and advisory services also are available. Network Impulse Response (65300S)

A network time domain impulse re- sponse measurement service for coaxial networks is offered at NBS. The

resulting data are in the form of a dis- crete waveform vector, normally

1024 points in length, with a time

window range of from 2 ns to 100 ns. Also, using discrete Fourier trans- forms, the associated frequency domain data (S21 [f]) are provided over a frequency range of 10 MHz to 10 GHz and a gain or loss range of 0 to 40 dB.

These measurements are accomphshed by use of the NBS Automatic

Pulse Measurement System, which

consists of a fast transition duration

pulse generator, a 20 ps, 50 ohm sampling oscilloscope and a minicomputer. Two waveforms are measured, one with the pulse generator

connected directly to the oscil- loscope, and the other with the un- known network inserted between the

generator and the oscilloscope. The

time domain network impulse re- sponse function and/or the frequency

domain scattering parameter, S21 (f), are then calculated using an NBSdeveloped deconvolution algorithm.

A wide variety of connectors can be

accommodated. The approximate limits of uncertainty are less than ±2%

for all parameters.

This measurement service includes

the previously offered measurement

service referred to in prior editions of

NBS SP250 as "Wideband Attenuation or Gain of Coaxial Networks."

Pulse Time Delay Through Coaxial

Transmission Lines (65400S)

NBS offers a special test service for pulse time delay using the same measurement system described in item

65300S above. The pulse time delay is measured in the range of 100 ps-100

ns with typical limits of uncertainty

of ±(1% + 10 ps). Smaller limits of

uncertainty are achievable in some

cases. Restrictions: 1. Customer's device

must utilize precision coaxial connectors for both delay ports.

2. Customer should pro- vide driving pulse generator if possible. First transition duration (rise

time) of driving pulse generator

162
should not exceed 10% of pulse time

delay to be measured.

3. Customer's device

should have nominal input and output

impedances of 50 ohms.

Measurements for other ranges and

configurations may be made by special arrangement. Consulting and ad- visory services are available. References—Pulse Waveform

Measurements

Impulse Generator Spectrum Amplitude Measurement Techniques, J. R. Andrews, IEEE Trans. Instrum. Meas. IM-25, 4, 280 (Dec. 1976).

Spectrum Amplitude Definition, Generation and Measurement, J. R. Andrews and M. G. Arthur, Natl. Bur.

Stand. (U.S.), Tech. Note 699 (Oct.

1977).

Pulse Techniques and Apparatus, Part

1: Pulse Terms and Definitions; Part

2: Pulse Measurements and Analysis,

General Considerations. lEC Publications 469-1 and 469-2, Intl. Electrotech. Com. (lEC) Geneva, (1974).

IEEE Standard Pulse Terms and

Definitions, IEEE Std. 194-1977; and

IEEE Standard on Pulse Measurement and Analysis by Objective

Techniques, IEEE Std. 181-1977,

Inst. Electrical and Electronic Engrs.,

New York, (July 1977).

Time Domain Automatic Network

Analyzer for Measurement of RF and

Microwave Components, W. L. Gans

and J. R. Andrews, Natl. Bur. Stand.

(U.S.), Tech. Note 672 (Sept. 1975). Present Capabilities of the NBS Automatic Pulse Measurement System, W.

L. Gans, IEEE Trans. Instrum. Meas., IM-25, 384 (Dec. 1976).

Pulsed Wavemeter Timing Reference

for Sampling Oscilloscope Cali- bration, J. R. Andrews and W. L. Gans, IEEE Trans. Instrum. Meas.,

IM-24, 82 (Mar. 1975).

Modeling of the Feed-Through Wideband (dc to 12.4 GHz) Sampling

Head, S. M. Riad and N. S. Nahman,

Digest. 1978 lEEE-MTT-S Intl. Mi- crowave Symp., Ottawa (June 1978).

Deconvolution of Time Domain

Waveforms in the Presence of Noise,

N. S. Nahman and M. E. Guillaume,

Natl. Bur. Stand. (U.S.), Tech. Note

1047 (Oct. 1981).

The Measurement and Deconvolution

of Time Jitter in Equivalent-Time

Waveform Samplers, W. L. Gans,

IEEE Trans. Instrum. Meas., IM-32,

1, 126 (March 1983).

163
Chapter

A Time and Frequency Dissemination

B Oscillator Characterization
Time and Frequency Measurements 761005-761108

Time and Frequency Dissemination

m Time and Frequency Division

Center for Basic Standards

Technical Contacts:

George Kamas

(Frequency)

Tel: 303/497-3378

David W. Allan Edna M. Jones

(Time) Administrative

Tel: 303/497-5637 and Logistics Tel:303/497-3753

Mailing Address: M.C. 524.00, National Bureau of Standards, 325 Broadway, Boulder, CO 80303

Shipping Address: M.C. 524.06, Room 4039, National

Bureau of Standards, 325 Broadway, Boulder, CO 80303

Test No. Items 761008 Special Tests of Time and Frequency; Frequency

Measurement Service—(Frequency delivered to

user's site) 761 lOS Special Tests of Time and Frequency; Global Time

Service. (Frequency and Time delivered to user's site)

NBS Broadcast of Time and

Frequency Signals (No Test No.)

NBS offers several continuous time

and frequency dissemination services

that are freely available to the general

public. These services are provided

via the radio broadcasts of stations WWV, WWVH and WWVB and a time-code disseminated from the

GOES satellites. WWV's signal is also available by dialing (303)

499-7111. A similar service from

WWVH is available by dialing (808)

335-4363. (These numbers are not toll free.)

Broadcasts from WWV (Fort Collins, Colorado) and WWVH (Kauai,

Hawaii) can be received on conventional shortwave receivers nearly

anywhere in the world. Broadcast

frequencies are 2.5, 5, 10 and 15 MHz

for both stations and 20 MHz for WWV only. Accuracies of 1 to 10 milliseconds in time and 1 X 10~* in frequency are typical from these

broadcasts. These stations provide

standard frequencies, standard time

intervals, time-of-day announcements,

a binary-coded-decimal (BCD) time

code, astronomical time corrections,

and certain public service announce- ments for other government agencies.

For individuals without receivers, the

telephone service provides the same NBS time and frequency signals. The

time signal by telephone is accurate

to only 30 milliseconds or better due

to unpredictable delays in cross- country telephone line routings.

