NATL INST OF STAND & TECH N18T

A11107 DSfl04b

NBSIR 75-932

PUBUCATIONS

The National Measurement

System for Temperature

James F. Schooley

Institute for Basic Standards

National Bureau of Standards

Washington, D. C. 20234

December 1975

Issued August 1 976

loo DEPARTMENT OF COMMERCE

LLS^ NAL BUREAU OF STANDARDS

NBSIR 75-932

THE NATIONAL MEASUREMENT

SYSTEM FOR TEMPERATURE

James F. Schooley

Institute for Basic Standards

National Bureau of Standards

Washsington, D. C. 20234

December 1975

Issued August 1 976

U.S. DEPARTMENT OF COMMERCE, Elliot L Richardson, Secretary

Edward O. Vetter, Under Secretary

Dr. Betsy Ancker-Johnson, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler. Acting Director

THE NATIONAL MEASUREMENT SYSTEM

FOR TEMPERATURE

J. F. School ey

Heat Division

Institute for Basic Standards
FOREWORD

CONCEPT OF A NATIONAL MEASUREMENT SYSTEM

"Concurrently with the growth and industrialization of this nation, there has developed

within it a vast, complex system of measurement which has made possible the very

growth that brought the system into being. This National Measurement System (NMS)

stands today as one of the key elements in a worldwide measurement system that links

all major nations together in a consistent, compatible network for communication and

trade.

"Briefly stated, the essential function of the NMS is to provide a quantitative basis in

measurement for (i) interchangeability and (ii) decisions for action in all aspects of

our daily life -- public affairs, commerce, industry, science, and engineering.

"Our National Measurement System is one of a number of mutually interacting systems within

our technologically based society that form the environment in which the individual

citizen must live and function. Familiar examples are the conmuni cation, transportation, educational, medical, and legal systems, all of which may be included under the

general heading of social systems.

"In view of the demonstrated value of the systems approach for the understanding and improvement of hardware such as computers and weapons, some of these social systems are being

subjected to the same type of analysis. The National Measurement System, which evolved

' in this country with little formal recognition as a system, is now being examined in

this way at the National Bureau of Standards (NBS) which undertook the study of NMS

partly because of a growing realization of the all -pervasive nature and great economic

importance of the nation's measurement activities, and partly because of the challenge

to NBS in putting its splendid new facilities to optimum use for the benefit of the

nation. Such optimum use can be approached only when NMS, of which NBS is a central

element, and the services it requires for effective operation are sufficiently well

understood.

"Because the government has wisely refrained from assigning leadership of NMS to NBS by law or executive order, the Bureau of Standards must maintain this leadership through demonstrated competence and general acceptance of its capability. This situation presents

both a challenge and a responsibility. The NBS must make a continuous effort to understand the structure and operation of the NMS, to assess the value of its services for

national objectives, and to develop means for evaluating its effectiveness.

"Our study of the National Measurement System is still in its early stages. There remains

much work to characterize inputs and outputs, interactions with other social systems,

involvement with national objectives, the functions of NMS elements, and couplings

between the elements."

This description of the National Measurement System was first published by Dr. R. D. Huntoon in Science, 1 58 , 67-71, October 6, 1967. Dr. Huntoon at that time was director

of the Institute for Basic Standards^ of the National Bureau of Standards. For the reasons stated in the above quotation. Dr. Huntoon began and fostered systematic studies of the

National Measurement System of which the following work is a part.
CONTENTS

Fane

EXECUTIVE SUMMARY ~V~

1. INTRODUCTION 3

2. STRUCTURE OF THE NATIONAL TEMPERATURE MEASUREMENT SYSTEM 4 2.1 Conceptual System of Temperature 4 2.2 Basic Thermometry Infrastructure 5 2.2.1 Documentary Specification System 5 2.2.1.1 Standardization Institutions 5 2.2.1.2 Survey of Documentary Standards 7 2.2.2 Thermometry Instrumentation System 8

2.2.2.1 Temperature Measurement Tools and Techniques 8

2.2.2.2 The Thermometry Instrumentation Industry 11 2.2.3 Reference Data 14 2.2.4 Thermometry Reference Materials 15

2.2.5 Science and People 15 2.3 Realized Thermometry Measurement Capabilities 16

2.4 Thermometry Dissemination and Enforcement Network 16

2.4.1 Central Thermometry Standards Authorities 16

2.4.2 State and Local Offices of Weights and Measures 18

2.4.3 Temperature Standards and Testing Laboratories and Services 18

2.4.4 Regulatory Agencies 20

2.5 Direct Measurements Transactions Matrix for Thermometry 21 2.5.1 Analysis of Thermometry Suppliers and Users 21 2.5.2 Highlights of Thermometry Users 21

3. IMPACT, STATUS, AND TRENDS OF THE TEMPERATURE MEASUREMENT SYSTEM 26

3.1 Impact of Thermometry Measurements 26

3.1.1 Functional, Technological and Scientific Applications 26

3.1.2 Economic Impacts - Costs and Benefits 28

3.1.3 Social, Human, Person-on-the-Street Impacts 28

3.2 Status and Trends of the Temperature Measurement System 28

4. SURVEY OF NBS SERVICES TO THERMOMETRY 34

4.1 The Past 34

4.2 The Present-Scope of NBS Thermometry Activities 34

4.2.1 Description of NBS Thermometry Services 34

4.2.1.1 Heat Division Activities, 1974 34

4.2.1.2 NBS Thermometry Activities Outside Heat Division 36

4.2.1.3 The NBS Thermometry Input-Output Table 37

4.2.2 Users of NBS Services 38

4.2.3 Alternative Sources 38

4.2.4 Funding Sources for NBS Thermometry Services 38

4.2.5 Mechanisms for Supplying Services 39

4.3 Impact of NBS Thermometry Services 40

4.3.1 Economic Impact of Major User Classes 40

4.3.2 Technological Impact of NBS Services 40

4.3.3 Pay-Off from Changes in NBS Services 40

4.4 Evaluation of NBS Thermometry Program 41 4.5 The Future of Thermometry at NBS 42

5. SUMMARY AND CONCLUSIONS 45

6. ACKNOWLEDGEMENTS 45

7. REFERENCES 46

APPENDIX A. Methodology of the Study 50

APPENDIX B. Summary of Background Documents 50

APPENDIX C. The 1927 International Temperature Scale 51 APPENDIX D. NBS Participation in Voluntary Standards Bodies' Thermometry

Activities 55 APPENDIX E. Resistance Thermometers 55 APPENDIX F. Other Temperature Sensors in More or Less Common Use 56

iii
LIST OF FIGURES

Page

Figure 2.2A Sketch of the structure of the International Electrotechnical

Commission, The International Standards Organization, and the

International Organization for Legal Metrology 6 Figure 2.2B Useful Sensor Ranges 10

Figure 2.2C Triple Point of Water 12 Figure 2.4A The U. S. Navy Temperature Calibration Chain 18

LIST OF TABLES

Table 2.2A Primary Fixed Points on the IPTS-68 7 Table 2. 28 Thermocouple Characteristics, from ASTM E230-72 9 Table 2.2C Sensors in Common Use at Various Temperatures 9 Table 2.4A The Structure of the General Conference on Weights and Measures .... 17

Table 2. 48 Range and Accuracy of U. S. Army Calibrations 19

Table 2.4C National Conference of Standards Laboratories,

List of Commercial Facilities 20

Table 2.5A The Thermometry Community and Its Roles as Suppliers and Users

of Thermometric Goods and Services 22

Table 2.58 Thermometry Input-Output Matrix 25

Table 4.2A N8S Thermometry Input-Output Table 37

Table 4. 28 Cryogenic Physics and Temperature Sections, Funding by Sources,

Fiscal Year 1974 39

Table 4.3A N8S-National Needs Chart 41

iv
THE NATIONAL MEASUREMENT SYSTEM FOR TEMPERATURE

J. F. School ey

Heat Division

Institute for Basic Standards

January 1976

ABSTRACT

The National Temperature Measurement System reaches quite literally into all phases of

American life. Comfort control in home, school, office and factory, health care, manufacturing, food preparation and storage, and all forms of powered transportation are just a few of the many facets of America's human activities that depend for their trouble-free

operation on the existence of reliable thermometry.

The Heat Division of the National Bureau of Standards collaborates with the national

laboratories of other nations in establishing an International Practical Temperature Scale

which represents thermodynamic accuracy insofar as current scientific practice permits.

The NBS is the only U.S. agency bearing this responsibility; in addition, only the NBS is

responsible for disseminating the International Scale to U.S. scientific and technical

activities.

The Study of the National Temperature Measurement System shows that the NBS continues

to contribute energetically to the quality of the International Scale. It further indicates

that NBS maintains a consistent and deliberate effort not only to provide access to the

Scale at the several levels required by U.S. science and technology, but also to participate

in solving special problems in thermometry. These are problems for which the nature of NBS

as an objective, expert resource in thermometry uniquely qualifies it to furnish effective,

practical solutions.

In briefly describing the many aspects of the National Temperature Measurement System,

this Study attempts to portray its great diversity of products, services, and people. The

System is largely organized, as might be expected, for the purpose of economic gain; the NBS

enters the picture only in those areas where highly accurate or intricate thermometry is

essential

V

THE NATIONAL MEASUREMENT SYSTEM FOR TEMPERATURE

J. F. School ey

Heat Division

Institute for Basic Standards

January 1976

EXECUTIVE SUMMARY

Temperature is a well-defined, basic

scale quantity. It is perhaps the most

conmonly-measured of all the physical units

(the possible exception being that of time).

This very ubiquity, however, has a double

effect. We desire (in principle) that we should have access to very accurate thermometry, but, on the other hand, we tend to take the measurements for granted, so that

our practice of thermometry is often of

poorer accuracy than we suspect.

The direct temperature measurement and

control industry is a large one by any

standards, including several dozen multimillion dollar firms. The amount of

economic leverage which thermometry exercises is multiplied greatly, however, by

the fact that good thermometry is essential

to the comnercial success of many industries,

such as semiconductor, steel, chemicals and

plastics manufacturing, medical testing and

care, and precision instrument manufacture

and use. Temperature is acquiring a new urgency in other areas as well, with the

tremendous demand for new sources of energy;

with the more stringent pollution and

efficiency requirements under consideration

for automobiles and aircraft; with the heavy

new demands for safety and output being

placed on nuclear power reactors; and with

the desire to map and exploit the ocean's

depths.

In briefest terms, NBS is meeting the

heaviest of today's demands. The temperature scale is known and can be transmitted

on demand with an accuracy which is satisfactory for most purposes in the range 20-

1300 K. The calibration services offered by

NBS for platinum resistance thermometers,

for liquid-in-glass thermometers, and for

thermocouples answer most of the direct

needs for accuracy in that range. Yet many human activities suffer a lack

of adequate thermometry, even in the same 20-1300 K range. The particular reasons for

this situation are numerous, but they come

down to a few general problems:

1) Adequate thermometry exists, but it

is not applied to the problem. The

whole field of practical medicine

suffers from this difficulty.

2) The type of measurement which is needed is not one for which

calibration rationale exists.

Fast-response, hostile environment, and geometricallyconstrained thermometry requirements exist in many fields of

endeavor; many of these are noted

in the full report.

3) The calibration procedure which

exists is often expensive. The

drugstore thermometer is an example of this problem— a $10

calibration of a $1 thermometer

is simply impractical.

Adding to these problems those which

exist where the temperature scale is not

adequate to today's needs gives one a fair

picture of the opportunities which lie before NBS in thermometry today.

Again in brief terms, NBS thermometry

programs lie in several general areas:

1) Generate an adequate scale below

20 K and above 1300 K. 2) Devise calibration and temperature

standardization procedures which

will solve people's problems,

rather than simply transmitting the

highest attainable accuracy.

3) Participate in the development of

thermometry methods in areas where

glaring weaknesses exist.

The NBS temperature measurement activities impinge on the U.S. temperature measurement system directly in a multitude of ways.

The most obvious, of course, is through the

calibration of precise temperature sensors.

A second interaction is through NBS participation on voluntary standards committees;

that is a quite important activity, because

it serves both to communicate to others

expertise and data originating at NBS and to alert the NBS staff to problem areas. A third major interaction with the temperature

community arises through NBS staff participation in the development of measurement

methods—in general, this interaction occurs directly with one or more technical

thermometry groups in industrial or scientific laboratories. Many such instances

are detailed in the report.

1
The National Measurement System study

has been a valuable tool in our effort to focus our limited resources on the most

pressing and susceptible problems. We

intend to continue to use this approach to assess and, as necessary, to modify the NBS

temperature program.

2
1 . INTRODUCTION

As the stewardess turned and walked to- ward the back of the plane, it banked

sharply and pitched forward. The pretty

woman in Seat 3A clutched her baby tightly

and glanced anxiously at her husband.

"What is it?" she asked.

"I don't know, replied her husband as

he instinctively steadied her and their

baby with one hand and placed the other on their sleeping son to his right. "We are surely going down in a hurry".

The plane dropped rapidly. Looking out

of the side window, the frightened couple

could see the rising lights of a city. The woman gasped as the plane pulled up just as

a crash seemed inevitable. The lights of a runway wheeled into view and disappeared

behind the nose of the aircraft as the

wheels bumped onto the pavement. A flashing red light appeared beside the plane,

testifying to the presence of an emergency

vehicle beside them.

Then, as the plane began to slow, the

voice of the pilot sounded over the cabin

intercom. "We're sorry for the hasty landing, folks, but we received an engine

overheat alarm up there, and the book says

'Bring it down while you still have two wings'. We'll check it out now and, if it was a false alarm, we'll be back in the air

in no time. Meanwhile, please sit back,

relax, and listen to some music".

The woman's husband, a physicist, em- ployed at the National Bureau of Standards,

audibly released his breath and, noticing

that his hands were still pressing forcibly

on his wife and children, he consciously

released his grasp. Leaning back in his

seat, he pondered the rush of events which

had followed the placid removal of his

dinner tray by the stewardess. Noting the

absence of any visible disturbance in the

engine nacelles looming darkly from the

wings on either side of the passenger com- partment, he wondered what the real cost

of this particular engine overheat alarm

sensor malfunction might be. First, there

was the extra landing— jet fuel, extra crew

time, airport fees. Then, whatever missed

appointments might take place as a result

of the inevitable delay here—wherever they

were. The story related above [IJ is true in

all of its elements. It points up several

features of the tale we want to tell in the

coming pages— temperature sensors do fail,

in spite of careful manufacture, selection,

and calibration; these failures are costly,

both in dollar and in human terms; and it is

in part the job of the thermometry program

at the NBS to consider whether such

problems can be alleviated and the costs

reduced by basic or applied research or other services which might be undertaken by

the NBS. This study is part of a large enterprise [2] which has a broad goal—to document the extent to which the NBS is

meeting its statutory responsibility to [3]

1) provide a central basis for a complete and consistent system of

physical measurement in the U.S.,

2) coordinate that system with those

of other nations, and

3) furnish essential services leading

to accurate and uniform physical

measurement in science, industry

and commerce.

It is a natural step to separate the

NBS activities according to the various units

of measurement, and to present the discussion

for each unit along the lines sketched in

the previous paragraph. Thus, this portion

of the overall study will discuss the extent

to which the NBS is meeting its statutory

responsibilities in the area of temperature

measurement.

The study of thermometry has a long

and honorable history. Undoubtedly, the

fundamental significance of temperature to thermodynamics and its importance to the

study of material properties has led to its

preeminence as a subject of painstaking

research and careful national and international deliberation. For whatever reason,

however, temperature is far and away the

most widely studied of all the standard

units. Thus we shall find that the conceptual bases for temperature and for its

measurement are soundly placed, and that

there is very substantial agreement on a well -developed temperature scale. Furthermore, the National Bureau of Standards has

a distinguished history of leadership in

thermometric affairs, and we shall see that

the NBS continues today to participate in

the expanding frontier of thermometry.

The very ubiquity of thermometry,

however, has led to two problems which this

study will treat: one problem is that so many temperature measurements are made and

so many thermometry facilities exist, that

even cataloging them, let alone their

analysis, is nearly impossible; the other is

that the familiarity of thermometry has, in

many cases, dimmed people's appreciation of

the desirability of characterizing the

accuracy of a given temperature measurement

and of the possible importance of that

accuracy to the problem at hand.

3
There are other questions which we

shall address as we explore the manifold

components which make up the national measurement system for contact thermometry.

Among these are whether the people who want

to measure temperature have available to them the thermometric equipment and the

accuracy required for a successful solution

to the problem at hand, what role the NBS

can play in solving difficulties which arise

in those situations, and whether adequate

mechanisms exist by which present deficiencies and future needs in the measurement system can be evaluated and overcome

through the NBS's efforts.

2. STRUCTURE OF THE NATIONAL TEMPERATURE MEASUREMENT SYSTEM

In this section the reader will begin

to see the awesome proportions of the U.S.

thermometry community. This giant takes on some of the aspects of a bustling city, with

its own map, currency, banks, factories,

emergencies, and policemen.

The reader can only find his way through

the community with the aid of maps--the

basic scale of temperature and the various

thermometry specifications and regulations

issued by the General Conference of Weights

and Measures, the American National

Standards Institutes and others of the

"city fathers". The currency of this realm

is composed of temperature measurements at

all levels of accuracy. The "really big

money"--the highest accuracy, International

Practical Temperature Scale measurements--

is rarely seen outside of the banks (the

major calibration laboratories), but no one doubts that the city needs the "big money"

just as much as it needs the small change

of less precise measurements which is readily seen throughout the city's factories

and homes.

We all live in this community, we buy

thermometers at home or at work, we measure

temperature more or less accurately, we complain when we are "shortchanged" by un- necessarily inaccurate or expensive

thermometry and we exult when a shiny new

coin of a more useful or less expensive

measurement comes into circulation. For

the next few pages, then, let us take a quick tour through Thermometry, USA--our

own hometown!

2.1 Conceptual System of Temperature

Temperature, like the quantities mass

and length, has a firm physiological basis,

so that the history of thermometry reaches

to the ancient Greeks [1]. By the beginning

of the 17th century, Galileo had demonstrated

an air thermometer, and before that century

ended, there were calls for thermometric

fixed points and for standardization!

Fahrenheit, a Pole, and Celsius, a Swede, were among the early contributors to temperature scales in the region between

ice and steam temperatures.

Efforts to discuss temperature and

thermometry in terms which are scientifically recognizable today resulted, in the 19th

century, in the definition of temperature

as "the thermal state of a body with re- ference to its ability to communicate heat

to other bodies" by Maxwell [2]. Lord Kelvin

(then William Thomson) placed the evaluation

of temperature (or "thermometry) on a sound

thermodynamic basis by considering the

efficiency of reversible heat engines [3].

This method, which is based on Carnot's

concept of heat engine cycles, permits the

definition of a thermodynamic zero of

temperature.

Clearly one can define a temperature

scale by defining an absolute zero of

temperature and by simultaneously assigning

a numerical value to the temperature at which a particular natural phenomenon

occurs. Alternatively, he can simultaneously assign numerical values to the temperatures characteristic of two separate

phenomena [4]. Either technique defines the

size of the unit of temperature and

evaluates the scale at two temperatures, thus

leaving the temperatures at which all other

phenomena take place as quantities to be determined by experiment.

While the science of thermodynamic

temperatures was slowly advancing, the

technologist busily set up temperature

scales on which the available natural

phenomena of melting ice, boiling water,

body temperature and the like could be

evaluated. As we mentioned above,

Fahrenheit and Celsius were involved in

this work, although they were certainly not alone. As one might suppose, the scales

which were proposed were suggested for

diverse reasons, and their evolutions were

not necessarily predictable. These efforts

resulted in the Fahrenheit scale, chosen so that 100 degrees separated human body

temperature from that of a cold winter day,

and the Centigrade scale, which was defined

so that one hundred degrees separated water's

freezing and boiling points at 0 °C and

100 °C, respectively. The Fahrenheit scale
was in use in the 18th century, but the

Centigrade scale was not produced until 1850.

The thermometric principle of defining

the temperature scale by assigning values to the temperatures of two natural phenomena

(in this case the Centigrade scale assignments) was chosen by the 31 -member Seventh

General Conference on Weights and Measures

in 1927 as the basis for the first Inter- national Temperature Scale. (ITS). The pracitcal aim of the General Conference in introducing the Scale of 1927 was to provice a con- venient reproducible scale for general use. The achievement of thermodynamic accuracy

was a difficult experimental problem, and

the General Conference hoped to enhance

work-a-day thermometric accuracy by defining the scale in terms of platinum

resistivity, thermocouple emf, and optical

pyrometry rather than in terms of gas

thermometry or other techniques capable of

thermodynamic accuracy. This idea appears

to have been quite a good one [5].

Because of the insight which it gives

into the nature of thermometry, the ITS of

1927 is included as Appendix C. We might

note that the Scale was based upon a proposal jointly presented by NBS, NPL

(Great Britain) and PTR (Germany), and that

the U.S. announcement was written by G. K. Burgess during his tenure as Director of

NBS [6].

The General Conference considered

that the ITS needed its own group

of specialists, so an Advisory

Committee on Thermometry was formed

in 1933 to address these problems directly.

The Advisory Committee prepared a new (and,

above 630 °C, an improved) version of the

ITS in 1948 which the International

Committee on Weights and Measures recommended

to the Ninth General Conference. The new

scale was adopted; it retained the definition

of the melting and boiling points of water

as 0 °C and 100 °C, although the name of the

unit was changed to Celsius to honor the

pioneering Swede [7]. Furthermore, the

thermodynamic scale was given the name of

Kelvin and defined by setting an absolute

zero of temperature and assigning the value

273.16 K to the triple point of water [8].

The awful truth that the practical

scale unit (°C) differed from the thermodynamic unit (the degree Kelvin) resounded

in the world's halls of state for twenty

years. In 1968, however, the 13th General

Conference at last adopted identical bases

for the two scales. Henceforth, the

Kelvin would be defined as 1/273.16 of the

temperature of the triple point of water,

and the degree Celsius was given an equal

value by defining Celsius temperatures as

t = T - Tq, where T is the thermodynamic

temperature in Kelvins, and Jq = 273.15 K [9]. We should note here that the satisfaction which thermometricians feel in knowing

that International Practical [10] Temperature

Scale (IPTS) temperatures are (potentially, at least) completely equivalent to thermodynamic

temperatures must be tempered by the knowledge that advances in thermometric research

will likely result in periodic adjustments

of the scale values, with consequent adjustments required in "science and

industry" [11].

