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INbS SPECIAL PUBLICATION 529

U.S. DEPARTMENT OF COMMERCE / National Bureau of Standards

Interagency Comparison of

Ultraviolet Photometric Standards

for Measuring Ozone Concentrations
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards' 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

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and the Institute for Computer Sciences and Technology.

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guidelines, and managing Federal participation in ADP voluntary standardization activities; provides scientific and technological advisory services and assistance to Federal Agencies; and

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The Institute consists of the following divisions:

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'Headquarters and Laboratories at Gaithersburg, Maryland, unless otherwise noted; mailing address Washington, D.C. 20234. Some divisions within the center are located at Boulder, Colorado, 80303.

The National Bureau of Standards was reorganized, effective April 9, 1978.
Iteragency Comparison of

Itraviolet Photometric Standards

r IVIeasuring Ozone Concentrations

1 1 2

. Wendt, J. Kowalski, A. M, Bass,

Ellis, and M. Patapoff^

lifornia Air Resources Board

^4onte, California 91734

Ltional Measurement Laboratory

lional Bureau of Standards

jshington, DC 20234

Ivironmental Protection Agency

1 earch Triangle Park

1 'ham, North Carolina 27709

Propulsion Laboratory

i adena, California 91104

IS. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

liordan J. Baruch, Assistant Secretary for Science and Technology

[TIONAL bureau of standards, Ernest Ambler, Director

I ued December 1978

JAN 2 1979

rv4?^ Ac c: - 0

^ U
Library of Congress Catalog Card Number: 78-600126

National Bureau of Standards Special Publication 529

Nat. Bur. Stand. (U.S.), Spec. Publ. 529, 25 pages (Dec, 1978) CODEN: XNBSAV

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1978

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

Stock No. 003-003-02002-8 Price $1.30

(Add 25 percent additional for other than U.S. mailing).
Interagency Comparison of Ultraviolet Photometric Standards

for Measuring Ozone Concentrations

J. Wendt, J. Kowalski, A. M. Bass, C. Ellis, and M. Patapoff

ABSTRACT

In August 1977, an interlaboratory comparison study was initiated

after the California Air Resources Board and the Environmental Protection Agency, Research Triangle Park independently designed and constructed ozone absolute ultraviolet photometers. These units augmented the

photometers already designed and in use by the National Bureau of

Standards and the Jet Propulsion Laboratory. Previous ozone comparisons

involving indometry, ultraviolet photometry and gas phase titration have

reported results differing by as much as + 30%. The protocol of this

study, performed at the California Air Resources Board, Haagen-Smit

Laboratory, El Monte, was a multipoint comparison using the NBS photometer as the standard. The results of the data analysis indicate

excellent agreement with a total variation of 2.8%. Compared to the NBS

photometer the EPA-RTP photometer read 1.3% low, the JPL photometer read

1.5% high and the ARB photometer read 0.4% low. The correlation coefficients of the same data sets were 1.0000, 1.0000 and 0.9999 respectively.

Keywords: Air pollution; atmospheric monitoring; calibration; ozone;

ultraviolet; photometry.

1
1. INTRODUCTION

For more than 100 years, ozone concentrations have been determined

by utilizing the chemical reaction between ozone and potassium iodide to

liberate iodine which is then measured by chemical or physical means.

The neutral buffered, potassium iodide (NBKI) method has gained wide

acceptance and is the calibration technique of the Federal Reference

Method for measuring photochemical oxidant concentrations . [6] Despite

variations in the chemical composition of the reagents, all of the

potassium iodide methods in common use assume a one to one stoichiometry

between the iodine released and the ozone reacted. [2]

Studies conducted by the California Air Resources Board and the

U. S. Environmental Protection Agency have shown significant departures

from the assumed stoichiometry. The stoichiometry departures were found

to depend on the buffering agent and potassium iodide concentrations.