WWVB (Ft. Collins, Colorado) of- fers accuracies of 0.5 milliseconds in time and 1 X 10~" in frequency, but

requires a special 60 KHz low fre- quency receiver. WWVB's time-code

signal is a BCD type needing special

decoding equipment. The GOES satellites broadcast an NBS time code

accurate to 100 microseconds to the

western hemisphere. These are geostationary weather satellites located at nominally 75 ° west and 135 ° west

longitude.

NBS broadcast services are coordinated with similar operations in other

countries. Commercial receivers designed to receive (and decode) NBS

broadcasts are available from several

manufacturers. A number of publications are available to assist users to properly record the time and fre- quency information available from

these broadcast services. Special Frequency Measurement

Service (76100S)

Frequency calibration requirements at the part in 10" to a part in lO'l level

165
can be satisfied using low frequency

radio signals from broadcast stations such as WWVB or Loran-C. This ser- vice involves the location at the

user's site of a low frequency receiver

and data logger system. The typical

system contains a receiver, microcomputer, disc units and printerplotter. The user's responsibility is to provide a dedicated phone line and

modem so that his data can be compared with that obtained at NBS, thus

providing assurance that the measurements are valid. The user will also receive a bulletin, either by tele- phone transfer or by mail, which re- ports the performance of many of the accurate signal sources accessible by

the system. To assist the user in getting the maximum benefit from he

service, NBS provides specific train- ing on the actual equipment.

Special Global Time Service (761 lOS)

This service uses the Global Positioning System (GPS) satellites and

an NBS-designed receiver which pro- vides much higher precision time and

frequency data and a high degree of

automation. The data from a receiver,

which is located at the user's facility, are automatically sent to an NBS

computer. The NBS computer then

stores the raw data, determines which

data are suitable for time transfer cal- culations, and provides an optimally

filtered value for the time and fre- quency of the user's clock with re- spect to the NBS atomic time scale.

The results are communicated to the user in a monthly report. The user is also given an account on one of the

NBS computers through which he

may access a preliminary NBS analysis which is calculated daily. Tests between receivers in California, Colorado, Washington, D.C., France, Germany, Spain and Canada have demonstrated an ability to perform time

comparisons with a precision of less than 10 nanoseconds and frequency

comparisons with a precision of

1 X

10"'"* or better (Icr) for averaging

times of 4 days and longer. While

useful characterization of frequency

stability is available to at least this lat- ter level, frequency accuracy is limited to 8x IS''*, the accuracy of the

NBS primary frequency standard.

References—Time and Frequency

Dissemination

NBS Time and Frequency Dissemination Services, Natl. Bur. Stand.

(U.S.) Spec. Publ. 432 (Sept. 1979).

New Time and Frequency Services at the National Bureau of Standards, S. R. Stein, G. Kamas, and D. W. Allan, Proc. 15th Annual Precise Time and

Time Interval (PTTI) Applications

and Planning Meeting, 17 (Dec.

1983).

Accuracy of International Time and

Frequency via Global Positioning

System Satellites in Common View,

D. W. Allan, et al. , IEEE Trans. In- strum. and Meas., IM-34, 2, 118 (June

1985).

166
Oscillator Characterization

t^m Time and Frequency Division

Center for Basic Standards

Technical Contacts:

James E. Gray Edna M. Jones

Tel: 303/497-3209 Administrative and Logistics Tel:303/497-3753

Mailing Address: M.C. 524.06, National Bureau of Standards, 325 Broadway, Boulder, CO 80303

Shipping Address: M.C. 524.06, Room 019, National

Bureau of Standards, 325 Broadway, Boulder, CO 80303

Test No. Items 77100C Precision Oscillator Frequency Calibration

771 IOC Characterization of Atomic Time and Frequency

Standards

77120C Characterization of Precision Oscillators: Time

Domain

77130C Characterization of Precision Oscillators: Frequency Domain

77140S Special Time/Frequency Measurements: Oscillators and Other Components

Precision Oscillator Frequency

Calibration (77100C)

Precision oscillators can be readily

calibrated in the frequency range

from 1 to 100 MHz. Reference cali- bration accuracy is nominally that of

the NBS primary frequency standard.

that is, 8x 10 The accuracy level transferable to the oscillator depends

upon the stability and noise properties

of the oscillator. Characterization of Atomic Time and

Frequency Standards (77 HOC)

An atomic standard is characterized

by introducing it as a member of the

NBS time scale system. The clock

output is sampled every two hours in sequence with the other regular

clocks in the time scale. The data are logged in the NBS time scale computer and the characteristics of the

standard are readily determined in re- lation to the performance of the time

scale ensemble of clocks. At additional cost, the user can be given an account on the NBS time scale computer through which the data may be

accessed in real time. The standard

test involves 30 days of data acquisition. The square root of the Allan

variance, cry(T) is measured to ±2X 10 T~'^^ for averaging times

of about 7200 to 10" seconds. The

time scale accuracy is about 1 X 10 and frequency drift is less than one

part in 10" per day. The actual values

transferable to the standard depend on its stability and noise properties.

Characterization of Precision

Oscillators: Time Domain (77120C)

For oscillator frequencies of 5, 10 and

100 MHz, the stability in terms of

(Tyij), the square root of the Allan

167
variance, is determined by repeated

measurements at 3 second intervals.

o-y(T) is measured to ±2x lO^'V"'''^ for averaging times of 3 to approximately 10,000 seconds and frequency

offset is measured to about 1 X 10"'\

As noted under the description of

tests 7710OC and 771 IOC, the trans- ferable accuracy depends upon the

stability and noise properties of the

calibrated oscillator. Characterization of Precision

Oscillators: Frequency Domain

(77130C)

For oscillator frequencies of 5, 10 and

100 MHz, phase noise, S^(f), can be

determined for Fourier frequency off- sets from the carrier of 0. 1 Hz to 50

KHz (higher by special request). The

phase noise is measured for only a few user-specified frequency offsets. For an offset of 1 Hz, S^(f) can be

measured to -115 dB (relative to 1

radianVHertz) and for an offset of 10

KHz, S^(f) is measured to -175 dB.

