Thomas M. Flynn

NBSIR 75-825

THE NATIONAL MEASUREMENT SYSTEM FOR CRYOGENICS

Thomas M. Flynn

Cryogenics Division

Institute for Basic Standards

Boulder, Colorado 80302

October 1975

U.S. DEPARTMENT OF COMMERCE, Rogers C. B. Morton, Secretary

James A. Baker, III, Under Secretary

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

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director
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) interchangeabil ity 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 communication, 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 al 1 -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. E. 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

Pa^e

FOREWORD

EXECUTIVE SUMMARY 1

1. INTRODUCTION 3

2. STRUCTURE OF THE MEASUREMENT SYSTEM .... 4

2.1 Conceptual System 4 2.2 Basic Technical Infrastructure 5 2.2.1 Documentary Specification System 5 2.2.1.1 Standardization Institutions 5 2.2.1.2 Survey of Documentary Standards 6 2.2.2 Instrumentation System 7 2.2.2.1 Measurement Tools and Techniques 7 2.2.2.2 The Cryogenic Instrumentation Industry . . 13

2.2.3 Reference Data 17 2.2.4 Reference Materials 19

2.2.5 Science and People 21 2.2.5.1 Cryogenic Measurements in Science 21 2.2.5.2 Cryogenic Science in Measurements 22

2.3 Realized Measurement Capabilities 24

2.4 Dissemination and Enforcement Network 26

2.4.1 Central Standards Authorities 26

2.4.2 State and Local Offices of Weights and Measures . . 27 2.4.3 Standards and Testing Laboratories and Services . . 28

2.4.4 Regulatory Agencies 28

2.4.5 Industrial Trade Associations 28

2.5 Direct Measurements Transactions Matrix 28

2.5.1 Analysis of Suppliers and Users 28

2.5.2 Input-Output Direct Measurements

Transactions Matrix 30

2.5.3 Highlights re Major Users 32

2.5.3.1 Industrial Gases and Equipment 32

2.5.3.2 Liquefied Natural Gas (LNG) 33

2.5.3.3 Research and Development 34

3. IMPACT, STATUS AND TRENDS OF THE CRYOGENIC MEASUREMENT SYSTEM . 34

3.1 Impact of Measurements 34

3.1.1 Functional, Technological and Scientific

Applications 34

3.1.2 Economic Impacts--Costs and Benefits 35

3.1.3 Social, Human, Person-on-the-Street Impacts .... 36

3.2 Status and Trends of the System 37

ii i
CONTENTS (continued)

Page

4. SURVEY OF NBS SERVICES '. . 39

4.1 The Past 39

4.2 The Present-Scope of NBS Services 39

4.2.1 Description of NBS Services 39

4.2.2 Users of NBS Services 40

4.2.3 Alternative Sources 42

4.2.4 Funding Sources for NBS Services 42

4.2.5 Mechanism of Supplying Services 45

4.3 Impact of NBS Services 45

4.3.1 Economic Impact of Major User Classes 45

4.3.2 Technological Impact of Services 47

4.3.3 Pay-off from Changes in NBS Services 48

4.4 Evaluation of NBS Program 49

4.4.1 Evaluation Criteria 49

4.4.2 Evaluation Panel Role 50

4.4.3 Why NBS? 51 4.4.4 Program Evaluation 51 4.5 The Future 53

4.5.1 Technology Assessments in Cryogenics 54

4.5.2 Driving Forces 56

4.5.3 Emerging Technologies 57 4.5.4 Impacts of the National Measurement System Study . . 57

, 5. SUMMARY AND CONCLUSIONS 57

5.1 Key Developments 57 5.2 Liquefied Natural Gas 58

5.3 Hydrogen 59

5.4 Superconductivity 59

5.5 Summary 60

Appendix A. Methodology of the Study A-1 REFERENCES R-1

LIST OF FIGURES

FIGURE 1. Internal input 41 FIGURE 2. External outputs 41 FIGURE 3. External inputs 43

FIGURE 4. Outside-outside interactions 43

FIGURE 5. Industrial measurement system 44

FIGURE 6. Liquid nitrogen flow program interactions 46

FIGURE 7. Emerging technologies in cryogenics 57

iv
LIST OF TABLES

Page

Table 1-1. Organization and outputs of NBS

Cryogenics Division 4

Table 2-1. Instrument Society of America Ad Hoc Committee on Cryogenic Flow Measurement 5 Table 2-2. Representative members of the Compressed Gas

Association 6 Table 2-3. Flowmeters in custody transfer of oxygen, nitrogen

and argon 14

Table 2-4. Typical flowmeter specifications 15

Table 2-5. Typical flowmeter data 15

Table 2-5. Resistance and thermistor thermometers 16

Table 2-7. 1973 Profile: instruments for measurement, analysis,

and control 17

Table 2-8 Cryogenic pressure transducers 24

Table 2-9 Some approximate characteristics of the most widely

used classes of cryogenic thermometers 25

Table 2-10. Direct measurements transactions matrix 31 Table 2-11. Net sales of major cryogenic companies in the U.S 33

Table 3-1. Instruments for measurement, analysis and control:

projections 1973-80 35

Table 4-1. Funding by sources 45

Table 4-2. Distribution of effort 49

Table 4-3. The crucial role of NBS 53

V
THE NATIONAL MEASUREMENT SYSTEM FOR CRYOGENICS

Thomas M. Flynn

Cryogenics Division

Institute for Basic Standards

October 1975

ABSTRACT

The Cryogenics Division of NBS has evolved as the nation's central

laboratory for cryogenics, much as NBS itself has evolved as the nation's

central laboratory with both broad and specific responsibilities. Cryogenic

measurement and data outputs provide the common foundation for all the institutions and agencies throughout the nation employing cryogenics to solve

their problems.

This Study of the National Measurement System showed that the Cryogenics

Division of NBS provides almost every category of measurement and data ser- vice that NBS itself provides: not just an instrumentation system (including,

for example, pressure, temperature, density, liquid level, flow rate, etc.),

but also properties of fluids (both thermodynamic and transport properties);

properties of solids (thermal, mechanical and electrical); an interface with

the users through systems integration and advisory and consulting services;

and a dissemination network through the Cryogenic Data Center.

This study documents the impact, status and trends of the cryogenic

measurement system and specifically illustrates these characteristics wherever

possible with a specific case study, a recently completed measurements and

data program for the flowmetering of liquid nitrogen.

Key Words: Cryogenics; data; flowmeter; instrumentation; measurements;

National Measurement System.

V i
THE NATIONAL MEASUREMENT SYSTEM FOR CRYOGENICS

Thomas M. Flynn

Cryogenics Division

Institute for Basic Standards

October 1975

EXECUTIVE SUMMARY

The National Bureau of Standards is not responsible for only one unit of measurement,

or even a set of measurements. Rather, the

legislative mandate calls for NBS to provide

a base for such a system, aoordinate that

system, and furnish essential services. Thus

it is the responsibility of NBS to assure the

proper functioning of the Nation's system of

physical measurement, the National Measurement System. Accordingly, the present

microstudy was conducted to examine and

document the way in which the NBS Cryogenics

Division is meeting its particular responsibility to assure the proper functioning of our system of cryogenic measurement.

The Cryogenics Division of NBS provides

the measurement and data services that support a whole technology. Almost every category of measurement and data service is offered that NBS as a whole provides: not just an instrumentation system (including,

for example, pressure, temperature, density,

liquid level, flow rate, etc.), but also

properties of fluids (both thermodynamic and

transport properties); properties of solids

(thermal, mechanical, and electrical); an interface with the users through systems

integration, and advisory and consulting

services; and our own dissemination network

through the Cryogenic Data Center,

This study shows that there are three

specific emerging technologies within this

broad area of Cryogenics which need a com- plete and consistent system of measurements

and data. For instance, a comprehensive measurement

system for liquefied natural gas needs to be

developed, with special emphasis on quantity

gaging in storage, flow-metering for both

mass and heating value, and basic measurements of thermal and mechanical properties

of structural materials.

Basic measurements and data are required

to support the development of hydrogen as a fuel, to improve hydrogen liquefaction efficiency, to recover liquefaction energy, to document hydrogen-compatible materials of

construction, to develop improved insulation

materials, plus measurement tools and techniques for the eventual commercial exchange

of liquid hydrogen.

Superconductivity connects cryogenic

measurements and data to the electrical power

industry, for power transmission, generation,

and storage. Knowledge needed here includes

heat transfer rates, behavior of helium re- frigerant flow systems, and the degradation

of the superconductors with time and stress. Other practical uses of superconductivity are becoming apparent, such as the application of

Superconducting Quantum Interference Devices

(SQUIDs) to problems ranging from mineral

prospecting to magnetocardiography . Accordingly, the needs to support this technology

encompass instruments and techniques for

physical measurements plus a technical data

base.

The technologies discussed above show the

importance of cryogenics in commerce in the

U.S. today, and also show its truly diverse

applications. If there were a "General

Cryogenics Corporation" like a General

Motors, it would appear in the top 10% of the

Fortune list of the 500 largest U.S. Industrial Corporations. But it is important to note that there is not a "Cryogenics Corporation", per se. Cryogenics is an infrastructure industry. Similarly, the national

system of cryogenic measurements is an infrastructure of cryogenic technology itself.

The crucial question of this report is, how

well does the measurement and data structure

support the technology as a whole?

This study shows that some parts of the

cryogenic measurement system seem to be

characterized by adequate services and quality assurance (cryogenic temperature measurements, for instance). It appears one

should have less confidence in other parts of

the system. Pressure measurements, for

instance, which are probably the measurement

most widely made in all of cryogenics,

appear not nearly so well supported, especially pressure measurements in extreme

environments. Attention by NBS to these

issues is in order.

Especially apparent at this time is the

need for a different kind of measurement,

namely one that describes the quality or availability of the commodity. Specifically,

we refer not so much to the flow measurement

of liquefied natural gas, for example, as to the need to measure its potential heating

value.
It appears that one component of the problem of cryogenic measurement is that the

field is somewhat static. There has been no concerted national effort since the peak of

the space program.

A second part of the problem arises from

the way cryogenic measurements fit into the

National Measurement System. As long as only

a single agency or one sector of our economy

(National Aeronautics and Space Administration, the aerospace industry) was using es- sentially all of the results of its own measurements, then that part of the National

Measurement System was internally consistent

and in harmony with itself. Now, however,

cryogenics is becoming more commercialized

and moving to the market place, and thus

external consistency as well as internal

consistency is required to make this part of

the National Measurement System work.

The third part of the problem is perhaps a derivative of the first. Because the field

is relatively static, a crucial question is not being asked: are there predictable technological developments that will either

create a need for new cryogenic instruments,

or possibly provide an altogether new mea- surement means?

Certain parts of the cryogenic measurement

system at the national level seem to be disconnected, or working independently of one another at this time. For instance, our perception is that the U.S. Coast Guard has

the necessary authority to regulate certain

aspects of liquefied natural gas transportation by setting certain physical standards,

measurement codes, and practices. They may do

this without necessarily having recourse to the NBS. Other national authorities, especially in the area of public safety come to mind. Accordingly, it appears that this part

of the measurement system is disjointed.

There is no objective reason why it should

remain so. It would be in accord with the

NBS mission and tradition to pursue these

issues and resolve them.

A goal of this study was to achieve both

conceptual breadth and depth by examining our

role in the national measurement system as a whole, and illustrating this role with a specific case study, the liquid nitrogen

flowmetering program. This program was instigated by the needs of state weights and measures officials, the industry concerned,

and the public for confidence in the custody

transfer of liquid nitrogen. This effort used

nearly every competence and capability that

NBS has developed: measurement services

(tests and calibrations of meters), property

data (thermodynamic property data for cryogenic fluids), standard codes and practices

(Handbook 44), dissemination services (Office

of Weights and Measures, the National Conference of Weights and Measures), and both

voluntary and regulatory standards activities

(through the most relevant industry group

concerned - the Compressed Gas Association,

and by adoption in state codes).

The general conclusion of this study is

that the cryogenic measurement system is

doing its job adequately at reasonable cost. There is no widespread feeling of inadequacy,

such as that which led to the creation of the

National Bureau of Standards seventy-five

years ago. On the other hand, there are both

systematic and specific deficiencies that can

and should be corrected. Further, there are

several areas in which the cryogenic measure- ment system will be subjected to severe

strains in the foreseeable future, unless

appropriate responsive steps are taken soon. Specific needs and responses, which are

only summarized here, are documented within

the body of the report.

2
1. INTRODUCTION

National commerce in cryogenics, a vital

outgrowth of the chemical industry, exceeds

$2 billion annually. It is both a domestic

and international business, which may be

broken down into three areas. They are:

- Industrial Gases and Equipment

- Liquefied Natural Gas

- Superconductivity.

Industrial Gases and Equipment . Industrial gases provided by cryogenic techniques

are very important commodities. According to the most recent Department of Commerce survey, the annual production of liquid oxygen

is about $300 million, 50% used in the production of steel and 20% in the chemical industry. Aerospace use is less than 2% -- even

less than that used for sewage disposal.

Minneapolis, Tampa, New Orleans, and Fairfax

County, Va. are among the many places that

use oxygen to speed up sewage treatment by

factors of 3 to 5. More than 50 oxygen

plants are planned or under construction in

the U.S. for sewage treatment.

Fifty to sixty percent of all the hospitals in the U.S. presently store their

breathing oxygen as liquid, and the American

Hospital Association states that every new

hospital costing $1 million or more uses liquid oxygen.

Annual sales of liquid nitrogen are about

$150 million, with over $50 million being

used for food freezing.

One major airline uses 1.8 million pounds

of liquid nitrogen per year for galley cooling. Company officials claim that "the

procedure is wondrously simple and reliable

and that the experience has been so favorable

that all future aircraft will use the same technique." The Department of Transportation

has watched this system closely to get a "feel" for the logistics of supplying cryogenics necessary for ground transportation

systems

Recently, a 400 ton-a-day liquid nitrogen

plant was opened at Stafford, Texas to supply

nitrogen to a major semiconductor device

manufacturer to protect electronic parts from

impurities during manufacture. Similar facilities exist in the Bay Area of California to support the electronics industry there.

Liquefied Natural Gas (LNG) . It is predicted that by 1985 10% of our natural gas

will be imported as LNG from Alaska or foreign sources. There are approximately 19 applications pending before the Federal Power

Commission for permission to import LNG or to liquefy and store it for interstate use.

These applications are not trivial. To illustrate, one peak shaving facility in Iowa will cost $23 million. Import terminals,

including ships and pipelines have been

described at costs for $2 to $6 billion.

Superconductivity . Although practical

uses of superconductivity are not extensive

at present, we expect these applications to grow and mature in the next few years. Present day superconducting magnets for liquid

hydrogen bubble chambers rank as the largest

solenoid magnets in the world.