These departures also depend on the nature of the buffering agent and

the absolute humidity of the sample air stream. [2,3]

As a result of the various studies, the California Air Resources

Board in May of 1975 adopted ultraviolet photometry as its reference

method for measuring ozone concentrations . [7] Since California's

adoption, interest in ultraviolet photometry as a standard for measuring

ozone concentrations has steadily escalated. Ultraviolet photometry is

now generally considered a prime candidate for replacing the existing

Figures in brackets indicate literature references at the end of this

paper.

2
NBKI calibration procedure and ASTM Methods for measuring photochemical

ozone concentrations.

By June of 1977, four agencies, the California Air Resources Board,

National Bureau of Standards, U. S. Environmental Protection Agency, and

the Jet Propulsion Laboratory independently designed and fabricated long

path ultraviolet ozone photometers. The four photometers are all of

different design with two located on each coast of the United States.

In August of 1977 the photometers or suitable transfer standards

were assembled at the California Air Resources Board's Laboratory in El

Monte, California. The four photometric standards were allowed to

sample a common ozone supply and their respective readings compared.

The results of the comparison are reported.

2. PHOTOMETER DESIGNS

2.1 National Bureau of Standards (NBS)

The NBS photometer is designed to measure ozone concentrations

ranging from 0.05 to 10.0 ppm with an accuracy of approximately 0.005

ppm by volume. The design of the photometer, shown in figure 1, incorporates

a double-beam arrangement to provide greater precision in the measurement

by elimination of variability in the UV source. The cells of the photometer are approximately 3 meters long and are made of 1-1/2" diameter

pyrex pipe; teflon gaskets are used to make vacuum-tight seals for the

fused silica windows. The light from a low pressure mercury discharge

lamp is passed through a narrow-band interference filter in order to

isolate the 253.7 nm emission line. The light is collimated by a fused

silica lens and passed through a partially-transmitting neutral density

filter which serves as a beam splitter. The two beams then pass through

3
the two absorption cells. Adjustable aperture stops limit the diameter

of the beams to ensure that there are no reflections from inner walls of

the cells. The light beams emerge from the cells and are recombined on

the face of a photomul tipl ier tube by another partially reflecting

filter.

Light passing through each sample cell is alternately allowed to

fall on the photomul tipl ier by means of a light chopper. A chopper

blade with a single hole is driven by a hysteresis synchronous motor.

Light emitting diode-phototransistor pairs are used to sense the positioning

of the hole in the chopper blade; the signal from the phototransistor

triggers a discriminator to start the timing and counting cycle for each

sample tube.

A logic system, triggered by the discriminators, controls pulse

counters associated with each sample tube. In order to ensure precise

counting times as the photomul tipl ier is exposed to each tube, an electronicjj

gate is used to ensure that the photomul tipl ier is fully (and not merely

partly) exposed to the light beam passing through the sample.

The pulse output from the photomul tipl ier is amplified, and pulse

counting is performed by conventional 100 MHz pulse counters and a rough

guide of overall pulse rate is provided by a rate meter. Counting time

is determined by a preset counter. At the end of a counting interval,

the results are printed out.

House air, dried and filtered, flows through one cell ("reference

cell"), then into an ozone generator from which ozonized air flows

through the second cell ("sample cell"). The measurement is made by

comparing the ratio of the signals transmitted by the two cells in the
presence and in the absence of ozone. This provides the transmi ttance

(Tr = J

), and the ozone concentration is determined by application of

0

the Beer-Lambert Law. Since the mercury lamp is viewed, nearly simultaneously, through both cells, fluctuations in lamp intensity do not

affect the measurement. Any impurity present in the air stream will be

observed in both cells and will not interfere with the 0^ determination, [8] unless it too is photolysed by the 0^ generator and it or the

products absorb at 253.7 nm.

2.2 Jet Propulsion Laboratory (JPL)

There are three components to the JPL photometer, the light source,

the absorption cell, and the light detector as shown in figure 2. A

low-pressure mercury lamp is used as a source of the 253.7 nm light. A

1/4-m monochromator was used to spectrally isolate the 253.7 nm line.