Special Time/Frequency

Measurements: Oscillators and Other

Components (77140S)

Frequency and time domain measurements can be made at frequencies

other than those cited in tests 77120C

and 77130C, but the accuracy and

cost is dependent upon the value of

the frequency. Given two or more oscillators, frequency multipliers, di- viders, synthesizers or amplifiers, rel- ative phase noise can be measured to a very high precision and the fre- quency for the measurement is not as

restrictive as above. Also, the one PPS (pulse per second) output of

atomic frequency standards can be

measured with an accuracy of 0.5 nanoseconds given an adequately defined, fast pulse.

References—Oscillator

Characterization

Properties of Signal Sources and

Measurement Methods, D. A. Howe,

D. W. Allan and J. A. Barnes, Proc. 35th Ann. Freq. Control Symp., A.l,

Phil. (May 1981).

168
ThePrimary Source:

For Accurate Spectrophotometric Analytical Results

Telephone (301) 921-2045

Wavelength SRMs

Transmittance/Absorbance SRMs

Stray Light SRMs

Ultraviolet

Visible Near Infrared

Infrared Others (see NBS SRM Catalogue)

For SRM technical and ordering information, contact:

Office of Standard Reference Materials

Room B-311, Chemistry Building National Bureau of Standards

Gaithersburg, MD 20899
ADDENDUM

Numerical Cross-Index

Old vs. New NBS Test Numbers

Old Test No New Test No DeficriDtion of Test

1 1 A I.IA 22 1 /Uo Special Mass Measurement Services

1 ID I. ID 22 1 oUM Measurement Assurance Prog, for Mass

I.IC 22010C-22030C Weight Sets (1 mg to 30 kg)

I.ID 22040C-22120C Smgle Weights

1. It, 22 1 3UC-22 1 oUC Weights tor JJeaa-weigiit rres.

1 1 l.ltj 1 /U2Uo Volume Standards, Special Tests

1 1 TT I.IH 17010C Volume Standards

l.lr 17030b Density ot bolids

I.IQ 1 7040S Density of Liquids

1 1 o I.IK loUlUC Reference Standard Hydrometers

1 1 A Length Standards

IIKJIUC Gage Blocks

11. jrl lU Line Standards

1 O T 1.3J 10030C Surveying and Oil Gaging Tapes

1.3K 10040S Surveying Leveling Rods

1.3m 10060b Sieves

1 /I A 1.4A 1 11)01)3 End Standards

1.4B 1 1070S Step Gages

1.4C 1 lOlOb Plug Gages

1 A 1.4JJ 1 lUzUC Measuring Wires tor 1 hreads and Gears

11.4t, /I c 1 lU3Uo Spherical Diameter Standards

1 A'C 1 1 (\Ar\c

1 lU4Uo Internal Diameter Standards

1 5 A 1 zUzUa Plain Conical Plug and Ring Gages

1 CD l.DD IzUJUb 1 hreaded rlug and King Gages

1.5C 12010C A T^T T^l J J Til J API Threaded Plug and Ring Gages

1 cc 1 2040b Calipers and Gages

1.5r 12050S Micrometer Screws and Dial Micrometers

1 zUoUb Penetration Needles

1.5J 1 2U7Ub Two Dimensional Gages

1 A I.OA liUlUb Optical Keterence Planes (rlats)

1.6F 13020S Roundness Standards

1.6G 13030S Roundness Calibration Specimens

1 /UTS Test no longer available

1.7A 14010C Angle Gage Blocks

1 TD 14020b Optical Polygons

1 7F» 114U4UO AOAnC Wedges

1.7F 14030S Rotary and Indexing Tables

1.7G 14050S Autocollimators

1.7H 14060S Angle Generators

1.8A 15010C Roughness Calibration Specimens

1.8B 15020C Surface Roughness Comparison Specimens

1.8C 15030C Step Height Measurements

1.9C 38090S Photographic Step Tablets

2.1A 25060S Acoustic Devices

2.1B 25010C Microphone WE Type 640AA or Equivalent

(50-10,000Hz)

2.1C 25020C Microphone WE Type 640AA or Equivalent

(50-20,000Hz)

2.1D 25030C Pressure Response: Tokyo Riko Type ECL

MR112, B&K Types 4134 (50-10,000Hz)

170
2. IE 25040C Same as 25030C (50-20,OOOHz)

2. IF 25050C Free Field Response: Tokyo Riko

Type ECL MR112, B&K Types 4133, 4134,

4165 and 4166 (2,500-20,000Hz)

2.1H 25070S Earphones

2.1R 26030S Ultrasonic Amplitude Reference Blocks

2. IS 260 IOC Ultrasonic Transducer Power and Frequency

2. IT 26020C Acoustic Emission Sensors

2.2A 24010C Vibration Pickup Sensitivity, 2-lOOHz

2.2B Test No Longer Available

2.2C 24020C Vibration Pickup Sensitivity, 10-3,500Hz

2.2D 24030C Vibration Pickup Sensitivity, 10-10,000Hz

2.2E 24060S Special Vibration Measurement Services

2.2F 24050S Special Vibration Pickup Sensitivity Tests 2.2G 24040S Special Shock Measurement Services

2. 3A 36070S Humidity Measurement Services

2.3B 36010C Dewpoint Hygrometers, -25 to -15°C

2.3C 36020C Dewpoint Hygrometers, - 15 to -70°

C

2.3F 36030C Electric Hygrometer

2.3G 36040C Coulometric Hygrometer

2.3H 36050C Aspirated Hygrometer

2.31 36060C Pneumatic Bridge Hygrometer

2.5A 23010C Force Transducers, to 25,000 Ibf, 1 mode

2.5B 23040C Force Transducers, to 25,000 Ibf, 2 modes

2.5D 23070C Force Transducers, 25,001 to 112,000 Ibf,

1 mode

2.5E 23100C Force Transducers, 25,001 to 112,000 Ibf, 2 modes

2.5G 23130C Force Transducers, 112,001 to 300,000 Ibf,

1 mode

2.5H 23160C Force Transducers, 112,001 to 300,000 Ibf, 2 modes

2. 5J 23190C Force Transducers, 300,001 to 1,000,000 Ibf,

1 mode

2.5K 23220C Force Transducers, 300,001 to 1,000,000 Ibf, 2 modes

2.5M 23250C Force Transducers, Over 1,000,000 Ibf, compression only

2.5N 23260S Special Force Measurement Services

23270S Pattern Evaluation Tests of Load Cells in Compression

2.7A 18050S Liquid and Gas Flow Rates 2.7B 18010C Single Turbine Meters

2.7C 18020C Tandem Turbine Meters

2.7D 18030C Flow Rate Meters, Direct Reading

2.7E 18040C Head Class Flow Measurement Devices

2.9A Test no longer available

2.9B 19030S Airspeed Measurements

2.9C 190 IOC Pitot-static Tubes

2.9E 19020C Low Airspeed Instruments

171
3.1 A 51100S Special Resistance Measurement Services

3. IB 51110M Measurement Assurance Program Services

for Resistance

3.1C 51130C Standard Resistor, Thomas-Type, Ifi

3. ID 51131C Standard Resistor, Evanohm Wirewound

High Precision, lOkfi

3.1E-3.1J 51132C-51142C Standard Resistors, Two- and FourTerminal, 0.0001 n to 1 Mn, Even Decades