The latest revision of IPTS [12], in

1968, continues the practice of assigning

values to a number of triple points, boiling

points, and freezing points. The usefulness

of these defining fixed points lies in their

ease of use as check points against which a given thermometer may be calibrated. In fact, few of them are easily used [13], and

consequently their practical value is

diminished. Recently some progress has

been made in the "fixed point business",

however; this will be discussed in Section 4.

2.2 Basic Thermometry Infrastructure

2.2.1 Documentary Specification System

2.2.1.1 Standardization Institutions

There are five hierarchies of standards

bodies which are concerned with thermometry.

One of these is headed by the General Conference on Weights and Measures (C.G.P.M.),

and it is devoted to the elucidation of the

Kelvin Thermodynamic and of the Inter- national Practical Temperature Scales. A second hierarchy generates many con- sensus standards for use in commerce,

industry, and other "public" situations,

ultimately leading to the International

Standards Organization and the International

Electrotechnical Commission. Thirdly, there

are various professional and manufacturing

associations. A fourth hierarchy is comprised

of U.S. regulatory agencies; and finally,

there are government and commercial standards

laboratories. (We should note that, although our own concern is temperature and

thermometry, each of these hierarchies

considers many other units as well J The

first, fourth, and fifth of these hierarchies are primarily concerned with physical

measurements per se and are discussed in

Section 2.4. The remaining two are described here.

a) Commercial Consensus Standards

The measurement of temperature in com- merce and industry has been a long-time

5
concern to professional associations and to organizations which have arisen solely to promote standardization. The latter group

has achieved wide acceptance because it

encourages the participation of

manufacturers of thermometric apparatus,

users of such equipment and objective third

parties; we shall discuss this latter group

fi rst.Three international bodies are concerned

with standards used in commerce, and their

recommendations are significant because many

countries accept them as legally binding for

national and international trade. These

bodies are the International Standards

Organization [14], the International Electrotechnical Commission, and the International

Organization for Legal Metrology [15]. The

American National Standards Institute [16]

provides the U.S. representation to the

ISO and lEC, and it, in turn, derives much

of its detailed recommendations from the

American Society for Testing and Materials

[17]. Figure 2.2A shows a sketch of these

organizations.

lEC ISO OIML

International Electrotechnical Commission

1906 "standardization

of electrical apparatus"

U.S. National Committee

to lEC - ANSI

NBS Rep. by C. H. Page

International Organization for

Standardization

1946 (1926 ISA) Federation of

54 Nat. Stds. Inst, "quality,

production, trade."

Member Bodies - for U.S. - ANSI

Standing and Tech.

and Subcommittees

Com.

American National Standards

Institute

Selects "American National

Standards"

Board of Stds. Review

Company Member Council

Member Body Council

Consumer Council

Technical Ad. Bds.

Technical Committees

Standing and Tech.

and Subcommittees

Com.

International Organization

for Legal Metrology

1955 (Aug. 1972, U.S.

joins) "recommends uniform

int'l. requirements to promote int'l. cooperation"

- Int. Conf . of Legal Met.

- Int. Bureau of Legal Met

lint. Committee of Legal Met. ^Working Groups

American Society for Testing

and Materials

develops "consensus" standards

Twenty-four

Board of Directors

H Technical Standing Committees

-{Professional Associations

FIGURE 2.2A. Sketch of the structure of the lEC, the ISO, and OIML,

The work of these standards groups is to develop standards for all manner of devices,

test methods and test equipment. The lEC

and ISO seek agreements which will facilitate international trade--in fact, some nations (most recently Denmark) [18] automatically accept these international

Standards as legally binding within their

own boundaries. The United States has re- cently joined OIML, whose function is to recommend uniform metrological requirements,

which relate to legal standards in its

member nations.

The most difficult problem which these

groups face may well be that they have

rather completely overlapping "jurisdictions", so that each may more or less

simultaneously write conflicting recommendations regarding essentially identical

materials or instruments. W. A. McAdams

Director of ASTM, pointed out recently that

the writing of international standards is more difficult in cases where the individual

member nations have international standards,

since these generally conflict in their

details; McAdams noted a trend toward

standardization first at the international

level and advised ASTM to "Reexamine its

role and effort in light of these trends"

[19]. If, in fact, international standardization were to precede national standardization, rather impressive coordination problems
might well develop. Currently ASTM has over

20,000 members who serve on 115 committees,

and these members would no doubt continue

to be interested in the details of any

international standards which concern the

products of their companies.

Also, NBS is involved in commercial

standards activities, at several levels.

Individual staff members serve on committees

and subcommittees of both the U.S. and the

international bodies; a partial listing of

such service is included as Appendix D.

b) Professional and Trade Associations

The second main category of voluntary

standards bodies comprises the professional

associations. This category can be further

subdivided into scientific associations and

commercial associations. Among the former

group may be included the International Union

of Pure and Applied Physics (lUPAP), the

American Institute of Physics (AIP), the

International Institute of Refrigeration

(IIR), the National Conference of Standards

Laboratories (NCSL), and the National

Conference on Weights and Measures (NCWM).

The latter group includes (but is certainly

not limited to) the American Society for

Mechanical Engineers (ASME), the Electronics

Industries Association (EIA), the Institution for Electrical and Electronic Engineers

(IEEE), the National Electrical Manufacturers

Association (NEMA), the Society for Automotive Engineers (SAE), Underwriters

Laboratory, Inc. (UL), the Scientific

Apparatus Makers Association (SAMA), and'

the Instrument Society of America (ISA).

2.2.1.2 Survey of Documentary Standards

The actual documents produced by the

five hierarchies of standards bodies show a great variety both in form and in number.

The General Conference of Weights and

Measures has issued but three basic documents in fifty years. These documents,

however, are the three editions of the

International Practical Temperature Scale

and they represent the final authority in

the field of thermometry. Table 2.2A shows

the primary fixed points on the IPTS-68,

and the full text is noted in reference 12. The standards issued by the American

Society for Testing and Materials are the

product of consensus agreements among manufacturers, users, and objective third parties, as we noted earlier. These standards

are issued annually in a multivolume Book of

Standards published by ASTM from its offices

at 1916 Race Street, Philadelphia, Penn- sylvania 19103. Many of these standards are selected by the American National Standards

Institute to be designated as American

National Standards. Standards so selected

are noted in the ASTM listing and the

Table 2.2A

Primary Fixed Points on IPTS-68

State

thermodynamic zero temperature

equilibrium hydrogen triple point

equilibrium hydrogen,

p = 33,330.6 N/m2

equilibrium hydrogen boiling point

neon boiling point

oxygen triple point

oxygen boiling point

water triple point

water boiling point

zinc freezing point

silver freezing point

gold freezing point

T (K)

J t (°C)

68

0 -273.15

13 81 -259.34

17 042 -256.108

20 28 -252.87

27 102 -246.048

54 361 -218.789

90 188 -182.962

273 16 0.01

373 15 100.00

692 73 419.58

1235 08 961.93

1337 .58 1064.43

7
information which they contain then forms

the basis for possible standards consideration by the U.S. National Committees to the

International Electrotechnic Commission and

to the International Organization for Legal

Metrology.

Professional associations are not uniform as regards their issuance of

standards. Many of them undertake very few

standardization activities, whereas

others (for example the National Committee

for (Medical) Clinical Laboratory Standards)

offer substantial standardization guidance

to their members.

The temperature measurement standards

issued by government agencies are in the

so-called Military Specifications handbooks

and in the particular calibration handbooks

issued by the individual calibration

laboratories, as noted in the previous

Section

2.2.2 Thermometry Instrumentation System

2.2.2.1 Temperature Measurement Tools and

Techniques

Many schemes for evaluating temperature

have been used since Cro-Magnon yanked his

fist out of the fire and grunted at his

mate to fetch some cold water. Not so many,

however, that we cannot mention some of

those in common use today. Galileo's air

globe, inverted over a dish of water, was the

forerunner of today's gas thermometer, which

is probably the most useful of the "thermodynamic" thermometers in the temperature

range 20-600 K. These instruments are based

on the ideal gas equation PV = nRT; commonly

either constant-volume or constant-pressure

ratios are taken at two temperatures, with

the final temperature, J 2> evaluated by the

product of the filling, or initial temperature, Tj, and the pressure (or volume)

ratio

T2 = Ti(P2/Pi) or Ti = Ti(V2/Vi).

The trick is to find an ideal gas and to avoid "pitfalls" [20].

Fahrenheit and Celsius developed mercury

thermometers, which rely on the different

thermal expansion properties of mercury and

glass. Although the relative instability

of the glass limits their accuracy to 0.01 °C to 0.03 °C, such thermometers enjoy

more extensive use today than any other

type. This situation is due to their low

cost, their simplicity in construction and

use, and, for moderate accuracy work, their

reliability. These characteri sties apply

equally well to another commonly used

expansivity thermometer, the bimetallic

element. These elements ordinarily are bonded strips of nickel steels; at 36% Ni

64% Fe, the alloy has a minimum coefficient

of thermal expansion and is called Invar. The alloy containing 18-27% Ni , on the other

hand, has a coefficient some twenty times

larger, so that the bonded pair forms a sensitive, stable mechanical thermometer

capable of 0.03 °C precision in the range

0-100 °C [21].

Similar in principle to the constantvolume gas thermometer is the liquid- or

1 iquid-and-vapor-fi 1 led pressure thermometer.

In this device a capillary tube connects

the sensing bulb to a pressure gauge or to a pressure-sensitive control device. The

filled thermometer, although capable of only

moderate accuracy, is commonly used because

the pressure gauging and control is convenient and reliable.

Resistance thermometry came into common

use late in the 19th century with the development of high quality galvanometers.

H. L. Callendar developed thermometric

elements of platinum wire and derived

specifications for evaluating the quality

of thermometers [22]. By 1927, much of the

ITS could be referred to platinum resistance

thermometry, and presently it is possible

to obtain measurements of the highest precision from 20 K to perhaps 1300 K by using

platinum resistance thermometers [23,24].

In addition to platinum metal resistivity, a variety of other resistive thermometers has become useful over the years. A brief listing of these is included in

Appendix E, since some of them will be

referred to in later sections.

Thermoelectric thermometry, on which is

based the widely used thermocouple, depends

on the Seebeck, Peltier, and Thomson

effects [25]. The Peltier effect is the

liberation or absorption of heat accompanying current flow through the junction of

dissimilar metals. The Thomson effect

describes the reversible production of

heat accompanying the flow of current along

a homogeneous conductor whose temperature

varies from one point to another. Seebeck 's observation that current will flow in a circuit consisting of dissimilar wires

connected in a loop in which the junctions

have unequal temperatures can be interpreted

in terms of the Peltier and Thomson effects.

The overall circuit emf can be described by

two Peltier coefficients at the junctions

and two Thomson coefficients in the two

dissimilar wires.

Since its discovery 150 years ago,

thermoelectric thermometry has come into

extremely wide use. Platinum versus 90%

platinum- 10% rhodium is the standard interpolating instrument of IPTS from 630 °C1064 °C, and other thermocouples have been

adopted for many temperature measurements

8
and control applications. Table 2.2B shows the ASTM letter designations for thermocouples [26].

Table 2. 28

Thermocouple Characteristics, from ASTM CO on *70

Symbol Elements (+/-) Useful temperature range

B Pt-30% Rh/Pt-6% Rh 0 to 1820 °C

E Ni-10% Cr/constantan -270 to 1000 °C

J Fe/constantan -210 to 1200 °C

K Ni-10% RH/Ni-5% (Ai,Si) -270 to 1372 °C

R Pt-13% Rh/Pt - 50 to 1768 °C

S Pt-10% RH/Pt - 50 to 1768 °C T Cu/constantan -270 to 400 PC

By virtue of the radiation given off by

a hot object, one can measure its temperature

with a radiation pyrometer. The radiation

instrument in most common use at present

is the disappearing filament optical

pyrometer. In its use, the current through

a filament is adjusted until its luminance

matches that of a glowing object (usually

at a wavelength near 650 nm). At that point,

the image of the filament blends into that

of the object; the filament current control

displays the measured temperature.

There are many other methods by which

temperature can be measured in particular

ranges and with particular accuracies

(especially with low accuracy). These

methods are listed in Appendix F, since

they comprise much of scientific and

industrial thermometry. A composite of

temperature sensors appropriate for various

temperature ranges is given in Table 2.2C.

Table 2.2C

Sensors in Common Use at Various Temperatures

Temperature Range Sensor (Approximate) Limiting Accuracy

0-20 K Semiconductor resistance ±1 mK

20-1000 K Platinum resistance ± 1 mK (at 20 K) to ±12 mK

(at 1000 k)

20-1300 K Thermocouples ±10 mK (at 20 K) to ±200 mK

(at 1300 K)

250-400 K Mercury-glass ±30 mK

250-400 K Bimetallic ±30 mK

250-500 K Thermistor Uncertain

1000 K Optical Pyrometer ±0.5 K to 20 K

The IPTS-68 designates the Planck the fixed points. These are shown in figure

radiation law, the platinum-10% rhodium 2.2B, along with other sensors which, while

platinum thermocouple, and the platinum re- not standard instruments, have come into

si stance thermometer as the standard inter- common use because of a combination of low

polating methods for temperatures between price and reasonable reliability.

9

As we noted earlier, the triple point of

water is of central importance to thermometry; the definition of its temperature as 273.16 K (plus the thermodynamic zero of

temperature) sets the "size" of the unit

temperature interval, and it thus provides

the scale on which the thermodynamic temperatures of all other natural phenomena must

be measured. The most common means of

realizing the temperature of the triple

point of water involves the use of a cell

like that shown in figure 2.2C.

The particular cell shown is designed for

use with standard platinum resistance

thermometers. When the ice mantle is correctly formed around the central tube

and the cell is surrounded by a mixture of

crushed ice and water, the cell will furnish

the triple point temperature very precisely, typically the standard deviation of

the platinum thermometer readings at the

triple point is less than 0.14 mi 1 1 idegrees

The simplicity of the triple point of

water cell, coupled with its excellent

thermometric reproducibility, makes it ideal

as the principal defining point for the

temperature scale. All but the most modest

thermometry facilities can readily incorporate such a cell for ready calibration of

temperature sensors. Although no other fixed point device is

quite so easily used as the water triple

point cell, many others, especially metal

freezing point cells, are in common use. The uses of such cells in thermometry are described in the excellent NBS Monograph 126

"Platinum Resistance Thermometry", by J. L. Riddle, 6. T. Furukawa, and H. H. Plumb,

from which figure 2.2B was abstracted.

In practice, the sensors described in

this section mostly require auxiliary equipment: the optical pyrometer requires, in

general, a calibrated lamp or voltage

divider; the thermocouple requires a re- ference junction and, depending on the

sensitivity needed for the particular

application, either a millivolt - or a microvolt-range meter; and the platinum and

other resistance thermometers require

Wheatstone or other bridge circuits or an equivalent means (such as a currentpotential measurement system) for measuring

their resistances. By and large, only the

liquid-in-glass and the bimetallic thermometers are free of this need.

As a result of the need for auxiliary

equipment, the performance of practical

thermometry generally reflects the quality

of a system, comprising the sensor plus its

associated equipment. For this reason, we

must concern ourselves to some extent with

the products and status of the electronics

industry, and we must be careful to take

proper account of the influence of the

measurement equipment used when considering

the reliability of a particular thermometry

system.

Much more remains to be said on the subjects of temperature and thermometry than

the trifle which comprises Section 2 of

this study. However, we have attempted to present here a concise discussion of the

scale of temperature as it is derived

scientifically and as it is defined in a practical way, and enough information on the

evolution and practice of thermometry so that one can appreciate the diversity and vitality of the activities to be

described in the balance of the study.

2.2.2.2 The Thermometry Instrumentation

Industry

The temperature sensors and associated

measuring equipment which form the basis of

the thermometry instrumentation industry

have been enumerated to a large extent in

the preceding Section. In turn, this equipment forms the basis for measurement and

control of a very great amount of processing

equipment, monitoring equipment, and durable consumer goods--examples of these are the

control equipment for the fractionation of

petroleum, the temperature monitors on the

coolant loop of a nuclear power plant, and

the several thermostats in a household

cooking range. In this Section, however,

we want only to describe the primary

thermometry instrumentation industry itself.

This group of people provides the means

by which the National Temperature Measurement System makes the bulk of its day-to-day

temperature measurements. It includes at least 25 companies with assets greater than

$1 million. Very few indeed are the people

who construct their own thermometers and

temperature control apparatus from scratch

(but these few are responsible for nearly

all of the advances in the field).

Much routine thermometry is accomplished

using thermocouples, (however, resistance

thermometry, because of its higher signalto-noise ratio, is rapidly gaining favor).

Many manufacturers provide preassembled

couples in various configurations [27], although most people use thermocouple wire

provided with the appropriate calibration

table to construct simple thermocouple

configurations

The existence of ASTM and other stan- dards for commercial devices will be noted

later. These standards are quite effective

in promoting uniform quality in thermocouple

thermometry since they allow the user to predict the uncertainty in a given temperature measurement, and, usually, in a

11
FIGURE 2.2C. Water triple point cell

A. Heavy black felt shield against ambient

radiation.

B. Polyethylene tube for guiding the SPRT

into the thermometer well.

C. Water vapor.

D. Borosilicate glass cell.

E. Water from ice bath.

F. Thermometer well (precision bore).

G. Ice mantle.

H. Air-free water.

I. Aluminum bushing with internal taper at upper end to guide the SPRT into the

close-fitting inner bore.

J. Polyurethane sponge.

K. Finely divided ice and water.

particular control application as well.

The great majority of manufacturing pro- cesses involving thermocouples require only coarse (perhaps 1%) control of temperature.

Typical of such applications are heat

treating furnaces; steam, hot water and hot

gas plants; and bearing temperature monitoring. The automotive, power generation,

metal fabrication, and motor manufacturing

industries all employ these applications

and use thermocouples in large quantities.

In general, manufacturers of thermocouples and thermocouple wire assure their

own conformance to industry standards by

using either thermocouples or platinum

resistance thermometers which are routinely

calibrated at NBS or at a secondary facility.

In addition, emf-temperature tables (recently

corrected by NBS to conform to IPTS-68) are available for all the common couples.

The construction of automatic reading

and recording devices and of temperature

control devices for use with thermocouples

is a major thermometric industry. Several

major companies [28] provide recorders and

meters which express common thermocouple

outputs directly in temperature units, and

these firms also make available control

circuitry which will activate heaters,

coolers, temperature limit devices, and the

like in order to automate processes which

involve processing at a particular temperature. The quality control exercised in

this industry is often quite thorough, with

individual checks on temperature accuracy

(in addition to similarly careful checks on mechanical and electrical integrity) using

high quality baths and measuring equipment

[29]. We have found this industry, taken

as a group, to be very conscious of its

responsibilities and to be grateful for the

active support of NBS through calibration

services and consultation.

Bimetallic thermometers, too, are widely used in thermometry and in temperature

control applications [30]. One common household thermostat employs two bimetallic

thermometers; one for visual indication

and the other in the control circuit [31].

Automotive choke and radiator thermostat

assemblies also employ bimetallic temperature

control units. Calibration of bimetallic

units is generally rather coarse, due to the

nature of the major applications.

The fastest growing of the temperature

sensor industries appears to be the thermistor industry. The thermistor* basically a semiconductor, is finding wide application in

the medical area due to its small size and

high sensitivity [32]. The same qualities

make it a desirable sensor in many other

areas, among which are automotive engine tem- peratures, surface temperatures of manifold
systems, micrometeorology, process control,

and air conditioning sensing and control.

The upper limit for good stability in

thermistors is about 300 °C. This industry

is made up of many small firms, so that re- latively little research has been done to characterize the response, stability, and

interchangeabil ity of these sensors. Nevertheless, much automatic reading and

control equipment is available for use with

thermistors. Some $10-20 million worth of

thermistor units are produced in the U.S.,

and perhaps one-fifth as many are imported

from Holland or Germany [33]. Since these

units are priced at perhaps 10(t each but serve much more expensive measuring and

control equipment, the thermistor temperature control industry is a large one indeed.

Some notion of the rapid progress in the

thermistor field can be gained from a recent

note [34] that a -5 °C to 45 °C field

thermometer system has been developed for

use with a voltage-to-frequency converter

circuit employing a portable counter.

Another area of rapid growth is in

miniature resistance thermometers [35].

The accuracy, sensitivity, and stability

of standard platinum resistance

thermometers has made them preeminent for

exacting thermometry up to 630 °C, and

commercial thermometers are now made in

many configurations, including some of

millimeter dimensions. We have at present

limited data [36] on which to judge the

extent of any sacrifice in sensor quality

resulting from miniaturization or other

changes; however, a recent advertisement

offers 0.1 °C resolution and ±0.5 °C

accuracy (interestingly, the accuracy

specification is correctly defined as a "total system" accuracy, a very encouraging

sign) [37].

Liquid-in-glass thermometers are widely

used for temperature measurement; once filled and calibrated, only column separation and breakage cause obvious changes in

the response of these thermometers. Bumping

or temperature cycling do, however, cause minute changes in bulb volume which are detectable in calibrations. Because of the

relative delicacy and expense of control

designs based on liquid-in-glass, however,

most uses are found in temperature monitoring applications such as batch chemical

processing, health care, and household

thermometry. There are several large

manufacturers of liquid-in-glass thermometers.

They sell some $5-6 million worth of ASTM

models, as noted earlier, perhaps $7-8

million worth of precision and research

thermometers, and roughly the same value

in student-group thermometers [38]. The

liquid-in-glass units intended for chemical

processing and health care are generally

calibrated to about ±0.1 °F, and quite

often the calibration is traceable to NBS. This is not generally true of the household

unit production, however [39].