Cryogenic processes seldom result in an end product in themselves, but rather play an essential supporting role in other more visible industries. As mentioned, 50% of the liquid oxygen production goes into steel making

and another 20% into chemicals. Forty percent of the space industry is cryogenic

based. The steel, chemical, and space industries are highly visible, but the cryogenics

industry is not. If one were to go shopping

for cryogenic merchandise, he would find

little, for cryogenics is indeed an infrastructure industry.

It is thus the nature of cryogenics that

it be largely hidden and obscure to most ob- servers, while at the same time occupying a central position of great potential leverage

on the nation's essential industries - steel,

chemicals, space, transportation, agriculture, sewage disposal, and so forth. It would therefore be imprudent to leave the

workings of cryogenics to chance, and ac- cordingly this study of the National Measurement System was undertaken to document and

evaluate the adequacy of our measurement

and data services to this vital technology.

In making an inventory of all of our mea- surement services, we find that we offer

nearly every type of service that NBS as a whole does, e.g., conceptual knowledge, instrumentation, reference materials, standard

samples, reference data, and specifications.

We have also documented our operations through

the dissemination network, e.g., regulatory

agencies, state offices, and central standards

authorities. We have achieved both conceptual breadth and depth by examining first our

role in the National Measurement System as a whole, and then illustrating this role with

a specific case study.

3
2. STRUCTURE OF THE MEASUREMENT SYSTEM

The National Bureau of Standards is not responsible for only one unit of measurement,

or even a system of measurements. Rather,

our legislative mandate calls for NBS to provide a base for such a system, coovdinate

that system, and furnish essential services.

Examination of these statues shows that the

NBS has both unique and special responsibilities in relation to the Nation's science and

technology, and very broad responsibilities

as wel 1

So it is with the cryogenics at NBS. We

are not responsible for "a" unit of measurement or even a tidy set of measurements.

Just as it is a general NBS role to make sci- ence useful, so it is our role to make cryogenics useful. We do not develop technology.

We do help others with applied research ser- vices to produce, diffuse, and enhance the

value of practical knowledge. Our goal is to strengthen and advance the Nation's cryogenic

science and technology— in short, make cryogenics useful.

Accordingly, since we do help support a whole technology, we find that we must provide almost every measurement and data service

that NBS as a whole provides: not just an instrumentation system (including, for example,

pressure, temperature, density, liquid level,

flow rate, etc.), but also properties of

fluids (both thermodynamic and transport properties); properties of solids (thermal, mechanical and electrical); an interface with

the users through systems integration, and

advisory and consulting services; and our own information dissemination network through the

Cryogenic Data Center.

Table 1-1. Organization and outputs

of NBS Cryogenics Division

Functional Organization

Metrology

Solids Properties

Fluids Properties

Systems Integration!

Data Center

Outputs

Measurement Techniques

Data for Decision Making

Data for Reliable Design

Technical Analyses

Safety Criteria

Impartial Assessment

Information Services

Technology Transfer

National Standards

A

Centralized

National

Effort

We are organized by function to provide

these outputs (see table 1-1). We have found

that such a functional approach generally

serves us better than a programmatic one. Cryogenics is an evolutionary technology and

our strength lies in being able to meet changing programmatic needs. We have in fact

evolved as the Nation's central laboratory for

cryogenics, much as NBS itself evolved during

its early years as the Nation's central technical laboratory with both broad and specific

responsibilities. Our outputs provide the common foundation for all the institutions

and agencies throughout the nation employing

cryogenics to solve their problems. The following sections will illustrate how we provide these services in practice.

2.1 Conceptual System

The Cryogenics Division of NBS is the only

federal laboratory exclusively in cryogenics

dedicated to helping develop and promote the

successful application of all aspects of this

science. As such, the conceptual system that

encompasses our work ranges from the generation of basic, conceptual knowledge (e.g.,

fundamental constants, superconducting quantum interference phenomena) to specific problem solving for government agencies and

other public institutions (e.g., technical

advice to the Electric Power Research Institute on refrigerators for cooling superconconducting electric power transmission lines).

The specific quantities and phenomena that

need to be measured relate to the properties

of liquids and solids needed by engineers

for design and construction purposes and also

by scientists to improve the understanding

of the physics of fluids. These properties

(see also Section 2.2.3) include, but are

not limited to, the thermodynamic property of

fluids (compressibility, entropy, enthalpy,

specific heats, sound velocities); electromagnetic properties (diekectric constant,

refractive index); and transport properties

(viscosity and thermal conductivity coefficients). The data required on solids (metals,

alloys, and composites) used at low temperatures include the mechanical, thermal, and

electrical properties.

Effective and reliable measurement systems

are required for certain physical parameters

at low temperatures, notably: pressure, tem- perature, density, liquid level, quantity,

and flow rate, and, more often than not a very

difficult parameter to realize in practice,

the total "usable" mass. The conceptual system also encompasses the

use of low temperature phenomena as tools for

the measurement of other physical parameters

(see section 2.2.5.2) such as the electrical

volt, noise, current, power, flux magnitude,

etc.
2.2 Basic Technical Infrastructure

As indicated in Section 1., the cryogenic

measurement system supports an international

technology that ranges from multinational

trade in liquefied natural gas to supplying

breathing oxygen for hospitals. Accordingly,

the technical infrastructure that supports

this system in turn runs from the International Organization of Legal Metrology to state weights and measures officials, as a minimum. The following sections will describe

some of the more important institutions and

systems that help make this part of the National Measurement System function.

2.2.1 Documentary Specification System

2.2.1.1 Standardization Institutions

Several states, an industry association,

and national and international organizations

recently cooperated in a technical program to assure adequate quality control in one part

of the cryogenic measurement system, namely

the flowmetering of liquid nitrogen. We

shall use this example to highlight the various standardization institutions that must

interact to assure effective measurement control in even so small a part of the cryogenic

measurement system.

Background . Liquid nitrogen is an important article of commerce--approximately

$150 million worth per year changes hands.

Its uses include food freezing, airline galley cooling, and providing a protective atmosphere for semiconductor manufacture and

float glass production. Regardless of its

wide use, it is a difficult commodity to measure for it is nearly always a boiling,

two-phase mixture, whose value depends in part

upon its density and in part upon its re- frigeration capability. Commonly used practices of custody transfer had a vague technical basis, which inhibited both compliance

and regulation, regardless of how well intentioned either party may have been.

In 1966, at least three groups took this

problem under consideration. The description

below is in approximate chronological order,

but no great significance should be attached

to the dates. The three groups did initiate

their work separately, but eventually worked

together toward a common solution, and often

with overlapping membership. This example

is presented to show an institutional structure through which standards are effected.

The Instrument Society of America Ad Hoc Committee on Cryogenic Flowmetering . The

decision of the Instrument Society of America

to establish this Ad Hoc Committee was based,

in part, on a recommendation for "Calibration

Standards for Turbine and Mass Flowmeters,

Particularly for Cryogenic Fluids" from the

first ISA Standards and Practices Panel Session held in conjunction with the 1965 Annual

Conference. The committee membership was broadly representative of all concerned--

States weights and measures officials, cryogenic fluid buyers and sellers, and meter

manufacturers. The membership is shown in

table 2-1.

Table 2-1. Instrument Society of America

Ad Hoc Committee on Cryogenic Flow Measurement

University of Colorado

National Bureau of Standards

Transcontinental Gas Pipe Line Company

Missiles & Space Division, Douglas Aircraft

Cox Instruments

Wyle Laboratories

Potter Aeronautical

Air Reduction Company

NASA - MSFC

California Bureau of Weights & Measures

The abstract of the final report by the

Ad Hoc Committee recommended: (a) a national

standard and transfer standards; (b) an ac- cepted methodology; (c) a national authority

to develop the standards, transfer standards,

and methodology; and (d) educating all personnel in the state-of-the-art of cryogenic

fluid flow measurements.

The Compressed Gas Association Model Code . The Compressed Gas Association is a non-profit

membership corporation chartered in the State

of New York that represents all segments of

the compressed gas industry in the United

States, Canada, and Mexico. They also have

associate members in European and Asian

countries. Among its membership are over 250

companies (including North America's largest

firms) devoted primarily to producing and

distributing compressed, liquefied, and

cryogenic gases, as well as leading chemical

industry corporations that have compressed

and liquefied gas divisions. A few of the

members of the Compressed Gas Association

who were most interested in liquid nitrogen

flowmetering are shown in table 2-2.

It is estimated that the domestic companies

listed below produce in excess of 95 percent

of the cryogenic fluids marketed in this country.

In June 1967, the Compressed Gas Association

proposed to the National Conference on Weights

and Measures a model code for flow metering of

cryogenic fluids. Although the Conference on Weights and Measures noted that cryogenic flow

measurement problems were, at that time, cen- tralized only in a few states, the Compressed

Gas Association proposal was a significant

step in national recognition of cryogenic

flow measurement problems.
Table 2-2. Representative members of the

Compressed Gas Association

Domestic:

Air Products and Chemicals, Incorporated

Air Reduction Company

Liquid Carbonic Corporation

Linde Division - Union Carbide Corporation

National Cylinder Gas Div. - Chemetron Corp.

International Oxygen Manufacturers Assoc.

CVI Corporation - Pensalt Chemical

Foreign:

British Oxygen Company

L'Air Liquide

Linde AG (Lotepro)

Messer-Griesheim

The California Code on Cryogenic Measuring Devices . The regulatory agencies saw a real need for traceability to a national standard since they are usually obligated by law

to perform "type approval" inspections. In the

fall of 1967, the State of California Bureau

of Weights and Measures began hearings on

its own proposed code for cryogenic fluid

measurement devices used in California. After

several hearings in the fall and winter of

1967-68, the code was adopted and made law in

California on June 1, 1968.

The State of New Jersey was not far behind

California with respect to such regulations.

New Jersey officials stated that with the

introduction of sales of cryogenic fluids to the trucking industry for use as a refrigerant, they would be forced to find some means

of developing an acceptable proving method.

Further, with the advent of the Sales Tax in

the State of New Jersey, and no exceptions

being known at that time given to the sale of

cryogenics at the retail level to trucks, it was felt that the commodity would be subject

to that tax. Because such state agencies are obligated

to promulgate regulations controlling the use

of any commercially used weighing or measuring

devices, including those used in cryogenic

fluid commercial sales or custody transfers,

the needs of these agency officials as expressed by them are pertinent and important to the subject at hand. They summarized their

needs as follows:

"(1) With respect to standards, there

should be a national "facility", a final

"authority", a "referee" that would not be

in competition with private industry.

(2) This "agent" should provide the necessary methodology to preserve the accuracy

and precision of field measuring methods.

(3) This "agent" should continue to investigate new measuring methods in order to advance the state-of-the-art."

The International Organization of Legal

Metrology . Just as the States preferred a central authority to coordinate these activities on a national scale, the gas producers themselves desired to coordinate

such a standardizing activity on an international scale. Accordingly, the Inter- national Organization of Legal Metrology

was brought into the program at the beginning to facilitate the adoption of the

findings of this program as an international

code. The collaborating countries are Austria, France, India, Italy, Japan, Netherlands, Poland, United Kingdom, Switzerland,

Czechoslovakia, and the USSR.

2.2.1.2 Survey of Documentary Standards

Measurement accuracy must be assured to avoid failure in complex engineering designs

and sophisticated experiments. But accuracy

is even more important when quantities of

goods or services in commerce are being

measured. If a free-enterprise economic system is to thrive in a modern industrial so- ciety, buyers and sellers in the marketplace

need to have as much confidence in the quantity and performance of goods exchanged as they do in the amount of moneys paid. We will continue to use the liquid

nitrogen flowmetering program as a specific

example of the process by which practices

and data become codified and have the

effect of law. As mentioned. State regulatory agencies

have a real need for traceability to a national standard since they are obligated

by law to perform type approval inspections.

This is clearly outlined, for example, in

the Business and Professions Code of the

State of California. One provision of this

code reads as follows:

"2500.5. The directory by rules and regulations shall provide for submission for

approval of types or designs of weights,

measures, or weighing, measuring, or counting instruments or devices, used for

commercial purposes, and shall issue cer- tificates of approval of such types or design as he shall find to meet the re- quirements of this code and the tolerances

and specifications thereunder.

"It shall be unlawful to sell or use for

commercial purposes any weight or measure,

or any weighing, measuring, or counting

instrument or device, of a type or design

which has not first been so approved by the

department; provided, however, that any

such weight, measure, instrument, or device

in use for commercial purposes prior to the

effective date of this act may be continued

in use unless and until condemned under the

6
provisions of this code. (Added by Ch. 893,

Stas. 1949.)"

After the hearings described in Section

2.2.1.1 had been held, the code was adopted

and made into law in California on June 1,

1968. Of the code specifications, one of the

most significant was tolerance.

"The maintenance tolerance shall be four

percent (4%) of the indicated delivery on underregistration and two percent (2%) of

the indicated delivery on overregistration.

The acceptance tolerance shall be one-half

the maintenance tolerances."

The State of California also suggested that

"best values" of data be included in the California Code. The gases under consideration

were limited to oxygen, nitrogen, argon, and

hydrogen. The scope of the data required was increased to include saturation densities over

a broad range of pressure and temperature for

each gas. At the request of both the Compressed Gas Association and the State of

California, a document was produced specifically to allow traceability of selected

values

These properties data are specifically

called out in the California Code and accordingly has the same weight of law as the flowmeter calibrations and tolerances themselves,

viz.

"3081.2.6 Saturated Liquid Densities.

Saturated liquid densities of Oxygen,

Nitrogen, Argon, and Parahydrogen as prepared by the National Bureau of Standards, Boulder, Colorado, shall apply

(Refer to National Bureau of Standards,

Technical Note No. TN-361)."

This program on cryogenic fluid transfer

is only one of the most recent instances where

common data have proven beneficial to industry and Government. Many other times government agencies with to evaluate efficiency

claims and production capacities projected by

"paper studies". A complete and consistent

set of design data is essential to this purpose. The National Aeronautics and Space

Administration, National Accelerator Laboratory, Navy and other government agencies,

for instance, specify that a common data base

be used in its proposals to provide a sound

basis for evaluation. Data so codified are

in a very real sense "documentary standards",

although not strictly speaking de cure

standards.

2.2.2 Instrumentation System

Cryogenic instrumentation as a discipline

is primarily concerned with the condition or state of cryogenic fluids, such as pressure

and temperature. Such information is typically required for process optimization and

control. In addition, as cryogenic. fluids

become increasingly commercially important,

there is the question of "how much" is there?

Accordingly, the instrumentation system must

be able to provide answers in terms of liquid level, density, and flow rate.

A derivative question is arising more and more frequently, namely, of what utility or quality (in the same sense as thermodynamic

availability) are the goods? As it is not

"good enough" to count BTU's alone in energy

conservation questions (the level of thermodynamic availability must be considered), so

it is that the "availability" of the cryogenic fluids must be taken into account.

This was a nagging question during the

space program when a so-called "empty" tank

of liquid hydrogen could still contain 2% or

so of its original mass, as a dense but un- usable fluid. It is of importance today in

the metering of liquefied natural gas, for

instance, where the integrated heating

value--which depends upon composition--is

the preferred unit of commerce, rather than

just the volume that has changed hands.