3.10 51143C-51150C Standard Resistors, 10 MH-10 GH

3.1P 51151C-51154C Standard Resistors, 100 GO-1 Tft

3.1Q 51100S Pressure Coefficient, Thomas Resistors

3.1R-3.1T 51160C-51163C Standard Resistors for Current

Measurements (Shunts), Service Only in May and Nov.

3.1U 51100S Adjustible Low Resistance Standard

3.1V-3.1Z 51133C-51141C Standard Resistors, Two- and FourTerminal, 0.001 a to .1 M ft. Odd Decades

3.2C 5411 OS Special Ratio Measurements and Tests of

Inductive Voltage Dividers

by Prearrangement

3.2Q-3.2R 54120C-54131C Inductive Voltage Dividers

3.2V-3.2W Test No Longer Available

3.3A 521 lOS Special LF Impedance Measurements

by Prearrangement

3.3B Temporarily Discontinued

3.3C-3.3D 52180C-52181C Fixed Inductors, Self or Manual—Mutual

(check 7. IB)

3.3E-3.3G 52140C-52150C Fixed Three-Terminal High Precision

Standard Capacitors with Coaxial

Connectors, High Accuarcy Test 3.3H-3.3I Tests No Longer Available

3. 3J 52130C Standard Fixed, Fused Silica Dielectric

Capacitor

3.3K-3.3L 52160C-52161C Fixed, Three-Terminal Standard

Capacitors with Coaxial Connectors

3.3M-3.3N 52170C-52171C Two- or Three-Terminal Solid

Dielectric Standard Capacitors

3.3X-3.3Y 52610C Eddy Current Conductivity Standards

3. 4A 53110S Special DC Voltage Measurements

by Prearrangement

3.4B 53120M Measurement Assurance Program for DC

Voltage

3.4C-3.4D 53130C-53131C Saturated Standard Cells

3.4E 53140C Platinum Resistance Thermometer

Temperature Determination for Standard

Cell Calibration

3.4F 53150C Unsaturated Standard Cells

3.4G Test No Longer Available

3.4H-3.4I 53160C-53161S Tests of Solid State Voltage

Reference Standards

3.5A 533 lOS Special AC-DC Measurement Services

by Prearrangement

3.5B-3.5D 53340C-53343C AC-DC Thermal Voltage and Current

Converters (to 1 MHz)

3.6A 54600S; 54310S; Special Tests of Dividers,

56120C; 51410S; Transformers, and AC Resistors

172
3.6B-3.6E 54510C-54513C Voltage Transformers, Ratio and Phase Angle

3.6F-3.6H 54520C-54522C Current Transformers, Ratio and Phase

Angle

3.61 562 lOM Measurement Assurance Program for Watthour Meters

3.6J-3.6M 562(X)C-56203C Watthour Meters, Percentage Registration

3.6N 542 IOC Resistors and Resistive Dividers,

Total Resistance or Voltage Ratio

51210C High-Voltage Standard Resistors

3.60 52400C Power-Frequency Capacitors

3.6P 54410S Pulse-Voltage-Measuring Systems

Including Kerr Cells

3.6Q 54420S X-ray Unit, Voltage Dividers

3.8A 51410S Special Tests of Resistors by Prearrangment

3.8B 561 lOS Special Tests of AC-DC Wattmeters

by Prearrangement

3.8C 532008 Low-Frequency AC Voltmeters and Sources,

0.1 Hz to 10 Hz, 0.5V to 7V, by

Prearrangement

3.9A 53500S Special Data Converter Services by

Prearrangement

3.9B-3.9F 53510C-53540S A/D or D/A Converters-Linearity Errors,

Correction Coefficients, Superposition

Errors; Differential Linearity Errors,

Equivalent RMS Input Noise; and

Offset/Gain Errors (Relative to Legal Volt)

4.1 A 61250S Special Attenuator Measurements

by Prearrangement

4.1B 61210C-61211C Coaxial Fixed and Variable Attenuators,

30 MHz and 100 MHz to 18 GHz (ANA)

4.1C 61215C Waveguide Circular Below Cutoff(Piston)

Attenuators, Coaxial Connectors

4.1D 61230C Variable Rectangular WaveguideAttenuators,

Attenuation Difference

61240S Special Attenuation Measurements of

Three-Port and Two-Port Devices at 1.25 MHz

4.1E 65300S-65301S Network Impulse Response of Coaxial

Networks, 100 kHz to 12.5 GHz

4.2A 63100S-63400S Special Test Services for Microwave Antenna

and Probe Parameter Measurements,

Including Special Consulting, Advisory,

and Other Services for Antennas

4.2B-4.2C 64100S-64400S Special Test Services for Electromagnetic

Field Strength and Antenna Measurements,

Including SpecialTest Services for Electromagnetic Interference

4.3A 52210C-52310S High-Frequency Standard Capacitors

(52710C-52711C; and Inductors (Calibration Services:

513 IOC) High-Frequency Standard

Resistors, Q-Standards)

4.3B 52210S Special Test of Two-Terminal, Low-Loss

(5221 IC) S^mdard Capacitors, 1 MHz (Calibration

Service: High Accuracy Capacitors of Same

Type

173
4.3C 52220C--52221C Calibration Services for Three-Terminal

Low-Loss Standard Capacitors

4.3D 52222C--52223C SnppiJil OL'^^lCll Tp^t^ X ^oto ofKJl T'Virpp-TprTTiinfil X 111 ^W X ^1 lllllldl (^As^d y ITXaWl—fW\^U poH

and Hanopol) Capacitors, 465 kHz

527 lOC--5271 IC TnHiirtive 0-StfinrlnrH« SO WT-T7-4.S A/fTTy

4.3F 61310C Complex Reflection Coefficient, Impedance,

cLllxj- V Ullage oiaiiLiiii^ vvavc xvdLiu Kji Coaxial Terminations by ANA, 0.1-18 GHz