(This component is not strictly necessary and can be replaced by an

interference filter to isolate the 253.7 nm line). Collimation of the

light beam was aided by use of a 25-cm focal length quartz lens. Stability

of the light source was enhanced by operation from a constant voltage

transformer and by enclosing the lamp in an aluminum block for increased

thermal inertia. The absorption cell is constructed of 2-in o.d. Pyrex

tubing, and has a path length of 5.00 m. Quartz windows are attached at

each end by means of epoxy cement, with care being taken to minimize

internal exposure of cement. The 253.7 nm light emerging from the cell

is monitored with a solar-blind, side-on photomul tipl ier tube. The

photomul tipl ier is operated at 340 V. The photomul tipl ier output

voltage is measured across a 10-11^2 resistor and is read with a four5
digit voltmeter. A 0.4-yfd condenser is placed in parallel with the

resistor to obtain a suitable time constant.

Ozone is generated in a stream of cylinder air by means of a

photochemical generator of conventional design, employing a low-pressure

mercury lamp with a sliding shield to vary the 0^ concentration. The

gas flow through the cell, usually 5-7 1/min, enters near one end of the

cell and exits at the opposite end. It has been established experimental]

that there is no appreciable gradient of ozone concentration in the

cell.

With carrier gas flowing, photomul tipl ier output voltages are read

periodically during the calibration procedure and are plotted as a

function of time. At intervals, transmi ttance readings are taken at

ozone concentrations in the range 0.00 to 0.85 ppm of O^. Transmi ttance

ratios (Iq/I-j-) then calculated, and ozone concentrations determined

by application of the Beer-Lambert Law. [9]

2.3 Environmental Protection Agency (EPA-RTP)

The EPA-RTP photometer, as shown in figure 3, is a two meter

instrument designed to demonstrate how off-the-shelf electronics could

be used to produce a high precision (+ 1 ppb) photometer. The absorp- ;

tion volume consists of two one-meter cells in a folded path configura- j

tion which reduces the overall instrument length to 1.27 meters and

greatly improves the system's portability. The cells are made of 12 mm

inside diameter pyrex tubing and are fitted with quartz windows via

teflon gaskets. The optical path is folded by means of small plane

mirrors which are located outside the absorption cell. i
The photometer is essentially monochromatic due to use of a Vycor

i-nvelope on the low pressure mercury source and solar blind vacuum

ihoto-diode detectors. A reference detector is used to monitor the

i ight source in a quasi-double beam configuration. A sample detector is

sed to monitor the absorption of the light in the cell.

An ozone concentration is determined by alternately filling the

ell with ozone-free reference air and the ozone calibration atmosphere,

he transmi ttance of the ozone sample is equal to the ratio of the

ormalized sample channel frequency obtained with ozone in the absorption

ell to that obtained with reference air in the cell. The ozone concentration

s calculated from the transmi ttance via the Beer-Lambert absorption

aw.

2.4 California Air Resources Board (ARB) -

The ARB photometer is designed to measure ozone concentrations

•anging from 0.02 to 15.0 ppm with an accuracy of 0.01 ppm over the

ntire range. To achieve the design accuracy, the photometer incorporates

double beam principle which eliminates errors resulting from light

ource or air supply variations. The cells of the photometer are

onstructed from 1/2 inch diameter Pyrex pipe with a path length of 260

iientimeters . Quartz windows, sealed with epoxy cement, are affixed to

ach end of the cells as shown in figure 4.

A low pressure mercury discharge lamp of sufficient length to span

;t*oth cells of the photometer is used as a source of 253.7 nm light. The

''ycor sheath of the lamp and the detector spectral response characteristics

imit the photometer sensitivity to the 253.7 nm emission line. Lamp

utput stability is achieved by operating the mercury discharge lamp

7
from a crystal controlled, chopped d.c. power supply, and housing the

lamp in a thermally controlled aluminum block.

Light passing through the sample and reference cells is converted

to analog current signals by separate detectors mounted in a thermally

controlled aluminum block. The analog current signals are converted to

frequency signals utilizing digital electrometers. The electrometer

outputs are connected to a dual channel frequency counter capable of

counting the reference channel to a preset value. Each time the preset

reference count is reached, the ratio of the sample detector count to

reference detector count is displayed.