This section addresses the measurement tools

and techniques that are currently used to probe this part of the cryogenic measurement

system.

2.2.2.1 Measurement Tools and Techniques

(1) Pressure . Of all the measurements

made on cryogenic systems, surely one of the

most common must be that of pressure measurement. Pressure measurements are made not only

to determine the force per unit area in a system, but also to determine flow rate (head

type meters), quantity (differential pressure

liquid level gages), and temperature (vapor

pressure or gas thermometers). Pressure

measurements are thus fundamental to the

smooth running of much of this part of the

National Measurement System.

Pressure measurements in cryogenic systems

have, for years, been made by simply running

gage lines from the point where the pressure

measurement is desired to some convenient

location at ambient temperatures and attaching a suitable pressure-measuring device, such

as the familiar Bourdon gage.
This system works quite well for most applications; however, there are disadvantages

to this straightforward approach that may

introduce problems in many systems. The two most important are: (1) reduced frequency

response and (2) thermal oscillations. In addition, heat leak, uncertainties in hydrostatic head within gage lines, and fatigue

failure of gage lines could become significant

in some applications. Such problems associated with pressure measurement at cryogenic

temperatures could be eliminated by installing

pressure transducers at the point of measurement, thereby doing away with gage lines.

Like all instruments, the output of a pres- sure transducer depends not only on the primary input, in this case pressure, but also

upon extraneous effects, such as the effect of

temperature on its various components. Erroneous pressure readings can be caused by both

steady state temperature effects and temperature gradient, or thermal shock effects.

While it is agreed that some available

pressure transducers are capable of performing satisfactorily at low temperature, other

types, e.g., piezoelectric, diode, inductance,

reluctance, and electrokinetic devices, may

perform equally well or better. It is therefore necessary, for the purpose of comparison,

that all types of pressure transducers be

tested at low temperature and at various frequencies to determine their potential for

cryogenic use. Because pressure sensing devices often behave quite differently in a cryogenic medium, a systematic, well documented testing program is presently needed

before all types can be evaluated and compared.

A cryogenic calibration system with varied

capabilities is essential for the successful

completion of such a program described above.

The details of such a system have been described by Arvidson and Brennan [2].

(2) Temperature . Most engineering mea- surements are made with metallic resistance

thermometers, non-metallic resistance thermometers, or thermocouples. Gas thermometers

and vapor pressure thermometers find little

practical engineering application, and hence

are mentioned only briefly in the following

paragraphs. A recent compilation of the

commercial availability of thermometers is

given in "Measurements and Data" [3].

Gas Thermometry . Constant-volume gas

thermometry is familiar as a technique for

accurate realization of the thermodynamic

temperature scale. In such work, the

pressure-temperature behavior is made as linear as possible by minimizing the ex- traneous volumes in the manometer and the

connecting tubing. Troublesome corrections for these extraneous volumes decrease

with decreasing bulb temperature, inasmuch

as the proportion of gas in the bulb in- creases. On the other hand, gas imperfection increases with decreasing temperature.

If, however, the sensing bulb is made small,

as compared to the external volume of the

system at ambient temperature, the characteristic is far from linear, the sensitivity

increasing greatly as the bulb temperature

decreases. By using a Bourdon gage to show

the pressure in this device, a simple gas

thermometer is achieved that is useful for

such purposes as monitoring the cool-down of

cryogenic apparatus.

In order to obtain accurate results in gas

thermometry, it is necessary to make many cor- rections. One must account for at least:

the imperfection of the gas; the effect of

the volume of the gas that is not at the

temperature being measured; and the change of

volume of the bulb with changing temperature.

Accordingly, for engineering applications,

gas thermometry is recommended only for indicating the approximate temperature or tem- perature trend.

Precision gas thermometry falls in the

category of fundamental thermometers rather

than empirical thermometers. It is much too demanding for common use. Vapor-Pressure Thermometry . As is well

known, vapor pressure is a sensitive but

nonlinear function of temperature, providing

convenient means for thermometry in limited

ranges of temperature that unfortunately,

do not join to provide continuous coverage of

cryogenic temperatures. For example, the

range from 40 K to 50 K is above the range of neon and below that of oxygen and nitrogen.

Within its limits, however, this type of

thermometer is very accurate.

These thermometers are most accurate in

the area of the normal boiling point of the

liquid used, and hence could be very useful,

albeit over a very limited temperature range.

Advantages of this type of thermometry are

that it is sensitive, can have good time

response, is not affected by magnetic fields,

and needs no calibration. The primary disadvantage is that it can be used only between

the triple point and critical point of the

fill liquid.

Metallic Resistance Thermometry . Since

the resistivity of an element or compound

varies with change in temperature, it has in

many instances been used as a simple and

reliable temperature-measuring device.

While there exist a number of metals that are more or less suitable for resistance

thermometry, platinum has come to occupy a predominant position, partly because of

excellent characteristics, such as chemical

inertness and ease of fabrication, and

8
partly because of custom: that is, certain

[desirable features such as ready availability

'in high purity and the existence of a large

body of knowledge about its behavior have

come into being as its use grew and have

tended to perpetuate that use. Its sensitivity down to 20 K and its stability are excellent.

A variety of platinum resistance thermometers designed for engineering applications is now available. As with other transducers, these devices are subject to extraneous effects (noise). In this case, we wish

to measure only the temperature dependence of

the resistivity. However, we may also unwittingly measure the strain dependency as well.

To avoid this, the engineering thermometers

are built to imitate the strain free con- struction of the precision laboratory type

thermometers.

There are two basic designs for engineering use: immersion probes and surface

temperature sensors. The inmersion probes

feature a high purity platinum wire encapsulated in ceramic or securely attached to a support frame. Features such as repeatability after thermal shocks, time response

in different environments, interchangeability, and mechanical shock tolerance differ

between companies and specific designs.

The second type of industrial sensor is

ibroadly known as a surface temperature

sensor, whose geometry is such that they make

good thermal contact with surfaces of various

shapes. Sensors are available for clamping

around small tubing, fitting into milled

slots, and clamping under bolt heads. The

principle advantages of these thermometers

are that they are small, typically 0.25 cm x 1.25 cm X 1.25 cm, with perhaps a factor of

two variation in any dimension.

Non-Metallic Resistance Thermometry . A number of semiconductors also have useful

thermometric properties at low temperatures.

A semiconductor has been defined as a material whose electric conductivity is much

less than that of a metallic conductor, but

much greater than that of a typical insulator. The most promising semiconductors

seem to be germanium, silicon, and carbon.

The latter, though not strictly a semiconductor, is included in this group because of

its similarity in behavior to semiconductors.

Of the three, germanium has received by

far the most attention, and germanium re- sistance thermometers are now available from

several comnercial sources. The resistance

element is usually a small single crystal.

Inasmuch as the resistivity is high, the

element can be short and thick. It is

mounted strain-free in a protective capsule.

|Because of this combination of features, the

germanium thermometer is both rugged and

reproducible.

The major disadvantage associated with the

use of germanium thermometers is the lack of

a simple analytical representation. Each

thermometer must be calibrated by comparison

at many points in the range of interest if

the inherent reproducibility of the thermometers is to be utilized.

Thermistors. Thermistors (thermally sen- sitive resistors) are essentially resistors

made up of sintered metal oxides. Frequently

used materials are nickel, manganese, and

cobalt oxides. The fact that these resistors

are becoming increasingly popular in measurement and control circuits is attested to by

the number of companies selling them [3].

The reasons for the increasing use are in

part: 1) they are small, which tends to make

the time response significantly less than one

second; 2) they are typically high resistance

units, which reduces the overall effect of

lead resistances, and 3) their temperatureresistance characteristics are dependent on materials and procedures which allows thermometers to be developed that are particularly

sensitive in limited ranges of temperature.

Thermocouples . Thermocouples have the

familiar advantage that the temperaturesensing junction can be reduced in size to almost any desired extent, so that the

disturbance to the object being sensed can be

made very slight, and the response time can

be very fast. They also have a familiar

disadvantage; rather small voltages must be

measured. In addition, they have a less

familiar but very serious disadvantage; the

net emf depends not merely on the materials

nominally used for the two wires, but also

on material inhomogeneities which, if located

in a temperature gradient, will introduce

parasitic voltages. These inhomogeneities

may arise from variations in chemical composition or may consist of crystal lattice imperfections introduced, for example, by

kinking the wires. Their presence can be

detected by various tests but cannot readily

be corrected for, so that testing merely

serves to indicate whether a given wire

should be discarded or not.

(3) Quantity or Liquid Level . Liquid

level is but one link in a chain of measurements necessary to establish the contents of

a container. Other links may include volume

as a function of depth and density as a function of physical storage conditions. For- tunately, the actual discernment of the liquid

vapor interface (liquid level) is often the

strongest link in this measurement process

due to the significant progress made here in

the course of the Nation's space program. As

a result of this intense interest, liquid
level measurements can be made with an accuracy and precision comparable to that

of thermometry, for instance, and often with

greater simplicity.

This period of development led to many

different physical embodiments of liquid

level sensors, and there are as many ways of

classifying these devices as there are

authors who write about them. We shall classify them according to whether the output is

discrete (point level sensors) or continuous.

Point Liquid Level Sensors . All liquid

level sensors depend for their operation on

the fact that there can be a large property

change at the liquid vapor interface, a significant change in density, for example.

This may not always be the case if the fluid

is stored near its critical point, for

instance, or if stratification has built up after prolonged storage. Be that as it may,

point level sensors are tuned to detect a sharp property difference and given an on-off

signal. Several of the more commonly used

types are described below.

The thermal or hot wire type senses the

large difference in the heat transfer coefficient between liquid and vapor. Since the

heat transfer coefficient is much larger in

the liquid than it is in the vapor, one can expect, for a given power input, that the

transducer will have a different temperature

and hence resistance, in the liquid than in

the vapor. It is this change in electrical

resistance that is actually sensed in a bridge circuit, and hence these devices can

be made both simple and fast. Small platinum

wires, solid carbon resistors, and thin-film

carbon resistors are examples of sensing

elements that are used.

The capacitive type depends upon the

difference in dielectric constant between the

liquid and vapor, which is essentially a function of the fact that the liquid is more

dense than the vapor. This sensor is usually

made in the form of a bulls-eye, with alternate rings forming the plates of the capacitor, and are installed so that the plane of

the rings is parallel to the liquid vapor

interface.

The optical type senses the change in

refractive index between the liquid and

vapor, which of course is closely related to the dielectric constant and density.

This type of transducer contains a light source and a light sensitive cell that are isolated from one another, but which do com- municate down a prism. The prism is cut in

such a way as to have total internal reflection when in gas, and yet let the light

escape when in liquid. This is possible

since there is a difference in the index of

refraction of the liquid and the vapor, and

since the critical angle for total internal

reflection depends upon the index of refraction. This type of transducer has a very

high in-out signal ratio, for the light detector is almost totally illuminated or totally dark.

There are also several acoustic or ultrasonic devices that depend upon the fact that

the damping of the vibrating member is greater in the liquid than in the vapor.

Often, a magnetostrictive element is driven

at a constant power and is more or less

dampened, depending whether it is in liquid or

in vapor. The end of these sensors is about

the size of a quarter dollar, but this does

not in any way indicate the limit of its

resolution. These devices can be tuned to detect only a fraction of the total damping

that would occur upon total immersion, so that

their sensitivity can be much smaller than

the total end of the device. Piezoelectric

versions of this acoustic type liquid level sensor are also available.

Continuous Liquid Level sensors take many

forms. Some methods determine mass, while

others are merely interface following, and

usually are just continuous analogs of some point sensor. Among the mass sensors are the

direct weighing schemes, nuclear radiation

attenuation, and RF techniques. The interface

following types include differential pressure

sensors, capacitance and acoustic techniques.

These are described below.

Direct weighing schemes have been used for

oxygen, nitrogen and other dense fluids, but

have been handicapped in hydrogen use by the

fact that the weight of the container is

often large compared to the weight of the

contents. In modern weigh-faci 1 ities however, the weight of the tank rarely exceeds

the weight of the contents (when the tank is

full). Calibrated balance weights and

strain-gage load cells are most commonly used

in this application.

Nuclear Radiation Attenuation has found

some success in oxygen and nitrogen systems,

but comparatively little use for hydrogen.

This is so because hydrogen is nearly transparent to the commonly available sources of

nuclear radiation, while the tank walls are relatively "thick" to the same radiation.

Hence the fundamental signal to noise ratio

is inherently low. Hydrogen does absorb

beta radiation rather well, but then "windows"

of beryllium or equivalent light metals must

be placed in the tank walls. On the whole,

this technique appears too sophisticated for

simple engineering measurements.

RF Cavity Detection . In this system,

microwave energy is introduced into a tank

to energize it by setting up electromagnetic fields throughout the entire volume

10
i

of the tank. The tank interior is a di el eerie region completely surrounded by conductng walls. Such a system is called a cavity,

and the resonant frequencies established are

the normal theoretical modes of the cavity.

Considerable development work has been done

recently on both uniform density fluids and

non-uniform density fluids, and this technique

continues to show considerable promise for

both mass-gaging and level-gaging in a variety of cryogenic fluids, including hydrogen.

RF transmission characteristics through co- axial cables can also be used to detect

liquid levels by measuring the time of flight

of a RF pulse through the cable [4,5]. This

latter technique is called time domain ref lectometry.

Differential pressure measurements are simple to visualize, but difficult to realize

in practice. "Noise" is always high due to boiling and potential thermal oscillations at

the lower pressure tap. Also, the unknown

level of the liquid in the gage lines can introduce hydrostatic head errors. In the case of hydrogen, the "signal" is low due to the unusually low density of hydrogen.

Better success is obtained with other cryogens of higher density.

Capacitance sensors are widely used for

the continuous measurement of the level of

cryogens. They do not truly follow the

nterface, but sense the total contents of

he container. That is, the dielectric

constant of the gas phase contributes to the

output signal, as well as that of the liquid

phase. This can be a serious source of error

in hydrogen because the density of the cold

gas (and hence its dielectric constant) is

significant compared to that of the liquid.

This problem is especially troublesome in

nearly empty tanks, but is often compensated

for by either: a) segmenting the capacitor

and ignoring the output from those sensor

sections located in the vapor phase as the

liquid level drops, of b) installing a few

point sensors at critical levels and routinely

calibrating the continuous sensor against

tern. Rod-to-blade and concentric tube con- figurations are most common in this type of sensor.

In the acoustic devices, the liquid

itself is used as the transmitting medium.

A transmitter feeds an electric pulse to a transducer where it is converted to an acoustic pulse traveling at sonic velocity to the liquid-vapor interface, reflected back at

the same speed to the transducer, where it is

reconverted to an electric pulse, and finally

sent to a receiver. Knowing the velocity of

sound in a given liquid, the pulse transit

time from transmi tter-to-interface-to-recei ver ecomes an indication of liquid level. Someimes an acoustic racetrack of known path

11

length and variable time of flight is included to provide a measure of the density of

the fluid. The product of the two measurements tends to give an indication of the mass

of the fluid contained in the tank.

