U.S.

(EPARTMENT

OF

COMMERCE

National

Bureau

of

„ '-.standards

ill-

?i J.

Universal Testing Machine of

12-Million-lbf Capacity at the

National Bureau of Standards
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards1 was established by an act of Congress March 3,

1901. The Bureau's overall goal is to strengthen and advance the Nation's science and

technology and facilitate their effective application for public benefit. To this end, the

Bureau conducts research and provides: (1) a basis for the Nation's physical measure- ment system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety.

The Bureau consists of the Institute for Basic Standards, the Institute for Materials

Research, the Institute for Applied Technology, the Center for Computer Sciences and

Technology, and the Office for Information Programs.

THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the

United States of a complete and consistent system of physical measurement; coordinates

that system with measurement systems of other nations; and furnishes essential services

leading to accurate and uniform physical measurements throughout the Nation's scientific community, industry, and commerce. The Institute consists of a Center for Radiation Research, an Office of Measurement Services and the following divisions:

Applied Mathematics—Electricity—Heat—Mechanics—Optical Physics—Linac

Radiation2—Nuclear Radiation2—Applied Radiation2—Quantum Electronics3—

Electromagnetics3—Time and Frequency3—Laboratory Astrophysics3—Cryogenics3

. THE INSTITUTE FOR MATERIALS RESEARCH conducts materials research leading to improved methods of measurement, standards, and data on the properties of

well-characterized materials needed by industry, commerce, educational institutions, and

Government; provides advisory and research services to other Government agencies;

and develops, produces, and distributes standard reference materials. The Institute consists of the Office of Standard Reference Materials and the following divisions:

Analytical Chemistry—Polymers—Metallurgy—Inorganic Materials—Reactor

Radiation—Physical Chemistry.

THE INSTITUTE FOR APPLIED TECHNOLOGY provides technical services to promote the use of available technology and to facilitate technological innovation in industry and Government; cooperates with public and private organizations leading to the

development of technological standards (including mandatory safety standards), codes

and methods of test; and provides technical advice and services to Government agencies

upon request. The Institute also monitors NBS engineering standards activities and

provides liaison between NBS and national and international engineering standards

bodies. The Institute consists of the following technical divisions and offices: Engineering Standards Services—Weights and Measures—Flammable Fabrics

Invention and Innovation—Vehicle Systems Research—Product Evaluation

Technology—Building Research—Electronic Technology—Technical Analysis

Measurement Engineering.

THE CENTER FOR COMPUTER SCIENCES AND TECHNOLOGY conducts re- search and provides technical services designed to aid Government agencies in improving cost effectiveness in the conduct of their programs through the selection, acquisition,

and effective utilization of automatic data processing equipment; and serves as the principal focus within the executive branch for the development of Federal standards for

automatic data processing equipment, techniques, and computer languages. The Center

consists of the following offices and divisions:

Information Processing Standards—Computer Information—Computer Services —Systems Development—Information Processing Technology.

THE OFFICE FOR INFORMATION PROGRAMS promotes optimum dissemination

and accessibility of scientific information generated within NBS and other agencies of

the Federal Government; promotes the development of the National Standard Reference

Data System and a system of information analysis centers dealing with the broader

aspects of the National Measurement System; provides appropriate services to ensure

that the NBS staff has optimum accessibility to the scientific information of the world,

and directs the public information activities of the Bureau. The Office consists of the

following organizational units:

Office of Standard Reference Data—Office of Technical Information and

Publications—Library—Office of Public Information—Office of International

Relations.

1 Headquarters and Laboratories at Gaithersburg, Maryland, unless otherwise noted; mailing address Washington, D.C. 20234.

2 Part of the Center for Radiation Research.

3 Located at Boulder, Colorado 80302.
mwm BUREAU OF STANDARDS

OCT 6 1971

UNITED STATES DEPARTMENT OF COMMERCE • Maurice H. Stans, Secretary

NATIONAL BUREAU OF STANDARDS • Lewis M. Branscomb, Director

Universal Testing Machine of 12-Million-lbf Capacity

At the National Bureau of Standards

Arthur F. Kirstein

Mechanics Division

Institute for Basic Standards

National Bureau of Standards

-h

National Bureau of Standards Special Publication 355

• » »

Nat. Bur. Stand. (U.S.), Spec. Publ. 355 18 pages (Sept. 1971)

CODEN: XNBSA

Issued September 1971

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402

(Order by SD Catalog No. C 13.10:355). Price 30 cents.
FOREWORD

As a result of a number of structural failures,

exemplified by the disastrous collapse of a lattice column

during erection of the first Quebec bridge in 1907, the

Federal Government became deeply involved in structuralmaterial testing. In 1910 this work was consolidated at

the National Bureau of Standards and expanded through the

acquisition of a 10,000,000 lbf compression testing machine

originally contracted for by the Geological Survey.