An ozone concentration measurement is accomplished by first admitting ozone free air to each cell of the photometer. The ratio I^/REFERENCE

INTENSITY (ratio of zero air to reference detector count) is recorded.

Ozonized air from the ozone generator is then admitted to the sample

cell with ozone free air flowing through the reference cell. The ratio

I/REFERENCE INTENSITY (ratio of sample to reference detector count) is

j recorded and the transmi ttance ratio I/I^ calculated. The ozone concentration is calculated from the Beer-Lambert Law.

3. EXPERIMENTAL ,

'

The experimental phase of the photometer comparison was conducted

at the California Air Resources Board's El Monte Laboratory utilizing

the experimental setup of figure 5. Clean, dry, ozone free air was

supplied to the experimental setup by an Aadco clean air supply designed !

to ARB specifications. The clean air was metered to a Monitor Labs Inc.

Model 8500 calibration system and to a multiported glass manifold by j mass flow controllers. The ozone output of the calibration system was
ducted to a mul tiported glass manifold. All interconnections were made

using Teflon tubing.

A direct comparison of the NBS and JPL photometers with those of

the ARB and EPA-RTP could not be accomplished due to the large size,

complexity and construction characteristics of the photometers. NBS and

JPL participation in the comparison studies was accomplished through the

use of Dasibi Corporation Model 1003 AH ozone monitors[10] as transfer

standards. Each transfer standard was calibrated against the respective

agencies' photometer before and after the El Monte comparison. Both the

ARB and EPA-RTP photometer, described herein, were used directly in the

comparison studies. It should be noted that the EPA-RTP photometer was

disassembled, shipped, and reassembled at the ARB laboratories. With

minimal checkout prior to the comparison, the precision and stability

the readings were less than in previous laboratory measurements.

A total of eight experimental runs, each consisting of pre and post

run instrument zero, and an ozone concentration ranging from 0.05 to

0.70 ppm, were completed. Following each experimental run, the respective

agencies calculated the ozone concentration recorded by their photometer

by making the necessary temperature and pressure adjustments using the

following equations:

ARB, EPA-RTP*

I -In 0

I

9
where:

JPL

T = absolute temperature, °K

P = absolute pressure in photometer, torr

L = photometer path length, cm

k = extinction coefficient, base e, cm~^ atm"^

intensity of light with zero ozone

I = intensity of light with ozone at concentration

* The EPA-RTP calculations also include a 1% correction for ozone

losses which occur in the photometer. [1 1

]

100 - ^

where:

NBS

where

C (pp.) = <^^^-°f^|in \Z:°f^ [12]

0.539

3 = correction constant for reference Dasibi S/N 1386; (1.0685)

B = Dasibi background reading

R = Dasibi ozone reading

P = absolute pressure, torr

T = absolute temperature, °K

C (pp„) = (^^^-QfS) in [13]

Al = change in light intensity between zero and ozonized air;

Dasibi reading)

T = absolute temperature, °K

P = absolute pressure, torr

3 = correction constant for reference Dasibi S/N 1707; (1.0134

54.6 = span factor of Dasibi transfer standard

1Q
The extinction coefficient used by all participants in the comparison

study was 308.5 cm~^ atm"^ base e.[14]

4. RESULTS

The final ozone concentrations for each participant are tabulated

as fol lows

:

TABLE I

. -

-

Ozone Concentrations

(Part per mi 1 1 ion)

Data Pt. NBS EPA-RTP JPL ARB

1 0.689 0.683 0.700 0.681

2 0.109 0.110 0.112 0.109

3 0.605 0.597 0.612 0.599

4 0.185 0.184 0.189 0.183

5 0.494 0.490 0.503 0.494

6 0.301 0.299 0.307 0.296

7 0.389 0.385 0.396 0.389

8 0.047 0.049 0.047 0.042

The NBS photometer was selected as the reference standard in the

data analysis. As indicated in Table I the data show excellent agreement.