Optical pyrometers are extensively used

in many industries. Subject to inaccuracies

owing to uncertain emissivity corrections

as well as to differences among particular

operators, optical pyrometers still are the

thermometers chosen in cases where contact

thermometry is especially difficult or where

radiation measurements are convenient and

reliable, as in surface thermometry.

Many other thermometer sensors are manu- factured for particular applications, and

control devices are constructed for their

employment. Our experience has been that,

taken as an industry, thermometer and

temperature control equipment manufacturers

employ relatively sophisticated personnel

and equipment in order to assure the quality

of their products in competition with other

suppliers of these units. In addition, some

of the individual manufacturers support

thermometry research and development efforts

on a continuing basis. This activity has

resulted in the recent development of such

advances as cryogenic temperature controllers utilizing semiconductor temperature

sensors [40], liquid crystal sensors said

to be sensitive to changes of 0.1 °F [41],

and radiation sensors which measure temperatures of millimeter-size areas for troubleshooting electronic circuitry [42]. A further measure of the instrumentation

industry is found in the Standard In- dustrial Classification Manual. (See

Appendix B). The following codes refer to thermometry:

3822 Measuring and Controlling Instruments

3823 Industrial Instruments for Process

Variables

3829 Measuring and Controlling Devices,

Other

These codes are further broken down into

subcategories for which meaningful economic

statistics are gathered by the Bureau of

the Census. Representative entries follow:

(current Industrial Reports, 1972)

38230 Electrical and Electronic Thermometers,

38 companies with 1972 shipments exceeding

$100,000; total shipments $40 million.

38230 Mechanical Thermometers, 40 companies

with 1972 shipments exceeding $100,000;

total shipments $39 million.

38230 Primary Thermocouples and Leads Wire,

6 companies with 1972 shipments exceeding

$100,000; total shipments $11 million.

38230 All other Primary Thermometers, 4 companies with 1972 shipments exceeding

$100,000; total shipments $10 million.

38220 Thermostats for heating and cooling.
11 companies with 1972 shipments exceeding

$100,000; total shipments $287 million.

38220 Temperature Controls for Appliances,

14 companies with 1972 shipments exceeding

$100,000; total shipments $140 million.

The 1973 U.S. Industrial Outlook notes

that in 1972 the Automatic Temperature

Controls category accounted the following

statistics:

$700 million shipments

105 establishments counted

38,000 people employed

, 4.2% (over $30 million) exported

The outlook projected the shipment level

of this category at $1 billion annually by

1980.

Other statistical data could be garnered

on the Automatic Temperature Controls

category or on other thermometry categories

as well. However, we believe that the

identification of the sources of such data,

together with representative figures showing the enormous volume of activity just in

this one facet of thermometry, serves to point up its importance to the U.S. economy.

For the main bulk of industrial shipments, such as those categorized above, the

quality of the included thermometric devices

is controlled by adherence to American

Society for Testing and Materials standards

or to similar voluntary or military

specifications. In turn, these resistance

or thermocouple devices are referred

to more accurate standards, and eventually

to the NBS. Unfortunately, neither user

nor manufacturer is always aware of lapses

in which the calibration chain has been

broken, with consequent deficiencies in

the performance of the equipment.

2.2.3 Reference Data

Much of the most accurate thermometry

is preserved on standard thermometers, as we shall see in the next Section. Of the

most heavily used thermometry, however,

the majority is preserved in the form of

reference tables. A notable example of

these data is a recent NBS publication.

Monograph No. 125 "Thermocouple Reference

Tables Based on the IPTS-68". A short

discussion of the history of this publication may illuminate the process by which

information becomes Reference Data.

In discussions with manufacturers and

users of thermocouples and with the

corresponding American Society for Testing

and Materials committee over a period of

years, it became clear that the thermocouple

industry relies most heavily on seven types

of thermocouple thermometers. With the

advent of the International Practical Temperature Scale of 1968, these manufacturer.

user, and standards groups suggested (both

as groups and in individual correspondence)

appropriate temperature ranges and tabular

intervals for which reference data for each

of the thermocouple types would be most

useful. In response to these requests,

staff members of the NBS (both in the

Temperature Section in the Gaithersburg

laboratories and in the Cryogenics Division

in Boulder) constructed the new tables of

Monograph No. 125. This was accomplished,

in some cases, by acquiring new basic

calibration data on wire furnished by

manufacturers. In other cases, the

calibration files were searched for appropriate data which summarized and converted

to the new 1968 Temperature Scale. In all cases, computer fitting techniques were

used to obtain smooth tabular values of

thermocouple e.m.f. versus temperature.

These particular thermocouple reference

tables are sold to the public both in the

U.S. and abroad through the U.S. Government

Printing Office. In an effort to avoid

"going out of print" in less than five

years, the Printing Office ran off 20,000

copies in the first printing.

Monograph 125 is now in use by thermocouple wire manufacturers, whose Quality

Control laboratories run continuing calibration checks to ascertain that the wire

as manufactured does yield the tabulated

emf versus temperature within limits

specified by the appropriate manufacturing

standard. The instrumentation industry

also uses Monograph 125 to determine that

meter outputs (often given directly in

temperature) correspond to the tabulated

values. (We might note here that this

industry specifically requested that a supplement to Monograph 125 be issued with

the tabular temperatures on the Fahrenheit

Scale, for those of their customers not yet able to use the metric Celsius scale.

NBS complied with this request within

one year.) Major users of thermocouples use Monograph 125 in the calibration of thermocouples employed in test stands, process

control instrumentation, and materials data

eval uation.

Thus we see, in the history of one document, the manner in which a technical need

is observed and answered by the NBS staff

in generating Reference Data in thermometry.

Similar Reference Data are now in the

process of being obtained at NBS for small,

commercial thermistor and resistance

thermometers. Some data obtained by

various industrial representatives are in

existence but their value is restricted

since the interchangeabil ity , stability and

accuracy limitations of the corresponding

sensors are not generally available or not

14
known. Such data, when available, will

play a role similar to that of Monograph

125.

Hardly data in the usual sense of the

word, the Reference Functions of the 1968

International Practical Temperature Scale

nonetheless constitute a primary source

which are used in the interpolation of the

temperature scale between fixed points of

temperature information. These functions

are found in the journal Metrologia 5 35

(1969); they are employed with the capsule

standard platinum resistance thermometer

to obtain values of temperature in the

range 13.81 K to 273.15 K.

2.2.4 Thermometry Reference Materials

The primary reference materials of

thermometry comprise the pure materials

used in fixed-point devices and in thermometers. For example, NBS Special

Publication 260 lists two Standard Reference Materials, high-purity zinc and tin,

which are suitable for use in the construction of freezing-point cells. These cells,

properly prepared and used, may then serve

to define calibration temperatures on the

International Practical Temperature Scale

of 1968 [43]. The high-purity platinum

wire which is used in constructing standard

resistance thermometers also constitutes a thermometry reference material. Similarly,

the thermoelectric standard Pt 67, soon to

be designated as a Standard Reference

Material by NBS, is a valuable reference

material in thermometry.

In one case, a fixed-point device may

be considered to comprise a thermometry

reference material. This is the Superconductive Thermometric Fixed Point Device,

which has been designated by NBS as Standard

Reference Material 767—when the device

leads are connected to a simple measuring

circuit, the user may rely on the thermometric reproducibility of the included

superconductive samples [44].

Somewhat less accurate thermometry

reference materials are under development

in the Physical Chemistry Division of NBS

[45]. These are standards for differential

thermal analysis.

Many scientific and industrial laboratories maintain "old faithful" materials

which they employ as thermometry reference

materials. Often, however, these materials

are of uncertain purity or are known to be

impure, so that they enjoy only a very local

usefulness. A value of the NBS Standard

Reference Materiel program lies in the fact

that their products, being generally of very

high purity and careful characterization^

can be readily duplicated. Thus their

thermometric properties can be utilized

throughout the Measurement System.

2.2.5 Science and People

In considering the National Temperature

Measurement System infrastructure, one must

first realize that temperature is not of

direct interest to most people who measure

it. For the most part, people who measure

temperature want to obtain a reproducible,

readily interpretable result for a clinical

laboratory blood test, or they want to en- sure that a batch of steel, semiconductors,

or plastic meets its specifications, or they

want to optimize the efficiency of a steam

boiler, of a turbine, or of a chemical process . It is true that many people are interested in the specific temperatures at which various physical and chemical

phenomena take place, and occasionally

they relate these temperatures to theoretical derivations; in addition the

temperature measurement industry is directly

interested in temperature -gev se. On balance, however, the less concerned the

average person has to be with the measurement process and the thermometry system

he is using, the happier he is. For this reason, the primary objective of thermometricians and of thermometry equipment

manufacturers is to make temperature measurement as accurate, as automatic, and as efficient as they can. The sciences of Physics and Chemistry

both underlie thermometry--rather , one might

better note that thermometry underlies both

of these fields and most of the engineering

sciences as well! Many of the fundamental

advances in thermometry have arisen as scientists reached for new tools with which

they could probe the mysteries of nature,

and it is still true that most professional

thermometrists have accompanying interests

in one of a variety of scientific areas. The scientific underpinning of thermometry is to be found in a great kaleidoscope

of scientific and technical societies and

their journals. The principal publications

are Metrologia, the international

journal of metrology, the Review of

Scientific Instruments, the Physical Review,

and the Journal of Chemical Physics.

Corresponding to these in technical areas

are journals such as Instrumentation Technology and the NBS Monograph series. The

American Institute of Physics and its member

societies, the Instrument Society of

America, and a wealth of scientific and

engineering organizations contribute

personnel to the study of thermometry.

15
2.3 Realized Thermometry Measurement

Capabilities

The ease with which precise and accurate

temperature measurement can be provided

varies considerably with the temperature

range and with the application of the user. The most-used range of temperature is

the range 0-200 °C; this is where most

human activities take place. The reader

will appreciate that these activities involve far and away the most numerous measurements of temperature of any part of

the national system. However, the "quality"

of thermometry required in these activities

is, for the most part, adequately met by

the cheapest and least accurate sensors available— the humble mercury-in-glass

and bimetallic thermometers and the

thermocouple. Offering accuracies of one degree or so and precisions of perhaps

one-tenth degree, these are the counterpart

of the "dollar watch"—cheap but adequate.

There is an aspect of each of the

items in the preceding paragraph to which

the free-and-easy remarks made there do not

apply. This aspect is that of the

professional in each of the areas named.

It is true that we can live and work

effectively in buildings whose temperatures

vary substantially from the norm; however,

the professional building designer can do

his job correctly only with the benefit

of thermometry which is much more precise

than our own requirements. The same is

true of the automotive designer, of

appliance manufacturers, and of the medical

profession.

The many different applications of

temperature measurement means that a great

deal of effort is involved in getting a comprehensive overview of the needs for

temperature precision and accuracy.

The major aspects of thermometry

capabilities have been noted already. They

appear in summary form in Tables 2.2B

and 2.2C and in figure 2.2B.

2.4 Thermometry Dissemination and Enforcement Network

The network of standardization institutions has already been examined in

Section 2.2.1. Here we shall note the

dissemination and enforcement institutions.

2.4.1 Central Thermometry Standards

Authorities

a) International organizations con- cerned with thermometry--The General Conference on Weights and Measures, including

its component bodies (the International

Committee for Weights and Measures, the

International Bureau of Weights and Measures,

the Advisory Committee on Thermometry, and

its Working Groups). This body is responsible for the construction and promulgation

of the International Practical Temperature

Scale.

Arising from the treaty of the Meter,

a 17-nation convention meeting in Paris in

1875, were a General Conference on Weights

and Measures, an International Committee

on Weights and Measures, and an International

Bureau of Weights and Measures [46]. The

General Conference meets at six-year intervals, when it considers agenda items which

are introduced by one or more Advisory

Committees, including (since 1937) an Advisory Committee on Thermometry (le Comity

Consultatif de Thermometrie, or C.C.T.).

Table 2.4A shows a sketch of the

General Conference structure:

16
Table 2.4A

General Conference on Weights and Measures

41 Nations subscribe, Conference meets at about six-year intervals - 14th meeting

was October 1971

International Committee on Weights and Measures

18 Nations, elected by the General Conference;

it is the executive body; meets at two-year

intervals at BIPM.

Advisory Committee on Thermometry

12 Major National Standards Laboratories

and some six individual advisors; 10th

Session was May, 1974 at BIPM. USNBS

Representative at 10th Session

R. P. Hudson, Division 221

H. H. Plumb, Temperature Section

Its Missions are:

I. Recommend scale improvement based on working group observations.

2. Study thermometric techniques.

Working Group 1 Working Group 2 Working Group 3 Working Group 4 Working Group 5

International Bureau of Weights and Measures

Paris, Pare de St. Cloud.

Its missions are:

1. Fundamental scale research.

2. International scale comparisons.

3. Coordination of measurement

techniques

4. Coordination of physical constants

measurements

Preston-Thomas, NPL, NBS (H. H. Plumb), IMM; Revisions of IPTS-68

IMGC, CNAM, NRC; secondary fixed points, simplified techniques

NPL, PTB, NBS (L. A. Guildner); Thermodynamic Temperatures above 100 K KOL, Swenson, NSL, IMPR; Thermodynamic Temperatures below 100 K NBS (R. P. Hudson), Japan, NPL; Practical Thermometry Below 30 K

As can readily be seen by a glance at Table 2.4A, the thermometry work of the

General Conference and its subsidiary

organizations is the definition of the

thermodynamic scale and the promulgation of

an International Practical Scale as closely

duplicating thermodynamic temperatures as can be accomplished within the limit of

practical utility. Within the United States,

the National Bureau of Standards is re- sponsible for coordinating this effort.

Much of the actual scale work is done at the

NBS, so that such efforts constitute a substantial part of the NBS thermometry.

A second international standards

authority is the International Organization

for Legal Metrology and its component bodies

(the International Bureau for Legal

Metrology, the International Committee for

Legal Metrology, and its Secretariats,

Technical Committees, and Working Groups).

The OIML issues International Recommendations

on technical data and instruments which are the concerns of Legal Metrology in member

countries. See Section 2.2.1.

b) U.S. Thermometry Authorities

National Bureau of Standards. The NBS

provides temperature calibrations based on the International Practical Temperature

Scale of 1968, and it provides consultative

services in thermometry to science, to industry, and to standards institutions at

all levels.

c) Other National Authorities

Many nations maintain primary standards

laboratories, some of which are also legal

metrological institutions. Among the more prominent national standards laboratories

are those of England, Canada, Australia,

France, Germany, Japan, Russia, Italy, and

The Netherlands.

17
2.4.2 State and Local Offices of Weights

and Measures

The state offices of weights and measures for the most part are inactive in

thermometry. Exceptions to this rule are

the states of Connecticut, Massachusetts,

and Michigan. These are "Seal States" (any

thermometers sold in the state must have

the approval of the State Office of Weights

and Measures). The offices in these states

maintain calibration laboratories and ex- amine a great many thermometers each year.

2.4.3 Temperature Standards and Testing

Laboratories and Services

The principal thermometry standards

laboratories (apart from those described

elsewhere) exist in Federal agancies, in

industrial instrumentation and manufacturing concerns, and, in a few cases, in

commercial testing laboratories.

Some of the most prominent of these are:

• Department of Defense calibration

centers, strategically located to serve the Navy, Army, or Air Force

needs

• Energy Research and Development Administration laboratories at Sandia

Laboratories, Savannah River and Oak

Ridge National Laboratory

. National Aeronautics and Space

Administration laboratories at Huntsville, Alabama and at Orlando,

Florida

• Standards and calibration laboratories

maintained by major thermometry instrument manufacturers and major

users of thermometry.

a) Government and Commercial

Temperature-Cal ibration Faci 1 ities

A great many facilities exist for the

calibration of thermometers and other

standard instruments. Of special interest

are facilities run by various government

agencies for the calibration of their own

and their contractors' instruments, and

commercial facilities which calibrate instruments for all comers on a fee basis.

We have examined in some depth the

system of calibration laboratories operated

by the U.S. Navy. This system is shown

schematically in figure 2.4A. NBS calibrates

instruments which are used in the primary

or Type I standards laboratories to calibrate

periodically all the secondary (Type II)

laboratory standards. In turn, these are

used to calibrate the 300-odd "calibration"

facilities which serve the Navy's own

and its contractors' needs.

NAVY FIELD CALIBRATION LABS

~ 100

U.S. NAVY CONTRACTORS

~ 200

TYPE II LABS

ALAMEDA, POMONA, INDIANAPOLIS, NEWPORT, NORFOLK,

OAHU. PENSACOLA

METROLOGY ENGINEERING CENTER

POMONA. CALIFORNIA

TYPE I EASTERN STANDARDS LABORATORY

WASHINGTON, D.C.

WESTERN STANDARDS LABORATORY

SAN DIEGO

NBS

IPTS

FIGURE 2.4A. U.S. Navy Temperature Calibration Chain.

18
The Army, as well, has a highly developed calibration system. The calibration

laboratory at Redstone is the Army Standards

Laboratory and it represents the highest

level (primary reference) of calibration

standards capability within the Army and

provides primary certification service for

Army calibration activities in the Continental United States (CONUS) and for the

Army Calibration Laboratories overseas. Army Calibration Laboratories provide CONUS

calibration service within designated geographical areas: Anniston Army Depot,

Alabama; Letterkenny Army Depot,

Pennsylvania; Lexington-Blue Grass Army

Depot, Kentucky; Pueblo Army Depot,

Colorado; Sacramento Army Depot, California;

Tobyhanna Army Depot, Pennsylvania; and

Tooele Army Depot, Utah.

The Redstone temperature facility is

directly dependent upon NBS. The following

discussion is taken from reference 47, p. 99

"Standard

"NBS traceability is maintained by a group of Myers type platinum resistance

thermometers which are periodically calibrated by NBS. Working standards are re- gularly checked against triple point of

water cells (.01 °C) to insure that the

measurement system is not drifting.

Range and Accuracies

Item/Parameter

Table 2.4B

Temperature

Range

Conventional S.I. Unit

Accuracy (±)

Conventional S.I. Unit

Liquid in Glass

Thermometer -38 to 500 °C 235 to 773 °K 0.01 °C 0.01 °K

Differential Hz in

Glass Thermometer 0 to 100 °C 273 to 373 °K 0.005 °C 0.005

Platinum Resistance

Thermometer -40 to 500 °C 90 to 773 °K 0.002 °C 0.002 °K

Thermocouple -40 to 1450 °C 233 to 1723 °K 0.25% for Pt-Pt

Rd to 1300 °C or 4 microvolts

0.25% for

Pt-Pt Rd

to 1573 °K

Black Body Radiation

Source Temperature (see thermocouple data)

Cryogenic

Thermometer -269 to -181 °C 4 to 92 °K 0.03 °C 0.03 °K

Techniques

"Platinum resistance thermometer (PRT)

certifications are performed by taking

measurements at the triple point of water

(.01 °C), the freezing point of tin

(231.97 °C), and the freezing point of zinc

(419.58 °C). The resistance of the thermometer at each temperature is determined with

a G-4 Mueller Temperature Bridge having

resolution to 1 micro-ohm.

"Platinum-platinum 10% rhodium thermocouples are certified by taking measurements

at the freezing point of anitmony (630.7 °C),

the freezing point of silver (961.9 °C), and

the freezing point of gold 1064.4 °C).

Measurements are referenced to the ice point

and voltages are determined with a potentiometer having resolution to .01 microvolt.

The freezing points of tin, lead, zinc,

aluminum, and copper are also available for

the calibration of thermocouples.

"Cryogenic temperature sensors are certified by comparison with a platinum

resistance thermometer in a stirred bath.

Bath media range from ethylene glycol

(-40 °C) to salt (500 °C)".

The range and accuracy of various

Army thermometry capabilities are shown in

Table 2.4B [48].

19
Similar calibration operations are maintained by the U.S. Air Force, by the USAEC,

and by NASA. Of course, the question of

whether all of these government calibration

facilities actually maintain the levels of

accuracy to which they aspire can only be

settled by Measurement Assurance Programs (MAP)

of the sort that are now in progress with

Sandia Laboratory, Redstone Arsenal, Leeds

and Northrup, and others. Even more difficult to answer are the questions of

whether the stated levels of accuracy are required by the needs of the using

organizations, and whether they actually

obtain the accuracy they need.

The National Conference of Standards

Laboratories has prepared a useful Directory

of Standards Laboratories [49] which lists

commercial facilities offering temperature

calibrations for a fee. Table 2.4C contains

a listing of these companies.

The purpose of displaying this list is to show the extent of calibration activities.

NBS has contact with this group primarily

through its calibration services and MAP activities. The latter determine actual

scale transferral accuracy and represents

a large undertaking.

2.4.4 Regulatory Agencies

The principal Federal regulatory agency

which is involved heavily in thermometry is the Food and Drug Administration. This

agency, like the three "Seal State" Weights

and Measures offices, has the responsibility

for regulating the sale of medical electronic

thermometers and for the thermometric aspects

of health instrumentation.

The nature of the activities of the re- gulatory agencies often demands rather quick

decisions on the safety or reliability of a given product. Because of this problem, these

agencies occasionally request information

which is difficult for NBS to supply on a short-term basis. A recent case in point is

that of medical electronic thermometers, which

come under the purview of FDA; to evaluate

the quality of particular instruments (let

alone the evaluation of the quality of the

manufacturing, which was the information

actually desired) appeared to require a substantial amount of time, if NBS were to conduct an orderly, statistical investigation.

Yet FDA felt constrained to quickly address

the question of the reliability of these

thermometers, since the public safety was involved. Similar situations, of course, can

be expected to recur in this and other areas,

and the problem offers a challenge to NBS to aid these agencies effectively.

Table 2.4C

NCSL Listing of

Commercial Calibration Facilities

Primary Secondary

Aerojet Electro Systems

Company X X All is Chalmers Manufacturing Company X X American Geophysical and

Instrument Company, Inc. X X AVCO-Lycoming X AVCO Corporation X X Bendix Corporation X Boeing Aerospace X X Boeing Wichita X X Burroughs Corporation X X Cannon Instrument Company X Colorado Engineering Expt.