4 3G-4 3H 61320C-61331S A/fapnitude of Reflection Coefficient of

Rectangular Waveguide (Mismatches)

XV^ll^L/lWl d dllU 1^ will dlCV^LllX^ VT a V &^UiU^

Ports and Matched Loads

4.4A 42010S Special Tests of Laser Power and Energy

by Prearrangement

4.4B 42020M-42090M Measurement Assurance Program for Laser

Power and Energy

4.5A 41010S Special Tests for Attenuation of Telecommunication-Grade Multimode Optical-Fibers

4.5B 41020S Special Tests for Bandwidth of TelecommuniCaliwll vJiCtLiC IVlUlUllllUUC V-/L>llwa.l 1 lUCl & 4. 6A 62020S OL'&V'lul ^r\pr*ia1 Plpptroma J-^l^W 1,1 WlllcX^ll^LlW (TTiptir* N^oi^p 1^\^13^ T'pmnprfitiirp X ^lllLl^l clLUl ^ Measurements by Prearrangement

4.6B-4.6C 62100S- 621 lis Snecial Tests for Effective Noise Temnerature

r\T i^r\5i Yi ill oic^ f^^rt^rctf/^rc yJl K^KJaAlai i^\Ji>C vJCliCidlUio 4.6D-4.6E 62120S62140S

55110S

62130S Special Tests for Effective Noise Temperature

KJl W d VC^UIUC DloC vJCllCl alKJl a Special Services for Earth Terminals Used in

^cif'#^lli1"f* f^/^TntniiTi ir*Ql"i/^tio Special Tests of Phase Angle Meters

hvcy XPrparr?iTi i^ciii dii^wiii^ii cxpmPTitv 552 lOC--55221C Special Tests of Very-High Frequency

Omnidirectional Range Instrument Parameters

55230S Special VOR Tests

4. 7A 61450S Special Tests of Phase Shifters

by Prearrangement

4.7B 61410C-61411C Coaxial Fixed and Variable Phase Shifters

4.7C 61420C Variable Rectangular Waveguide Phase

Shifters

4.7D 65400S Special Tests for Pulse Time Delay Through

Coaxial Transmission Lines

4. 8A 61190S Special Microwave and RF Power Measurement Services by Prearrangement

4.8B 61110S61160S

61111S Special Tests for Coaxial Power Meters

(Effective Efficiency and Reflection

Coefficient) at Selected Single Frequency in Range 0.1 to 10 MHz

Special Test for Output of Power Reference in TE Power Meters

174
4.8C 61 120S-61 122s Special Tests for Coaxial Power Meters

(Calibration Factor, tirectiveEiiiciency,

Eriiciency Factor, Ketlection Coeincient) at Specified Frequencies in Range 10

to lUUU MrlZ

61 123i>-61 128b Special Tests for Coaxial Power Meters

(nttective bniciency, ttnciencyFactor,

Reflection Coefficient) atSpecified

Frequencies in Range 1 to 18 GHz

61 14Ua-oll4oo Special Tests for Rectangular-Wave-guide

Power Meters (Effective Efficiency,

Efficiency Factor, Reflection Coefficient) at Specified Intervals in FrequencyBands

Covering z.o to 18 orlz

/;i 1 ino 111c Special Tests for Rectangular-Wave-guide

Power Meters (Effective Efficiency,

Reflection Coeiricient)at Selected Single

rrequency vvitnin lo oriz to 4U Lrriz

(WR42, WR28)

61 147b-61 135b Special Tests for Rectangular-Wave-guide

Power Meters (EffectiveEfficiency,

Efficiency Factor,Reflection Coefficient)

at Specified Intervals in FrequencyBands

Covering Total Range 18 to 96GHz

(WR42, WR28, WR15, WRIO)

A OT Test No Longer Available

4. 9A 53405S Special Tests of AC Thermal and Current

Voltage Converters (lUO rizl Lrriz)

by Prearrangement

4.9B 53410C-53415C Low-Frequency TVCs, total range 0. 1 kHz to

1 r\r\ n T 100 MHz

4.9C 53420C-53421C High-Frequency TVCs, total range 10

to KXX) MHz

53440C-53445b RF Micropotentiometer Calibrations

4.9H 651(XJb Special Tests for Impulse GeneratorSpectrum

Amplitude (50 ft) A QIA QT ODZUvJo Special Tests for Fast Repetitive Baseband

Pulse Parameters

53430S-53431S Special Tests for Peak-to-Peak Detectors

5.1A 76100S Special Frequency Measurement Service

5.1B 761 lOS Special Global Time Service

5.2A 77140S Special Time/Frequency Measurements

5.2B 77100C Precision Oscillator Frequency Calibration

5.2c 77120C-77130C Characterization of Precision Oscillators

Time Domain andFrequency Domain

5.2D 77140S Time Pulses

771 IOC Characterization of Atomic Time and

Frequency

6.1 18800S Special Tests of Cryogenic Liquid Flow

6.2 Test No Longer Available

7.1A 31260S Special Thermometry Services

by Prearrangement

175
7.1B-7.1F 31010C--31061C Laboratory Thermometers

7.1G 31070C--31071C Calorimetric Thermometers

7.1H 31080C--31081C Beckman Thermometers

7.11 31200S Preliminary Examination of Ineligible

Thermometer

7.1 J 31250S Additional Copy of Report

7.1K-7.10 31100S- 31161S Special Tests of Thermometers

7.2A 321 SOS Special Tests of Thermocouples and

Thermocouple Materials

7.2B-7.2F 320 lOC--32044C Thermocouple Comparison Calibration,

Temperature Measured with Thermocouple

7.2G 32070C TC Materials Tested Against Platinum

Standard

7.2H 32050C--32051C Comparison Calibrations, Additional Point

for 32050C

7.2K-7.2M 32090C--32092C Thermocouple Calibration at Metal Freezing

Points

7.2N-7.20 32100C--32101C Calibration of Pyrometer Indicators

7.2R-7.2U 321 lOC--32147C Comparison Calibration of Thermocouple

Materials; Tested Against Pt Thermoelectric Standard, Temperature Measured

with Pt Resistance Thermometers

7.3A 33 IOCS Special Tests of Resistance Thermometers

7.3B-7.3C 33010C--33020C Long Stem PRTs

7.3D 33030C Calorimetric Type PRTs

7.3E-7.3F 33040C--33050C Capsule Type PRTs

7.3G-7.3H 33070C--33080C Additional Copies of PRT Data Tables

7.31 33090C Minimum Charge for Unsuitable

Thermometers

7.3J 33120M Measurement Assurance Program for Temperature

7.3K 331 lOS Special Tests of Thermometric Fixed

Point Devices

7.3P 33060S Special Tests of Germanium Resistance

Thermometers (2 to 20K)