This large testing machine, and other facilities of

the Engineering Mechanics Section of NBS, were used for extensive research into the mechanical behavior of such

structural components as columns, struts, masonry walls,

ship structures, and bridge members. When the NBS relocation to the Gaithersburg, Maryland, site was being planned,

it was evident that the 10,000,000 lbf capacity machine was

inadequate for current and projected needs. A modern machine, incorporating the technological advances of recent

years, was needed to enable NBS to continue its leadership

in research on large structural components and in calibration of large force measuring devices. These plans resulte

in the development and construction of a unique 12,000,000

lbf capacity universal testing machine.

This machine represents a significant addition to the

Nation's facilities for research and testing in the field

of large structures. The National Bureau of Standards welcomes the opportunity to use this unique facility in

cooperation with academic, industrial and government organi

zations in solving a wide variety of problems of National

concern.

Lewis M. Branscomb, Director

II
TABLE OF CONTENTS

1. INTRODUCTION 1

2. PRINCIPAL DIMENSIONS 2

3. FOUNDATION AND TIE -DOWN FLOOR SYSTEM . . 2

4. LOADING STRUCTURE 3

5. FORCE MEASURING SYSTEM 3

6. CONTROL CONSOLE 4

7 . ACCESSORIES 5

8. RESEARCH AND FORCE CALIBRATION 6

9. SUMMARY 6

10 . REFERENCES 7

FIGURES . 8-14

Library of Congress Catalog Card Number: 73-179678

III
In view of present accepted practice in this

technological area, U. S. customary units of

measurement have been used throughout this paper.

It should be noted that the U. S. is a signatory

to the General Conference on Weights and Measures

which gave official status to the metric SI

system of units in 1960. Readers interested in

making use of the coherent system of SI units

will find conversion factors in ASTM Standard

Metric Practice Guide, ASTM Designation E 380-70

(available from American Society for Testing and

Materials, 1916 Race Street, Philadelphia, Pennsylvania 19103) . Conversion factors for units

used in this paper are:

Length 1

1

in = 0.0254 meter

ft = 0.3048* meter

Force 1 lbf = 4.448 newton

Stress 1 lbf/in2 = 6895 newton/meter2

Moment 1 lbf-ft = 1.356 newton meter

Mass 1

1

ton = 907.2 kilograms

lb = 0.4536 kilograms

Exact values

IV
Universal Testing Machine of 12-Million-lbf

Capacity at the National Bureau of Standards

Arthur F. Kirstein

A 12-million pounds-force capacity universal

testing machine, which is believed to be the

largest of its kind in the world, has been put

into operation in the Engineering Mechanics Laboratory of the National Bureau of Standards in

Gaithersburg , Maryland. This hydraulically

operated machine, which has an overall height of

over 100 feet, was designed to test full scale

structural components and to apply the forces

needed to calibrate large capacity force measuring devices. The testing machine is capable of

applying axial forces of 12,000,000 lbf in compression, 6,000,000 lbf in tension, and a transverse force of 4,000,000 lbf to a flexural

specimen

.

Key words: Force calibration; large test

facilities; structural testing;

universal testing machine.

1. INTRODUCTION

For many years the National Bureau of Standards has been aware of

the increasing requirements for a large force generating facility which

would be suitable for tests of large full scale structural components

and for calibration of large force measuring devices. To satisfy these

requirements, plans were made for the design and construction of a 12,000,000 lbf capacity universal testing machine—plans which were consummated with the construction of a new large testing facility in the

Engineering Mechanics Laboratory in Gaithersburg, Maryland (fig. 1).

This hydraulically operated machine is a vertical, four-screw type

with the main fixed platen flush with the floor (fig. 2). It projects

approximately 78 feet above the floor level, and extends about 23 feet

into a pit. It is capable of applying 12,000,000 lbf in compression,

6,000,000 lbf in tension, and 4,000,000 lbf to a flexural specimen.