Station X X E.G. and G. , Inc. X Electro-Scientific

Industry, Inc. X X John Fluke Manufacturing

Company X General Dynamics Corporation X X General Electric Company X Hercules, Inc. X Hewlett Packard Company X X Honeywel

X X ITT Research Inst. X X Leeds and Northrup X X Clifton (Litton Ind.) X Lockheed-California Company X X LTI Research Foundation X LTV Electrosystems, Inc. X X McDonnell Douglas

Astronautics X X Martin Marietta Corporation X X National AstroLabs/Metrolonies X North American Rockwell X X NAR, Rocket Dyne Division X Sanders Associates, Inc. X Singer General Precision,

Inc. X Sperry Electronic Tube

Division X SSCO Standards Lab X Teledyne McCormick Selph X Teledyne Systems Company X X TRW Systems Group X X Tucker Electronics Company X Varian Associates X Volumetrics X X Westinghouse Electric

Company X X

20
As de facto regulatory agencies, the

College of American Pathologists and the

American Hospital Association participate

in the accreditation of hospitals through

the certification of the quality of their

thermometry capability. By and large, this

certification procedure comes down to evidence of treaceability to the NBS.

2.5 Direct Measurements Transactions Matrix

for Thermometry

2.5.1 Analysis of Thermometry Suppliers and

Users

In order to attempt a codification, or evaluation of the thermometry activities of

the U.S. in summary form, it is necessary

to categorize the various components--as

indeed we have done in the preceding Sections.

For the purposes of this Section, we

shall tabulate fifteen sectors of the

thermometry conmunity in an order which

is common to all portions of the NBS Measurement System study. In this Table 2.5A are listed representative entries, their

principal roles as suppliers of thermometric

sensors, instruments, data, or information,

and all the corresponding roles as users.

We have also indicated, where appropriate.

Standard Industrial Classification codes

which apply to these entries.

In addition to Table 2.5A, describing

the various supplier and user roles in the

National Temperature Measurement System,

we have attempted to construct a matrix

describing the transactions which occur

between supplier and user groups. In this

Direct Measurements Transactions Matrix,

Table 2.5B, groups described in Table 2.5A

are listed in columns 1-25 in their roles

as users of thermometry, and in rows 1-25

as suppliers. The code to the entries is as

fol lows:

A. In the center of each matrix

element, the numbers indicate the magnitude

of the activity between supplier and user

None - trivial

1 - minor

2 - moderate

3 - important

4 - major

B. In the lower left corner, any change

in the activity level is shown.

N - declining

0 - stable

2 - growing

4 - growing explosively

C. In the upper left corner, the level

of importance of the activity is indicated

1 - purely convenience

2 - strongly desirable

3 - no real alternative

4 - essential

D. In the upper right corner, the

adequacy of the activity is indicated.

0 - entirely adequate

1 - could be improved

2 - marginal

3 - serious deficiencies

4 - really unsatisfactory

E. In the lower right, the primary

type of thermometry activity supplied is

coded according to the letter equivalents

in Table 2.5A.

2.5.2 Highlights of Thermometry Users

The major users of thermometry, as might be expected, are the manufacturing

concerns of categories (4) and (14), although all of the categories listed in Table

2.5A use two or more of the letter-coded

thermometry goods and services.

The number of classes of such thermometry users is so large, as we noted in the

introduction to this study, that we can scarcely hope to list them, let alone

discuss their individual needs. Let us rather submit that in the general case, their requirements for accuracy and

precision are not high and are adequately

met by available thermometry.

Ultimately, of course, even the drug

store thermometer manufacturer relies on NBS

for the integrity of his product. One such

supplier referred to NBS as "the heart of

(his business). We could not function without NBS" [50]. The reason that this is so

is that both voluntary standards and most

legal requirements refer specifically to NBS as the final authority in matters of

temperature. This situation leads to a continuing need for NBS to maintain calibration services for the various sensors and

ranges in common use. Besides its role as an "invisible"

partner in much of our daily lives, temperature figures more prominently in many other

areas. It is the life-blood of the temperature controls industry, of course, and it

plays a strong role in the broader classifications of general controls and of precision

instrumentation through the frequent pre- sence of temperature stability or temperature

regulation requirements. The petroleum industry is the biggest single user of liquidin-glass thermometers, whose sales volume is

$5-6 million in ASTM-specified models alone.

The chemicals industry, steel and automotive

equipment manufacturing (in fact, the general

class of manufacturing) all feature multitudes

of carefully-maintained standards and quality

control laboratories which uniformly include

temperature standards. Power companies;

the aerospace industry; the Department of

21
Table 2.5A

The Thermometry Community and Its Roles as Suppliers and Users of Thermometric Goods and

Services

Key to Supplier/User Entries

A - Thermometric Reference Data and Compilations of Such Data

B - Temperature Calibrations

C - Temperature Sensors and Associated Instruments

D - Thermometric Instruction and Consultation

E - "Thermometry Needs" Information

F - New Thermometry Methods

G - Thermometry Texts and Literature

H - Temperature Control Devices

J - Temperature Standards and Regulations

K - Money for Thermometric Research and Development

L - Durable Goods Incorporating Temperature Control

Sector Suppl ies Uses

(1

(2)

(3)

(4)

(5)

The Knowledge Community

Scientific Organizations AD A

E F C Academic Institutions G F Professional Societies H Technical Publishers L SIC Codes: 2721, 2731, 2741, 7391, 8071, 8221, 8231, 8911, 8922, 8999

International Metrological Organizations

General Conference of Weights and Measures; A B A Standards Laboratories of England,

France, Australia, Holland, Italy,

Japan, USSR, Canada

Documentary Specification Organizations

International Electrotechnical Commission,

International Organization for Legal

Metrology, American National Standards

Institute, American Society for Testing

and Materials, Department of Defense

Military Specification Activities

The Instrumentation Industry

Manufacturers of temperature sensors measurement equipment, temperature

control equipment

SIC Codes: 3822, 3823, 3829

National Bureau of Standards

Plant Division, Instrument Shops Division,

Electricity Division, Mechanics Division,

Heat Division, Optical Physics Division

Cryogenics Division, Electromagnetics

Division, Time and Frequency Division,

Analytical Chemistry Division, Polymers

Division, Metallurgy Division, Inorganic

Materials Division, Reactor Radiation

Division, Physical Chemistry Division,

Engineering and Product Standards

Division, Electronic Technology Division,

Center for Building Technology, Center

for Fire Research

SIC Codes: 8922

22
Table 2.5A (Continued)

Sector Supplies Uses

(6) Other U.S. National Standards Authorities

This is a null entry for thermometry.

(7) State and Local Offices of Weights and

Measures

A B C D

J

(8) Standards and Testing Laboratories

Army, Navy, Air Force, National B D A B Aeronautics and Space Administration, C D Energy Research and Development G H Administration, Major Instrument and J User Corporations Calibration

Laboratories

SIC Codes: 9611, 9661, 9711

(9) Regulatory Agencies

U.S. Food and Drug Administration, J K A B College of American Pathologists, C D American Hospital Association G

SIC Codes: 9431

10) U.S. Department of Defense E F A B (except Certification and K CD

Calibration Laboratories) F G

H J K L SIC codes: 9711

11) Other Government Agencies (except

Calibration Laboratories)

Energy Research and Development E F A B Administration, National Aeronautics K CD

and Space Administration, Health, F G

Education and Welfare Department, H J Department of Conmerce, United States K L Department of Agriculture, Interior

Department, Housing and Urban Development

SIC Codes: 9531 , 9532, 9661

(12) State and Local Government (except C D Offices of Weights and Measures H L Essentially a null entry

(13) Industrial Trade Associations

Scientific Apparatus Makers' Association, E D J Instrument Society of America, Society

for Automotive Engineers, National

Electrical Manufacture Association, etc. SIC Code: 8911

(14) Intermediate Industrial Users or

Suppl iers

Manufacturers of durable goods of all D E A B types (e.g., laboratory furnaces, F H CD

household ranges, washers, dryers, K L E F air conditioners, airplanes, automobiles G H and parts); manufacturers of chemicals, J K plastics, fertilizers, etc.; mining and L petroleum companies; transportation

companies; industrial and household

repair companies; (and many others)

23
Table 2.5A (Continued)

Sector Supplies Uses

(14) (Continued)

SIC Codes: Truly too numerous to list!

(15) General Public E • Each of us as individuals rather than

as employees of a particular organization

6 H

L

Defense, State Weights and Measures Bureaus

and other governmental agencies all need to measure temperature to a greater or lesser

accuracy. For many of these portions of

the NMS, temperature is an important

parameter which helps govern whether an instrument, a process, or a product will

meet specified criteria, and the thermometric

activity amounts to using a well-known

sensor in a standard way to ensure adequate

results. In other cases, primarily research

and development activities, a stable sensor

does not exist, and the problem is avoided

by widening tolerances or the group involved becomes a (probably unwilling) party

to thermometric research.

The group of customers for temperature

instrumentation is so broad as to be

apparently of little value as a subject for

discussion--if the reader considers the heading for a moment, he will realize that just

about everybody belongs to it. The automotive manufacturing industry, power manufacturers, and the petroleum, plastics,

chemicals, glass, aerospace, electrical

appliance, and electronics industries are using temperature as a process parameter.

In answer to the obvious question, we hasten

to observe that an important characteristic

is shared within this group. This

characteristic is an attitude toward temperature measurement as a necessity to be subdued

as painlessly as possible. Of course, the

quality of thermometry which is accomplished

by members of this group varies widely, and our feeling, based upon conversations with

many individuals, is that this quality

depends very strongly on the equipment and

information which is at hand. In the case

of corporate activities, especially, cost

considerations also play a large part in

determining the nature of such "incidental"

thermometry.

The significance of this perhaps obvious

observation is that any activity which

raises the level of awareness of the utility

and availability of adequate thermometry, or which raises the quality of thermometry

available at a given cost, will have farreaching effects simply because of the

great numbers of people involved.

Even among such an erudite group as re- search scientists (and we do not exclude

NBS!), individuals occasionally unnecessarily degrade the quality of their research

by failure to apply careful thermometric (or

other standard) techniques . Corporate ex- amples can be chosen almost at will from

the ranks of manufacturers of all kinds of

commodities; two such examples might illustrate the nature of the problem: in one case an experimental laboratory in the

automotive industry only now (and with non- professionally trained personnel) is

attempting to base engine design upon

temperature and pressure profiles; in

another, a major power producer expressed

no oonoem that uncertainty in temperature

measurement might well be decreasing the

thermodynamic operating efficiency by

several percent, thus wasting dwindling fuel

supplies.

Balancing these examples, of course, are others in which thermometry development is

underway to enhance the quality of a product--one corporation, for example, is

studying the miniature platinum resistance

thermometer in order to improve its

differential thermal analyzer [51], and a large computer firm is active in thermometry

in order to make its semiconductor manu- facturing more efficient, requiring ±1 °C

for 16 hours at 1200 °C [52]. Nonetheless,

it would appear that effective work in this area by NBS will be very productive in terms

of increased quality of thermometry.

The opportunities for NBS to make con- tributions in this area are varied and

economically impressive. To cite a few

examples, a major film maker reported a need

for temperature reproducibility at the ten

millidegree level and a desire for stability

at the one millidegree level from 0-65 °C,

both presently beyond their capability [53];

a kiln requires, for optimum output, con- tinuous monitoring of an air atmosphere

within 5 °F at 1800 °F, again beyond its present capability [54]; most flow measurements

require temperature calibration, for

accuracy as well as for subsidiary pollution

24
DIRECT MEASUREMENTS TRANSACTIONS

MATRIX FOR

SUPPLIERS

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1 E

2 1 2 e2 1 2

E

2 1

1 E

2 1 2

E

3 1 4 A

2 3 2

15 HEALTH SERVICES

(SIC Major Gp 80)

2 1

1 E

2 1

1 E

2 3

3

2 E

2 1 3

? F

1

2 1

1 E

3 1 4

n

4 3 4

2

""^ GENERAL PUBLIC 2 3

2

?

1

2 1 2

2

2

3 1 4

n Key to Matrix Entries

C - Importance of Transactions

1 - Purely convenience

2 - Strongly desirable

3 - No real alternatives

4 - Essential

B - Rate of Change

N - Declining

0 - Stable

2 - Growing

4 - Growing Explosively

E - Thermometry Services Supplied

See Table 2.5A

? - Unknown

X - Not studied

Blank = 0

C D

A

B E

25

(In)adequacy of Services

- No improvements needed

- Could be improved

- Marginal

- Serious deficiencies

- Out of control

A - Magnitude of Transactions

0 - Trivial

1 - Minor

2 - Moderate

3 - Important

4 - Major
measurements, and this is simply not available; National Marine Fisheries Service, of

NOAA, has found that a fraction of a degree

change in water temperature can "radically

alter" the feeding habits of tuna. This

finding has implications both for the value

of oceanographic temperature mapping and

for pollution studies. One resulting

activity taking place is called the MidOcean Dynamics Experiment [55]. We have already discussed some of the

nuclear power reactor activities. Here the

need is for stable, accurate fuel centerline temperatures in a hot, intensely radioactive environment, and similar stability

in hot liquid sodium (LMFBR) or hotter

gaseous helium (HTGR) [56]. In the geothermal power search, the emphasis is on stability and accuracy of rock temperatures,

both to identify potential sources of geothermal power and to monitor the depletion,

with time, of a given source [57]. An accurate, quick method for determinina the

enthalpy of liquified natural gas is an essential feature of equitable custody

transfer, and this is not available.

The ability of a competent instrumentation scientist to influence the growth of

medical practice has been described in terms

of "forcing a definition of the real re- quirements of a measurement need to avoid

simply making gadgets for the M.D." [58].

Another opportunity is in the coming use of

fluidic sensors to measure turbine inlet and

outlet temperatures [59]; such a device is

in increasing use in the aircraft industry,

but, though it is both durable and stable,

its temperature characteristics are re- latively unknown [60].

Many applications of infrared sensing

have been developed, and each of these

contains the potential for temperature

mapping on both a fine and a macro scale.

Such activities as thermal pollution

monitoring, plant and soil field studies,

paper processing, rubber and textiles

curing, printing and painting, food processing, and microcircuit analysis are all

currently in operation. However, the

temperature data which would allow

correlation with other variables is very

qualitative, because of uncertainties in

calibration [61].

3. IMPACT, STATUS, AND TRENDS OF THE

NATIONAL TEMPERATURE MEASUREMENT SYSTEM

3.1 Impact of Thermometry Measurements

3.1.1 Functional, Technological and

Scientific Applications

We have already noted that thermometry

26

touches virtually every person in the U.S.

The quality of thermometry routinely available governs his health, his comfort, and

often his manner of earning a living. The

major manufacturing industries depend to a great extent on high-precision temperature

measurement and control. Finally, scientific research in many areas produces useful

data only to the extent that it employs

sound, accurate thermometry. Some examples

of these applications follow.

a) Thermometry in Medicine

Clinical laboratories are becoming

highly automated in their testing and a large fraction of the results obtained are sufficiently sensitive to temperature to demand that small, stable, highly sensitive,

accurate, and rapidly-responding temperature

sensors be used. Those sensors should also

be capable of producing electrical signals

that can be digitized in order to be used

with data recording and analysis systems.

In instruments for enzyme rate analysis

in which samples of only a few microliters

are used, the requirements for accuracy,

response time and size of the temperature

sensor are paramount, and in instruments for

acidity and blood gas analysis, temperature

measurements in the immediate vicinity of

the measuring electrodes require small,

accurate sensors. In routine clinical tests

that are presently being performed, temperature errors produce such a variation in the

results of enzyme tests that comparisons

among laboratories, and even within a given

laboratory, are useless. This is a sad

state of affairs, especially when one realizes that inadequate thermometry in

clinical laboratory tests may result in

incorrect diagnosis and improper treatment

of the patient.

At the present time, 20% of all

temperature measurements of patients in

hospitals and in physician's offices are taken using rapid, disposable and inexpensive temperature sensors which are rapidly

displacing conventional mercury-in-glass

thermometers and, yet, these sensors have

not been adequately evaluated!

Just as in the case of the electronic

fever thermometers, the temperature sensors

in use today throughout the medical field

appear to have many of the required qualities, but they have never been adequately

characterized. In addition to having sensors with the desired properties, it is

necessary to be able to check their

calibrations periodically in the field or

to enable new calibrations to be made

accurately. The best way of doing this

would be through the use of a set of
standard temperature-reference-points in the

range of biological interest and a practical

simple mechanism to relate the patient

temperature measuring instruments and the

various devices utilized in the clinical

laboratory to those reference points.

None exists at the present time.

Miniature temperature sensors which

are insensitive to electromagnetic fields

are needed in order to be able to determine

the temperature distributions produced in

tissues being irradiated by the electromagnetic waves in diathermy (a medical

treatment in which heat is produced in the

tissues by a high frequency electric

current). Temperature mapping the tissues

is required in order to set standards of

safe levels of electromagnetic radiation

from the diathermy machines. This technique

is required since direct measurements of

electromagnetic field intensities in tissue

are difficult to perform, and, in any case, temperature is the critical variable inside

the tissue. Heretofore, such temperature

measurements have not been performed in a satisfactory way.

b) Thermometry in Building Design and

Comfort

Human thermal comfort has always been

a consideration in the design of buildings,

whether homes or businesses. In the "good

old days" when energy was plentiful and

inexpensive and buildings did not need to

be so carefully designed, the thermostat

in the room or building could be set such

that one would be comfortable at any given

location in the room. When his location was changed to a different part of the building

or even a different part of the same room, however, it is very likely that a change

in the thermostat setting would be necessary

in order for the person to be made comfortable again. Since energy required to keep

one comfortable is now very expensive and

becoming more and more so with likelihood

of an energy shortage, well insulated

buildings designed with human thermal

comfort maintained by a minimum use of

energy are a prime consideration.

A number of different types of

thermometers have been used by design

engineers and probably the one most

widely used at the present time is the

globe thermometer. This is a very crude

thermometer system which attempts to measure

the mean radiant energy over a solid angle

of 4 TT steradians. Such a thermometer is not a good indicator of human thermal

comfort. This can easily be seen by a simple example. The human body is, to a first approximation, a 2-dimensional system

and if a person is near a fire, then one side (say his front) is exceedingly hot

whereas the other side (his back) may be

excessively cold. As a result of this ex- change of radiant energy, the person is most

uncomfortable but since the globe thermometer

measures the mean radiant energy over 4 ir steradians, it would indicate a temperature

which would be pleasingly comfortable to the

person. This, then, points up the problem

with such a thermometer.

We have noted earlier, of course, that

the home, office, and factory are heated and

cooled according to temperature-sensitive

controls which operate furnaces, fans, re- frigeration units, and sometimes ventilating

windows or doors.

c) Thermometry in Manufacturing

One may consult the Standard Industrial

Classification Codes noted in Table 2.5A for

an indication of the groups of manufacturers

which employ thermometry.

The uses to which temperature measurement amd control are put include steel

making (not only to adjust the furnace

temperature itself, but also to monitor and

control the temperature of gas streams,

cooling ingots and coke ovens as well),

manufacturer of both ferrous and non ferrous

metal products (chiefly in heat-treating

furnaces), and food preparation (much of

the U.S. food preparation industry utilizes

assembly-line manufacturing principles,

techniques, and instrumentation)

which involves storage temperature

measurement and control as well as process control

A great variety exists not only in the

wide-ranging products of U.S. manufacturing,

but also in the thermometry techniques which

it employs. Liquid in glass or metal

thermometer systems, bimetallic, resistance,

and thermoelectric thermometers, and

radiation pyrometers are used individually

or in concert to measure, record, and control

temperature in manufacturing.

d) Thermometry in Science

The variety of thermometers employed in

scientific research and development is nearly as great as that used in manufacturing. High-precision resistance or quartz

oscillator thermometers are used in calorimetric studies and in other physical and

chemical thermal data acquisition. Less precise but more versatile or smaller

thermometers are employed in basic studies

where temperature is not of primary importance. The range of temperature which is measured and controlled in scientific
experimentation ranges from above the melting

point of the most refractory material (as,

for example, in research on thermonuclear

fusion) to within one degree of absolute

zero. Innovation is the order of the

day in much of this v^^ork, and most advances

in thermometry arise from the efforts of

scientists to measure and control temperature.

3.1.2 Economic Impacts - Costs and Benefits

Some idea of the costs involved in

the use of thermometry equipment by the

National Temperature Measurement System

has been given by figures quoted earlier in

this Study. For example the annual sales

of thermometers exceed $5 million just in

ASTM-specified liquid-in-glass; electrical

and electronic thermometer sales in 1972

exceeded $40 million; over $10 million worth

of thermistors are sold annually; annual

sales of thermostats for heating and cooling

exceed $280 million.

Such figures indicate the economic

magnitude of thermometry (which is clearly

enormous in itself and possesses a great

deal of leverage to boot, since thermometry

comprises only a small portion of the value

of manufactured goods), but they do not

address the individual questions of the

benefit which may be derived by a given

company or industry upon introducing more

effective thermometry. This latter type of

information is difficult even for an individual company to obtain in a reliable

way. Still less visible is the cost of not introducing improvements in technology such

as thermometry.

This study has benefited from the advice of trained economists in numerous ways,

from simple familiarization with economic

statistics to the principles of technicaleconomic forecasting. A detailed discussion

of the cost-benefit relationship in the

National Temperature Measurement System is out of the question as a practical matter

and, we think, beyond the proper scope of

this study. Even this brief overview of

the System, however, makes abundantly

clear the general situation that thermometry

investments in the National Temperature

Measurement System are large and growing and

that the use of automatic thermometry equipment is increasing steadily.

3.1.3 Social, Human, Person-on-the-Street

Impacts

The ma.ior benefits of thermometry in

many social terms relate, for example, to the

precision and efficacy of medical treatment;

people are alive today because U.S. Industry

has provided U.S. medicine with a certain

level of quality of thermometry. (We have

not reached the millenium in this particular

area, however, as we have seen!) They relate

also to his safety, as temperature control

of dangerous systems such as chemical pro- cessors and boiler plants has improved to the point that serious plant accidents are

rare. They relate as well to his comfort

and standard of living, insofar as he owns a thermostated oven, toaster, automobile, home,

air conditioner, laboratory, hot water

heater, office, greenhouse, or any manufactured item for which the materials of con- struction owe their properties to the careful

temperature control which is now so widely

available.