7.4A 35070S Special Tests of Radiation Pyrometers

7.4B-7.4E 35010C--35040C Optical Pyrometers

7.4F-7.4G 35050C--35060C Ribbon Filament Lamps

7.5A 39070S Special Tests of Radiometric Sources

7.5B-7.5D 390 IOC--39030C Spectral Radiance Ribbon Filament Lamps

7.DG 39U4UC Spectral Radiance QuartzzHalogen Lamps

/. jrl Photodiode Spectral Response Rental

7.5J 39050C Spectral Irradiance Deuterium Lamps

7.6A 40040S Special Tests of Radiometric Devices

in the Near and Vacuum Ultraviolet

7.6B 4001 OS Spectral Irradiance Standard, Argon

Mini-Arc

7.6C 40020S Spectral Radiance Standard, Argon Mini-Arc

7.6D 40030S Spectral Irradiance Standard, Deuterium

Arc Lamp

7.7A 371 SOS Special Photometric Tests 7.7B-7.7H 37010C-37070C Luminous Intensity Standards, Frosted

Tungsten Lamps

7.7I-7.7M 37080C-37120C Luminous Flux Standards, Tungsten Vacuum

and Gas Filled Lamp

176
7,.7N -7.7P 37 HOC

-

-37160C Airway Beacon Lamps for Color Temperature

7.7Q 37130C Luminous Flux Standards, Miniature Lamps

7.7R 37170C Opal Glass Luminous Directional Transmittance Standards 7.8A 38060S Special Tests of Spectral Transmittance and

Reflectance 7.8B- 7.8E 38010C--38040C Spectral Transmittance Standards, 390-750 nm

7.8F 38070M-38074M Measurement Assurance Programs for Luminous Intensity of Retroreflectors

7.81 38050C

38080M

Wavelength Standards (Holmium Oxide

Glass) Measurement Assurance Program for Transmittance 7.9A 30040S; 29040S

30050S; Special Tests of Pressure and Vacuum

Gages

7.9B 290 IOC Deadweight Piston Gages

7.9C 29020C Controlled Clearance Piston Gages

7,9D 29035C Mercurial Barometers and Manometers

7.9E 29030C Pressure Gages and Transducers 7.9G 300 lOC--30020C Low Absolute and Differential Pressure Gages

7.9H 30030C High Vacuum Gages

8.1A 44100S Special Tests of Neutron Sources and

Dosimters

8.1B-8.1C 44010C--44020C Natural Standard Neutron Sources

(10'- 10"' n/s) 8.1H- 8. IK 44040S- 44070S Special Tests of Neutron Dosimeters—Ther- mal Beam, Filtered Beam, Californium, and Van de Graff Sources

8. IP 44030S Activated Foil Irradiation with Thermal

Neutrons

8.1Q-8.1R 44080C--44090C Activated Foil Irradiation-Californium and Cavity

Fission Sources 8.2A 43060S- 43090S Special Tests of Radioactive Solution Sources 8.2C 430 IOC Gamma-Ray-Emitting Radionuclides in Solution-Half Lives Greater than 15 Days

8. 2D 43020C Gamma-Ray-Emitting Radionuclides in Solution-Half Lives Less than 15 Days

8.2H-8.2J 43030C--43050C Alpha-Particle-Emitting Solid Sources Various Counting Systems

8.2P 43060S Special Tests of Beta-Particle-Emitting

Solution-Liquid

Scintillation Counting

8.2Q-8.2R 43070S Special Tests of Beta-Particle Emitting

Solution Sources—Other Techniques 8.3A 46050S Special Tests of X-Ray and Gamma-Ray

Measuring Instruments 8.3B- 8.3C 460 IOC

-4601 IC Radiation Detectors-Calibration/Correction

Factors, Various Beam Qualities

8. 3D 46030S Special Tests of High-Gain Electrometers- Charge Sensitivity 8.3M--3.3N 46020C--4602 IC Irradiation of Passive Dosimeters

8.3R 46040S Special Tests of X-Ray Penetrameters, Ardran-Crookes Type

8.4A 47040S Special Tests of Gamma-Ray and BetaParticle Sources 8.4E-8.4F 470 lOC--4701 IC Gamma-Ray Sources-Exposure Rates

0.1-100 (/xR/S)m- 8.4K 47030C Beta-Particle Sources Calibrated forSurface Dose Rate 8.5A 48020S Special Tests of Electron-Beam Dosimters

8.5B-8.5C 480 lOC--4801 IC Irradiation of Ferrous-Ferric Dosimeters 8.6A 4901 OS Special Tests of Customer Supplied Dosimeters Irradiated with Cobalt-60 Gamma-Rays

8.6B- 8.6C 49020S- 49030S Dose Interpretation of NBS-Packaged

Dosimeters Irradiated by Customer

8.6D- 8.6E 49040S- 4904 IS Spectrophotometric Reading of Dosimeters

8.6F 49050S Special Measurement Services forDosimeter Response

177
ALPHABETICAL CROSS-INDEX

Item Test Number

Absolute pressure 30010C

Ac resistors 51410S

Ac-dc thermal converters (to IMHz) 53310S-53343C

Ac-dc thermal converters (100 Hz to 1 GHz) 53405S-53445S

Ac voltmeters, low-frequency 53200S

Ac-dc wattmeters 561 10S-56210M

Acoustic emission sensors 26020C

Acoustic devices 25060S

Activated foil irradiation with thermal neutrons 44030S

Activated foil irridiation—Californium and cavity fission sources .... 44080C-44090C