A linear regression and correlation coefficient (r) analysis of the data

confirms the agreement. From the analysis, the following relationships

were obtained:

11
^^3\bS ' (^-013) C03]^p^_f^^p - (0.002) r - 1.0000

f^^S^NBS

' (0.985) [03]jpL - (0.001) r » 1.0000

^^S^NBS ' (1-004) ^^s'^m ~ (0.002) r - 0.9999

Figures 6, 7, and 8 are linear regression plots of the NBS ozone

concentrations versus the EPA-RTP, JPL, and ARB ozone concentrations.

It should be emphasized that for the comparison, both NBS and JPL

utilized transfer standards, rather than the actual absolute photometers.

Additionally the EPA-RTP photometer was shipped from North Carolina and

assembled at the ARB laboratory with a minimum of checkout. The ARB

photometer was the only unit compared in its stationary position. With

this realization, the agreement to within 2.8% of all four units is

highly significant.

The analysis indicates an excellent agreement utilizing the ultraviolet photometric techniques. The linear regression confirmed the

accuracy of each method, with the correlation coefficients indicating a

high degree of precision.

5. ACKNOWLEDGMENT

The authors wish to thank Drs. Jimmie Hodgeson (NBS), Richard Paur

(EPA-RTP) and William DeMore (JPL) for their technical assistance and

support of these studies. In addition, the authors thank Jolene Hori

,

Kevin Kalthoff, Jack Horrocks, and Kahirup Torre of the California Air

Resources Board for their assistance throughout various phases of this

effort.

This work was supported in part by the National Bureau of Standards'

Office of Environmental Measurements Program,

12
6. REFERENCES

1. Hodgeson, J. A., "A Survey of Calibration Techniques for Atmospheric

j Ozone Monitors," NBSIR 76-1191, National Bureag of Standards, Washington,

DC, December 1976.

2. DeMore, W. B., Romanovs ki, J. C. , Feldstein, M., Hamming, W. J., Mueller,

P. K., "Comparison of Oxidant Calibration Procedures", Ad Hoc Oxidant

Measurement Committee, California Air Resources Board, February 3, 1975.

' 3. Torre, K. J., "A Study of the Effect of Atmospheric Humidity on Analytical Oxidant Measurement Methods", presented at 15th Conference - Methods in Air Pollution Studies, AIHL, Calif. Dept. of Health, Air

Resources Board, Long Beach, Calif., Jan. 14-15, 1976.

4. DeMore, W. B., Patapoff, M. , "Comparison of Ozone Determinations by

Ultraviolet Photometry and Gas-Phase Titration", Environmental Science

and Technology, 10, 897 (1976).

j

' 5. Flamm, D. L., "Analysis of Ozone at Low Concentrations with Boric

Acid Buffered KI", Environmental Science and Technology ]]_, 978 (1977).

6. Federal Register, 36 (228), 22392 (Nov. 25, 1971).

J 7. State of California Air Resources Board Resolution 75-30, Board meeting,

May 15, 1975, Sacramento, Calif.

8. Bass, A. M., Ledford, A. E. Jr., and Whittaker, J. K., NBS paper,

"Ultraviolet Photometer for Ozone Calibration, in Methods and Standards

for Environmental Measurement" (NBS Special Publication 464)

9-15 (1977).

I'l 9. DeMore, W. B., "Ozone Determination by Ultraviolet Absorption

Photometry", presented at 15th Conference - Methods in Air Pollution

Studies, AIHL, Calif. Dept. of Health, Air Resources Board, Long Beach,

Calif., Jan. 14-15, 1976.

it

'i 10. Bowman, L. D., Horak, R. F., "A Continuous Ultraviolet Absorption

Ozone Photometer", ISA AID, 72430 (103-108) 1972.

11. Ellis, C, Southern California Edison Company, Rosemead, California,

private communication, Oct. 1977.

i 12. Patapoff, M. , Jet Propulsion Laboratory, Pasadena, California, private

communication, Sept. 1977.

13. Bass, A. M., United States Department of Commerce, NBS, Washington,

DC, private communication, Feb. 1978.

13
14. The value of k used in this work (308.5 cm" atm" ) is based on an evaluation by R. Hampson and D. Garvin of measurements reported in

the published literature:

(a) Inn, E. C. Y. and Y. Tanaka, J. Opt. Soc. Am. 43, 870 (1953).