3.2 Status and Trends of the Temperature

Measurement System

In coming to grips with the National

Temperature Measurement System, its current

status and trends, we called upon the personal knowledge accumulated by our staff

over the years. We found that we had great

stores of data on sensors, their stability

and calibration properties, and that we had

a limited knowledge of the needs of various

people.

The real core of the National Measurement System is, of course, people. Only

people and the purposes of people given

meaning to thermometric devices and the

numbers which come from them.

In attempting to analyze the "National

Measurement System" for temperature, we realized that only by becoming

conversant with the activities of people in

many different occupations could we begin

to understand their interrelationships and

to identify their capabilities and needs.

The best way to familiarize ourselves

with the activities of the National

Temperature Measurement System is by face-to-face discussion and laboratory or plant visits. In such extended contact

we obtained some or all of the following

types of information:

1) The nature of the group's thermometry interest;

2) the relevance of this interest to other group's activities and to national problems;

3) the practical precision and accuracy

desired, and that realized;

4) relevant economic data--costs or

sales of calibrations, sensors, thermometry or associated equipment;

5) impact of their work upon national,

industrial, or social problems;

6) value of NBS thermometric services

to their own activities, and particular needs which NBS might be

28
able to supply.

Travel restrictions, coupled with the

large expenditure which travel involves,

have the effect of limiting the amount of

such face-to-face discussion. The

effectiveness of telephone or mail contact

in eliciting the type of information we

seek is not nearly so great, unless a previous contact with the individual has

created an easy relationship.

As a consequence of several such

familiarization visits, we were able to discern patterns which allow us to separate

groups of people according to the manner in

which their activities impinge on thermometry.

Underlying the whole structure of the

National Temperature Measurement System is the International Practical Temperature

Scale. NBS thermometricians improve the

scale with the help of academic researchers

who, though an independent lot, bring solid

accomplishments to strengthen the scale.

It is only a little oversimplification

to describe the three NBS calibration

services as the main pillars of support for

the rest of the structure: in fact we have

found a universally high regard for these

services and a desire to see them more widely available.

The NBS provides calibration services

to the various sensor manufacturers,

although, as we have indicated, the

thermistor industry needs special help. In turn, the sensor manufacturers support the

temperature control equipment manufacturers

and the large government and commercial

temperature-cal ibration faci 1 ities

Finally, the commodity industries, both

large and small, rest strongly upon the

combined bases of temperature control devices

and sensors. Another aspect of the National

Temperature Measurement System concerns

health and safety in thermometry. We found,

in this area, that the problem of medical

temperature standards is severe. Doctors

J. H. V. Brown and D. J. Lowell of Health,

Education and Welfare discussed the question

of standardization and health care in a cogent article which points out that, with

acequate standardization, the medical

profession could well concentrate on maintaining the health of the 220 million

citizens rather than simply curing the 1.3

million sick. There are no widespread

criteria for manufacture of hospital equipment to prevent electrical shock, they say;

inadequate control of pacemaking equipment

is rampant; the safety of ultrasound and

microwave equipment is completely unevaluated; clinical tests are widely variant

from hospital to hospital and even within

29

a single lab; and the medical community

really doesn't know how to set up standards.

They suggest that the Federal government

guide the medical profession and the instrument manufacturers in this task [1]. A similar theme is sounded by R. S. Melville

of the National Institute of General

Medical Sciences, who notes the lack of

adequate clinical laboratory standards and

the formation of a Committee for the study

of automation in medical laboratories; he

stresses the utility of microcalorimetry

work at NBS (in the Thermochemistry Section)

and of the Standard Reference Materials

program [2]. Mai Schechter, writing in

Lab World, urges Health, Education and

Welfare and National Institute for

Occupational Health and Safety to work with

American National Standards Institute, the

National Committee for Clinical Laboratory

Standards, and NBS on comprehensive medical

standards [3]. Dr. Nathan Gochman, Chief

of Clinical Chemistry for the Veterans

Administration Hospital in San Diego,

focused on temperature as a vital parameter

in a talk on automated clinical testing, in

which he pointed out that the use of enzyme

analyses and other temperature-dependent

tests enhance noticeably the requirement

for temperature standardization and control

[4]. As will be noted in Section 4, NBS is

beginning a comprehensive program of

measuring the relatively unknown

characteristics of the ubiquitous thermistor,

and of providing the technical leadership

for medical standardization.

The regulatory agencies, too, have

difficulties. One example of this problem

is a recent case before the New York Public

Utilities Commission involving the re- location of the official thermometer by the

Orange and Rockland Utilities, Inc.; the

utility had moved the thermometer from a relatively protected position to an unsheltered one, and sought rate relief of

$1 million based on the colder readings [5]. An enormous current and developing

problem centers around automotive pollution

and mileage; we noted earlier that automotive design is often unscientific, in

part owing to poor thermometry in design.

This leads to mediocre mileage-to-weight

ratios. Emission control also suffers

from poor thermometry. Privately, the

industry admits that health and safety

considerations rank low in its priority

listing [6]. The regulatory agencies,

however, must decide on workable goals in

the face of conflicting arguments; the auto

industry has been described by the

Secretary of Commerce as "spending nearly

$2 billion in 1973 on safety and emission

standards" [7], and the Coordinating
Research Council-Air Pollution Research

Advisory Committee has been both criticized

as an industry slave [8] and praised as an independent force [9]. P. G. Hansel, VicePresident of Research for an NCR subsidiary,

recently called for major programs to en- hance engine efficiency [10]. Accurate

measurement of temperature and pressure in

each cylinder and an electronic gasoline

control system are being considered as a mechanism for reducing emissions and improving mileage of automobiles.

The problems of the medical community

also occur, of course, with respect to regulatory agencies. We have already alluded

to the uncertainty of ultrasonic and microwave diathermy safety. The reliability of

electronic thermometers [12] is also regulatory concern of FDA, as well as of several

states. The principal challenge to NBS is to provide useful guidance to these agencies

within their relatively short time requirements .In the various power and energy areas, we find the active people uncertain as to how to proceed with measurement and control

problems. In the very active area of

nuclear power reactors, the question of

public safety is the subject of continuing

controversy. Fortunately (for the NBS

thermometry program, that is) the primary

controversy centers around radiation

safety [13]. However, the lack of really

adequate temperature measurement capability

has contributed to the difficulty of

introducing substantial quantities of nu- clear power into the U.S. energy network

[14]. The U.S. currently has about 17,500

megawatts of nuclear power--about 10% of that

currently projected to 1980. This is about

the same amount of power as is produced by

TVA from non-nuclear sources [15,16].

Finally, in the area of commodity

manufacturing, the problems of health and

safety often are not readily visible, and

they often are not willingly exposed to

view.

Another area of immediate concern is

that of industrial standards. We believe

the keys to this situation are information

and cooperation, with NBS data and technical

advice connecting the individual manufacturer

and standards groups and among the various

standards groups themselves.

In forming these ideas, we drew upon

many years of combined experience of

service to the National Temperature ^ Measurement System (although we have not always thought of it in those terms) and

upon familiarization visits to particular

faci 1 ities

During the past year or so, we have

visited well over fifty facilities of

various types. We attempted to visit

power manufacturers, aerospace manufacturers,

regulatory agencies, medical research and

health care facilities, government calibration laboratories, oceanographic facilities,

temperature control and temperature sensor manufacturers. In addition, we have

attended numerous scientific, technical,

and commercial standards meetings.

As a consequence of these visits, it

became obvious to us that we could significantly affect the quality of medical

patient care in the U.S. by undertaking a combined technical and liaison program in

medical thermometry. Reprogramming of

personnel to this end has enabled us to begin already a 3-4 person effort which is more fully described in Section 4. We have found, as might be expected,

that many parts of the National Temperature

Measurement System have generated ways of

solving their own problems in temperature.

One case which is worth citing is that of

critically evaluated data, in which an attempt is made to analyze existing data to arrive at "best values" for a given

quantity [17,18]. The NAS/NRC has sponsored

a Report on Physics in Instrumentation, in

which the integrity and needs for thermometry instrumentation are evaluated. Many

professional associates have sponsored

research groups, such as the American Gas

Association and the Electric Power Research

Institute, and many non-NBS groups sponsor

meetings and research projects on thermometry and control. A few examples

of these are the ORNL Instrumentation and

Controls Division Annual Information meeting;

a course on Measurement Systems Engineering

given annually by Arizona State University,

and "Physics Opportunities in Energy Problems", offered by the American Physical

Society in February 1974.

Although sufficient to give us a picture

of the basic status and trends of the

National Temperature Measurement System,

the field investigations conducted to date

are by no means sufficient either to delineate completely the natures of the

various groups or to point the way un- equivocally to correct courses of future

action. To these ends, we have outlined

further specific inquiries which we shall

note later.

30
4. SURVEY OF NBS SERVICES TO THERMOMETRY

NBS has contributed to the National

Temperature Measurement System since the

Bureau was established in 1901. In this

section, we will present some discussion of

early contributions and we will detail the

nature of present activities. It should be

noted at the outset that the present thermometry activities cross Institute as well

as Division lines, and we made a definite

attempt to present a balanced view of NBS

thermometry without chauvinism. The reader

can easily determine how well we succeeded

by soliciting comments from outside the NBS

Heat Division.

4.1 The Past

From the first International Temperature

Scale of 1927 (submitted by NBS, NPL, and

PTR, and described for the U.S. public by

G. K. Burgess, at that time director of

NBS) [1], the National Bureau of Standards

has maintained a leading role in U.S.

thermometry: With the National Research

Council, NBS cooperated in preparing the 1939

Temperature Symposium and provided half of

the papers on temperature scales and on precision thermometry [2]; NBS established

temperature calibration facilities for the

various standard instruments (Over 500 firms were listed among recent calibration

services customers). With the AIP and the

U.S. Army, NBS sponsored the 1954 Temperature

Symposium and again contributed key papers

on fixed point apparatus and temperature

scales [3]; similar comments apply to the

1961 and the 1971 Symposia; in addition,

NBS has disseminated tables, monographs

on measurement techniques, and original

research in thermometry through journal

articles, colloquia, seminars, and other

scientific meetings.

Two very useful compilations of NBS

thermometry contributions are Vol. 2^ of NBS

Special Publication 300, "Precision

Measurement and Calibration-Temperature"

[4] and its companion volume on Heat [5].

The former contains an assortment of papers

on temperature scales including IPTS-48;

the 1939 Hoge-Brickwedde gas-thermometer

scale recorded on platinum resistance

thermometers between 14 °K and 83 °K; its

correction in 1955; the 1965 NBS 2-20 K velocity of sound scale of Plumb and

Cataland; and the 0.002-2 K scale based on the paramagnetism of cerous magnesium

nitrate by Hudson and Kaeser. In addition,

there are resistance, thermoelectric,

liquid-in-glass, and spectroscopic

thermometry and optical pyrometry; in all, some twenty-five papers.

31

The latter volume likewise is a mine of

NBS expertise, this time in the general

field of calorimetry, with many of the

thirty-odd papers being of fundamental

importance to thermometry.

It is worthwhile to review the NBS

contributions to the Fifth Temperature

Symposium, [6] since a good idea of the

level of NBS thermometry can thus be gained.

R. P. Hudson, Chief of the Heat Division;

H. J. Kostkowski, Chief of the Optical

Radiation Section; H. H. Plumb, Chief of the

Temperature SEction; and W. R. Tilley,

Chief of the Office of Technical Publications

served on the General Committee. H. H. Plumb

was Chairman of the Program Committee, as- sisted by H. J. Kostkowski, R. D. Cutkosky

(Electricity Division), and R. L. Powell

(Cryogenics Division) in addition to the

twenty or so members from outside NBS.

In the technical program, NBS contributed some 27 papers ranging in nature from

very fundamental thermodynamic thermometry

to temperatures in building environments.

All of the foregoing Section represents

only a portion of the thermometry activities

of NBS in the recent past. Consultations,

reports to sponsors, other publications and

contributions to other scientific meetings

must be added to complete the picture.

4.2 The Present--Scope of NBS Thermometry

Activities

4.2.1 Description of NBS Thermometry

Services

In order to give the reader a flavor of

the range of thermometry activities at NBS we shall note recent accomplishments of the

appropriate programs. In the next subsection

we shall review the thermometry programs

within the Heat Division [7], and

subsequently other thermometry highlights

within NBS.

4.2.1.1 Heat Division Thermometry Activities,

1974

The new year brought a change in leadership to the Temperature Section. R. P. Hudson, Chief of the Heat Division, acceded

to H. H. Plumb's long-standing desire to return to a more active scientific role in

the Section's activities, thus bringing to

an end an era that began in October, 1966.

Under Dr. Plumb's leadership, the

Temperature Section gained both stature and

versatility. In 1966, over 50% of the

Section's effort was devoted to calibration

activities; this figure is now below 20%.

Projects have been initiated in calorimetric

measurement of thermodynamic temperatures.
in medical thermometry, and in a continuing

study of the national temperature measurement system. The Section participated

closely in the formulation of the new Temperature Scale [8], and it is presently represented on two of the four

working groups of the CCT which were in

existence in January, 1974, as well as on the temperature committees and subcommittees

of both the American Society for Testing and

Materials and the American National

Standards Institute.

Several of the highlights of the year's

activity in the Temperature Section appear

in the Minutes of the May, 1974 meeting

of the CCT at the International Bureau

of Weights and Measures (BIPM) in S6vres,

France [9]. The National Bureau of Standards

was represented at that meeting by

R. P. Hudson, Chief of the Heat Division,

and by H. H. Plumb. Technical contributions were submitted by staff members of

the Cryogenic Physics Section, of the

Equation of State Section, and of the Temperature Section. A summary of the

Temperature Section contributions follows:

1) A brief discussion of the cryostat

and methods used in the calibration

of capsule platinum resistance

thermometers from 13.81 K to 90.188 K;

2) recent gas thermometry results

which provide information on the

differences between the IPTS-68 and

thermodynamic temperatures from

the triple point of water to 415 K (142 °C). Working group 3,

of which L. A. Guildner is a member,

reported it;

3) a brief description of apparatus,

currently under construction, for

the comparison of standard platinum

resistance thermometers (SPRT's)

from 90 K to 900 K;

4) the results of a study of the

freezing temperatures of six

experimental aluminum freezingpoint cells; and

5) editorial suggestions regarding

changes in the text of the IPTS-68.

Consideration of possible revisions

of the text was a particular duty

of Working Group 1 of the CCT, of

which H. H. Plumb is a member.

As usual, the Section offered a weeklong seminar on precision thermometry. The

attendance, however, was more than double

the usual number. Some twenty-seven

participants crowded the calibration

laboratories during the week of 10-14 March.

In addition to providing both that seminar

and a three-hour thermometry session which

formed a part of a local university's short course in standards laboratory operation,

the calibration staff tested over one thousand precision thermometers and answered

a like number of written and verbal inquiries on thermometry to round out a very

satisfactory year.

The Section's work in thermocouple

thermometry included the publication of the

long-awaited Thermocouple Reference Tables,

Monograph 125, and highly successful study

of a new high-temperature nickel-siliconchromium thermocouple system developed in

Australia.

The low-temperature acoustic thermometer

program yielded results of thermodynamic

measurements of the transition temperatures

of two elements of the NBS superconductive

fixed-point device.

The medical thermometry program, begun

only a year ago but now the largest in the

Section, has made rapid progress toward its

goal of improving the nation's medical care

by improving the quality of thermometry in

medicine. New precision clinical laboratory

thermometers were developed, equipment and

procedures for characterization of thermistors and small platinum resistance thermometers were completed, collaborative work

on an environmental scanning radiometer and

on thermometry in medical diathermy was accomplished, and exchange of equipment and

ideas took place between the medical thermometry group and staff members of

hospitals, clinics, and medical instrument

manufacturers

Closely allied to the field of medical

thermometry, as well, is a new project

begun in the past year by W. S. Hurst.

Partially funded by the National Institutes

of Health, this project will be an experimental study of thin-film capacitance thermometry . R. J. Soulen is utilizing a sensitive

superconductive tunnel junction to determine

noise temperatures according to the Nyquist

theorem. This technique was suggested by

R. A. Kamper of the Cryogenics Division.

At present Soulen 's results agree within ±2

mK from .02 - .04 K with results of yet

another thermodynamic temperature determination undertaken by H. Marshak. These

latter measurements involve the measurement

of the anisotropy of y-i^adiation emitted by

60-Co nuclei in a single crystal of cobalt;

the various nuclear data determine the

anisotropy due to decay of nuclei in the

magnetic energy levels, and the Boltzmann

32
distribution function governs the level

populations.

In addition to the cryogenic physics

discussed above. Heat Division programs

include the generation of Superconductive

Thermometric Fixed Points from 0.5 K to 7 K, developed as NBS Standard Reference

Material 767 by J. F. Schooley and R. J. Soulen, Jr. [10], and study of paramagnetic

sensors below 20 K by B. W. Mangum and

D. B. Utton. The overall Cryogenic Physics

Thermometry Program is discussed in some

detail in NBS Technical Note 830 "NBS

Cryogenic Thermometry and the Proposed

Cryogenic Extension of the IPTS".

In this section, an indication has

been given of the range of NBS activities in

temperature standards. Appendix D lists

most (dare one say alll) of the NBS staff

members who officially participated in these

activities

To this catalog we add a recent anecdote

which may be illustrative of NBS' role in

industrial standards. Having joined the

International Organization for Legal

Metrology (OIML) in August, 1972 [11], the

U.S. was given the opportunity to vote on

a current draft recommendation on electrical

resistance thermometers composed of Pt, Cu,

and Ni (PR 41). In order to develop a position on the recommendation, J. Schooley

distributed copies of it during the ASTM

Resistance Thermometry (E-20) Committee

meeting in June, 1973. Other copies were distributed to interested companies who were

alerted by ASTM. In all, correspondence

took place with some two dozen firms.

Their comments on the draft were consolidated

into a U.S. response with the help of

Mr. E. D. Zysk, of Engelhard Industries,

a representative to lEC, and Mr. J. E. French

of the Scientific Apparatus Manufacturers

Association. Mr. W. E. Andrus, U.S.

representative to OIML, communicated this

(negative) response officially [12].

4.2.1.2 NBS Thermometry Activities Outside

Heat Division

a) Thermal Efficiency of Buildings

Temperature measurements play a large

role in several parts of the Center for

Building Technology programs. One of these.

Project Breakthrough [13], was commissioned

by HUD to examine the feasibility of

applying the principle of overall energy

consumption to a building complex; all the

"waste heat" from the power generators is to

be used for building air and water heating.

P. R. Achenbach and J. B. Coble are attempting to assess the economic features, including the heat balance, of the complex. A

33

similar program is underway with HUD, AEC,

NASA, and EPA cooperation [14]. Since 20-

25 percent of the nation's energy use goes

for space and water heating or for lighting,

significant power savings can result from

these programs.

The Center also has an experimental

townhouse in which the thermal balance is

measured. B. A. Peavy, D. M. Burch, J. D. Allen, and D. R. Showalter have instrumented

the house heavily, including some 140 airtemperature sensors and 58 wall and window

surface temperature probes [15]. The CBT

environmental test chamber provides a temperature environment ranging from -50 °F to +150 °F. In one recent study, the fuel

economy of nighttime reduction of the

thermostat set point was evaluated and

shown to be quite substantial.

In other, related CBT programs, T. Kusuda

and F. J. Powell are studying thermal

storage and heating cycles in buildings [16];

and J. Stern and S. Edelman are studying

plastic infrared detectors [17] and their

use in scanning thermal detectors [18].

b) High-Speed Thermophysics

A. Cezairliyan, of IMR, has been studying for some time the simultaneous measurement of a variety of thermophysical

properties of refractory metals. In addition to such information as electrical

resistivity and heat capacity, he obtains

temperature values for the sample data by

optical pyrometry. Recently, this technique

provided information on the thermal properties of niobium alloys in the range 1500-

2700 K [19]. In addition. Dr. Cezairliyan

has studied the relation between radiance

temperature and actual temperature at the

melting point [20].

c) Microcalorimetry

Microcalorimetry is a science which

is of particular value to research biochemists and to clinical laboratories

because of its ability to analyze

extremely small samples. This very requirement, of course, brings its own emphasis

on the use of small, sensitive thermometer

probes. NBS, in its Thermochemistry Section

of IMR, has a very active group including

G. T. Armstrong, E. J. Prosen, R. N. Goldberg,

R. N. Boyd, B. R. Staples, and M. V. Kilday.

An NBS clinical microcalorimeter which was described in a recent report [21] uses a quartz thermometer (sensitive to ±10 yK)for

overall temperature stability evaluation,

and a thermopile is used in the primary

energy detection.
4.2.1.3 The NBS Thermometry Input-Output

Table

The present activities of NBS in thermometry can be summarized in a variety of

ways. Perhaps the most useful technique

would show a dollar value which each

portion of the program provides to the

various components of the national measurement system, but this technique is absolutely

beyond the competence of mere scientists,

involving as it does an economic evaluation

of basic temperature scale studies which

predate their useful consequences by many

years. Two methods, however, are at once feasible and useful. One of these is the

source-output diagram, and the other is a national needs-thermometry activities

matrix.

In the source-output table 4.2A, we

attempt to show the origin of the current

thermometry activities (which we have

discussed briefly in this section) and the

major outputs which result from these

activities. The distribution of calibrations, research efforts, and consultations

over the various user areas conspire to make the estimates of the percentage outputs very uncertain; however, these numbers

may be useful even in a qualitative way.

Table 4.2A

NBS Thermometry Request Sources

NBS - Provide direct requests for calibrations and consultations.