(4) Density measurements are closely akin

to quantity and liquid level measurements

because: 1) both are often required simultaneously to establish the mass contents of a tank, and 2) the same physical principle may

often be used for either measurement, since,

as noted, liquid level detectors sense the

steep density gradient at the liquid-vapor

interface. Thus, the methods of density

determination include the following techniques: direct weighing, differential pressure, capacitance, optical, acoustic, and

nuclear radiation attenuation. In general,

the comments made above about the various

liquid level principles apply to density

measurement techniques as well.

Two exceptions are noteworthy. In the case of homogeneous pure fluids, density can usually be determined more accurately by an indirect measurement; namely, the measurement

of pressure and temperature which is then

coupled with the analytical relationship

between these intensive properties and density through accurate thermophysical properties data.

The case of non-homogeneous fluids is quite different. Liquefied natural gas

is often a mixture of five or more components

whose composition and hence density varies

with time and place. Accordingly, temperature and pressure measurements alone will not suffice. A dynamic, direct measurement is required, embodying one or more of the liquidlevel principles described above. Such

"densitometers" are presently under development, and it is premature to discuss their

capability at this time.

(5) Flow . There are three basic types of

flowmeters which are useful for cryogenic

liquids. These are the: 1) pressure drop or

"head" type, 2) turbine type, and 3) momentum type. We shall discuss each in turn. Head Meters . This type of meter embodies

the oldest method of measuring flowing fluids.

The distinctive feature of head meters is that

a restriction is employed to cause a reduction

in the static pressure of the flowing fluid.

This pressure change is measured as the

difference between the static heads on the

upstream and downstream sides of the restriction.

Theoretical development of the flow equations for head type meters may be found in

publications of the American Society of

Mechanical Engineers [6].

The appeal of these meters in cryogenics

is more than simplicity, and stems from the

possibility of eliminating the necessity for
calibration, if proper design, application

theory, and practices are followed. Design

methods for orifices, flow nozzles, and

venturi tubes are available in publications

of the American Society of Mechanical Engineers [6]. Recommended practice for flangemounted sharp-edge orifice plates can be

found in publications of the Instrument

Society of America [7] and the International

Standards Organization [8].

The characteristics of the head meter are

as follows. The device is strictly a volumetric meter; that is, it can of itself give

no information regarding mass flow rate. With appropriate pressure sensing, the range

can be extended up to 10 to 1. It is the

very nature of these devices that they

generate a decrease in pressure by accelerating the fluid. If we are dealing with a saturated cryogen, then this sudden decrease

in pressure could lead to vapor formation

(cavitation) in the flowing stream and an erroneous flow measurement. Many experiments

[9], however, have failed to show any illeffects attributable to cavitation. Nonetheless, it is good design practice to maintain

static liquid pressures within the meter well

above the fluid saturation pressure. In spite of all shortcomings, head meters are widely used and quite reliable.

The turbine-type volumetric flowmeter is

probably the most popular of the various

flowmeasuring instruments, principally due to their simple mechanical design and demonstrated repeatability. The turbine- type

volumetric flowmeter is a simple mechanism

that consists of a freely spinning rotor

having a number of blades, each inclined at

an angle to the axis of flow. The rotor is supported in guides or bearings mounted in a housing that forms a section of the pipeline. The angular velocity (rpm) of the rotor

may be detected by one of a number of methods;

e.g., a permanent magnet encased in a rotor

body will induce an alternating voltage in an inductive pickup coil mounted on the housing,

or the core of the pickup coil may consist of

a permanent magnet and the rotor constructed

of a magnetic material so that the change in

magnetic circuit reluctance, as each rotor

blade passes the coil core, causes an alternating current to be induced in the coil.

Capacitive and photoelectric methods of

observing rotor rpm have also been used. The

primary requirement, however, is that the

angular velocity of the rotor be directly

proportional to volumetric flowrate, or more

accurately, to some average velocity of the

fluid in the pipe. A variation of the turbine type meter is

the "twin turbine" type. In this case, two turbines of different blade pitch are coupled

together by means of an elastic restraint.

Because of the difference in pitch, they

would tend to revolve at different speeds.

However, this is prevented by the elastic

coupling so that they do revolve at the same

speed, but with a "phase angle" between them.

The magnitude of the phase angle is a measure

of the flow rate and is said to be, in fact,

a measure of the mass flow rate. The vortex shedding meter is also a single-phase fluid rate-velocity meter, like

the turbine meters, but in a distinct class

by itself. The phenomena upon which it is based is the Karman vortex trail and its

application to the measurement of flow of

liquids and gases is fairly recent [10],

probably because only recently have sensors become available to detect the vortices.

The Karman vortex trail is used to explain

certain phenomena associated with the flow

around cylinders, ellipsoids, and flat

plates. For flow around an object, eddys

break off alternately on either side in a periodic fashion. Behand the object is a staggered, stable arrangement or trail of

vortices. The alternate shedding produces a periodic force acting on the object normal to the undisturbed flow. The force acts first

in one direction and then in the opposite

direction, setting up a natural frequency of

vibration.

If the frequency of the vortex peeling

approaches or equals the natural frequency of

the elastic system, consisting of the bluff

object and its supports, the object may have

a small alternating displacement normal to the stream flow. (The vibration of some smoke stacks, the vibration and the fatigue

failure or progressive fracture of some transmission lines have been attributed to this resonance phenomenon).

The vortex sensors consist of electronically self-heated resistance elements whose

temperatures and therefore resistances vary

as a result of the velocity variations

adjacent to the body. These velocity variations reflect directly the action of the

vortices as they peel off from the downstream

edge of the bluff body. The meter factor

(pulses/gallon) depends only on the inside

diameter of the pipe and the width across the

bluff body face. Cryogenic evaluation is limited, to date, but performance on liquid

nitrogen and oxygen shows promise.

Momentum Mass Flowmeters . Mass reaction

or momentum flowmeters are of three types.

There are those in which an impeller imparts

a constant angular momentum to the fluid

stream, and then the variable torque on a turbine which removes this momentum, is measured. There are those in which an impeller

is driven at a constant torque, and then the

12
variable angular velocity of the impeller is

measured. And there are those in which a loop of fluid is driven at either a constant

angular speed or a constant oscillatory motion,

and then the mass reaction measured.

The performance of such flowmeters was determined in a National Aeronautics and

Space Administration sponsored flowmeter

evaluation program [11 J. From the results of

this program, it appears that several cryogenic mass flowmeters have been developed

that are capable of liquid hydrogen mass flow

measurement accuracies on the order of ±0.5

percent. There appears to be degradation of mass flow measurement accuracy, however, when

subjected to a two-phase flow.

There are several other concepts of cryogenic fluid flowmeters that are available or are in development. Since they were not

evaluated in the previously mentioned

National Aeronautics and Space Administration

sponsored program, definitive performance

results, on the scale of the previously discussed mass flowmeters, are not yet available. These flowtieters are inferential mass flow measurement devices, having in common measurements of fluid density and fluid volume flow or fluid volume flow- induced momentum.

(6) Summary, Measurement Tools and Techniques . Since measurements are the basis of

technology and dictate the fineness of our

physical observations and control, it appears

that this part of cryogenic technology may be

lagging. One may conclude: 1) little is

being done to bring the cryogenic instrumentation technology of the space program to the

market place, 2) if it were, adequate primary

instruments and facilities do not exist to bring this part of the National Measurement

System under control, and 3) no concerted

effort exists to explore the consequences or exploit the opportunities of new technological opportunities.

These conclusions appear to apply generally to each area of cryogenic instrumentation, although, of course with varying

degrees of severity. Specific analyses and

conclusions appear in each major instrumentation area in Section 2.3, "Realized Measurement Capabilities."

2.2.2.2 The Cryogenic Instrumentation

Industry

Commerce in cryogenics is largely an extension of the chemical process industry

(SIC Major Group 28). Even such special

government programs as the space effort were

built upon the existing foundation of the

industrial gases and equipment industries to supply liquid hydrogen in unprecedented

quantities of many tons per day. Similarly,

there is no such entity as a cryogenic instrumentation industry. Rather, those same

firms that supply instrumentation to the

chemical processes industries modified and

extended their existing capabilities into

the cryogenic regime. In a few instances,

largely due to unique requirements or limited

applications, the airframe companies developed a special measurement capability themselves (e.g., measurement and control systems

for liquid oxygen in life support systems).

The result has been the measurement tools and

techniques described earlier in Section

2.2.2.1.

Economic Magnitude . The economic magnitude and rate of growth of cryogenic instrument sales would be interesting to note. However, as indicated above, there is no such

entity as a cryogenic instrument industry.

Hence the data we might desire are obscured

by the data on the measurement industry itself, SIC Major Group 38: Measuring, Analyzing, and Controlling Instruments; Photographic, Medical, and Optical Goods; Watches

and Clocks.

Close inspection of SIC Group 38 reveals

that cryogenic instruments for laboratory use

are found in Code 3811: Engineering, Laboratory, Scientific, and Research Instruments

and Associated Equipment. Some of the instru

ments found in this category are: Chemical

Laboratory apparatus

Gas analyzing equipment

Laboratory testing and scientific instruments

Physics laboratory apparatus and instruments, and

Standards and calibrating equipment.

By far the greater number of cryogenic

instruments will be found in Group 382:

Measuring, Analyzing and Controlling Instruments. For instance, Group 3822--Automatic

Controls for Regulating Residential and

Commercial Environments and Appliances--

includes:

Float controls

In-built thermostats, filled system, and

bimetal types

Liquid level controls

Refrigeration controls (pressure)

Refrigeration thermostats

Temperature controls, automatic

Thermocouples, vacuum: glass.

Group 3823--Industrial Instruments for

Measurement, Display, and Control of Process

Variables; and Related Products--includes

establishments primarily engaged in manu- facturing industrial instruments and related

13
products for measuring, displaying (indicating and/or recording), transmitting, and

controlling process variables in manufacturing, energy conversion, and public service

utilities. These instruments operate mechanically, pneumatically, electronically, or electrically to measure process variables

such as temperature, humidity, pressure,

vacuum, combustion, flow, level, viscosity,

density, acidity, alkalinity, specificgravity, gas and liquid concentration, sequence,

time interval, mechanical motion, and rotation. Some specific examples pertinent to this study are: Flow instruments, industrial process type

Level and bulk measuring instruments,

industrial process type.

Liquid level instruments, industrial

process type

Magnetic flow meters, industrial process

type

Pressure gages, dial and digital

Pressure instruments, industrial process

type

Primary elements for process flow measurement: orifice plates, etc. Resistance thermometers and bulbs, industrial process type

Temperature instruments: industrial

process type, except glass and bimetal

Thermistors, industrial process type

Thermocouples, industrial process type

Thermometers, filled system: Industrial

process type

Turbine flow meters, industrial process

type.

The final classification of interest to us

is Group 3824: Totalizing Fluid Meters and

Counting Devices, which includes establishments primarily engaged in manufacturing

totalizing (registering) meters monitoring

fluid flows, such as watermeters and gasmeters; and producers of mechanical and

electromechanical counters and associated

metering devices. Instruments of interest

found here are:

Counter type registers

Gages for computing pressure- temperature

corrections

Impeller and counter driven flow meters

Meters: gas, liquid, tallying, and mechanical measuring - except electrical

Positive displacement meters

Propeller type meters with registers

Totalizing meters, consumption registering, except aircraft

Turbine meters, consumption registering

Vehicle tank meters.

Close inspection of the 1967 census of

manufacturers reveals the not surprising fact

that all temperature sensors or all pressure

gages are lumped under one code, regardless

of their use. Accordingly, one cannot directly get at the magnitude of the cryogenic

instrument business through such conventional

means, and other means must be found.

For instance, an industry association oc- casionally has found it useful to look at a specific segment of their industry. The

Instrument Society of America special

corrmittee mentioned in Section 2.2.1.1 made

such a survey of flow meters, and their

findings are shown in table 2-3.

Table 2-3 makes no allowance for the flowmeters that may be employed for liquid hydrogen and LNG custody transfers from trucks or trailers. The total investment of flowmeters

is based on a price range of $700 to $2500

per flowmeter.

These figures refer only to the custody

transfer (sale) of cryogenic fluids. Much

more is at stake if one considers the total

production of industrial gases, which are in

fact made by cryogenic processes and include

in-plant process transfers.

Table 2-3. Flowmeters in custody transfer of oxygen, nitrogen, and argon

Year Total No. Total Investment Custody

of Flowmeters Flowmeters in Millions Transfer/Year

1966 1000 $ 1.6 200,000

1967 1140 1.8 228,000

1968 1300 2.1 260,000

1969 1482 2.4 296,400

1970 1689 2.7 337,800

1971 1925 3.1 385,000

14
These figures were developed by the Instru- ment Society of America to help demonstrate

that flowmetering had an economic magnitude

such to merit attention, and that, in fact,

this part of the measurement system could

not be certified to be in control.

Substructure and Composition; Firms In- volved . Several very recent and comprehensive reviews of specific cryogenic instruments and measurement systems have been prepared by the Cryogenics Division of the

National Bureau of Standards for the National

Aeronautics and Space Administration

Aerospace Safety Research and Data Institute.

This series includes flow measurement technology [12], low temperature measurements

[13], density and liquid level measurements

[14], and pressure measurements [2]. These

are truly benchmark publications that discuss

not only the technology of the measurement,

but also give specific performance data.

The data below are typical of the level of

detail that may be found in all of the re- ports. They are taken from the treatise on flow measurement [12] for an oscillating

piston volumetric flowmeter, as an example:

"The name plate specifications on the 1-1/2

inch meter are: size - 0.0381 meters (1-1/2 inch)

maximum flow rate - 0.0044m s (70 gal /mi n)

minimum flow rate - 0.0088m s (14 gal /mi n)

2 maximum pressure - 2.413 MN/m (300 psia)

material - aluminum piston, brass case.

Table 2-4. Typical flowmeter performance

Flow Rate LO2 Water Deviation LO2

Gal/h Deviation Deviation from water

300 -0.4 -0.53 +0.13

450 -0.55 -0.47 -0.08

800 +0.8 -0.5 +1.3

1700 +0.35 -0.7 +1.05

2100 +0.22 -1.05 +1.27

"From this table, the mean deviation of LO2

from water calibration is equal to 0.73

percent (deviation from standard 14.67

counts per gallon). It may be expected

that water can be used for the routine

testing of meters of this type and a factor applied to obtain the correct

liquid oxygen calibration.

Table 2-5. Typical flowmeter performance

1-1/2 Inch

Oscillating

Piston

Precision (3a) at Start, % Precision (3a) at End, % Bias at Start, % Bias at End, %

3 Vol . Metered, m (gal

)

3 Max. Flow Rate, m /s (gpm)

Min. Subcooling, K

±0.63

±0.54

+1.33

+0.61

1225 (323,800)

0.0044 (70)

5

"Data on only one of the 1-1/2 inch nominal

size meters are presented as a second

meter underwent a reduction in registration

by about 1 percent during these tests and

was replaced. The change in bias is significant and indicates wear."