(b) Hearn. A. G.

.

Proc. Phys. Soc. 78, 932 (1961),

(c) DeMore, W. B. and 0. Paper, J. Phys. Chem. 68, 412 (1964).

(d) Griggs, M. , J . Chem. Phys. 49, 857 (1968).

(e) Simons, J. W.

J. Chem. Phys

, R. J. Paur, H. A. Webster and E. J.

. 59, 1203 (1973).

Bair,

(f) Becker, K. H. Kinet. 6, 725

, U. Schurath, and H. Seitz, Int. J. (1974).

Chem.

Disclaimer:

Certain trade names and company products are identified in order to

adequately specify the experimental procedure. In no case does such

identification imply recommendation or endoresement by the National

Bureau of Standards, nor does it imply that the products are necessarily

the best available for the purpose.
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16
17
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19

0.8

NBS O3 (ppm)

FIGURE 7

21
0.8 n

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

NBS O3 (ppm)

FIGURE 8

22
BS-1 14A (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBS SP 529

2. Gov't Accession

No.

3. Recipient's Accession No.

. TITLE AND SUBTITLE

Interagency Comparison of Ultraviolet Photometric Standards

for Measuring Ozone Concentrations

5. Publication Date December 1978

6. Performing Organization Code

J

AUTHOR(S)

. Wendt, J. Kowalski, A. M. Bass, C. Ellis, M. Patapoff

8. Performing Organ. Report No.

1. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No.

11. Contract/Grant No.

2. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP) 13. Type of Report & Period Covered

14. Sponsoring Agency Code

i. SUPPLEMENTARY NOTES

Library of Congress Catalog Card Number: 78-600126

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

bibliography or literature survey, mention it here.) In August 1977, an inter laboratory comparison study was initiated after the

California Air Resources Board and the Environmental Protection Agency, Research

Triangle Park independently designed and constructed ozone absolute ultraviolet

photometers. These units augmented the photometers already designed and in use by

the National Bureau of Standards and the Jet Propulsion Laboratory. Previous ozone

comparisons involving indometry, ultraviolet photometry and gas phase titration have

reported results differing by as much as ±30%. The protocol of this study, performed

at the California Air Resources Board, Haagen-Smit Laboratory, El Monte, was a multiooint comparison using the NBS photometer as the standard. The results of the data

analysis indicate excellent agreement with a total variation of 2.8%. Compared to the

-IBS photometer the EPA-RTP photometer read 1.3% low, the JPL photometer read 1.5% high

and the ARB photometer read 0.4% low. The correlation coefficients of the same data

sets were 1,0000, 1.0000 and 0.9999 respectively.

. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons

\ir pollution; atmospheric monitoring; calibration; ozone; ultraviolet photometry

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NBS TECHNICAL PUBLICATIONS

PERIODICALS

OURNAL OF RESEARCH—The Journal of Research

f the National Bureau of Standards reports NBS research nd development in those disciplines of the physical and

ngineering sciences in which the Bureau is active. These

iiclude physics, chemistry, engineering, mathematics, and

pmputer sciences. Papers cover a broad range of subjects, Hth major emphasis on measurement methodology, and

jie basic technology underlying standardization. Also in- |!uded from time to time are survey articles on topics closely

;;lated to the Bureau's technical and scientific programs. As

I special service to subscribers each issue contains complete

[itations to all recent NBS publications in NBS and non-

^IBS media. Issued six times a year. Annual subscription:

lomestic $17.00; foreign $21.25. Single copy, $3.00 domestic;

13.75 foreign.

ifote: The Journal was formerly published in two sections:

iection A "Physics and Chemistry" and Section B "Mathelatical Sciences." |tIMENSIONS/NBS

|his monthly magazine is published to inform scientists, igineers, businessmen, industry, teachers, students, and

bnsumers of the latest advances in science and technology,

ith primary emphasis on the work at NBS. The magazine

ighlights and reviews such issues as energy research, fire TOtection, building technology, metric conversion, pollution

batement, health and safety, and consumer product per- ormance. In addition, ii reports the results of Bureau pro-

'rams in measurement standards and techniques, properties

f matter and materials, engineering standards and services, jistnimentation, and automatic data processing.