Electricity Division, Physical

Chemistry Division, Mechanics

Division, Optical Physics Division,

Cryogenics Division, Analytical

Chemistry Division, Polymers Division,

Electromagnetics Division, Metallurgy

Division, Inorganic Materials Division,

Electronic Technology Division, I Structures, Materials, and Life Safety

Division

Industrial Requests - For sensor development

and characterization, calibration,

thermometry consultation. -500 individual firms, 10-12 trade associations

Voluntary Standards Groups - Provide direct

requests for technical guidance in

writing standards. Provides information on current and planned development in scale work. CCT, ASTM, ANSI,

lEC, ISO, OIML

Regulatory Agencies - Provide direct re- quests for consultation and measurement services. Provide information

on future needs. FDA, HUD, EPA, OSHA

Other Government Agencies - Provide direct

requests for calibrations, consultations on thermometry problems.

Provide information on future needs.

USN, USA, USAF, NOAA, AEC, NASA, HUD,

DOT, NIH Medical Groups - Provide direct requests for

calibrations, and consultation. Pro- vide information on future needs.

NCCSL, CAP, Medical Instrument Manufacturers, Individual hospitals,

physicians, and medical researchers

Thermometry Equipment Manufacturers - Provide

direct requests for calibration and

consultation services. Provide information on state-of-the-art design.

-100 firms, ISA, SAMA

University Researchers and Professional

Journals - Provide information on advanced thermometry principles and

techniques. Provide collaboration on research and development problems.

-1000 universities, -50 journals

NBS Outputs, with Percentages

10%

NBS - Calibrations. Consultation,

Colloquia. Reports.

10%

Industrial Firms - Calibrations (-$75,000 in

FY-73). Consultations. Reports.

10%

Voluntary Standards Groups - Meetings

attendance (-100 estimated in FY-74).

Technical evaluation of standards proposals (-10 estimated in FY-74).

5%

Regulatory Agencies - Consultations - OSHA,

FDA, HUD, DOT, EPA. Reports.

25%

Other Government Agencies - Calibrations

(-$40,000 in FY-74). Reports on sponsored research (estimate

$500,000).

15%

Medical Groups - Calibrations (-$15,000

in FY-74). Reports on sponsored

research. Consultations.

10%

Thermometry Equipment Manufacturers - Consultations. Calibrations

(-$20,000 in FY-74).

15%

Scientific Research Journals - Scientific

papers (-50 in FY-74). Colloquia.

34
4.2.2 Users of NBS Services

The major users of National Bureau

of Standards thermometry services

have been identified in Section 2.5.

They comprise the "Knowledge

Community" (Scientific and Educational

groups), Metro! ogical and Standards bodies,

the Thermometry Instrumentation industry,

NBS itself, government and commercial

calibration laboratories, various government

agencies, manufacturing groups, and health

services. Typical examples of their uses

of NBS services are the employment by a thermometry manufacturer of a calibrated

Standard Platinum Resistance Thermometer

to determine the accuracy of a production

temperature sensor-readout system; and the

conversion by a new company of NBS instruction on the manner of establishing a calibration laboratory, into a set of orders for

space, environmental control, and precision

thermometry equipment.

4.2.3 Alternative Sources

It is difficult to say how the various

thermometry responsibilities of the NBS would

be met by the National Temperature Measurement System in the unlikely circumstance

that NBS were to cease to exist.

The fundamental difficulty with such a step would lie in the responsibility of NBS

to participate with other industrialized

nations of the world in maintaining a uniform

International Temperature Scale which is

based on thermodynamic measurements. This is

a very expensive undertaking, since it demands the long-term involvement of highlyqualified scientists. We know of no organization--governmental , university, or industrial --which could commit sufficient

resources to meet this responsibility. Thus

any such attempt would necessarily involve a consortium of organizations with the

attendant management problems.

A similar difficulty appears in meeting

the responsibility of Scale dissemination.

A likely solution would entail the verification of Scale integrity by each of the major

industrial and governmental calibration

laboratories. This solution carries with it

the inherent problem that a given laboratory

would have a financial stake in minimizing

the expense involved in certifying the

accuracy of its thermometric measurements.

The lack of objectivity in such a system

would almost certainly lead eventually to the generation of a "National Bureau of

Regulatory Standards" somewhere within the

federal government.

The easiest of NBS' current responsibilities to meet is that of contributing to

35

broad, general problems in thermometry

measurement science. In thermometry these

problems are met by very small NBS efforts —two-to four-person programs undertaken in

collaboration with university, governmental, or industrial groups. The efforts

are commonly mounted in response to needs

perceived as affecting an entire industry

or measurement area. The fact that the

NBS efforts in these general areas are miniscule in comparison with those of

other government or industrial laboratories,

coupled with the fact that workers in the

particular areas involved are generally

motivated to solve their own problems,

indicate that the NBS efforts here are

the least essential of its services. A modicum of foresight and modest resources would permit the NBS effort in applied

thermometry to be duplicated elsewhere.

The missing elements in this solution are those which NBS can contribute in special

circumstances: organizational resources

to bring particular problems to light as

is done in periodic workshops and con- ferences generated by NBS; objective

expertise to apply to important national

questions such as the quality of particular

energy-conserving measures or effective

means of improving U.S. medical care by

application of more relevant standards of

thermometry; and the combination of stateof-the-art facilities, expert staff, and

flexibility in programming to "bear down"

on a particular problem before it becomes

a bottleneck to progress by a whole

industry.

4.2.4 Funding Sources for NBS Thermometry

Services

Overall, NBS thermometry is funded

about 50% from external sources and 50%

by direct congressional appropriation.

The outside funding support comes chiefly

from calibration income and the Executive

Departments of Health, Education, and

Welfare, of Housing and Urban Development,

and of Defense.

The distribution of this funding is not uniform throughout the NBS programs,

however. Most of the outside funding

accrues to applied thermometry programs

outside the Heat Division (excepting

calibration income), while the major direct

appropriation support goes to Heat Division

scale research and dissemination activities.

The following summary of Fiscal Year

1974 funding of the Cryogenic Physics and

Temperature Sections (the two principal

thermometry activities of the Heat Division)

helps to illustrate this situation.
Table 4.2B

Cryogenic Physics and Temperature Sections

Funding by Source, Fiscal Year 1974

Source Percent

NBS

Direct Appropriation

Standard Reference Materials

Other NBS Divisions

80

1

1

Total NBS 82

Other Government Agencies

National Oceanographic Administration

Food and Drug Administration

Department of Justice

13

4

Total OGA 8

Cal ibrations 10

Grand Total 100%

4.2.5 Mechanisms for Supplying Services

The dissemination mechanisms by which

NBS supplies its thermometry services take

many forms, reflecting the diversity of NBS

activities. Most of these have been

discussed elsewhere in this study and will

be mentioned here only briefly.

Scale Research results are communicated

to the general scientific community through

articles published in the open literature.

In addition, direct communication is made

to the International Thermometry Committee

(the "CCT") of the General Conference on Weights and Measures both in written reports

and by verbal presentation at periodic

meetings.

Cal ibrations are rendered upon

thermometry equipment owned by governmental

and industrial laboratories. Test results

are given in written form and occasionally

analyzed as a class to yield information

on the overall precision and accuracy of

NBS temperature calibrations. These

summaries are made available to the public

in general through the NBS Technical Note

series.

Measurement Assurance Programs , Consultation and Instruction involve the

NBS staff directly with individual governmental, industrial, and medical thermometrists. Test summaries, recommendations,

handbooks and instructional materials are

written and distributed during discussions

with the users of these services.

Basic and Applied Thermometry results

and services are communicated through the

writing of reports-to-sponsor, NBS technical

publications, or research papers. In addition, of course, lectures, seminars,

and technical meetings serve as outlets for

this type of information. In many cases, particular devices make up a portion of

these services.

Standard Reference Materials and Data

results appear as items for sale through

the Office of Standard Reference Materials

(listed in the NBS Special Publication 260),

or as reference tables or other data

published in the NBS Monograph series.

Voluntary Standards services generally

appear indirectly. New or revised industrial standards often are based in part or wholly upon data or measurement techniques

originating at the NBS. Examples of this

activity arise primarily because the NBS

thermometry staff actively participate in the

work of the American Society for Testing and

Materials, the American National Standards

Institute, and their international counterparts. Writing and editing of publications

issued by or at the request of such groups

often falls to NBS thermometrists because

of their great familiarity with the topic.
4.3 Impact of NBS Thermometry Services

4.3.1 Economic Impact of Major User Classes

The major thermometry users have been

identified in Section 2. In terms of

immediate economic importance, certainly

the largest contribution comes from the

manufacturers of durable goods. These

people build and sell refrigerators, air

conditioners, automobiles, aircraft, stoves,

furnaces, furniture, and many other products

which may include thermometers or thermometric controls or may simply require

thermometric monitoring or control in

their manufacture. These people are NBS

thermometry calibration customers. It is

difficult to assign a value added by

NBS services to this group.

Mining, agriculature, chemicals

manufacturing, and metals and plastics

producers regularly send their highest

quality thermometers to NBS for

thermometry calibrations. Again the

economic impact may be stated simply as "large".

The automatic temperature controls

industry is separately classified by the

Census Bureau. The various components

of this industry annually ship goods worth

several hundreds of millions of dollars

annually. By this time, our listing is

reaching groups whose representatives not only buy calibrations from NBS, but also

consult frequently on measurement problems.

As the user-group output becomes more

specialized, its direct and immediate

economic impact is smaller, but its longrange importance appears to be larger.

The manufacturers of thermocouple thermometers, resistance thermometers, liquid-inglass thermometers, bimetallic and thermistor

thermometers ship annually goods valued at $10-50 million in each subgroup. However,

these products govern the quality and

performance of those enormous user classes

listed earlier.

Still longer range in economic impact

is the government-funded research and

technology activity, containing the U.S.

executive Departments, the national

laboratories, and federally funded laboratories in the industrial sector. NBS helps

the people who staff these organizations in

ways we shall note in the next section; and

although their immediate economic impact is small (or negative!) their importance for

the future of the U.S. is large.

4.3.2 Technological Impact of NBS Services

In addition to the obvious influence

which basic research on the international

temperature scale at all temperatures carries

to the areas of competence in international

trade and of the general improvement of the

quality of U.S. goods and services, very

specific technological improvements result

from NBS activities in thermometry.

Among these improvements are techniques

of calibration and measurement, which enable

higher quality to be delivered for less

expense; new knowledge of the characteristics

of medical sensors, which permits their use

at new levels of accuracy; new types of hightemperature thermocouples, leading to advances

in the instrumentation and design of nuclear

reactors, high-temperature turbines and

engines, and high-temperature industrial

processes; new accuracy in cryogenic

instrumentation; new techniques for

differential thermal analysis and other

basically microcalorimetric applications; new knowledge of fast temperature measurement

techniques; and more accurate and reliable

thermal analysis of walls, buildings, and

dwelling complexes.

A National Needs-Thermometry Activities

Chart was devised in a series of meetings

of the Temperature Section staff as a con- venient means of monitoring particular

areas where NBS thermometry efforts have an impact upon various national needs.

Table 4.3A contains a listing of various

areas of importance to the nation in the

first column. The second column contains

a listing of many projects and services of

the thermometrists at the NBS. Following

each entry in column two is a list of

numbers which denote the national needs which

are, in part, met by the particular NBS

service or project.

This method of presentation has provided us with the ability to see how our own programs impinge on national

problems and indicate that we are more

readily able to plan our programs with a perspective arising from consideration of

those needs.

4.3.3 Pay-Off from Changes in NBS Services

Over the years, NBS has begun new services and dropped others, with consequent

adjustments by the U.S. Temperature Measurement System. One such change was the

cessation of calibrating fever thermometers.

This change helped bring down the price of

such thermometers, and it simultaneously

forced the manufacturers to establish and

regulate for themselves their calibration.

A second example of such a change is

the institution of medical thermometry as a program in the Temperature Section two

years ago. This change has already begun to show benefits in improved thermometry as well

37
Table 4.3A

NBS- National Needs Chart

National Needs Thermometry Activities

1

Energy 1

Thermocouple Development 1

,

5, S, 11 2. Measurement Assurance 2. Miniature Resistance

Thermometer 1

,

5, 9, 10, 11

3. Meteorology 3. Noise Thermometry 1

,

9, 10

/I 4. Oceanography 4. Radiation Thermometry 1 . r5, 9 , 10, 11 5. Health 5. Fixed points 1

,

5, 9 , 10

6. Safety 6. Thermistor Characterization 5, 9, 10, 11

7. Environment 7. Transistor Thermometry 5 8. Consumer Protection 8. Cal ibrations 2, 5,

o n 1 r» 11 8, 9, 10, 11 (i.e., product integrity)

9. Industrial Standards 9. Tiny Sensors 5 10. An Accurate Temperature Scale 10. Mi crocal or i met ry 5, 9, 12

1 1Temperature Control 11Electronic Thermometers 5, 8

12. Temperature Measurement Systems 12. Liquid Crystals 5, 9, 10

13. Thermal Pollution 13. Quartz Thermometers 3, 4, 5 14. Safety in Thermometry 6 15. Theory of Thermometry 10, 11, 12

16. Regulatory Agencies 5, 6, 7, 8

17. Practical Thermometry Tips 2, 8, 9 18. Intercompari son of Standard

Platinum Resistance

Thermometers 2, 10

19. Gas Thermometry 9, 10

20. Transient and Dynamic

Thermometry 1, 2, 12

3, 4, 9, 11,

21. New Equipment Development 2, 9, 11, 12

22. Cryogenic Sensors 1, 2, 10, 11, 12

23. Nuclear Resonance

Thermometry 10, 12

as an increased awareness of the importance

of accurate thermometry to effective medical

practice.

As thermometry projects at the NBS are completed, or reach a point where further

work would bring diminished returns, the

institution of new projects becomes

possible (in the present climate which prevails throughout the U.S. economy, NBS is

making every effort to maintain a lively

effective standards program without overall

growth in its staff). A large part of the advance planning

prior to such opportunities concerns explicit

questions of scientific and technical payoffs accompanying various options. These

are necessarily balanced against questions

of available facilities and major strengths

in the thermometry staff.

4.4 Evaluation of NBS Thermometry Program

The NBS thermometry program is continually evaluated by its own staff and by NBS

management in periodical reviews. In addition to these self-appraisals, an ex- plicit evaluation of the program is supplied

by a panel of experts on an annual basis.

The Evaluation Panels have been established

through the National Academy of Sciences in

conjunction with the National Academy of

Engineering and the National Research

Counci 1

The Heat Division Evaluation Panel is

made up of some ten members, which in

recent years have represented the following

organizations

. Argonne National Laboratory

• University of Illinois Center for
Advanced Study

• Pennsylvania State University, physics

department

• Eastman Kodak Company, di rectorate of

research

• Hunter Associates Laboratory, Inc.

• Los Alamos Scientific Laboratory

• General Electric Corporate Research

and Development

• Lawrence Livermore Laboratory

• General Telephone and Electronics

Sylvania Lighting Center

• Cornell University department

of chemistry

. California Institute of Technology

department of physics

• Bell Laboratories, Murray Hill

• University of Rochester, department

of physics and astronomy

• University of Wisconsin, Space Science

and Engineering

An estimate of the opinion of the Heat

Division Evaluation Panel on the quality of

the thermometry program may be obtained from

the following, quoted from the most recent

report:

"The Panel believes that the thermometry

program in the Heat Division, which includes

the work in the Temperature Section and in

the Cryogenic Physics Section as well as the Optical Pyrometry project in the

Optical Radiation Section, is excellent.

The objectives of the program are sound and

they are appropriate. The staff working

on thermometry are very competent and they

are enthusiastic about their work. The

accomplishments of the program in terms of

publications and the thermometer developments

made by the staff are significant in respect

to both quantity and quality."

The Panel recommended that the program

should be more heavily funded and staffed,

but expressed an understanding of NBS

limitations in that regard. Detailed

discussions of some individual projects

give considerable guidance to NBS in its

efforts to maintain a lively, effective

program.

The criteria by means of which NBS

evaluates possible additions to its programs

can be listed as follows:

• Relevance to the basic program

• Possible Scientific or Technical

Advancement

• Adequacy of Resources (staff, equipment, and space)

• Available NBS Leadership.

In addition to the above criteria, work

contemplated for other agencies must be of

such a nature that NBS, its staff, or its

facilities are uniquely suited for the

project.

In the opinion of its line management,

the major strength of the NBS thermometry

program is that it has competent staff.

Because of this fact, those areas which are treated at all receive intelligent attention.

A second strength lies in the variety of the

thermometry activities: The Heat Division

staff performs calibrations, and basic and

applied research in standard sensors; the

Physical Chemistry Division staff studies

thermometry as applied to differential

thermal analysis and microcalorimetry; and

the Center for Building Research studies

thermometry applied to energy flow in con- struction materials.

The major weakness of the NBS Thermometry

programs is that so many areas of thermometry are not under study at all . A second

weakness is that there is too little interaction between the metrological thermometry

in the Heat Division and the applied

thermometrists working elsewhere in NBS. The Evaluation Panel of the Heat Division

generally supports these findings, offering

high praise for the program as performed but

regret at the thinness of its coverage of the

field.

4.5 The Future of Thermometry at NBS

The considerations which have been

treated in this study demonstrate a need

for a number of activities for NBS

thermometry, some along well -traveled

paths and others in new directions,

a) The National Temperature Measurement

System Study

In the first place, the assessment of

the needs of the National Temperature Measurement System is clearly a valuable tool in

directing NBS programs, and we believe that

it should be a continuing process. Field

visits, which currently occupy a great deal

of effort (and not a little money) are an excellent source of information, much of

which cannot be obtained in other ways. We

see this activity diminishing in intensity

within the next two years, hov;ever, as we become more knowledgeable regarding the

National Temperature Measurement System.

We expect then to continue the field visits

at a reduced level

As personal contacts become more firm

and widespread, we expect to make greater

use of telephone and correspondence as a means

of maintaining liaison with current activities

in facilities which we have already visited.

This procedure will then form a substantial

and continuing channel of communication.

A particularly important part of the

study activity should be closer liaison

39
between the Heat Division staff and the other

NBS thermometry personnel . Where the programs require collaboration, it seems to take

place in a satisfactory manner; however,

lack of awareness and communication is

apparent in many areas, and this problem is

compounded by difficulties such as competition for external funding.

b) Calibrations

Secondly, our studies show a continuing

need for a calibration capability in

platinum, liquid, and thermocouple thermometers at the highest attainable levels of

accuracy to maintain a uniform scale of

temperature for both science and technology.

The construction of comparison

facilities for calibration between fixed

points and the design and installation of

automatic bridging and data logging equipment can be expected to permit increased

versatility in the calibration services.

One potential feature of such services is an extended measurement assurance program which

will permit NBS to evaluate selected calibration facilities, at their request, in the

field.

As part of the calibration activities,

the capability for fixed-point determinations is necessary. As part of this

activity, the possibility of utilizing

transitions in well -characterized solids

will be examined. Such solid-state fixed

points would be substantially easier to realize and to promulgate than most of

those in existence at present.

c) The International Temperature Scale

Thirdly, work on the temperature

scale should be continued. In particular,

the gas thermometer investigation of the

scale integrity should be pressed to an ultimate overlap with radiation thermometry.

The extension of the scale through the

cryogenic range should be brought to fruition--if necessary, through NBS

initiation of an international discussion

to this end. The NBS acoustic thermometry

has stimulated a similar effort at NPL in

England, where acoustic thermometry results

are being compared with others from gas and isotherm thermometry. The NBS noise

and gamma-ray anisotropy thermometry may both

overlap the acoustic thermometer range,

offering a direct comparison of three

fundamentally different thermometers.

The superconductive fixed point program

may provide, in addition to the five points

presently existing between 7.2 K and 0.5 K, further points at 18 K, 13 K, 0.1 K, and

0.2 K; an evaluation of these as potential

40

defining points on the cryogenic scale should

be pressed. The generation of a convenient,

accurate, and reliable thermometer for

transmitting the cryogenic scale to the

cryogenics industry is a vital part of this

program, as well. The nuclear magnetic

resonance thermometer offers not only an alternative cryogenic sensor, but a means

of following current research trends toward

ever-lower temperatures.

Another area of temperature scale

research involves the convenient, accurate

measurement of temperatures in the 600 - 2000 °C range. At present, neither

thermocouple nor resistance thermometry

is completely satisfactory in this range,

and as industrial needs expand, NBS clearly

can provide substantial help by continuing

to work in this area. Finally, NBS should respond to the

various thermometry needs which have become

evident in the National Temperature

Measurement System study. We can assume

that only a small fraction of the total

problems have been discovered up to the

present time, and that others will demand

attention as the study continues.

d) Medical Thermometry

In the area of Medical Thermometry, work

has begun on the characterization of

thermistors and of commercial platinum re- sistance thermometers. In addition, B. W. Mangum and S. D. Wood are actively building,

in collaboration with the medical community,

with the Food and Drug Administration, and

with the Bureau of Radiological Health, a further technical base for medical

thermometry. The expected end product is

standardization of medical thermometry with

a consequent dramatic improvement in the

quality and uniformity of patient care in

the U.S.

e) Needs for Improved Thermometry in

Energy

Major changes are occurring in the worldwide production and use of energy. The

current crisis in oil -based energy has

propelled the U.S. into careful studies of

alternative sources. Most of these studies

indicate that new extensions of existing

thermometer capabilities will be necessary

if the U.S. is to generate appreciable new sources of energy.

Take, as an example, increased

utilization of nuclear fission reactor

power. Present technology, while virtually

free of serious accidents, still is in such

a state that remote siting of power reactors

offers the best means of widespread accep-
tance. In turn, remote siting places heavy

demands on the capability for low-loss

transfer of electric power over long distances and into major cities; in our opinion,

this problem calls for the introduction in

large quantity of superconductive power

transmission lines. These lines, composed

of a central conductor coaxial with a flowing coolant and an enclosing return

conductor, are of such tremendous currentcarrying capacity that a superconducting

gaseous-helium-cooled cable the size of a man's arm can carry as much power as some twenty high voltage towers can support.

They require cryogenic installation and,

probably, underground siting. One cable,

however, is expected to supply so much

power that, for example, Brookhaven National

Laboratory expects that its coming experimental switchover to 100% superconducting power

cable will not even provide test data on the ultimate capacity of a single cable.