This new universal testing machine has replaced a 10,000,000 lbf

capacity compression testing machine, which has been in service since the

early nineteen-hundreds . A comparison of the features of the new machine,

described in this paper, to those of the 10,000,000 lbf machine, as

given in references 1 and 2, will show the many advances that have been

made through the years and are incorporated in this new machine.

1
2. PRINICIPAL DIMENSIONS

The 12,000,000 lbf capacity universal testing machine, shown in

figure 3, projects approximately 78 feet above the floor and extends

about 23 feet below into a pit. The overall height of the machine is

then approximately 101 feet, and its gross weight is about 2,000,000

pounds. The base of the machine is attached to its reinforced concrete

foundation with a prestress force of 4,000,000 lbf. A test floor 90

feet long is an integral part of this foundation.

The test openings and the sizes of the test fixtures govern the

sizes of specimens that can be tested in this machine. The vertical

opening between the bedplate, which rests on the main platen (fig. 2),

and the compression leveling plate assembly, which is on the sensitive

crosshead, is infinitely adjustable along the screw columns to provide

vertical openings up to 58 feet for compression tests. For tension tests

the vertical opening from the top of the sensitive crosshead to the bottom of the tension crosshead is infinitely adjustable from zero to 53

feet. These dimensions allow for the full 5 foot power stroke of the

main hydraulic cylinder. For convenience, the tension head can be located at the notched positions along the two main columns as shown in

figure 3. These notches are located 32, 42, 52, 62, and 72 feet above

the main platen of the machine. Both of the test openings given above

can be increased by two feet if the compression leveling plate assembly

and the bedplate are removed from the machine. The clear horizontal

working space between the screw columns is 8 feet 4 inches, and the

working surface of the main platen is 8 feet 4 inches by 15 feet. The

bedplate is 7 feet in diameter and 1 foot thick. The working surface of

the foundation, which extends beyond the main platen, contains a tiedown floor system that can be used to support transverse or flexural

specimens up to 90 feet in length.

3. FOUNDATION AND TIE-DOWN FLOOR SYSTEM

The reinforced concrete foundation for this machine includes a tiedown floor system which provides the capability to perform transverse or

flexural tests on specimens up to 90 feet in length. A plan view of the

foundation is shown in figure 4. The pit through the central portion

contains the hydraulic and electric equipment to operate the machine as

well as the lower 23 feet of the machine. The overall dimensions of the

tie-down floor are 90 feet in length and 16 feet 8 inches in width.

Other pertinent dimensions of the 126 tie-down bolt locations are shown

in figure 4.

2
The working strength values for the tie-down floor system are:

Longitudinal bending moment 12,500,000 lbf-ft

(over central 40 feet) 20,000,000 lbf-ft

Tranverse bending moment 467,000 lbf-ft/ft of width

(over central 40 feet) 750,000 lbf-ft/ft of width

Uniform bearing 940 lbf/in2

Tensile force on anchor bolts 150,000 lbf/bolt

4. LOADING STRUCTURE

The loading structure consists of a fixed frame and a movable frame.

The fixed frame is built around the main platen and includes the main

platen, main columns, top tie plate, and tension crosshead (fig. 3). The

movable frame is supported by the fixed frame, and includes the main

hydraulic cylinder, screw columns, and sensitive crosshead. Compression

tests are performed between the sensitive crosshead and the bedplate, and

tension tests are performed between the sensitive and tension crossheads.

Flexural tests may be performed between the sensitive crosshead and

either the main platen or the tie-down floor system. In all cases the

test load is applied by pressurizing the main hydraulic cylinder which

pulls the screw columns through the main platen thus drawing the sensitive crosshead downward and providing the force required for compression,

tension, or flexural testing.

An important feature of the loading structure is the backlash elimination system, which locks the sensitive crosshead to the screw columns.

This feature prevents recoil damage to the threads of both the screw

columns and drive nuts of the crosshead. It also provides for greater

stability of the movable frame.

Two hydraulic capsules are installed in the sensitive crosshead.