This level of detail is typical of all of

the studies mentioned above, and accordingly

they are highly recommended as source documents . Certain trade journals also review the

instrumentation field. Measurements and

Data Journal is published bi-monthly by the

Measurements and Data Corporation, 1687 Washington Road, Pittsburgh, PA 15228. In 1974,

for instance, this journal published annual

staff surveys on: Piezoelectric pressure transducers

Force measurement

Reluctive, inductive, and eddycurrent pressure transducers

Mass flow

Capacitive pressure transducers

Thermocouples and accessories

Resistance and thermistor thermometry

Strain-gage pressure transducers

Turbine flowmeters

Potentiometric pressure transducers.

These commercial surveys usually include

a glossary of terms, physical theory,

range, sensitivity, stability, cost, and

accuracy. A small part of a typical table

on resistance and thermistor thermometers

from Measurements and Data , Vol. 8, No. 2,

(March/April 1974), is given in table 2.6

to illustrate the very practical and com- prehensive data that may be found.

15
Table 2-6. Resistance and thermistor thermometers

riuuc 1 r r I VrfC

Thermal Systems

1001 Ni, Pt -100/600F Industrial probe; 100 ohms $32

Hpriprril niimn<ip RTD $125

Model 5004 -100/500F Etched Balco, thin surface sensor $25

Model 5001-19 -260/400C General purpose surface sensor; $50

500 Ohm

Model 1064 -452/500F . . Cryogenic platinum RTD $400

1 lUUC 1 1 U 1 VJ $Rnn

1 sjKj/ uuu

i?5

Mnrlpl 1 lUUC 1 RIdR J I to riiiticiLurc pruuc

ThoKTnn Plo^'f"^'!^ Pri lilcilllU QfcV.'Ul 1^ UU« 9 1 t 11., • 16301 Pt Sensor -200/500C 0.26C at OC for 50-ohm element; 3 C at 500C

Thermometries, Inc. Series. P20, P30^ -100/300C To +.5% thermistor probe $1 (Quantity)

P60, PlOO

Series HTP60, -100/450C Same; hi temp thermistor probes $5 (Quantity)

HTPlOO

Series B10,B14,B43 -100/300C To +.5% thermistor beads $l-$4

Series HTB43 -100/450C Same; hi temp thermistor beads $5

Series 1F,2F, FM -50/150C To +.5% thermistor flakes $3-$20

Series FM Same Same $.60

Every manufacturer that wishes to cooperate is included. Coverage is very close to 100% indeed. The above data were chosen

simply as an illustrative but not nearly

exhaustive example.

Trends. Trends in instruments for mea- surement, analysis»and control as a whole

can be a helpful indicator even though the

actual value of the cryogenic instruments

specifically may evade use. The following

discussion of trends is taken almost en- tirely from the "U. S. Industrial Outlook,

1974, with Projections to 1980", a U. S. Department of Commerce annual publication.

"Total industry shipments by manufacturers

of measuring and controlling instruments

are expected to reach $1.92 billion in

1974, a 7 percent rise over the $1.8

billion estimated for 1973. Industrial

process instruments compose approximately

50 percent of this composite group.

Business prospects for process instruments are closely related to the trend

in capital expenditures for plant and

equipment. Major sectors of the process

group are the petro'leum and chemical

industries, prime markets for industrial

process instruments.

"Additional industrial instruments are needed for the construction of plants to manufacture synthetic natural gas (SNG)

from light oil, and for the facilities

required to process and transport {at

avyogenia temperatures in liquid form)

natural gas from overseas sources to depots in the U.S.

"Maintaining the pace required of a dynamic

high-technology industry, manufacturers

of measuring and control instruments

continue to make substantial investments

in newly designed products. These

developments reflect customer demands

for monitoring and control systems that

improve process management, maintain

tighter product specifications, achieve

economy in production, enhance operating

safety, and add to the protection of the

environment. New high-temperature and

cryogenic technology imposes requirements for innovative measuring instrument sensors capable of performing

dependable and accurate measurements of

ultra-hot and super-cold processes."

16
International Trade . With respect to international trade patterns, the same source continues:

"Technology continues to foster automated

monitoring and control of industrial

processes, and residential and com- mercial facilities in the U.S. and

world-wide. The automatic temperature

control industry, and manufacturers of

measuring and control instruments,

produce and distribute instruments whose

common technology crosses national boundaries.

"Industrial processes and building methods

are universal, and can be served throughout the world by instrumentation of similar design. Global leadership demands

alert attention to chanqinq reauirements

in various market sectors, and continuous

advances in new product design. Manufacturers in these industries take part in numerous trade shows and exhibits in the

U.S., and actively participate in scheduled trade shows and trade missions

organized by the Office of International

Marketing to reach foreign markets.

Exports by both sectors of the instrument industry have steadily increased

since 1968, with exports of the measuring and control instrument group progressing at an annual growth rate of 9 percent from 1967 to 1973.

"The Office of International Marketing has

prepared a Global Market Survey on Industrial and Scientific Instruments , depicting business prospects in se- lected foreign markets: Global Market

Survey, Industrial and Scientific Instruments, Office of International Marketing,

1972, U.S. Department of Commerce."

Examples of specific international interactions may be found in Section 2.2, where

the NBS cryogenic flowmetering program is

used to illustrate the process. In this

program alone, the NBS Cryogenics Division:

cooperated with the International Organization of Legal Metrology (OILM) to facilitate final adoption of our technical

recommendations; performed "type testing"

of meters of foreign manufacture -- affiliates of U.S. concerns; and encouraged and

facilitated the visits and participation of

international observers from the PTB; Linde, AG; Messer-Griesheim GMBH; Compteurs

Schlumberger, France; and the British Oxygen Co. , London.

The Industry as a Whole . A profile of

this industry as a whole is given in the

Box:

Table 2-7. 1973 Profile:

instruments for measurement,

analysis and control

SIC code 3821 3822

Value of industry shipments $1800 $740

(millions)

Number of establishments 661 105

Total employment (thousands) 67 40

Exports as a percent of 27.8 4.3

product shipments

Imports as a percent of 5.5 n.a. apparent consumption

Compound annual average

rate of growth 1967-73

(percent)

Value of shipments 3.6 3.0

(current dollars)

Value of exports 9.4 4.2

(current dollars)

Value of Imports 25.7 n.a. (current dollars)

Employment 9.2 0.8

n.a.= Not available.

2.2.3 Reference Data

Reference data are needed by the cryogenic community on both fluids and solids.

The following sections describe some data

producing activities, their users, and the

principal means of dissemination.

Properties of Fluids . Pure fluids of

interest in the Cryogenic Measurement

System include helium, neon, argon, hydrogen,

deuterium, nitrogen, oxygen, fluorine,

methane, ethane, ethylene, propane, carbon

monoxide and carbon dioxide.

The mixtures include air (N„, O^, Ar),

natural gas (CH4, other hydrocarbons, nitrogen), synthetic natural gas (CH4, H2, CO,

CO2), FLOX (F2, O2) and GDL laser fluids

(He, N?, CO2).

Properties of interest are the thermodynamic properties (compressibility, entropy,

enthalpy, specific heats, sound velocities);

electromagnetic properties (dielectric

constant, refractive index); and transport

properties (viscosity and thermal conductivity coefficients).

17
Properties of Solids . The solids (metals,

alloys and composites) used at low temperatures include aluminum and aluminum alloys,

copper and copper alloys, nickel and nickel

alloys, the austenitic stainless steels,

titanium alloys, selected ferritic steels, a variety of superconducting materials, glass

epoxy composites, and many more. The data on these materials at the required low operating

temperatures include the mechanical, thermal,

and electrical properties.

Needs for Data and Their Users . These

data are required for many, and often diffuse,

purposes including: a) data for material

selection in the decision-making phase programs; b) data for equipment or process design and optimization (for example, refrigerator and liquefaction equipment, separation

of gases, and storage and transport of liquids); c) data for analysis of the system or experiment, including safety criteria; and d)

data for instrumentation and gaging, including sale or custody transfer.

It is important to note that these data

are used by the entire cryogenic community,

the $2 billion per year industry that supports a wide variety of technologies. To

illustrate, the use of less expensive but

structurally adequate metal could save $0.3

million on the cost of a single liquefied

natural gas storage tank or $1.0 million on

the cost of a single ship carrying liquefied

natural gas--a total cost saving of as much

as $15 million per year. In addition, economic analyses show that the value of the

thermodynamic data to the design of a plant

or facility is worth 1 percent or more of the

capital cost of the entire unit—of considerable value when used for the design of large

cryogenic units, many of which run into tens

of millions of dollars [15]. A less quantifiable but equally important

use of the reference data base is in establishing codes, standards, and recommended

practices. These data often form the technical foundation for regulatory decisions by

such agencies as the Federal Power Conmission, the Department of Transportation, and

the Office of Pipeline Safety, as well as the

National Fire Protection Agency.

Methods of Acquisition . Data on fluid and

solid properties at cryogenic temperatures

are obtained by a wide variety of groups in

industrial, government, university, and non- profit laboratories. These data are referenced, compiled, correlated, and critically

evaluated by our staff and form the basis for

deciding what new measurements are required

and which ones are not needed. Our staff

performs comprehensive accurate measurements

to fill important da£a gaps and reconcile

inconsistencies where necessary.

Methods of Dissemination . The NBS Cryogenic Data Center [16] was established in

1958 and publishes a bi-weekly current awareness list of articles in the fields of

cryogenic engineering and cryogenic physics

which have appeared in the open literature.

In collaboration with the Standard Reference Data Program, an accumulated total of

nearly 100,000 technical articles have been

received, cataloged and indexed for ready

access. In addition, specialized quarterly

bibliographies are prepared for: Superconducting Devices and Materials; Liquefied

Natural Gas; and Hydrogen as a Future Fuel.

The cryogenic community, including libraries,

purchase these documents on a subscription

basis, which covers the NBS cost of preparation. Subscriptions to these periodicals

total nearly 1300 [17].

In addition, the staff of the Data Center

responds to over 500 technical inquiries

each year. Some of these requests require

the use of an automated information system,

in which case the user pays a fee for just

the costs involved in the automated search.

The Cryogenics Division is the focal point

for the measurement and data requirements of

the cryogenic community. We established the

National Cryogenic Engineering Conferences

(CEC), now in their 20th year and NBS con- tinues to be the secretariat. The 20 volumes of the conference proceedings "Ad- vances in Cryogenic Engineering" are major

resource documents for the workers in this

field. In addition, we sponsor specialized

conferences, like the International Cryogenics

Materials Conference, and workshops to aid in

dissemination of data.

The most prestigious of our outputs are the

individual research publications, approximately 60 per year, or roughly one openliterature publication per professional manyear. Special purpose publications are much more numerous, and often more specific and

timely. For instance, progress reports and

NBS Technical Notes are frequently distributed directly to other agency sponsors and

known users on a quarterly basis.

Pattern of Use of the Data in the Measurement System . As mentioned, the users of

reference data by the cryogenic community

are many and varied. Selected examples have

been chosen to illustrate these uses.

a) Nat. Bur. Stand. (U.S.) Tech. Note No.

361 "Standard Liquid Densities of Oxygen,

Nitrogen, Argon and Parahydrogen" by Roder,

McCarty and Johnson, was prepared in 1968 at

the request of the Compressed Gas Association

and the State of California, Office of Weights

and Measures. Subsequent revisions (1972 and

1974) have extended the range of data and

(

18
provided a metric supplement. The latter

was requested and paid for by the German

Government for use in the European trade in

cryogenic fluids. These data have now been

adopted as a tentative code (law) by the

"57th National Conference on Weights and

Measures" and are now used as the data base

for custody transfer (sale) in all commerce

in the Western World for these fluids.

b) A comprehensive program on the thermophysical properties of pure methane has

recently been completed. Nat. Bur. Stand.

(U.S.) Tech. Note No. 653 "The Thermophysical

Properties of Methane, from 90 to 500 K at pressures to 700 Bar", by R. D. Goodwin,

contains the most comprehensive and accurate

tables and interpolation functions available

for methane, and NBS has already convinced

the American Gas Association to accept these

reference data as "agreed upon" data for the

Nation's gas industry. NBS has made similar

recommendations to the American National

Standards Institute (ANSI) and the International Liquefied Natural Gas Conference,

LNG-4, held in Algiers in the Suirmer of 1974.

c) A compilation and critical evaluation

of data: "Thermal Conductivity of Solids at Room Temperature and Below" by Chi Ids,

Ericks and Powell, NBS Circular 131, is the

basic reference document for all thermal

conductivity data in this field. In addition

to presenting the available data, it points

to the data gaps and guides future research,

d) Many times NBS is called upon by other

government agencies to evaluate efficiency

claims and production capacities projected by

"paper studies". A complete and consistent

set of design data is essential for this

purpose. The National Aeronautics and Space

Administration, Department of Defense and the

Energy Research and Development Agency, for

instance, specify that NBS data be used in

its proposals to provide a coninon, sound

basis for evaluation. Similarly, our recom- mendations to the regulatory agencies would

be open to question if it were not for a sound foundation of valid and consistent data.

e) Accurate density measurements and calculation methods for liquefied natural gas

mixtures are being obtained to provide a basis for custody transfer agreements and for

mass, density, and heating value gaging

throughout the fuel gas industry.

The basis for the custody transfer of

liquefied natural gas is its heating value.

It is difficult to determine and agree on the

heating value of extremely large volumes of

natural gas in the liquid state. For example,

methods for calculating the heating value of

a liquefied natural ^as mixture require knowing its density, which in turn depends on its

composition, temperature, and pressure.

As the composition of LNB mixtures vary

considerably, depending on the sources of the

gas and the processing conditions, accurate

methods are needed for calculating liquid

densities at arbitrary compositions, temperatures, and pressures. The accuracy is important because of the extremely large volumes

of liquid involved (e.g., 125,000 cubic meters

per ship). This project is being funded and

guided by a consortium of 18 energy companies, and the results will be the industry

"agreed upon" reference data.

2.2.4 Reference Materials

Reference materials are well characterized

(and sometimes certified) materials produced

in sufficient quantity to assure long term

integrity of the measurement process. Reference materials for low temperature applications are continually being developed and

characterized to help fulfill our goal of

furnishing complete and comprehensive service

to the cryogenic coimunity. The materials

studied are primarily metals, alloys, and

composites. The electrical, thermal, and

mechanical properties are the prime characterization parameters. These activities are described below.

Nature of the Data . Reference materials

for cryogenic measurement standardization are principally solids, especially pure metals

and alloys. Because of the economic significance of heat loss minimization and energy

conservation, insulating reference materials

are also of considerably importance at this

time.