The reader should note well with respect

to superconductive power transmission, that

the entire cable except for its outer shield

will be existing at a temperature completely

beyond the range of the present International

Scale!

Superconductive power transmission

figures heavily too, in our opinion, in the

intensive use of solar and geothermal power.

These sources do not occur near the great

cities whose power needs they may fulfill,

so that low-loss, high capacity, long lines

will be a necessity for their use. Field calibration of accurate thermometers used for lifetime prediction for

geothermal sources will become quite

important, in our opinion. Such on-site

calibration will go far to break the

"calibration chain" effects of long time

delays in calibration and concomitant loss

of instrumental accuracy.

In the Energy Research and Development

Administration, an Assistant Administrator

for Conservation has been formed. Success,

for this group, must be measured in terms

of thermodynamics. A whole new order of

thermometric accuracy, convenience, and

persistence must be considered if its

efforts are to be effective and appreciated.

Household energy use as well may call

for thermometric improvement. The growing

trend to condominium and apartment dwellings

dictate consideration of central power

sources for heat and light, but how to monitor energy consumption?

In the area of thermometry in energy, we are investigating the employment of

thermometry as one tool in enhancing the

efficiency of present power production

facilities and in effective safety and

control of fast breeder reactor plants.

41

In addition we are probing the thermometric

aspects of the thermocline oceanographic

heat pump power generation and that of

geothermal, controlled thermonuclear

reactor, and solar power plants. It should

be noted, however, that the scientific

problems appear to be by far the simplest

feature of increasing the efficiency of

existing power facilitips. Economic and

political considerations here ("who pays for

it?") are not trivial

f) Industrial Standards

In the area of industrial standards, we

will undertake basically a liaison role

which has two tasks. First, catalog the

standardization activities of the various

groups which were noted in Section 2, and

second, communicate directly with the

individual industries of Section 2 and with

the "standards industry" so that they can

cooperate in writing standards if they so desire. The next few years are certain to

be critical ones for U.S. industry because

of the competition of foreign manufacturers,

and part of the problem will arise through

international standardization. NBS

participation in the standardization process

by providing technical advice and effective

liaison can benefit both the American

consumer and U.S. industry.

A continuing and challenging problem area exists in trying to promote the production of

higher quality, safer, and more internationally

competitive products through industrial

thermometry. This is an activity which con- cerns primarily the group noted in Section 2. Both of these tasks are difficult. Although our experience to date may be atypical,

we found that many commodity manufacturers

are interested in thermometry primarily as

it relates to the efficiency of manufacture;

they show little interest in thermometry

applied to the ability of the product to perform its function or to its durability.

The principal reason given for this attitude

is an economic one, and the challenge is to provide the means by which the economic

question can be overcome. Tools which can

be used in this effort include a reference

service for thermometry expressly intended

and publicized to offer technical information (on sensors and measurement techniques)

and locator information (on geographic

availability of calibration and engineering

laboratories) to help eliminate that portion

of thermometry problems which arises through

a lack of awareness of existing technology

and a well -planned Measurement Assurance or Measurement System Calibration program to sample thermometry competence in "willing",

selected facilities.
5. SUMMARY AND CONCLUSIONS

To summarize the state of the National

Temperature Measurement System is to summarize the state of the U.S. economy,

its science and its technology. Thermometry is literally an al 1 -prevading

activity.

In this Study we have attempted to portray the structure of the National

Temperature Measurement System, beginning

with the most basic concepts, noting the sensors and other thermometry tools, and

sketching the composition of the major

developers and users of thermometry. We

have discussed the technological and economic

aspects of thermometry as they relate to the

life of the average American. Finally we

have presented a picture of the thermometry

activities of the NBS, attempting to show

the many ways in which the Bureau provides

technical resources to help the nation

to progress in thermometry.

We conclude that temperature measurement and control in the U.S. is sufficiently

precise and accurate to accomplish its

stated objective. Areas which are deficient

(medicine, new energy sources) are areas which involve new technology or in which no clear mechanism exists to focus on problems

and to eliminate them.

Areas in which we see particular needs

developing over the next few years are:

• High-temperature thermometry

measurement and control

• Thermometry in cryogenics

• Fast-responding sensors

• Time dependent measurements

• Measurements in hostile environments

• Calibration of measurement systems

• Calibration of reduced-accuracy

thermometers

• New working relations between na- tional and international

I standardization groups

Building on the foundation of this

study, NBS thermometry must maintain a lively

interest in the activities of groups throughout the National Temperature Measurement

System and continually evaluate and assess

the priorities of potential NBS programs in

the light of the needs of the entire System.

6. ACKNOWLEDGEMENTS

As noted at the outset, this study

was written by a single individual.

However, most of the members of NBS

Sections 221.03 and 221.11 have contri-

{ buted directly to the study, and many

people, including H. H. Plumb, G. T. Furukawa, R. J. Soulen, G. W. Burns,

W. S. Hurst, H. Marshak, and B. W. Mangum

• 42

i

in addition to the author, have visited

various facilities on its behalf. The

assistance of all of these people is

gratefully acknowledged.
7. REFERENCES

Section 1. Introduction

[1] Private communication, colleague at NBS.

[2] The National Measurement System study

is a collection of over twenty individual "micro studies" of activities

in the Institute for Basic Standards,

U. S. NBS.

[3] U.S. Department of Commerce Organization Order 30-2B,

Section 2. Structure of the System

[1] A short history of thermometry can be

found in an article by R. B. Lindsay in

Vol. 3, Part 1, p. 3 of "Temperature,

Its Measurement and Control in Science

and Industry" edited by C. M. Herzfeld,

Reinhold, N. Y., 1962.

[2] H. T. Wenzel (then Chief, Pyrometry

Section, NBS) in the lead article in

Vol. 1 of "Temperature, Its Measurement

and Control", Reinhold, N. Y., 1941.

[3] W. Thomson, Phil. Mag. 33, 313 (1848).

[4] The word "clearly" here may have been

somewhat optimistic, although it seems clear to us. Reference 2 and an article

by C. M. Herzfeld on p. 41 of the volume

referred to in reference 1 both discuss

this point.

[5] Even today, neither thermodynamic

thermometry nor any fixed points other

than the triple point and the boiling

point of water are in common use; nevertheless, the standard instruments

used in practical thermometry re- produce the most heavily-used portion

of the scale within about 100 ppm of

thermodynamic temperatures.

[6] G. K. Burgess, J. Res. NBS, 1, 635

(1928).

[7] The scale is described in an article by

J. A. Hall of NPL on p. 115 of Vol. 2 of "Temperature, Its Measurement and

Control in Science and Industry,

Reinhold, N. Y., 1955.

[8] The chief reason for the separate definitions, according to Hall (Ref. 7),

is that whereas the 100 °C interval

between the ITS defining points was

known to ±.001 °C (thus the ITS degree

Celsius was reproducible to ±10 ppm)

the thermodynamic accuracy of the

triple point was ±.01 °K so that the

degree Kelvin could be known only to ±30 ppm.

[9] "The Committee", Metrologia 5, 35

(1969).

[10] This adjective was added in 1960.

[11] In fact one such adjustment has already been suggested by L. A. Guildner

of NBS, who points out that his gas

thermometer only reads 99.97 °C at the boiling point of water. This and

other NBS contributions to current

thermometry are discussed in Section

4.

[12] Metrologia 5, 35 (1969).

[13] At NBS, for example, only five of

these exist.

[14] International Standards Organization

"Memento 1972". Copies of this and

other documents relating to ISO might

be obtained from the ISO at 1, rue de

Varembe', 1211 Geneve 20, Switzerland.

The same address applies for the lEC.

[15] The NBS Technical News Bulletin,

February 1973, contains on p. 47 a short discussion of the O.I.M.L. and

the beginning of U.S. participation

therein.

[16] The pre-1970 history of ANSI can be

traced through "The Magazine of

Standards" articles in January 1967,

January 1968, September 1968,

November, 1968, April 1969, and

October 1969. Presently, ANSI

activities are described in the "ANSI

Reporter", published biweekly by ANSI,

1430 Broadway, New York 10018.

[17] ASTM, 1916 Race Street, Philadelphia,

19103, publishes the "ASTM Standardization News", a monthly magazine

which discusses its affairs in concise

but informal fashion.

43
[18] ASTM Standardization News, February

1973, p. 4.

[19] Ibid., p. 32.

[20] J. A. Beattie, Vol. 2, p. 63, of

"Temperature", Reinhold, (1955).

[21] W. D. Huston, Vol. 3, Part 2, p. 949

of "Temperature", Reinhold, (1962).

[22] E. F. Moeller, on p. 162 of the volume

cited in reference 1, discusses

Callendar's work in the general context of precision resistance

thermometry.

[23] We shall discuss further, in Section

4, the paper by J. P. Evans and

5. D. Wood, Metrologia, 7, 108 (1971).

[24] G. T. Furukawa, Vol. 3, Part 2, p. 320

of "Temperature", Reinhold, 1962.

[25] A comprehensive summary of the principles and practice of thermoelectric

thermometry appear in Section 1 of

Vol. 3, Part 2 of "Temperature"

Reinhold, 1962.

[26] ASTM Handbook of Standards, Part 30,

1972.

[27] The Thomas Register (Thomas Publishing Company, 461 Eighth Avenue, N. Y. 10001) is a good source of information

on commercial products and manufacturers.

[28] One instrument manufacturer estimates

privately that 40-45% of all sales are concerned with temperature-control

apparatus.

[29] See the discussion in Sections 2.2.2.1

and 2.5.

[30] See Section 2.2.2.1 and figure 2.2F

for references to these various

sensors

[31] This is a control thermostat manu- factured specifically for household

use.

[32] It is not unusual for thermistors to vary in resistance by a factor 5 or

10 over a 100 °C interval.

[33] Private communication, thermistor

manufacturer.

[34] Industrial Research, June 1973, p. 64.

[35] Many of the manufacturers listed in

reference 27 fabricate these sensors.

[36] K. R. Carr, Vol. 4, Part 2 of "Temperature" 1972, p. 971. Dr. Carr has

privately told the author of some additional work on this topic.

[37] Commercial ad in Research/Development, November 1973, p. 37.

[38] Private communication, thermometer

manufacturer.

[39] The variation in the readings found on "drug store thermometers", often as much as several degrees Fahrenheit, is

probably a consequence of economics.

We shall see.

[40] Artronix Instrumentation, in the

December 1973, Physics Today.

[41] Private communication.

[42] Private communication.

[43] Catalog of NBS Standard Reference

Materials, NBS Special Publication 260,

June 1975, p. 51

[44] Preparation and Use of Superconductive

Fixed Point Devices, SRM 767, NBS

Special Publication 260-44, December

1972.

[45] Dr. K. Churney. Private communication.

[46] See J. Terrien, Metrologia 1, 15 (1965).

[47] "Men and Measurements - United States

Army Metrology and Calibration Center",

prepared by the Program Management

and Administrative Office of the U. S. Army Metrology and Calibration Center,

Redstone Arsenal, Alabama 35809,

April 1970.

44
[48] Ibid., p. 98.

[49] "A Directory of Standards Laboratories"

can be obtained from NCSL Directory

Committee, c/o NBS 200.01, Washington,

D. C. 20234.

[50] Comment by the president of a thermometer company, during a visit

by an NBS staff member.

[51] Private communication, via the 28th

Annual Calorimetry Conference; 13-15

June 1973 at Worcester, Massachusetts.

[52] Electronics, October 1973, p. 88.

[53] Private communication.

[54] Private communication.

[55] Commerce Today, April 30, 1973, pp. 30-32.

[56] Discussions with AEC and ORNL personnel.

[57] Private cormiunication , M. Smith, LASL.

[58] W. Vannah (of Foxboro Corp.) in NASNRC Physics Instrumentation Report,

1971.

[59] J. G. McMillan, R. H. Pamperin, SAE

Congress, Detroit, January 1972.

[60] Private communication, industrial

scientist.

[61] T. Berlincourt, in NAS/NRC Physics

Instrumentation Report, 1971; private

communication, H. J. Kostkowski, Chief,

Optical Radiation Section.

Section 3

[1] J. H. V. Brown and D. J. Lowell, IEEE Transactions in Biomedical Engineering,

Vol. BME-19, 331 (1972).

[2] R. S. Melville, Chemical Instrumentation 4, 63 (1972).

[3] Mai Schechter, Lab World, May 1973,

p. 26.

[4] Nathan Gochman, IMR Special

Colloquium, NBS, 23 March, 1973.

[5] Wall Street Journal, 17 July, 1973.

[6] Private discussion with the chief of

an experimental automotive research

laboratory, 1973.

[7] F. B. Dent, Commerce Today, August 6,

1973, p. 25.

[8] Deborah Shapley, Science, 182, p. 732

(1973).

[9] P. C. White, Science, 182, 23 November

1973.

[10] P. G. Hansel, Industrial Research/

Development, p. 8, July 1973.

[11] NBS Technical News Bulletin, January

1973.

[12] Brooklyn Thermometer Co., Inc., $60;

AMI-Therm. , $15 and $20.

[13] Nuclear News, p. 39, September 1973.

[14] Conversations with the Directorate of

Reactor Development, AEC; with the

Instrumentation and Controls Division,

AEC; and with a representative of

Bechtel Corporation, nuclear engineers.

[15] Nuclear News, September 1973, p. 53.

[16] 1973 Press Handbook, TVA.

[17] An example of this activity in thermal

conductivity is Y. S. Touloukian,

R. W. Powell , C. Y. Ho, and P. G. Klemens, Thermophysical Properties

Research Center Data Series, 1, IFI/

Plenum Data Corp. , 1970.

[18] Even here, NBS enters the picture.

Through the National Standards

Reference Data Service, NBS fosters

a large proportion of this analysis.

Section 4

[1] G. K. Burgess, J. Res. NBS 1 , 635 (1928).

[2] "Temperature", Vol. 1, 1941, Reinhold,

New York.

[3] "Temperature", Vol. 2, 1955, Reinhold,

New York.

45
[4] "Precision Measurement and Calibration-Temperature", NBS Special

Publication 300, Vol. 2, 1968.

[5] "Precision Measurement and CalibrationHeat", NBS Special Publication 300,

Vol. 6, 1970.

[6] "Temperature", Vol. 4, 1972, Instrument Society of America, Pittsburgh.

[7] "Temperature Section Activity Summary,

1974" J. F. Schooley, ed. NBS Technical Note 869, June 1975.

[8] The International Practical Temperature Scale of 1968", Metrologia 5,

35 (1969).

[9] The minutes are published (in French)

by the International Bureau of Weights

and Measures, Pavilion de Breteuil,

F 92310, Sfevres, France.

[10] J. F. Schooley, R. J. Soulen, Jr.,

and G. A. Evans, Jr., NBS Special

Publication 260-44, December 1972,

and R. J. Soulen, Jr., J. F, Schooley,

and G. A. Evans, Jr., Rev. Sci. Instr.

44, 1537 (1973).

[11] NBS Tech. News Bulletin, February 1973,

p. 47.

[12] Sad to say, OIML approved the draft

recommendation over the U. S. objections! Therefore, the end of this

particular story will come only after

the U. S. has attempted to amend the

draft.

[13] NBS Tech. News Bulletin, May 1973.

[14] Commerce Today, 6 August 1973, p. 10.

[15] D. Burch, NBS Standard, 5 December

1973, p. 5.

[16] NBS Dimensions, August 1973, p. 181.

[17] J. Cohen, S. Edelman, and C. Vezzetti

,

Nature Phys. Sc. 233, 12 (1971).

[18] NBS Tech. News Bulletin, December 1972,

p. 277.

[19] A. Cezairliyan, J. Res. NBS 77A, 45

(1973).

[20] A. Cezairliyan, J. Res. NBS 77A, 333

(1973).

[21] E. J. Prosen and R. N. Goldberg, NBS

Interim Report 73-180, April 1973.

46
APPENDIX A. METHODOLOGY OF THE STUDY

The study of the National Temperature

Measurement System was accomplished by

utilizing several sources of information:

. The literature of thermometry,

especially useful because periodic symposia

on "Temperature, Its Measurement and Control

in Science and Industry", for years held

with NBS sponsorship, provides a detailed

summary of active areas of thermometry.

The journal Metrologia, trade association

periodicals, and the scientific and en- gineering literature all were methodically

consulted in order to develop a comprehensive overview of the state of thermometry

in the U. S.

. Personal knowledge on the part of NBS

staff members provided individual insights

into the strengths and needs of U. S. thermometry. These were augmented by a series of visits to less well--known areas

of thermometry applications in order to build a collection of personal contacts which

will continue to provide information through

telephone and written communication.

Participation in scientific and

technical meetings, as well as the delivery

of talks, instructional seminars, and tours,

provided up-to-date information on areas where thermometry is advancing, where it is stymied for lack of fundamental research

results, and areas in which future efforts

are most likely to be rewarding.

Economic data were obtained from personal contacts in government and industry.

The rough impressions of many staff

members were integrated to build a picture

of the System, in an early draft of the study,

and later efforts focused on areas where un- certainty remained. Successive visits,

telephone discussions and correspondence

generally served to bring out the requisite

information, so that we did not resort to

formal polling techniques.

APPENDIX B. SUMMARY OF BACKGROUND

DOCUMENTS

1. "Temperature, Its Measurement and Control in Science and Industry", Vol. 4,

H. H. Plumb, Editor-in-Chief, Instrument

Society of America, Pittsburgh, 1972.

This three-part volume is an essential

reference for understanding the position

of thermometry at the present time. A significant history of the International

Practical Temperature Scale by H. Preston-Thomas, of the National Research

Council Laboratories in Ottawa, opens

the volume, and the volume covers the

topi cs

. Temperature Scales and Fixed Points

. Radiation Thermometry

Resistance Thermometry

. Magnetic and Quantum Thermometry

. Temperature Control and Calibration

. Bridges and Potentiometers

. Thermoelectric Thermometry

. Biology and Medicine

. Geophysical and Astrophysi cal Thermometry

2. "The International Practical Temperature

Scale of 1958" Metrologia 5 35 (1969).

This document is the defining text for

the current International Temperature

Scale. It contains the assigned values

and definitions of the scale fixed points

and the descriptions of the standard

interpolating sensors.

3. "Standard Industrial Classification

Manual", Office of Management and Budget.

The SIC code defines industries in

accordance with the composition and

structure of the economy and covers the

entire field of economic activities.

4. "U. S. Industrial Outlook Series"

Domestic and International Business

Administration, U. S. Department of

Commerce. This series of reports is oriented toward the future economic

patterns of the U. S. Detailed analysis

of some 200 industries, covering about

85% of the total value of shipments in

the U. S. , are presented with projections

to 1980.

5. "Annual Survey of Manufacturers Series"

Social and Economic Statistics Administration, Bureau of the Census, U. S. Department of Commerce. This series con- tains reports of product shipments for

perhaps 1000 classes of manufactured products. It is a very useful tool for the

economic examination of particular

i ndustries

6. "The U. S. Government Organization Manual".

General Services Administration. A very

useful guidebook to the Federal bureaucracy

47
APPENDIX B. SUMMARY OF BACKGROUND

DOCUMENTS

7. "The Thomas Guide to Manufacturers"

(Thomas Publishing Company, N.Y. 10001).

A comprehensive guide to products and

organizations of U. S. industry.

8. "A Directory of Standards Laboratories",

Prepared by the National Conference of

Standards Laboratories. This directory

serves as a "classified index" of U. S. standards laboratories.

APPENDIX C. RP 22, NBS Journal of Research,

Vol. 1 , 635 (1928) THE INTERNATIONAL TEMPERATURE

SCALE, George K. Burgess

In 1911, the directors of the national

laboratories of Germany, Great Britain, and

the United States agreed to undertake the

unification of the temperature scales in use in their respective countries. This

endeavor was approved formally in 1913 by

the Fifth General Conference on Weights and

Measures, and in 1921 the Sixth General

Conference voted to expand the field of

activities of the International Committee

and International Bureau by including

physical constants, such as standard temperatures, and the coordination of results

obtained in other institutions. This action

was duly ratified by the several governments adhering to the conference.

Finally, in 1927, the Seventh General

Conference, representing 31 nations, on the

recommendation of the three laboratories

above mentioned, which had consulted with

the Leiden Cryogenic Laboratory as to low

temperatures, adopted unanimously the following resolution, proposed by the International

Committee of Weights and Measures:

Le Comite, reconnaissant 1' importance

pratique de la representation d'une 6che11e

thermom^trique internationale, recommande

a la Conference d' accepter, a titre provisoire, les repferes de temperature, les

formules d' interpolation et les methodes

de mesure proposes d'un commun accord par

les trois laboratories nationaux

d'Allemagne, des Etats-Unis d'Amerique, et

de Grande-Bretagne.

Le Comite recommande aussi que le texte annexe soit maintenu a

1 'etude dans le programme des Conferences speciales de

Thermometrie qui seront tenues sous ses auspices

The English text is as follows:

TEXT CONCERNING THE ADOPTION OF AN INTER- NATIONAL TEMPERATURE SCALE SUBMITTED FOR

DISCUSSION BY THE BUREAU OF STANDARDS,

NATIONAL PHYSICAL LABORATORY, AND

48

PHYSIKALISCH-TECHNISCHE REICHSANSTALT

INTRODUCTION

The experience of the Bureau of Standards,

as of the National Physical Laboratory and

of the Reichsanstalt , has for many years

past indicated the necessity, for industrial purposes, of international agreement on a scale of temperatures ranging

from that of liquid oxygen to that of

luminous incandescent bodies. As a result

of discussion extending over a considerable

period, agreement has been reached by the

three laboratories, subject to possible

minor drafting amendments on the attached

specification for a practical scale, as affording a satisfactory basis on which

uniformity in certification of temperature

measurements for industrial purposes may

be maintained.

It is to be understood that this proposal

does not purport to replace the absolute

temperature scale which it is recommended

should be adopted, on principle, by the

International Conference on Weights and

Measures. It is intended merely to re- present this scale in a practical manner

with sufficient accuracy to serve the every

day needs of the laboratories for the purpose of industrial certifications, and is to be regarded as susceptible of revision

and amendment as improved and more accurate

methods of measurement are evolved.