A/D and D/A data converters 53500S-53540S

Air-speed indicators 19010C-19030S

Alpha-particle-emitting solid sources 43030C-43050C

Aluminum ultrasound reference blocks 26030S

American Petroleum Institute gages 120 IOC

Analog-to-digital data converters 53500S-53540S

Angle gage blocks 140 IOC

Angle generators 14060S

Angle measurements 14010C-14060S

Antenna parameter measurements, microwave 63100S-63400S

Attenuation, optical fibers 410 lOS

Attenuators, rf and microwave 61210C-61250S

Audio-frequency phase meter 55110S

Autocollimators 14050S

Bandwidth, optical fibers 41020S

Barometers 300 IOC

Beckman thermometers 31080C-31081C

Beta-particle-emitting sources 43060S-47030C

Calipers 12040S

Calorimeter thermometers 31070C-31071C

Capacitance and inductance measurements, low-frequency 521 10S-52150C

Capacitors, dielectric 52130C

Capacitors, high-frequency 52210C-52223C

Capacitors, low-frequency 521 10S-52150C

Capacitors, power frequency 52400C

Capacitive dividers 543 lOS

Coaxial attenuators 61210C-6121 IC

Coaxial power meters 61110S-61128S

Coaxial terminations and reflection coefficients 613 IOC

Color temperature 37140C-37160C

Conductivity, eddy current 526 IOC

Conical plug and ring gages 12020S

Converters, A/D and D/A 53500S-53540S

Cryogenic flow measurements 18800S

Cryogenic temperature measurements 33030C-33100S

Current and voltage transformers 54510C-54600S

178
Data converters, A/D and D/A 53500S-53540S

Dc resistance measurements 51 lOOS-51 163C

Dc voltage measurements 531 10S-53190S

Deadweight piston gages 290 IOC

Density measurements, liquids 17040S

Density measurements, solids 17030S

Deuterium lamps 39050C

Dew-point hygrometers 36010C-36020C

Diameter measurements 1 lOlOS-1 1080S

Differential pressure gages 30020C

Digital-to-analog data converters 53500S-53540S

Dimensional metrology 10010C-14060S

Dividers, capacitive 5431 OS

Dividers, inductive 54 1 1 OS-54 1 3 1

C

Dividers, mixed 54410S-54420S

Dividers, resistive 542 IOC

Dosimeters, electron beam 48010C-48020S

Dosimeters, high dose 49010S-49050S

Dosimeters, neutron 44040S-44070S

Dosimeters, radiochromic 49020S-49030S

Dosimeters, spectrophotometric reading 49040S-49041S

Dosimeters, x and gamma-ray 46010C-46021C

Earphones 25070S

Eddy Current Conductivity 52610C-5261 IC

Electromagnetic field-strength parameter measurements 64100S-64400S

Electrometers 46030S

Electron beam dosimetry 48010C-48020S

Energy and power measurements, low frequency 561 10S-56210M

End standards of length 1 1060S

Ferris-ferric dosimeters 48010C-4801 IC

Field strength measurements, electromagnetic 64100S-64400S

Filament lamps, ribbon 35050C&39010C

Filters, spectral transmittance 38010C-38040C

Fixed-point devices, thermometric 33110S

Flats, optical 1301 OS

Flowrate meters, liquid and gas 18010C-18050S

Flux standards, luminous 37080C-37130C

Foils, neutron irradiated 44030S

Force transducers 23010C-23240C

Frequency and time measurement services 76100S-761 lOS

Gage blocks lOOlOC

Gage block. Measurement Assurance Program 10070M

Gages, API 120 IOC

Gages, plug and ring 12030S

Gages, pressure 29010C-29040S

Gages, two dimensional 12070S

Gages, vacuum 30O10C-3OO50S

Gamma-ray dosimeters 46010C-46021C

Gamma-ray-emitting sources 43010C&

47010C-47011C

Gas flowmeters 1 8050S

Germanium resistance thermometers 33060S

179
High dose dosimetry 49010S-49050S

High-frequency standard capacitors and inductors 52210C-52223C

High-frequency standard resistors 5 13 IOC

High-vacuum gages 30030C

High-voltage resistors 5 12 IOC

Humidity measurements 36010C-36070S

Hydrometers 16010C

Hygrometers 36010C-36070S

Impulse generator spectrum amplitude 65100S

Impulse response of coaxial networks 65300S

Inductance and capacitance measurements, low-frequency 521 10S-52150C

Inductance and capacitance measurements, high-frequency 52210C-52223C

Inductive voltage dividers 541 10S-54131C

Intensity standards, luminous 37010C-37070C

Internal diameter standards 1 1040S

Irradiance sources 40010S-40040S;