One of these annular cells provides the force measuring function for

compression, tension, and flexural testing. The other cell provides the

preloading that is required for proper operation of the force measuring

cell. Pressure transducers, located within a constant temperature oven

on the sensitive crosshead, sense the pressure within the force measuring cell and transform it into an electrical signal. This signal is

transmitted to the control console where the applied load, in poundsforce, is displayed by analog and/or digital indicating systems. The

full scale ranges of these indicating systems are:

5. FORCE MEASURING SYSTEM

3
Analog ranges Digital ranges

lbf lbf

12,000,000 12,000,000

6,000,000 1,200,000

3,000,000 120,000

1,200,000

600,000

All ranges have been calibrated, and generally do not exhibit errors

greater than 0.5 percent of the applied load.

There are two other features incorporated in the force measuring

system which are worthy of note. One device is incorporated with the

analog indicator to transmit force measurement output signals directly

to a data acquisition system. This records the force along with the

strain and displacement measurements for future reference and study, and

also provides the machine operator with a visual means to monitor and

control the progress of the test. The other device provides for the use

of an auxiliary (external) load cell with the analog indicating system.

This feature permits the selection of a wide number of full scale ranges

not available from the internal force measuring system.

The majority of the machine operations are controlled and monitored

from the control console which is located on the floor adjacent to the

testing machine (fig. 2). Auxiliary controls are provided at convenient

locations on both the movable work platform and the sensitive crosshead

to facilitate their operation.

The hydraulic and electric controls for the loading and unloading

operations for both the main and auxiliary pumps are manipulated from

the console. Two sets of valves are provided to permit the machine

operator to use coarse or fine control of the flow of hydraulic fluid to

and from the main cylinder. This, in effect, lets the operator select a range of combinations from needle valve control of the low flow auxiliary

pump to coarse valve control of the flow from the main pump. The fine

control is useful in calibration set ups, which may require maximum

crosshead motions in the order of 0.035 inch to apply the full calibration force. Coarse controls are generally used for testing less rigid

structures where applications of the desired test loads may require

crosshead motions up to the full 5 foot power stroke of the machine.

6. CONTROL CONSOLE

4
As mentioned previously the force measuring system is monitored

from the console on analog and/or digital indicating systems. These

systems are conveniently located in front of the operator to aid in the

manual control of the loading and unloading operation.

Other operations which can be controlled from the console are raising and lowering the movable work platform, locking and unlocking the

backlash elimination system, and positioning both the tension and sensitive crossheads prior to testing.

7. ACCESSORIES

The machine is equipped with basic accessories such as compression

and tension test fixtures, specimen restraining structures, a movable

work platform, and load-handling equipment to facilitate the installation

of test specimens in the machine.

A compression leveling plate assembly is mounted on the underside of

the sensitive crosshead to accommodate nonparallel ends of compression

specimens. This assembly, which can bear the full 12,000,000 lbf compression capacity of the testing machine, can be tilted as much as 0.5

inch, in a 60 inch diameter, toward any point of the compass.

To apply the full 6,000,000 lbf tension capacity to specimens, the

machine is supplied with assemblies consisting of wedge blocks, nuts,

spherical washers, tension rods, and either threaded couplings or clevis

fixtures. One of each of these fixtures is shown in figure 5. Threaded

couplings are available with 11-3ACME-2G and 15-3ACME-2G general purpose

threads. Each pair of couplings is equipped with right and left hand

threads to facilitate assembly. The clevis fixtures have 16 inch diameter pins, a 25 inch throat, and 12 inches clear between lugs to accommodate the tab ends of test specimens. In addition the machine is

presently equipped with both flat and V-type wedge grips (fig. 5) which

are capable of transmitting 3,000,000 lbf in tension to flat and round

specimens, respectively. The flat grips can accommodate plate specimens

up to 24 inches wide by 4 inches thick. The V-type grips can accommodate

round specimens from 2.75 to 8 inches in diameter.

In the testing of large structural components, there is the ever

present danger that the sudden release of energy due to abrupt specimen

failure could cause considerable damage by expelling part or all of the

specimen from the machine. In order to lessen this danger the machine is

equipped with basic restraining structures, recoil assemblies, and other

retaining devices which can be assembled into the machine as required.

Other accessories for the machine, which are independent of the

testing equipment, are a movable work platform and load-handling equipment. These accessories are shown in figure 2. The movable work platform

operates vertically along the four guide columns and is raised or lowered

by electric motors which can be controlled from either the platform or

from the testing machine control console. A ladder on one of the guide

5
columns, which extends to the full height of the machine, provides

convenient access to the platform at all positions above floor level.