It is anticipated that this scale will

shortly be adopted by the three laboratories

for the purposes indicated, and the attached draft is presented to the conference

for consideration, with the recommendation

that it should be officially adopted with

such amendments, if any, as may be agreed

on, as the best practical realization at the present time of the ideal thermometrie

scale.

Part I. DEFINITION OF THE INTERNATIONAL

TEMPERATURE SCALE

1. The Thermodynamic Centigrade Scale,

on which the temperature of melting ice,

and the temperature of condensing water

vapor, both under the pressure of one standard atmosphere, are numbered 0° and

100°, respectively, is recognized as the

fundamental scale to which all temperature

measurements should ultimately be referable.

2. The experimental difficulties incident to the practical realization of the

thermodynamic scale have been expedient to adopt for international use a practical

scale designated as the International Temperature Scale. This scale conforms with

the thermodynamic scale as closely as is possible with present knowledge, and is

designed to be definite, conveniently and
accurately reproducible, and to provide

means for uniquely determining any temperature within the range of the scale, thus

promoting uniformity in numerical statements of temperature.

3. Temperatures on the international

scale will ordinarily be designated as "°C",

but may be designated as "°C.(Int.)" if it

is desired to emphasize the fact that this

scale is being used.

4. The International Temperature Scale

is based upon a number of fixed and re- producible equilibrium temperatures to which numerical values are assigned and

upon the indications of interpolation

instruments calibrated according to a specified procedure at the fixed temperatures . 5. The basic fixed points and the

numerical values assigned to them for the

pressure of one standard atmosphere are

given in the following table, together

with formulas which represent the temperature (t ) , as a function of vapor pressure

(p) over'^the range 680 to 780 mm of mercury.

6. Basic fixed points of the International Temperature Scale-- °C

(a) Temperature of equilibrium

between liquid and gaseous

oxygen at the pressure of one standard atmosphere

(oxygen point)--- -182.97

t = tyeo +0.0126 (p-760) -0.0000065

P (p-760)2

(b) Temperature of equilibrium

between ice and air-saturated

water at normal atmospheric

pressure (ice point) — 0.000

(c) Temperature of equilibrium

between liquid water and its

vapor at the pressure of one standard atmosphere (steam

point) 100.000

t„ = t76o + 0.0367 (p-760)

P -0.000023 (p-760)2

(d) Temperature of equilibrium

between liquid sulphur and

its vapor at the pressure

of one standard atmosphere

(sulphur point) 444.60

= tyeo + 0.0909 (p-760)

^ - 0.000048 (p-760)2

(e) Temperature of equilibrium

between solid silver and

liquid silver at normal

atmospheric pressure

(silver point) 960.5

(f) Temperature of equilibrium

between solid gold and

liquid gold at normal

49

atmospheric pressure

(gold point) 1063

Standard atmospheric pressure is defined as the pressure due to a column of

mercury 760 mm high, having a mass of

13.5951 g/cm^, subject to a gravitational

acceleration of 980.665 cm/sec^ and is equal to 1 ,013,250 dynes/cm2.

It is an essential feature of a practical

scale of temperature that definite numerical

values shall be assigned to such fixed

points as are chosen. It should be noted,

however, that the last decimal place given

for each of the values in the table is significant only as regards the degree of

reproducibility of that fixed point on the

International Temperature Scale. It is not understood that the values are necessarily

known on the Thermodynamic Centigrade Scale

to the corresponding degree of accuracy.

7. The means available for interpolation

lead to a division of the scale into four

parts

(a) From the ice point to 660 °C the

temperature t is deduced from the resistance

R. of a standard platinum resistance thermometer by means of the formula

= Rq (1 + At + Bt2).

The constants R , A, and B of this formula

are to be deterfnined by calibration at the

ice, steam, and sulphur points, respectively.

The purity and physical condition of the

platinum of which the thermometer is made

should be such that the ratio R,/R shall

not be less than 1.390 for

°

t = 100° and 2.645 for t = 444.6°.

(b) From -190° to the ice point, the

temperature t is deduced from the resistance

R. of a standard platinum resistance thermometer by means of the formula

h

= D + 1^^ + Bt2 + C (t-100)t3].

The constants R , A, and B are to be determined as specified above, and the

additional constant C is determined by calibration at the oxygen point.

The standard thermometer for use below 0°

C must, in addition, have a ratio R./R less

than 0.250 for t = -183°. ^

°

(c) From 660 °C to the gold point, the

temperature t is deduced from the electromotive force e of a standard platinum vs platinum-rhodi urn thermocouple, one junction

of which is kept at a constant temperature

of 0 °C while the other is at the temperature t defined by the formula

e = a + bt + ct^.

The constants a, b, and c are to be determined by calibration at the freezing

point of antimony, and at the silver and

gold points.
(d) Above the gold point the temperature

t is determined by means of the intensity

J2 of monochromatic visible radiation of

wavelength x cm, emitted by a black body at the temperature t2, to the intensity or radiation of the same wavelength emitted by

a black body at the gold point, by means

of the formula

J2 C2 ] 1 1 ^°9e -jY

= — [t;336 " (t + 273)

The constant C2 is taken as 1.432 cm degrees. The equation is valid if (t + 273)

is less than 0.3 cm degrees.

Part II. RECOMMENDED EXPERIMENTAL

PROCEDURE

1. OXYGEN

The temperature of equilibrium of liquid

and gaseous oxygen has been best realized

experimentally by the static method, the

oxygen vapor-pressure thermometer being

compared with the thermometer to be

standardized in a suitable low temperature

bath.

2. ICE The temperature of melting ice is realized experimentally as the temperature at which pure, finely divided ice is in

equilibrium with pure, air-saturated water

under standard atmospheric pressure. The

effect of increased pressure is to lower

the freezing point to the extnt 0.007 °C per atmosphere.

3. STEAM

The temperature of condensing water vapor

is realized experimentally by the use of a hypsometer so constructed as to avoid

superheat of the vapor around the thermometer, or contamination with air or other

impurities. If the desired conditions have

been attained, the observed temperature

should be independent of the rate of heat

supply to the boiler, except as this may

affect the pressure within the hypsometer,

and of the length of time the hypsometer

has been in operation.

4. SULPHUR

For the purpose of standardizing re- sistance thermometers, the temperature of

condensing sulphur vapor is realized by

adherence to the following specifications

relating to boiling apparatus, purity of

sulphur, radiation shield, and procedure.

The boiling-tube is of glass, fused silica,

or similar material, and has an internal

diameter of not less than 4 or more than

6 cm. The vapor column must be sufficiently long that the bottom of the radiation

shield is not less than 6 cm below the top

of the heat insulating material surrounding the tube. Electric heating is

preferable, although gas may be used, but

the source of heat and all good conducting

material in contact with it must terminate

at least 4 cm below the free surface of the

liquid sulphur. Above the source of heat

the tube is surrounded with insulating

material. Any device used to close the end

of the tube must allow a free opening for

equalization of pressure.

The sulphur should contain not over 0.02

percent of impurities. Selenium is the impurity most likely to be present in quantities sufficient to affect the temperature of the boiling point.

The radiation shield is cylindrical and

open at the lower end, and is provided with

a conical portion at the top, to fit closely

to the protecting tube of the thermometer.

The cylindrical part is 1.5 to 2.5 cm larger

in diameter than the protecting tube of the

thermometer and at least 1 cm smaller in

diameter than the inside of the boiling tube.

The cylinder should extend at least 1.5 cm beyond each end of the thermometer coil.

There should be ample opening at the top of

the cylindrical and below the conical portion

to permit free circulation of vapor. The

inner surface of the shield should be a poor reflector. The shield may be made of

sheet metal, graphite, etc.

In standardizing a thermometer the

sulphur is heated to boiling and the heating

so regulated that the condensation line is at least 1 cm above the top of the insulating material. The thermometer with its

radiation shield is inserted in the vapor,

and when the line of condensation again

reaches its former level simultaneous observations of resistance and barometric

pressure are made. In all cases care should

be taken to prove that the temperature is independent of vertical displacements of the

thermometer and shield.

5. SILVER AND GOLD

For standardizing a thermocouple, the

metal to be used at its freezing point is contained in a crucible of pure graphite,

refractory porcelain, or other material

which will not react with the metal so as to contaminate it to an appreciable extent.

Silver must be protected from access of

oxygen while heated.

The crucible and metal are placed in an electric furnace capable of heating the

contents to a uniform temperature.

The metal is melted and brought to a uniform temperature a few degrees above its

melting point, then allowed to cool slowly

with the thermocouple immersed in it as described in the next paragraph.

The thermocouple, mounted in a porcelain

tube with porcelain insulators separating

the two wires, is immersed in the molten

50
metal through a hole in the center of the

crucible cover. The depth of immersion

should be such that during the period of

freezing the thermocouple can be lowered or

raised at least 1 cm from its normal

position without altering the indicated

emf by as much as 1 microvolt. During

freezing, the emf should remain constant

within 1 microvolt for a period of at least five minutes.

As an alternative to displacing the

couple, as a means of testing the absence

of the influence of external conditions

upon the observed temperature, both freezing and melting points may be observed and

if these do not differ by more than 2 microvolts, the observed freezing point may be

considered satisfactory.

6. THE STANDARD PLATINUM RESISTANCE

THERMOMETER

The diameter of the wire should not be

smaller than 0.05 or larger than 0.2 mm. The platinum wire of the thermometer must

be so mounted as to be subject to the mini- mum of mechanical constraint, so that

dimensional changes accompanying changes of

temperature may result in a minimum of

mechanical strain being imposed upon the

pi atinum.

The design of the thermometer should be

such that the portion, the resistance of

which is measured, shall consist only of

platinum, and shall be at the uniform temperature which is to be measured. This may be

accomplished by either of the accepted

systems of current and potential, or com- pensating leads.

After completion, the thermometer should

be annealed at a temperature of at least

660°.

7. THE STANDARD THERMOCOUPLE

The platinum of the standard couple shall

be of such purity that the ratio R^./R is initially not less than 1.390 for °

t = 100°. The alloy is to consist of 90

percent platinum with 10 percent rhodium.

The completed thermocouple must develop an electromotive force, when one junction is at 0° and the other at the freezing point

of gold, not less than 10,200 nor more than

10,400 international microvolts. The diameter of the wires used for standard

thermocouples should lie between the values

0.35 and 0.65 mm. The freezing point of antimony, specified

for the standardization of the thermocouple,

lies within the range of 0° to 660° where

the international scale is fixed by the

indications of the standard resistance

thermometer, and the numerical value of

this temperature is therefore to be determined with the resistance thermometer.

In the appendix the result of such determinations is given as 630.5°, but the tem- perature of any particular lot of antimony

which is to be used for standardizing the

thermocouple is to be determined with a standard resistance thermometer.

The procedure to be followed in using the

freezing point of antimony as a fixed tem- perature is substantially the same as that

specified for silver. Antimony has a marked tendency to undercool before freezing.

The undercooling will not be excessive if

the metal is heated only a few degrees

above its melting point and if the liquid

metal is stirred. During freezing the

temperature should remain constant within

0.1° for a period of at least five minutes.

8. SECONDARY POINTS

In addition to the basic fixed points,

the temperatures of a number of other points

are available and may be used in the calibration of secondary temperature measuring

instruments. These points and their tem- peratures on the international scale are

listed below. The temperatures given are those corresponding to a pressure of one standard atmosphere. The formulas for the

variation of vapor pressure with temperature

are valid for the range from 680 to 780 mm.

°C Temperature of equilibrium between

solid and gaseous carbon dioxide-- -78.5

t^ = tyeo + 0.1443{t^ + 273.2)

P logio(p/760) P

Temperature of freezing mercury

Temperature of transition of

sodium sulphate —

Temperature of condensing

napthalene vapor

t = tyeo + 0.208(t +

P logio (p/760) P 273.2)

-38.87

32.38

217.96

231 .85

305.9

273.2)

Temperature of freezing tinTemperature of condensing

benzophenone vapor

t = tyeo + 0.194(t +

P logio (p/760) P

Temperature freezing cadmium— 320.9

Temperature of freezing lead — 327.3

Temperature of freezing zinc — 419.45

Temperature of freezing antimony-- 630.5

Temperature of freezing copper

in a reducing atmosphere 1,083

Temperature of freezing palladium 1,555

Temperature of melting tungsten 3,400

The Bureau of Standards, therefore, in common with the other national laboratories,

will use until further notice in its

scientific work and for the calibration of

instruments, the standard temperatures,

interpolation formulas, and methods of

51
measurement as laid down above by the

General Conference of Weights and Measures

on October 4, 1927. It is recommended that

scientific workers elsewhere conform to the

International Temperature Scale as above

set forth.

It is expected that international thermometric conferences will be called, as occasion requires, by the International

Committee on Weights and Measures, so that

this temperature scale may be revised as the need arises.

Washington, September 12, 1928.

APPENDIX D. NBS Participation in Voluntary Standards

Bodies' Thermometry Activities

1. R. P. Hudson, Chief 221: U. S. representative to 10th CCPM Advisory

Committee on Thermometry session;

General Chairman of 5th Temperature

Symposium, and Chairman of CCT Working

Group 5. 2. H. H. Plumb, Program Chairman of 5th

Temperature Symposium and Editor-inChief of the Proceedings; Member

Working Group 1 of CGPM Advisory

Committee on Thermometry; Member NBS

Commodity Standards Committee; Member

ASTM Committee E-20; Member, ISA.

3. L. A. Guildner, 221.11: Member, Working Group 3 of CGPM Advisory Committee

on Thermometry.

4. G, W. Burns, 221.11: Member, ASTM

Committee E-20; Member ANSI Committee

C-96; Member, ISA.

5. G. T. Armstrong, Chief 316.02: Member

ASTM Committee E-20.

6. W. S. Hurst, 221.11: Member ANSI

Committee C-96; Member, ISA.

7. J. A. Wise, 221.11: Member ASTM

Committee E-20.

8. C. A. Douglas 232.11: Member, lES.

9. J. P. Evans, 221.11: Member, ISA.

10. R. K. Kirby, 312.06: Member ASTM

Committee E-1

11. F. R. Kotter, 211.06: Member ASTM

Committee on Temperature in Power

Systems

12. R. H. Kropschott, 275.00: Member

ANSI Committee C-16.

13. L. R. Moffitt, 272.00: Member ANSI

Committee C-105.

14. F. J. Powell ,462.00: Member ASTM

Committee on Heat Transfer.

15. R. L. Powell, 275.00: Member ASTM

Committee E-20.

16. Richard Raybold, 425.03: Chairman,

Instrumentation Subcommittee, Oceanographic Measurements Society.

17. J. L. Riddle, 221.11: Member, ASTM

Committee E-20.

18. T. B. Douglas, 425.03: Member ASTM

Committee E-20.

19. J. F. School ey. Chief 221.11: Member

ASTM Committee E-20.

APPENDIX E. RESISTANCE THERMOMETERS

1. Doped germanium. (References: S. A. Friedberg, p. 359, Vol. 2, "Temperature",

Reinhold (1955). J. E. Kunzler, T. H. Geballe, and G. W. Hull, Jr., p. 391,

Part 1, Vol. 3 "Temperature, Its Measurement and Control in Science and Industry",

Reinhold, N. Y. (1962); W. R. G. Kemp,

J. G. Collins, C. P. Pickup, R. Muijlwijk, p. 85, Part 1 , Vol . 4 "Temperature", ISA, Pittsburgh, 1972). The

doped germanium resistance thermometer

is widely used to preserve the cryogenic

temperature scale in the same way that

platinum resistance is used at higher

temperatures. The reproducibility of

selected germanium thermometers is better

than 1 millikelvin from 4 K down to .02

K, and the devices are useful to temperatures as high as 20 K. Basically semiconductors, these resistors show a modified exponential temperature dependence of resistivity, so that the useful

span of temperatu»-e is about a factor

ten or twenty for a given unit. In general they show pronounced magnetic

field dependences (L. J. Neuringer,

A. J. Perlman, L. G. Rubin, Y. Shapira,

RSI, 42, 9 (1971)).

2. Carbon radio resistors. (References:

J. R. Clement, E. H. Quinnell, RSI 23,

213 (1952); W. C. Black, Jr., W. R. Roach, J. C. Wheat! ey, RSI, 35, 587

(1964); A. C. Anderson, p. 773, Part 2,

Vol. 4, "Temperature", ISA, Pittsburgh,

1972. H. Weinstock, J. Paupia, p. 785,

Ibid.) The carbon radio resistor is a semiconductor whose resistivity, like

that of doped germanium, obeys a modified exponential dependence. Its reproducibility is inferior to that of

the germanium, but its trivial cost

allows its use in low-precision monitoring and control applications below 100 K. Like germanium thermometers, carbon

thermometers are quite magnetroresisti ve.

3. Metals with small amounts of magnetic

impurities. (Reference: A. R. Harvey,

S. Legvold, and D. T. Peterson, Phys.

Rev. B4 400 3 (1971 )). A small temperature dependent resistivity which

occurs in Kondo alloys continues to vary at temperatures of 1 K and below,

raising the possibility of secondary

thermometry by this means.

4. Metal films. (Reference: A. J. Laderman,

G. J. Hecth, and A, K. Oppenheim, Vol. 3,
Part 2, p. 943 of "Temperature", Reinhold, 1962.) Metal fi Im thermometry

can be used at temperatures from

cryogenic to the melting point of the

metal. The sensor is quite fast-responding, but generally not stable in

resistance.

5. Thermistors. (References: Sections 29

and 30 by C. R. Droms and H. B. Sachse

in Vol. 3, Part 2, p. 339 and p. 347 of

"Temperature", Reinhold, 1962.) Basically semiconductors, these sensitive

sensors have come into extremely wide

use at temperatures up to 300 or 400 °C because of their small size and high

sensitivity. They will be further

discussed in Section 3. 6. Miniature platinum thermometers.

(Reference: D. A. Lucas, Vol. 4, Part 2, p. 963 of "Temperature", ISA,

1972.) These millimeter-size

thermometers can display reproducibilities of 10 ppm at the triple

point of water, and can be used from

13.8 K to 500 K.

7. Nickel resistance thermometers.

(Reference: D. A. Grant and W. F. Hickes, Vol. 3, Part 2, p. 305, "Temperature", Reinhold, 1962.) The use of

nickel resistors to meet the ruggedness

and interchangeabil ity demands of industry has resulted in their growing

use as thermometers.

8. Ceramic thermometers. (References:

A. R. Anderson and T. M. Stickney,

Vol . 3, Part 2, p. 361 , and W. N. Lawless, Vol. 4, Part 2, p. 1143,

"Temperature", Reinhold, 1962, and

ISA, 1972, respectively). The first

reference deals with ceramics as hightemperature resistance thermometers,

and the second, with ceramics as cryogenic capacitors, thermometers

which are nearly independent of

magnetic fields.

APPENDIX F. OTHER TEMPERATURE SENSORS IN MORE OR LESS COMMON USE

1. Paramagnetic susceptibility (/)•

Reference: T. C. Cetas and C. A. Swenson, p. 57, Part 1, Vol. 4, "Temperature", ISA, Pittsburgh, 1972.

2. Liquid vapor pressure. Reference:

Section I-B, pp. 121-168, Ibid.

3. Noise. Reference: R. A. Kamper, p. 349,

Ibid.

4. Acoustic. References: (High temperatures) G. L. Innes, p. 689, Ibid.;

(Low temperatures) A. R. Colclough,

p. 365, Ibid.

5. Resonant frequency of quartz. Reference:

A. Benjaminson, and F. Rowland, p. 701,

Ibid.

6. Electronic junction devices. Section

IV-F, pp. 1097-1136, Part 2, Ibid.

7. Nuclear resonance. Section V-A, pp. 1197-1238, Ibid.

53

NBS-114A iREv. 7-73)

U .S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

L PL!HLI( Al lON OR Kl^PORT NO. NBSIR75-932

2. Cuiv 't Accession

No.

3. Recipient's Accession No.

4. TITLE AND SISHTH LI:

The National Measurement System for Temperature

5, Put^li cation Date December 1975

6. Performing Organization ( ode 221.11

7. AUTHOR(S)

James F. Schooley

8. Performing Organ. Report No. NBSIR75-932

9. PKRFORMINC, ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

2210110

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Addres.s (Street, City, State, ZIP)

Same as Item 9.

13. Type of Report & Period Covered

Final

14. Sponsoring Agency Cod(-

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary ol most si^ilicant information. If document includes a significant

bibliography or literature survey, mention it here.)

The National Temperature Measurement System reaches quite literally into all phases of

American life. Comfort control in home, school, office and factory, health care, manufacturing, food preparation and storage, and all forms of powered transportation are just a few ofthe many facets of America's human activities that deoend for their trouble-free

operation on the existence of reliable thermometry.

The Heat Division of the National Bureau of Standards collaborates with the national

laboratories of other nations in establishing an International Practical Temperature Scale which represents thermodynamic accuracy insofar as current scientific practice permits.

The NBS is the only U.S. agency bearing this responsibility; in addition, only the NBS is responsible for disseminating the International Scale to U.S. scientific and technical

activities.

The Study of the National Temperature Measurement System shows that the NBS continues

to contribute energetically to the quality of the International Scale. It further indicates

that NBS maintains a consistent and deliberate effort not only to provide access to the Scale at the several levels required by U.S. science and technology, but also to participate

in solving special problems in thermometry. These are problems for which the nature of NBS

as an objective, expert resource in thermometry uniquely qualifies it to furnish effective,

practical solutions.

In briefly describing the many aspects of the National Temperature Measurement System,

this Study attempts to portray its great diversity of products, services, and people. The System is largely organized, as might be expected, for the purpose of economic gain; the NBS enters the picture only in those areas where highly accurate or intricate thermometry is essential.

17. 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

)

Data; International Practical Temperature Scale; Measurements; National Measurement

System; Standards; Thermometry

18. AVAILABILITY S Unlimited

1 For Official Distribution. Do Not Release to NTIS

[

' Order From Sup. of Doc, U.S. Government Printing Office Washington, D.C. 20402, SD Cat. No. CH

Order From National Technical Information Service (NTIS)

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