Properties of interest include the thermal

conductivity, thermal diffusivity, thermal

expansion, specific heat, and electrical

resistivity. These properties are among those

that depend significantly on variable material production factors,

A broad range of reference materials for

each useful property is required to include

the range of measurements encountered in

practice. For example, thermal conductivity

reference materials are required to span

conductivities from the low conductivity

insulating materials to the very high con- ductivity pure metals, a range of one million

or more. The reference data for these ref- erence materials must be accurate to near state-of-the-art levels. At this stage in

the evolution of cryogenic technology, how- ever, the prime requirement is for characterizing more new materials, rather than

higher accuracy measurements on "older"

materials

19
It should be noted that reference data may

be of little use without corresponding ref- erence materials. Reference data of material properties can be grouped into two broad

categories: those which are not significantly

affected by variations in production techniques and those which are. The latter class

of reference data require reference materials

for their continued usefulness and are of

principal importance at low temperatures.

Need for Data and Their Users . Reference

materials and concomitant reference data are required primarily for three purposes, all

of which form a basis for our national cryogenic measurement system's compatibility and

accuracy: 1) to perform comparative mea- surements in which the measured property

value is given directly in terms of the

standard; 2) to perform apparatus check-out,

thus basing the performance of the apparatus

on the standard; and 3) to train new personnel, thus propagating a high level of reliability and expertise. We must be prepared

to fulfill all three of these requirements to ensure compatibility within the Nation's

measurement system and to promote meaningful

measurements.

Methods of Acquisition . Reference materials are produced by industry and government

under carefully controlled production conditions to assure maximum homogeneity of the

material lot. The NBS Office of Standard

Reference Materials (OSRM) produces, certifies, and issues reference materials and, as such, is the world's largest. Reference data

for these materials must be determined by

standards laboratories of the highest recognized expertise in order to realize their

full utility.

The Properties of Solids Section of the

Cryogenics Division of NBS has been active in

establishing thermal conductivity, electrical

resistivity, and thermoelectric reference ma- terials. Recent efforts have resulted in

establishing three metal reference materials

covering a wide range of conductivity and

temperature. These reference materials have

been described by Hust, Sparks, and Giarratano

[18, 19, 20, 21]. Another pertinent cryogenic reference device, and associated ref- erence materials for measuring very low temperatures, has been described by Schooley [22].

Current plans are to extend this effort to insulating materials and other solid materials. One program to establish several

insulating reference specimens, in conjunction with the National Aeronautics and

Space Administration space effort, was undertaken by this laboratory, but remains incomplete at this time..

20

The NBS Office of Standard Reference Materials, as the world's largest source of ref- erence materials, offers approximately 850

different items for sale. About 33,000 units

worth approximately $1.6 million are sold

annually. Information regarding these ref- erence materials is available directly from

the Technical Representative of the Office of

Standard Reference Materials, Mr. R. W. Seward, phone (301) 921-2045, and also by

catalog [23].

Certificates are issued with these materials listing the property and their ac- curacies . "Uncertified" reference materials, usually . known as research materials, are also provided by this office and other components of

NBS. They serve a very valuable purpose as common source materials in round-robin intercomparison, as do the Standard Reference

Materials. They also play a unique role in

the calibration of research apparatus and

methods, as opposed to engineering, or process

quality control uses. These research ma- terials are especially valuable as a foundation for comparing data obtained from different sources or by different means during

the course of an experimental program.

Patterns of Use of Materials in the Measurement System . A few specific examples may

be helpful to illustrate how reference materials are used. For instance, Hust [18]

describes the preparation and characterization of an electrolytic iron. This

thermal conductivity sample was characterized

over the range 4 to 300 K to meet industry

and government needs in 1971. The temperature range of this material was just recently

extended by Hust and Giarratano [21] to 1000 K. Only a few of these materials are sold annually, especially when compared to the large

volume of chemical composition samples that

are distributed. However, the impact of

this small number of samples may nonetheless

be comparable, if one considers the improved

reliability and confidence in the data that

are subsequently published, following the common use of these materials in many laboratories employing many different procedures.

Many research groups routinely "prove"

their apparatus with these research materials

before publishing any data. In the past,

discrepancies of 50% in thermal conductivity

data were not uncommon. In one documented

instance, a team at a major Mid-Western

University has spent two years improving

their data accuracy and credibility through

the use of precisely the research material

just described. In another instance, during

the late 1960's, NBS was requested to provide

consultation services for a thermal and electrical properties project in conjunction with

a nuclear powered rocket program for the
National Aeronautics and Space Administration.

Several measurement laboratories were involved, and the question of data accuracy

between laboratories became a significant

problem. To answer this question, we ar- ranged a round-robin study on four reference

materials. The results of this study were

essential to the laboratories involved. In general, it showed that good agreement could

be expected, but it also showed that large

discrepancies could occur, even with simple

measurements such as electrical resistivity.

For instance, one of the four laboratories

reported vastly different results that were

later proven to be erroneous.

NBS has initiated a conscious and deliberate program of establishing selected re- search materials. These are referred to as "uncertified reference materials" since they

are not accompanied by reference data. They

are, however, highly characterized from the

standpoint of homogeneity. These materials

provide an excellent basis for intercomparisons of data. Subsequent studies performed on them allow a more logical intercomparison of data, thus improving our theoretical knowledge of the behavior of

materials. This program is still in its

infancy, and while much remains to be done,

it also shows much promise.

2.2.5 Science and People

2.2.5.1 Cryogenic Measurements in Science

Cryogenics and measurements at cryogenic

temperatures are widely used in research and

investigation in basic science. Many Nobel

Laureates received their honors either be- cause of work directly in cryogenic sciences

or because of work in which cryogenic mea- surements were indispensable. An imposing

list of such Nobel Prize winners follows:

1902 Pieter Zeeman

Influence of magnetism upon

radiation

1904 Lord Rayleigh

Density of gases and his

discovery in this connection

of Argon

*1910 Johannes Van der Waals

For his work concerning the

equation of state of gases

and liquids

*1913 H. Kammerlingh Onnes

For his investigations into the

properties of bodies at low

temperature that led, among

other things, to the preparation

of liquid helium

1920 Charles Guillaume

Finding cheaper materials for

national prototype standards

(Ni-Steel) INVAR

*1934 H. C. Urey

Discovery of D2--was produced

by distillation

1936 P. J. W. Debye

Debye theory of specific heats

*1949 W. F. Giauque

For his contribution in the

field of chemical thermometry,

particularly concerning the

behavior of substances at extremely low temperatures

*1957 T. D. Lee and C. N. Yang

Upsetting the principle of

conservation of parity as a fundamental law of physics

1960 D. A. Glaser

Invention of bubble chamber

1961 R. L. Mossbauer

Recoilless nuclear resonance absorption of gamma radiation

*1962 L. D. Landau

Pioneering theories of condensed

matter, especially liquid helium

(He^)

*1968 Luis W. Alvarez

Decisive contributions to elementary particle physics, in

particular "for his discovery

of resonant states" through his

development of hydrogen bubble

chamber techniques and data

analysis

*1972 John Bardeen, Leon N. Cooper,

and J. Robert Schrieffer

Exposition of the "B-C-S" theory

to explain superconductivity on

a microscopic basis

*1973 B. D. Josephson, Ivar Giaever,

and Leo Esaki

The discovery of tunnelling

supercurrents (the JosephsonJunction)

Cryogenics crucial to the investigation
The kinds of people working in this part

of the National Measurement System, and the

fields of science that support it, are in

part illuminated by the above list, especially during the last decade or so. There

may be a trend away from the very basic work

of Mossbauer and Landau, for example, to work

of almost immediate practicality (BCS, Josephson, etc.). This is probably only an apparent trend, for who is to say that any work

meriting the Nobel prize in physics is not

basic?

Of more immediate concern to us is not only the ubiquitous nature of cryogenics in

basic science, but also how often NBS has

directly played a key role. For instance,

the Lee-Yang parity hypothesis was experimentally proven by an NBS team--Dr. E. Ambler, and others. The BCS Theory was supported in part by the "isotope effect"

experiments by Emmanuel Maxwell at NBS in the

1950's. Luis W. Alvarez, in his Nobel ac- ceptance speech, said in part:

". . . problems involved in building and

housing the 72-inch bubble chamber. We were also extremely fortunate in being

able to interest the National Bureau of

Standards in the Project. Dudley Chelton , B ascom Birmingham , and Doug Mann spent a great deal of time with us, first educating us in large-scale liquid hydrogen

techniques, and later cooperating with us

in the design and initial operation of the

big chamber."

(The first publication on the 72-inch bubble

chamber was authored by NBS Cryogenics

Division Staff.

)

2.2.5.2 Cryogenic Science in Measurements

This list of Nobel Laureats may also serve

to illustrate the use of cryogenic science in

measurements--employing cryogenics per se to develop new or improved measurement technology in fields outside of cryogenics.

For instance, Donald Glaser invented

the bubble chamber that won him his Nobel

Prize. Glaser recognized the principal limitation of the Wilson cloud chamber namely,

that the low density particles in the cloud

could not intercept enough high-energy particles that were speeding through it from the

beams of powerful accelerators- Glaser'

first bubble chamber operated near room temperature and used liquid diethylether. To avoid the technical difficulties presented by

such a complex target as diethylether. Professor Luis Alvarez of the University of

California devised a bubble chamber charged

with liquid hydrogen. Since hydrogen is the

simplest atom, consisting only of a proton

and an electron, it interferes little with

the high-energy processes being studied with

the giant accelerators, although it is readily ionized and serves well as the detector

in the bubble chamber.

The first large liquid hydrogen bubble

chamber was installed at the Lawrence Ra- diation Laboratory of the University of

California and first operated in March 1959.

A remark was made that this 72-inch liquid

hydrogen bubble chamber would be the equivalent of a Wilson cloud chamber one-half mile

long. They could not really be equal,

however, because the cloud chamber does not

have the great advantage of utilizing the

simplest molecules as the detector.

The most recent application of cryogenic

phenomena to measurement science involves the

so-called Josephson junction. Some of the

most exciting phenomena worth, exploiting in

instruments and devices occur at weak electrical contacts between superconductors,

known as Josephson junctions. They can be

simple structures, consisting only of two pieces of superconducting metal lightly

touching together. Often one of them is a fine wire reminiscent of the "cat whisker" of

the early days of radio. Sometimes the

structures are thin evaporated films, with

barriers consisting of very thin layers of

insulating material (or normal metal) or very narrow constrictions. The importance of

Josephson junctions arises from the extraordinary way they respond to voltage and

magnetic flux.

Under the influence of a small applied

voltage, the current through a Josephson

junction oscillates at a frequency strictly

proportional to the voltage. The factor of

proportionality (about 484 MHz per yV) is

a fundamental constant of nature; twice the

electric charge of the electron divided by

Planck's constant. It has been measured with

high accuracy (about one part in 10^) by

Langenberg and his group at the University of

Pennsylvania. The accuracy of this measurement was limited at the time by the definition of the volt. Frequency was (and still

is) the quantity which could be measured

best, and the standard volt was maintained by

a group of chemical cells. However, the

Josephson junction has proven itself, and the

legal volt has been maintained by this means

since July 1 , 1972.

If a Josephson junction serves to close a small superconducting loop, it becomes sen- sitive to magnetic flux as a result of

quantum mechanical interference between

electrons travelling around the loop. This

results in a periodic response to magnetic

flux, the period being the magnetic flux

quantum (h/2e, or about 2 x 10"^ ^W),

22
another fundamental constant of nature. This device has come to be known as a SQUID,

an acronym for Superconducting QUantum Interference Device. It is the world's most

sensitive magnetic sensor.

A most promising application of the SQUID

is in magnetocardiography . The action of a beating heart generates small electric

currents that can be magnetically recorded

with the aid of a SQUID. The resulting

record bears a strong resemblance to an electrocardiogram, but no electrodes are used

to obtain it. Mere proximity of the instrument is sufficient. It has been discovered

that, in addition to the short pulses of

current generated by normal action of the

heart, steady currents associated with

various kinds of injury may also be detected.

This may give useful diagnostic information

that is not readily obtainable in any other

way without surgery.

Another application that has been established in the field is electromagnetic

sounding to depths of a few kilometers in the

earth. A SQUID magnetometer has proven to be

the best instrument for these measurements

and has been used to map a geothermal energy

basin in California.

Other applications of these very sensitive

magnetometers include magnetoencephalography

,

geomagnetism, and conmiuni cation through

ground or water at frequencies of a few

hertz, which would rapidly attenuate signals

at higher frequencies.

The periodic response of the SQUID to magnetic flux suggests a new style of electrical metrology. One could measure current

by counting off magnetic flux quanta in the same way that we measure length by counting

off wavelengths of light. The Cryoelectronics Section at NBS is working on this now. Preliminary results indicate that it will be

a powerful technique both for direct current

and for radio frequencies up to the microwave

range. Another advantage of electrical

measurements employing cryogenic devices in

general is the high sensitivity attainable

because of the freezing out of thermal

background noise.

The last area of activity to mention in

applying cryogenics to other measurements is the extension of radio technology into the

submi 1 1 imeter-wave to far-infrared range of

frequency. Possibilities include communication, radar, and astronomy. The recent

development of powerful, coherent sources

(such as the hydrogen-cyanide, water-vapor,

and carbon-dioxide lasers) has stimulated

exploration in this field. Receivers have

lagged behind the development of transmitters, but with Josephson junctions we can hope for receivers of the same quality as we

have at normal radio frequencies. The

pioneering work was done by Grimes, Richards,

and Shapiro when they were all at the Bell

Telephone Laboratories. An NBS team, notably

McDonald and Evenson, are synthesizing signals of stable and accurately known frequency

throughout this range by using Josephson

junctions to generate harmonics and mixtures

of signals from the primary sources. One of

their objectives is to extend this activity

up to the range of visible light (using

devices other than Josephson junctions for

the final stages) and to measure the frequency of visible light of a well defined

wavelength, such as is used for the standard

of length. This raises the possibility of

using a single standard for both length and

time. Such a standard will have practical

advantages as well as satisfying admirers of

the theory of relativity. The technology

they are generating will be directly usable

for the other purposes mentioned.

These are just a few examples of the many

existing and future applications of cryogenics, especially superconductivity, applied

to electronics. The first few commercial

instruments are appearing on the market; we

can expect their number to grow.

One of the barriers to the widespread

application of superconducting devices is of course the need to provide a liquid-helium

environment. For small instruments, dissipating minute quantities of power, this is not such a severe problem as it might be for

big machines. Liquid helium is widely

available. Compact, portable containers

can be engineered to run for several days

between refills. In fact, the development of

the SQUID, which has an established reputation as the world's most sensitive magnetic

sensor, has now reached the stage that it is becoming the most convenient and portable

instrument for many geophysical measurements.

In collaboration with the United States

Geological Service, a SQUID magnetometer

was tested for electromagnetic prospecting

for geothermal sources in the geyser basin near Clear Lake, California. It proved

to be a handy instrument for this purpose.

The same instrument was also taken as airline hand luggage to the Republic of Chad

in Africa to make magnetic observations

during the solar eclipse. Weighing only

10 kg, the instrument gave no trouble and

showed that it is ready for use in even the

most remote parts of the world.