In order to facilitate the placement of test specimens in the machine,

both the tension and the sensitive crossheads are equipped with loadhandling equipment. This equipment consists of pairs of monorails and

hoists which are mounted on the underside of each crosshead as shown in

figure 2. Each hoist on the tension crosshead can handle loads up to

eight tons while each of those on the sensitive crosshead has a twelve

ton capacity. Test specimens are raised from the floor or are transferred from a thirty-ton capacity overhead crane to these monorail

hoists, and are then transported into the machine along the monorails.

8. RESEARCH AND FORGE CALIBRATION

For the first time it is possible to load large column sections up

to 12,000,000 lbf. The heavy stub column shown in position between the

bedplate and the sensitive crosshead of the machine in figure 6 has an

estimated yield load of 7,200,000 lbf. The test of this 23H681 stub and

its 36-foot long companion column have awaited the completion of this

machine as no other existing machine offered the necessary size and load

capacity

.

Other tests of fabricated columns, large eye bars, large diameter

drill rod for undersea drilling operations, heavy specimens of wire

rope, and structural configurations of column and beam connections are

planned as future work for this unique testing machine.

This machine is also capable of applying forces for the calibration

of force measuring devices having capacities up to 12,000,000 lbf. Calibrations of large elastic force measuring devices are made in this machine using a configuration similar to that shown in figure 7. Here a large capacity load cell is compared with a group of smaller cells, each

of which was calibrated previously against known force standards such as

the NBS deadweight machines.

9 . SUMMARY

Recognizing needs for a new large testing facility for large force

calibrations and for full scale tests of large structural components,

NBS has planned, developed, and placed in service a unique 12,000,000 lbf

capacity universal testing machine which is believed to be the largest in

the world. To extend the versatility of this machine the reinforced concrete foundation incorporates a floor tie-down system which will accommodate flexural test specimens up to 90 feet in length.

The use of this machine makes it possible to obtain information on

the strength and behavior of structural components which because of their

size and load capacity could not be tested previously. Plans discussed

in the preceding section for force calibration and for tests of large

structural components show the impact that the machine has on NBS programs.
10. REFERENCES

1. Mosley, T. J. and Griffith, J. H., What Our Large Testing Machines

Have Accomplished, Engineering News-Record, 7J3, 4, April 26, 1917.

2. Griffith, J. H. , and Bragg, J. G. , Tests of Large Bridge Columns,

Bureau of Standards Tech Paper No. 101, June 27, 1918.

7
8
Figure 2. Universal testing machine of 12,000,000 lbf capacity.

9
Figure 3. Drawing of the 12,000,000 lbf capacity universal testing machine.

10
7 bolts 2' -0" o. c.

D

• • •

oo

m

CaH

-P

cd -p

CO oo

If"

I

oo

i

oo

N

COC

O

•HP

(0 -P

to

oo

11
12
Figure 6. Heavy stub column in the 12,000,000 lbf capacity universal

testing machine.

13
14
FORM NBS-114A (1-71)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBS-SP-355

2. Gov't Accession

No,

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

Universal Testing Machine of 12-Million-lbf

Capacity at the National Bureau of Standards

5. Publication Date

September 1971

6. Performing Organization Code

7. AUTHOR(S)

At* flu it* U

1 ill LllUL r o Ifi JX-L rchoin 1 o LC ill

8. Performing Organization

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 2130141

11. Contract/Grant No.

12. Sponsoring Organization Name and Address

Same as No . 9 .

13. Type of Report & Period

Covered

Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.)

A 12-million pounds- force capacity universal testing machine, which is believed

to be the largest of its kind in the world, has been put into operation in the

Engineering Mechanics Laboratory of the National Bureau of Standards in Gaithersburg

,

Maryland. This hydraulically operated machine, which has an overall height of over

100 feet, was designed to test full scale structural components and to apply the

forces needed to calibrate large capacity force measuring devices. The testing

machine is capable of applying axial forces of 12,000,000 lbf in compression,

6,000,000 lbf in tension, and a transverse force of 4,000,000 lbf to a flexural

specimen.