39040C; 39050C

Kerr cells 544 lOS

Laboratory thermometers 31010C-31 161S

Lamps, deuterium arc 39050C-40030S

Lamps, incandescent 37010C-37140C

Lamps, quartz halogen 39040C

Lamps, ribbon filament 35050C&39010C

Laser power and energy measurements 42010S-42090M

Length measurements 10010C-10070M

Length and diameter, special tests 11050S

Line standards 10020C

Liquid flowmeters 18010C-18050C

Liquid-in-glass thermometers 31010C-31 161S

Load cells 23010C-23270S

Luminous directional transmittance standards 37170C

Luminous intensity and flux standards 37010C-37130C

Luminous intensity of retroreflectors 38070M

Luminous transmittance filters 37170C

Mass measurements 22010C-22180M

MEASUREMENT ASSURANCE PROGRAMS

Dc resistance 511 lOM

Dc voltage 53120M

Gage blocks 10070M

Laser power and energy 42020M-42090M

Mass 22180M

Platinum resistance thermometry 33120M

Retroreflectors, luminous intensity 38070M-38074M

Transmittance, spectral 38080M

Watthour meters 562 lOM

Mercurial Barometer and Manometers 2903 5C

Microcopy resolution test charts 38100S

Micrometer screws, dial micrometers 12050S

Microphones, pressure and free-field response 25010C-25050C

Micropotentiometers, rf 53440C-53445S

180
Microwave antenna parameter measurements 63100S-63400S

Mixed voltage dividers 54410S-54420S

N-port scattering measurements 61520S

Neutron dosimeters 44040S-44070S

Neutron sources 44010C-44020C

Noise temperature measurements, coaxial and waveguide 62020S-62140S

Oil gaging and surveying tapes 10030C

Opal glass transmittance standard 37170C

Optical fiber attenuation and bandwidth 41010S-41020S

Optical Hats 1301 OS

Optical polygons 14020S

Optical pyrometers 35010C-35040C

Optical reference planes 1301 OS

Oscillator characterization 77100C-77140S

Penetrameters, x-ray 46040S

Penetration needles 12060S

Phase angle standard and phase meters, audio-frequency 5511 OS

Phase shifters, rf and microwave 61410C-61450S

Photodiode spectral response 39060C

Photographic step tablets 38090S

Photometry 37010C-37180S

Photometric tests, special 371 SOS

Pickup sensitivity 24010C-24030C

Piston gages, controlled clearance 29020C

Piston gages, dead weight 290 IOC

Pitot-static tubes 190 IOC

Platinum resistance thermometers 33010C-33050C

Plug gages IIOIOS

Pneumatic bridge hygrometers 36060C

Polygons, optical 14020S

Power and energy measurements, low-frequency 561 10S-56210M

Power meters, rf and microwave 61110S-61190S

Pressure gages and transducers 29030C

Pressure gages, low absolute 300 IOC

Pressure gages, low differential 30020C

Pressure gages, special tests 29040S

Proving rings 23010C-23270S

Pulse waveform measurements 65100S-65400S

Pulse voltage measuring systems 5441 OS

Pyrometer indicators 32100C

Pyrometers, optical 35010C-35040C

Pyrometers, radiation 35070S

Q-standards 527 lOC-527 1 IC

Quartz halogen lamps 39040C

Radiance standard sources 39010C-39050C;

40020S

Radiant energy detectors 39060C

Radiation detectors 46010C-4601 IC

Radiation pyrometers 35070S

Radiation thermometry 35010C-35070S

Radioactive sources, alpha-emitting 43030C-43050C

181
Radioactive sources, beta-emitting 43060S-43070S

Radioactive sources, gamma-emitting 43010C-43020C

Radioactive sources, neutron-emitting 44010C-44030S

Radiochrometric dosimeters 49020S-49030S

Radiometry sources, special tests 39070S

Radionuclides 43010C-43090S

Reflection coefficients, coax, and waveguide terminals 61310C-6133IS

Resistance measurements, dc 51 lOOS-51 163C

Resistance thermometers 33010C-331(X)S

Resistive voltage dividers 542 IOC

Resistors, ac 51410S

Resistors for current measurements 51160C-51163C

Resistors, high-voltage 51210C

Resistors, high-frequency 5 13 IOC

Resistors, megohm 51 142C-5 1 1 50C

Resistors, high-precision standard, dc 51130C-51154C

Retroreflectors, coefficient of luminous intensity 38070M

Ribbon filament lamps 35050C-35060C

Rods, surveying leveling 10040S

Rotary and indexing tables 14030S

Roughness calibration standards 150 IOC

Roundness measurements 13020S-13030S

Saturated standards cells 53130C-53131C

Scattering measurements, 2-port 61520S

Shock tests 24040S

Sieves, special tests 10060S

Sources, low-frequency, ac voltage 53200S

Spectral irradiance lamps 39040C-39050C

Spectral irradiance 40010S;40030S;

39040C;39050C

Spectral radiance 40020S;

39010C-39030C

Spectral radiance, lamps 39010C-39030C

Spectral response, photodiode 39060C

Spectral transmittance filters 38010C-39040C

Spectrophotometric standards 39010C-39060S

Spherical diameter standards 11030S

Standard voltage cells 53130C-53150C

Step gages, length 11070S

Step height measurements, surface 15030C

Step tablet density, photographic 38090S

Surface roughness standards 15020C

Surveying and oil gaging tapes 10030C

Surveying leveling rods 10040S

182
Thermal voltage converters (to 1 MHz) 53310S-53343C

Thermal voltage and current converters (100 Hz-1 GHz) 53405S-53445S

Thermocouples 32010C-32044C

Thermocouple materials 32070C-32110C

Thermometers, calorimetric type 33030C

Thermometers, cryogenic type 33060S

Thermometers, germanium resistance 33060S

Thermometers, laboratory 31010C-31161S

Thermometers, platinum resistance 33010C-33050C

Thermometric fixed-point devices 33 11 OS

Thermometry, radiation 35010C-35070S

Thread measuring wires 11080S

Threaded plug and ring gages 12030S

Time and frequency measurement services 76100S-761 lOS

Transformers, voltage and current 54510C-546OOS

Transmittance filters, spectral 38010C-38040C

Transmittance, luminous directional 37170C

Two-port scattering measurements 61520S

Turbine flow meters 18010C-18020C

Ultrasonic transducer power, special test 26070S

Ultrasonic transducers, power and frequency 260 IOC

Unsaturated standard cells 53150C

Vacuum gages 30030C

Vacuum measurements 30010C-30050S

Vacuum ultraviolet radiometric measurements 40010S-40040S

Very-high-frequency omnidirectional range (VOR) meas 55210C-55230S

Vibration and shock measurements 24010C-24060S

Voltage dividers, capacitive 5431 OS

Voltage dividers, inductive 541 10S-54131C

Voltage dividers, mixed 54410S-54420S

Voltage dividers, resistive 542 IOC

Voltage reference standards, solid state 53160C-53161C

Voltage and current transformers 54510C-54600S

Voltmeters, low-frequency, ac 53200S

Volume standards 170 IOC

VOR measurements 55210C-55230S

Watthour meters 56120C-56210M

Wattmeters 56110S

Waveform measurements, pulse 65100S-65400S

Waveguide power meters 61130S-61155S

Waveguide terminations and reflection coefficients 61320C-61331S

Wavelength standards 38050C

Wedges 14040S

Weights (mass standards) 22010C-22180M

Wires for thread and gear measurements 11020C

X-ray dosimeters 46010C-46050S

X-ray penetrameters 46040S

X-ray voltage divider units 54420S

183


U.S. Department of Commerce

National Bureau of Standards

Office of Physical Measurement Services

Rm. B362, Physics BIdg.

Gaithersburg, MD 20899

Return Postage Guaranteed

Official Business

Penalty for Private Use, $300

Bound Printed Matter Postage & Fees Paid NBS

PERMIT No. G195