I Annual subscription: Domestic, $1 1. 00; Foreign $13.75

' NONPERIODICALS

fonographs—Major contributions to the technical liter- cure on various subjects related to the Bureau's scientific nd technical activities. handbooks—Recommended codes of engineering and indusial practice (including safety codes) developed in coopera- on with interested industries, professional organizations, nd regulatory bodies.

lecial Publications—Include proceedings of conferences

lonsored by NBS, NBS annual reports, and other special

ablications appropriate to this grouping such as wall charts,

Dcket cards, and bibliographies.

ipplied Matbematics Series—Mathematical tables, manils, and studies of special interest to physicists, engineers,

lemists, biologists, mathematicians, computer programmers,

id others engaged in scientific and technical work,

ational Standard Reference Data Series—Provides quantitive data on the physical and chemical properties of

laterials, compiled from the world's literature and critically

^/aluated. Developed under a world-wide program co-

"dinated by NBS. Program under authority of National

jjj:andard Data Act (Public Law 90-396).

NOTE: At present the principal publication outlet for these data is the Journal of Physical and Chemical Reference Data (JPCRD) published quarterly for NBS by the American Chemical Society (ACS) and the American Institute of Physics (AIP). Subscriptions, reprints, and supplements

available from ACS, 1155 Sixteenth St. N.W., Wash., D.C.

20056.

Building Science Series—Disseminates technical information developed at the Bureau on building materials, components,

systems, and whole structures. The series presents research

results, test methods, and performance criteria related to the

structural and environmental functions and the durability and safety characteristics of building elements and systems. Technical Notes—Studies or reports which are complete in themselves but restrictive in their treatment of a subject.

Analogous to monographs but not so comprehensive in scope or definitive in treatment of the subject area. Often

serve as a vehicle for final reports of work performed at NBS under the sponsorship of other government agencies.

Voluntary Product Standards—Developed under procedures

published by the Department of Commerce in Part 10, Title 15, of the Code of Federal Regulations. The purpose

of the standards is to establish nationally recognized require- ments for products, and to provide all concerned interests with a basis for common understanding of the characteristics of the products. NBS administers this program as a supple- ment to the activities of the private sector standardizing

organizations.

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.

Order above NBS publications from: Superintendent of Documents, Government Printing Office, Washington, D.C.

20402. Order following NBS publications—NBSIR's and FIPS from

the National Technical Information Services, Springfield, Va. 22161.

Federal Information Processing Standards Publications (FIPS PUB)—Publications in this series collectively constitute the Federal Information Processing Standards Register.

Register serves as the official source of information in the Federal Government regarding standards issued by NBS

pursuant to the Federal Property and Administrative Services Act of 1949 as amended, Public Law 89-306 (79 Stat. 1127), and as implemented by Executive Order 11717

(38 FR 12315, dated May 11, 1973) and Part 6 of Title 15 CFR (Code of Federal Regulations).

NBS Interagency Reports (NBSIR)—A special series of

interim or final reports on work performed by NBS for outside sponsors (both government and non-government).

In general, initial distribution is handled by the sponsor;

public distribution is by the National Technical Information

Services (Springfield, Va. 22161) in paper copy or microfiche form.

BIBLIOGRAPHIC SUBSCRIPTION SERVICES

he following current-awareness and literature-survey bibli- P'aphies are issued periodically by the Bureau:

ryogenic Data Center Current Awareness Service. A litera- ture survey issued biweekly. Annual subscription: Domestic, $25.00; Foreign, $30.00.

iquified Natural Gas. A literature survey issued quarterly, nnual subscription: $20.00.

Superconducting Devices and Materials. A literature survey

issued quarterly. Annual subscription: $30.00. Send subscription orders and remittances for the preceding bibliographic

services to National Bureau of Standards, Cryogenic Data

Center (275.02) Boulder, Colorado 80302.
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