17. KEY WORDS (Alphabetical order, separated by semicolons)

Force calibration; large test facilities; structural testing; universal testing

machine.— » 18. AVAILABILITY STATEMENT 19. SECURITY CLASS

(THIS REPORT)

21. NO. OF PAGES

18

[Xl UNLIMITED

UNCLASSIFIED

1 I FOR OFFICIAL DISTRIBUTION. DO NOT RELEASE

TO NTIS.

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

22. Price

30 cents

, USCOMM-DC 66244-P71

<r U. S. GOVERNMENT PRINTING OFFICE : 1971 481-325/58

NBS TECHNICAL PUBLICATIONS

PERIODICALS

JOURNAL OF RESEARCH reports National

Bureau of Standards research and development in

physics, mathematics, chemistry, and engineering.

Comprehensive scientific papers give complete details

of the work, including laboratory data, experimental

procedures, and theoretical and mathematical analyses. Illustrated with photographs, drawings, and

charts.

Published in three sections, available separately:

• Physics and Chemistry

Papers of interest primarily to scientists working in

these fields. This section covers a broad range of

physical and chemical research, with major emphasis on standards of physical measurement, fundamental

constants, and properties of matter. Issued six times

a year. Annual subscription: Domestic, $9.50; $2.25

additional for foreign mailing.

• Mathematical Sciences

Studies and compilations designed mainly for the

mathematician and theoretical physicist. Topics in

mathematical statistics, theory of experiment design,

numerical analysis, theoretical physics and chemisty, logical design and programming of computers

and computer systems. Short numerical tables. Issued

quarterly. Annual subscription: Domestic, $5.00;

$1.25 additional for foreign mailing.

• Engineering and Instrumentation

Reporting results of interest chiefly to the engineer

and the applied scientist. This section includes many

of the new developments in instrumentation resulting

from the Bureau's work in physical measurement,

data processing, and development of test methods.

It will also cover some of the work in acoustics,

applied mechanics, building research, and cryogenic

engineering. Issued quarterly. Annual subscription:

Domestic, $5.00; $1.25 additional for foreign mailing.

TECHNICAL NEWS BULLETIN

The best single source of information concerning the

Bureau's research, developmental, cooperative, and

publication activities, this monthly publication is designed for the industry-oriented individual whose

daily work involves intimate contact with science and

technology

for engineers, chemists, physicists, re- search managers, product-development managers, and

company executives. Annual subscription: Domestic,

$3.00; $1.00 additional for foreign mailing.

Order NBS publications from:

NONPERIODICALS

Applied Mathematics Series. Mathematical tables,

manuals, and studies.

Building Science Series. Research results, test methods, and performance criteria of building materials, components, systems, and structures.

Handbooks. Recommended codes of engineering

and industrial practice (including safety codes) developed in cooperation with interested industries,

professional organizations, and regulatory bodies.

Special Publications. Proceedings of NBS conferences, bibliographies, annual reports, wall charts,

pamphlets, etc.

Monographs. Major contributions to the technical

literature on various subjects related to the Bureau's

scientific and technical activities.

National Standard Reference Data Series.

NSRDS provides quantitative data on the physical

and chemical properties of materials, compiled from

the world's literature and critically evaluated.

Product Standards. Provide requirements for sizes,

types, quality, and methods for testing various industrial products. These standards are developed co- operatively with interested Government and industry

groups and provide the basis for common understanding of product characteristics for both buyers and

sellers. Their use is voluntary.

Technical Notes. This series consists of communications and reports (covering both other agency and

NBS-sponsored work) of limited or transitory interest.

Federal Information Processing Standards

Publications. This series is the official publication

within the Federal Government for information on

standards adopted and promulgated under the Public

Law 89-306, and Bureau of the Budget Circular A-86

entitled, Standardization of Data Elements and Codes

in Data Systems.

Consumer Information Series. Practical information, based on NBS research and experience, covering

areas of interest to the consumer. Easily understandable language and illustrations provide useful background knowledge for shopping in today's technological marketplace.

NBS Special Publication 305, Supplement 1,

Publications of the NBS, 1968-1969. When ordering, include Catalog No. CI 3. 10: 305. Price $4.50;

$1.25 additional for foreign mailing.

Superintendent of Documents

Government Printing Office

Washington, D.C. 20402
U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Washington. D.C. 20234

OFFICIAL BUSINESS

Penalty for Private Use, $300

POSTAGE AND FEES PAID

U.S. DEPARTMENT OF COMMERCE