23
2.3 Realized Measurement Capabilities

This section summarizes state-of-the-art

technology for cryogenic instruments.

Pressure transducers are normally placed

in a temperature controlled environment near

room temperature. Some available pressure

transducers are capable of performing satisfactorily at low temperatures, but new types

such as piezoelectric, diode, electrokinetic,

etc., may perform equally well or better. In- formation on their performance is needed.

For a detailed review of the ranges,

accuracies, and precisions attained in

pressure measurements, see the comprehensive

review by Arvidson [2]. Table 2-8 below is

reproduced from that work.

Temperature measurements are unquestionably in better shape than any other cryogenic

measurements. Adequate calibration facilities exist, as well as a large body of knowledge that together help keep this part of

the National Measurement System in control.

Industrial type platinum resistance thermometers are routinely used, for instance.

Improvements in their interchangeabi 1 ity

would be desirable, as well as some simple

thermometry for crude temperature indications

and the monitoring of process trends.

Table 2-9 summarizes some representative

characteristics of the best known types of

cryogenic thermometers.

The terms "reproducibility" and "accuracy"

require some explanation. Reproducibility

means the variability observed in repeating a given measurement using the best

present-day laboratory techniques. Changes

produced on thermal cycling of the thermometer to and from ambient are included in this

parameter. Accuracy means the significance

with which the thermometer can indicate the

absolute thermodynamic temperature. This

includes errors of calibration and as errors due to nonreproducibil ity, the

Table 2-8. Cryogenic pressure transducers.

Characterlitic > Strain Cage Capacitance Crystal Reluctance

Frequency rciponse, Hz to 40 k Hs to 500 K Hs 0. 5 to 1 M Ha 1 K Hz (approx.

)

Nominal •ensitivlty, % full (cale 0.5 1.0 0.5 1.0

Thermal stability Excellent for compensated

bridge winding Approx. temperaturedrift; 0.025 % per deg F

Good Approx. 0.02% per deg F

Linearity, % < 0.1 -1.0 0.5 -1.0

Response to vibration,

noise, acceleration

Negligible for light-dia* phragm and fully-rigid typesLow, but noticeable Can be appreciable; also

highly sensitive to electrical "noise"

Low, but noticeable; about 1.0% per 100 G

Drirt, % negligible 1.0 (excluding temperature

drift) 2.0

Hysteresis, % Approx, 0. 2 1.0 negligible 0. 5

Open-circuit full-scale output Order of 50 mv Order of 5 v Order of 1 mv Order of 5 v

Overload, % Generally about 100; to 500 for special types Order of 100 Satisfactory for elastic limit of crystal; poor for

liigher loads

Order of 100

Ease of calibration straightforward straightforward No static calibration possible; dynamic calibration tricky

slraightforward

Typlcal^resBure sensing devicetube or diaphragm diaphragm c rystal fliaplira);m or twisted

torsion tube

Cooling Some designs air or water

cooled (special types have

heat-transfer rates to about 7.0 nxU/lnV"

Some designs air or water

cooled (special types have

heat-transfer rates to about 7.0 DTU/inV»

Generally none possible Generally none possible

Remarks and limitations Good all-around. Expensivic repair and replacement of parts on high-performance

doflign.s

Excellent instrument except for drift. Larger and more complex than strain RageUnique In ultra-high fre- quency range. Not useable below about 5 tiz.

Maximvmi (cmpcralure

200 F. Low frequency

rt-sponHO

24
former usually being much more significant.

The approximate numbers given for these

quantities represent good current practice.

It may be possible to do better by extreme

care. On the other hand, in most engineering

measurements a lower order of accuracy is permissible, and this may allow relaxation of

certain requirements such as strain-free

mounting of resistors, homogeneity of thermocouple materials, purity of vapor-pressure

fluid, sensitivity, and accuracy of associated

instruments, etc. For temperatures above about 20 K, the

metallic resistance thermometers are more sinsitive than the nonmetallic resistance

thermometers. Temperatures above 20 K can

be measured routinely with an industrial type

platinum resistance thermometer with an accuracy of better than 100 mK and time responses

somewhat better than 1 second. Accuracy at the millidegree level requires a precision

capsule type platinum resistance thermometer

and careful calibration.

Carbon thermometers are generally used for

low temperature measurements (T < 80 K) when

accuracies of ± 0.1 K or ± 1% of the absolute

temperature are needed. Millidegree accuracy

is attainable using germanium resistance

thermometers at temperatures below 20 K. The

primary drawback to germanium thermometers is that no simple analytical representation is

available that represents the resistance

versus temperature characteristics, even for a

given class of doped germanium crystals. A many point comparison calibration is required

if all the inherent stability of the resistor

is to be utilized.

Vapor pressure and gas thermometry offer

sensitive methods of temperature measurement

with the advantage that no calibration is

necessary. Further advantages are that these

transducers are not sensitive to magnetic

fields or electric fields. In the case of

vapor pressure thermometers, the time re- sponse may be made comparable to the resistance thermometers.

A sensible recommendation about which type

to use cannot be made without knowing the

specific measurement requirements. The

generalization most likely to hold true,

however, is the following: for crude temperature indications and monitoring trends, a gas thermometer will probably be suitable;

for more accurate work, vapor pressure or resistance thermometry is recommended; for

engineering application in this latter area, the need is for inexpensive devices that do not call for unique calibration.

An outstanding review of cryogenic temperature measurements has recently been

published by Sparks [13]. The above material

borrows freely from this excellent benchmark

study.

Level detectors for cryogenic fluids were extensively developed during the space

program, but it is remarkable how little

Table 2-9. Some approximate characteristics of the most

widely used classes of cryogenic thermometers.

BEST BEST RESPONSE

TYPE RANGE REPRODUCIDILXTY accuracy" TIME K K S

RESISTANCE THERMOMETERS

Platinum 10-900 io"3-io-^ 10-2-10"* 0.1-10

Carbon 1-30 io"2-io-3 10-2-10-3 0.1-10

Gcrraanlum 1-100 io"3-io"* 10-2-10-3 0.1-10

THERMOCOUPLES Cold-Cobalt va Copper A-300

-1 -2

10 -10 10-1 0.1-1

ConstanCan V3 Copper 20-600 10-1-10-2 10-1 0.1-1

VAPOR PRESSURE Ucllum 1-5 lO'-'-io"* 10-3 0.1-100

Hydrogen 14-33 10-3 10-2 0.1-100

Nitrogen 63-126 10-2-10-3 10-2 0.1-100

Oxygen 54-155 10"2-10-3 10-2 0.1-100

a-Includlng nonreproduclbllltyt calibration errors and tcmperoture scale uncertainty

25
space hardware is actually used in the

commercial sector. A deliberate effort to adapt space instrumentation to commercial and

industrial applications may be worthwhile.

Primary instruments and facilities to calibrate liquid level devices do not exist,

and accordingly it is questionable whether

this part of the National Measurement System

is in control. Furthermore, a large body of

knowledge and experience needs to be developed to move with assurance from this relatively clean measurement to the practical

measurement question of "how much does the

tank really contain?"

Performance characteristics vary widely,

depending upon the fluid being measured, its

temperature, pressure, and even orientation.

Accordingly, no brief summary is possible.

The best complete review of this measurement

may be found in the work of Roder [14].

Density is an inferential measurement and,

as such, it should be traceable to a national

standard, such as a national density refer- ence system. Primary instruments to calibrate densitometers do not exist.

Several physical principles of cryogenic

density measurement have been brought well

forward by the space program. Notable are

the capacitance, vibration, and nuclear

radiation attenuation schemes. Microwave

methods are recently moving to the forefront.

Roder [14] has recently summarized this field

as wel 1

Flow . There is no shortage of physical

principles upon which to base a cryogenic

flowmeter. Depending on the need, they range

from simple pressure drop meters to sophisticated mass reaction types. Flow, however,

is a derived quantity, and as such flowmeters

require traceability to a reference system to establish credibility.

Summary . One component of the problem of

cryogenic instrumentation is that it is

largely static. Not much has been accom- plished technically since the peak of the

space program. There is little evidence

of the commercialization of these instruments . A second part of the problem arises from

the way cryogenic measurements fit into the

National Measurement System. As long as only

a single agency or one sector of our economy

(National Aeronautics and Space Administration,

the aerospace industry) were using essentially

all of the results of their own measurements,

then that part of the National Measurement

System was internally consistent and in harmony with itself. Now, however, the prospects

are that cryogenics is becoming more commer- cialized and moving tq the market place and

thus external consistency as well as internal

consistency is now required to make this part

of the National Measurement System work.

Primary instruments and facilities to calibrate the derived quantities--liquid

level, density, and flow--do not exist.

Accordingly, there is less confidence

that this part of the cryogenic measurement

system is as well under control as temperature is.

The third part of the problem is perhaps

a derivative of the first. Because the field

is static, a crucial question is not being

asked: are there predictable technological

developments that will either create a need

for new cryogenic instruments or possibly

provide an altogether new measurement means?

2.4 Dissemination and Enforcement

Network

Standards are the means used to judge

something as authentic, good, or adequate.

They are the measures to determine what a thing should be, or whether it is correct.

Thus, there are standards for measurements--

prototypes, artifacts, the physical realization of a conceptual measurement--standard constants, including property data;

standards of quality, of performance, and of

practice (codes). The public outputs are usually pieces of paper--documentary standards. Behind all of these paper standards

are the physical measurement standards that

national authorities keep in their custody as artifacts, or that they define in terms of some physical phenomena.

Every form of standard, from the documentary standards to the physical embodiments,

are essential to the proper functioning of

the measurement system. In the discussion

below, the word standard will be used deliberately ambiguously to indicate that all

types of standards are involved in the

dissemination and enforcement network.

Much of the Dissemination and Enforcement

Network has been discussed in Section 2.2,1.1,

"Standardization Institutions" and 2.2.1.2,

"Survey of Documentary Standards." Here, we

shall highlight this network with a specific

case study, the Cryogenics Division's liquid

nitrogen flowmetering program.

2.4.1 Central Standards Authorities

National Conventions . In the case chosen

as the illustrative example, NBS itself was

the relevant national authority.

This came in part because NBS has the

ability to provide both national standards

and international standards through such well

established NBS mechanisms as NBS Handbook

44. It also came in part because our most

useful and important type of standard setting

activities may be the de facto standards --

26
which exist and are accepted just because NBS

exists and is accepted -- such as the thermodynamic properties work mentioned in Section

2.2.1 .2. The State of California, during the

hearings in the fall and winter of 1967-68,

clearly developed and documented their need

for a central, national authority. The

record shows in part:

"With respect to standards, there should be a national facility, a final authority, a referee, that would not be in competition

with private industry."

This expresses rather clearly the need for

a centralized national effort in such matters

that at first do not appear to transcend

state boundaries.

International Conventions . The Compressed Gas Association was strongly

motivated to deal with one national laboratory rather than 50 state laboratories.

Recognizing this problem on an international scale, we at NBS have:

• Cooperated with the International

Organization of Legal Metrology (OILM) to facilitate the adoption of the findings of

this program as an international code;

• Performed type testing of meters of

foreign manufacture as an integral part of

the program. (See for instance, NBS Tech.

Note 624, "An Evaluation of Several Cryogenic Turbine Flowmeters");

•Promoted and facilitated a six week

visit by Dr. Josef A. Eberle of the

Physi kal i sch-Techni sche Bundesanstal

t

(PTB). One result of Or. Eberle's visit

was his translating into German of our NBS

Report 9778, "Cryogenic Flow Research

Facility Provisional Accuracy Statement"

to be used as a model by the PTB. Other

international observers included Dr. Walter Linde and Dr. Klaus Schmidt of

Lotepro, Inc., (a subsidiary of Linde,

Germany); Dr. Helmut Peter and Dr. S. K. Windgassen of Messer-Griesheim, Germany;

Dr. Heribert Wenzel of Linde (Munich,

Germany); Dr. Jacques Hermel of Compteurs

Schlumberger, France; and Dr. J. B. Gardner

of the British Oxygen Co., England.

•One of the most important transactions occurred in an un-official way.

Specifically, the Compressed Gas Association, which supported the eventual flowmetering program, formed a steering com- mittee to help provide a degree of quality

control to the program, but especially to help substantially b^ providing guidance

and advice at critical stages of planning

and implementation of the program. This

committee met three to four times a year

27

during the nearly eight year life of the

program. In addition, state weights and measures officials routinely attended

these meetings, which provided an invaluable forum for the cooperative solution of

vexing problems. The real impact of this

type of program may indeed lie in this

kind of cooperation and communication.

NBS-Infrastructure . Within the NBS itself, there is a very strong and viable

infrastructure that undergirds the whole

standards setting activity. In this case,

for instance, it included:

•The Institute for Basic Standards

itself, whose statutory responsibility to provide basic measurements and standards

made the cryogenic flowmetering program

possible.

•The Office of Measurement Services,

which provided guidance on accuracy statements, and experience in conducting round

robins

•The Patent Advisor, who provided guidelines for handling proprietary information on the performance of specific flow meters.

•The Office of Weights and Measures,

(OWM), which publishes Handbook 44 and provides the secretariat to the National Conference on Weights and Measures (NCWM). The

OWM gave our program the direction and

mechanism to make its results have the effect

of law.

•The Applied Mathematics Division, which

helped plan experiments for statistical

soundness and assisted in analyzing the

results. This provided a scientific basis

for interpreting claims in the trade literature of "accuracy" and "repeatability".

• The Cryogenics Division itself provided

the essential technical base and resources.

It is true time and again that the sound

fixing of standards cannot occur in an ivory

tower. It requires good judgment, and this can be applied only when there is sound

comprehension not only of the science involved, but also of the ways in which it is

being applied, and more subtly, of the ways

in which it is likely to be applied in the

future.

2.4.2 State and Local Offices of Weights and

Measures

The state regulatory agencies saw a real

need for traceability to a national standard

since they are obligated by law to perform

"type-approval" inspections. In the fall of

1967, the State of California Bureau of

Weights and Measures began hearings which

have already been described in Section

2.2.1.1. With the assistance of NBS, a code
was adopted that was felt to represent

equitably the capability of the meters then

used in commerce. It must be admitted, how- ever, that the tolerances chosen were arbitrary, with little or no cryogenic testing to back them up. The State of California,

frustrated by their legal requirement to regulate the sale of liquid nitrogen, but

with no technical capability to do so, essen- tially had no other choice. They set the same standard for liquid nitrogen as was then

in force for gasoline. The suppliers, in

effect, said "prove it". This impasse was resolved by the liquid nitrogen flow program.

Fortunately, perhaps, the original tolerances proposed by the State of California

were later demonstrated by NBS to be rea- listic and feasible, a finding which facilitated the early adoption of the code. The

producers were especially pleased to be

able to deal with one central laboratory

rather than 50 separate state labs. We

regard this as a good example of "New

Federalism" at work--as NBS competence is

directly transferred to the states.

2.4.3 Standards and Testing Laboratories

and Services.

Round-robin intercomparisons are at the

heart of transferring the NBS measurement

capability to the states, producers, and

meter manufacturers. For instance, especially in the earlier stages of the physical

evaluation of our own flow system, roundrobins were conducted with industrial

testing laboratories. These included the

facilities of the Linde Co. at Tonawanda,

N.Y., Air Liquide near Paris, The British

Oxygen Co. in London, and Messer-Griesheim

at Dusseldorf, Germany. This cooperation

not only gave us a feeling of confidence

in our own facility, but also opened the

door for international agreement (via the

OILM, for instance).

In addition, it is known that the State

of California has already calibrated over

95% of all the meters used there in liquid

nitrogen commerce. To further facilitate

such intercomparisons, NBS has built and

is currently proving a transfer standard

of its own. 2.4.4* Regulatory Agencies

For this case study, consumer organizations per se , federal agencies (regulatory

and otherwise), and the National Conference of Standards Laboratories (NCSL), a quasi -governmental regulatory unit, did

not play a major role, although they

surely would in other types of studies.

This is so because the specific program

highlighted here, concerning the metering

of liquid nitrogen, was prompted by an

28

unresolved technical controversy between

certain state weights and measures bodies

and the producers of a specific commodity.

Accordingly, federal agencies, other than our own, had little or no interest or part

to play; direct contact with the consumer

was not necessary. The consumer's viewpoint was adequately represented by the

State bodies, and in fact, the California

hearings deliberately solicited the con- sumer's opinion. The National Conference of

Standards Laboratories (NCSL) as a whole was

of little interest to this particular

study, for a much more narrow and intense resource existed as a sub-set of the NCSL,

namely the ISA Ad-Hoc committee already

mentioned.

2.4.5 Industrial Trade Associations

An unusually significant and interesting

interaction occurred in the following way.

The Compressed Gas Association, which supported the eventual flowmetering program,

formed a steering committee to help provide a degree of quality control to the program, but

especially to help substantially by providing

guidance and advice at critical stages of

planning and implementation of the program.

As mentioned, this committee met three to four times a year during the nearly eightyear life of the program. In addition, state

weights and measures officials routinely

attended these meetings at our request, and

often with our financial support. This

provided an invaluable forum for the co- operative solution of vexing problems. The

real impact of this program may indeed lie in

this kind of cooperation and communication--

structured yet unofficial.

2.5 Direct Measurements Transactions

Matrix

Understanding the National Cryogenic

Measurement System is closely related to understanding the cryogenic community, which

is largely related to the production and use of cryogenic fluids. The following section

profiles the supply and use of cryogenic

fluids.

2.5.1 Analysis of Suppliers and Users

The cryogenic fluids with the largest

dollar value of sales are: oxygen, nitrogen,

helium, hydrogen, argon, and liquefied natural gas. Krypton, neon, and fluorine are also considered to be cryogenic fluids, but

the quantities produced are very small and

are not discussed here.

The value of the six fluids considered

here was about $166 million in 1960. By 1968

the value had tripled to about $532 million.

(These are values of liquids and gases produced by cryogenic processes and do not
include low-purity gases or gases produced by

electrolysis.) From 1960 to 1968 the annual

growth rate averaged about 15%. However, the

market began leveling off at $795 million in

1973. By examining each fluid and its market

in turn, we see that it is not reasonable to expect both a constant and uniform growth

rate for all fluids. The arguments for this

less optimistic projection follow for each

fluid.

Oxygen . High purity (greater than 99.5%

pure) 1 iquid oxygen is mainly produced by

cryogenic air separation processes (electrolytic oxygen amounts to much less than 1%

of high purity production). Low purity

production (less than 99.5% pure) is about

1/6 of the high purity oxygen production.

A major use of oxygen is in the basic

oxygen process for steel, which consumes

about 80 X 10^ std ft^ per year, and

open-hearth steelmaking where oxygen

lances use over 50 x 10^ std ft^ annually.

These uses are the main factors in the

growth of oxygen production in recent years.

The chemical industries come next, using

some 15% of production, followed by welding,

nonferrous metal refining, aerospace and

breathing uses. It might be pointed out

that the chemical industry is growing much

faster than most segments of the United

States economy and thus might be expected

to contribute even more to the growth of

oxygen production than does steel.

Shipments^ of liquid oxygen are decreasing as a fraction of total production. This can be attributed to the fact

that more liquid oxygen facilities are being built right at the users' doorsteps,

and also that National Aeronautics and

Space Administration consumption of liquid

oxygen is decreasing.

Looking ahead, the industry itself

predicts annual growth rates of 5-15% for

the coming decade [24]. Using an average

of 10%, we should reach 10^^ std ft^ by

1983.

New uses of oxygen could change this

outlook materially. For example, the

treatment of sewage and wastes by bubbling

large amounts of oxygen through the tanks

offers cleaner discharge, better phosphate

and nitrate removal, and reduces the need

for agitation, which speeds the sludge

separation process. Approximately four

times the oxygen concentration can be

achieved in this way as compared to air

Shipments is used in the special sense

that it occurs in the Census of Manufacturers. It means the value of shipments,

which is the net selling value, f.o.b.

plant, after discounts and allowances and

excluding freight charges and excise taxes.

bubbling, thus improving the bacterial

degradation rate and helping the environment support aquatic life. The amounts of

oxygen needed for this purpose in two or three decades could equal the amounts now

used in steel

Nitrogen . The economic importance of

nitrogen is about half that of oxygen. It

is the fastest growing of the major industrial gases. Nearly all high purity

nitrogen is produced by the air separation

process. More liquid nitrogen is shipped

(as opposed to in-plant transfers) than is the case with oxygen. This is apparently

so because the producers (often located near oxygen consumers) are not always located

close to the nitrogen consumers, such as the

food freezing industry. Nitrogen is used as

an inert atmosphere in many metal, electronic, chemical, and aerospace industries.

(See Section 1 .0)

Looking beyond 1975, industry spokesmen

feel that the past rate of growth will not be

maintained, but will be greater than that of

oxygen [24]. From 1960 to 1968, the rate was about 26%, but this is predicted to level out

at 15-20% in the next decade.

Nitrogen is already widely used for food

preservation, refrigerated transportation,

and cryo-biology. Practically all the frozen

shrimp in the U.S. are processed in this way,

and nearly all the west coast lettuce shipped

to the East comes under a cold nitrogen

blanket. There are now approximately 500

truck stops in the U.S. where a truck can take on diesel fuel at one end, and liquid

nitrogen at the other. The essential feature

is that each truck now carries a simple tank

of liquid nitrogen instead of a mechanical

refrigerator.

Hel ium . The great majority of the proven,

economically recoverable helium sources in

the Western Hemisphere are found in the

Texas-Oklahoma-Kansas area of the United

States. These known reserves are estimated

at over 150 x 10^ std ft^

Most of the helium used in the United

States has gone to government agencies such

as the National Aeronautics and Space Administration, the Department of Defense, and the

Atomic Energy Commission, which are required

to buy their helium from the Bureau of Mines

in order to finance the conservation program.

Private producers entered the market with

deliveries almost equal to that of the Bureau

of Mines in 1967. The decreasing aerospace

budget has resulted in smaller deliveries by

the Bureau of Mines, which means less helium

can be bought for conservation. (Each cubic

foot of lost sales reduces the reserve purchases by 2.4 cubic feet.) These factors

indicate that a readjustment of helium price

structures may occur in the near future.

29
One of the first tasks assigned by the

Congress to the newly created Energy Re- search and Development Administration is to conduct a thorough study of the need for

helium in energy applications (e.g., superconducting electrical power systems). The

recommendations of this study will doubtlessly have a profound effect upon future

helium conservation efforts in the United

States.

Hydrogen . Liquid hydrogen production

depends more on defense and aerospace activity than does oxygen or helium. Since

the National Aeronautics and Space Administration used between 1/3 and 1/5 of the

hydrogen produced, its variations had a large

effect on the total picture. While the

average rate of annual growth was greater

than 30% during the 60' s, it would appear

that 10% is more likely during the 70's.

Fields of hydrogen use, which seem likely to grow, are hydrogenation of edible oils,

atmospheric control in the electronic and

electrical machinery industries, and deoxidation in heat treating of metals. If

hydrogen realizes its potential as a fuel,

there may be explosive growth here (See

Section 5.0).

Argon . Some 70% of the argon produced

is used for welding reactive metals, but

the continuous casting process of steel

production could potentially use many

times the current production (worth around

$32 million in 1968) as a blanketing

agent. Argon has shown an historical

growth of about 17% annually from 1960 to 1968, matching the growth rate of oxygen

for the same period. This is logical,

since argon is produced cryogenically as a by-product in the air separation process

for oxygen. If the continuous casting

technology develops sufficiently to create

a huge demand for argon, it would also

give impetus to the oxygen producers

located near the steel mills. If this new market does not develop, the growth of

argon will probably be held to about the same rate as oxygen, or 10%.

Liquefied Natural Gas (LNG) . In 1968,

the least economically important of the

cryogenic fluids was LNG, worth about $24

million. However, in 1972 it had already

grown {o third place and may be first shortly after 1976. LNG is used mainly for

peak shaving purposes in areas where large

volume gas reservoirs are unavailable, and

also for base load supplies where pipeline

gas is not feasible. It is predicted that

LNG produced in the United States will have

a value of about a billion dollars a year

by 1976 [25], or over^ 10% of the total

natural gas production of the country.

LNG is used as a replacement for gasoline in some vehicles to reduce pollution

and gain in operating economy. All the

fleet vehicles of San Diego Gas and Electric run on LNG, as well as about half the

buses of the Chicago Transit Authority.

All the off-the-road equipment of U.S. Steel in the Mesabi range likewise use

LNG.Other uses investigated include tem- porary consumer supply during pipeline

disruption or maintenance, as a petrochemical feedstock, desalinization of sea water through freezing, and refrigeration

and power supply for food freezing plants.

The concept of clustering several industries

that need refrigeration around a re-gasification facility should be considered more

thoroughly. Many re-gasification plants

waste the huge cold-potential by absorbing

their heat from the air or ocean. Profile Summary . In conclusion, then, it

would appear that the growth of the cryogenic

fluids industry will continue, but at a rate

somewhat smaller than during the past decade,

LNG excepted. A growth rate of around 10% seems a reasonable expectation, arrived at by

weighting the growth rates of the individual

gases according to the 1968 production figures. However, if LNG fulfills its promise,

the rate could be much higher.

2.5.2 Input-Output Direct Measurements

Transactions Matrix

General . A matrix has been constructed to show the transactions between suppliers and

users. The elements indicated on table 2-10

include, for instance: The knowledge com- munity, standards organizations, the instrument industry, NBS, regulatory agencies at

all levels, industrial associations, and the

general public. The entries in the intersection boxes describe the interaction as a whole within the Cryogenics Measurement

System, not just those involving the Cryogenics Division of NBS alone, and certainly

not just the flowmetering program used

elsewhere in this report as a specific example.

Format . In the center of each box is a numeral indicating the magnitude of the

transaction on a semi -quantitative "volume"

basis:

0 = Trivial

1 = Minor

2 = Moderate

3 = Important

4 = Major

In the lower left hand corner , there is a digit describing the rate of change of transactions at this intersection:

30
Table 2-10. Direct measurements transactions matrix

DIRECT

I'lCMOUnLI lull 1 o TRANSACTIONS

MATRIX FOR

U

S

pt.R

S

Knowledge

Community

International

Metrological

Organizations

Documentary

OJ

Standards

Organizations

Instrumentation

Industry

(/I ca

z.5

^

Other

U.S.

Nat'l.

Stds.

Authorities

-J

State

&

Local

OWM's

^

Private

Stds.

Laboratories

1

.D

Regulatory

Agencies

oDepartment

of

Defen- j

_,

Other

Federal

Agencies

j

_

State

&

Local

Govt.

Agencies

i

_,

Industrial

Trade

"

Assoc.

_,

Misc.

Industrial

&

Commercial

i

Q_

(Uc

<u C315

1

SUPPLIERS \

Knowledge Community

4 1 2

?

4 1 24 1 22 1 3

4 1 43 1

1 2

3

2 2

2 1 3

3 1 2 2

2 1 3

2

3 1 2

2

2

1 2

2 4

2

3

2lnternational Metrological

Organizations

4 1 24

4

4 1 22 1 2

N

4 3 4

2

3 1

1 2

2

1 N

2

2 N

3

2

3

1

2

1

1 2

1 2

3Documentary

Standards

tlrganizatinns

4 1 24

2

4 1 43 1 3 ?

4 1 3

7

3 1

1 2

3 1 3

2

2 1 2

3 1 4

2

3

1 2

2

2

2

2

2

2

2 1 3

2

2

3

2

2 1

1

4Instrumentation

T n H 1 1 c "f" 1'* \y 1 ilUUb LI jr

2 1 3

2 1 3

3 1 3

2

2

3

3 1 3

2

3 1

1 2

3 1 2

2

2 43 1 2 22

3

2

2

2

1

2 31 31

5NBS

4 1 4

4 3 4

2

4 1 3

2

3 1 3

2

4 1 3

?

3 2

1 2_

3 1 2 2 , 2

1

2

2

2 1

1 2

3 4 Z

2 1 4

2

2 1 2 2^2 1 4

2

2 1 3

2

1 2

1 2 ^Other U.S. Nat'l.

JLU^> MULrlUl ILICD

3 1

1 2

3 1

?.

3 1

1 2

3 1

1 2

3 2

1 2

3 2 3

2

1

2

2

2

3 3

2

2 1 2 21

1 2

2 1 2

2

2

1 2 7state & Local OWM's

3

2

2

3 3 1 3

2

3 1 2

2

3' 1 2

2

3

1 4 1 4

2 1 33 1

1 2

1

1 2

2 1 3

2

2 1

1 2

2 1

1

o Private Stds. Laborator i es

2 1 32 2 1 22 42

2 2

1

1 3

1

2

2

1

2

1

2

2

2

2

2

2

2

2

1

1

9Regulatory Agencies

3 1 2 23

2

3 1 2

2

2 1

1 2

2

2 2

3 1

1 2

2

1

2 1 2 21 1

1 2

1 1 2 21 1 2 22 1 3

2

2 1 2

2

2 2

1 2 10Department of Defense

2 1 3

2

3 3

1 2

2 33 4

2

3

3

2

2

1

1 1

1

2 1 4

2

2 1 3

2

1 1

1 2

2

1

1

1 2

1

1

^^Other Federal Agencies

3 1 4

2

2 2 2

2

2

2

2 1 4

2

2 1 2

2

2

2

1 1 2

2

2 1 3

2

2 1 3

2

2 1 2 2

2 1 3 2

1 1

1

2 2

1 2 ^^State & Local Govt. Agencies

2

1 ?

2

2

?

2

1

2 1 2

2

1

1 2

1

1 2

2

2

1 1 2

2

1 1

1

2 1 2

2

2 2

2 2 %'

2

1 1

1 2

2 2

2

2 13 Industrial Trade

Assoc.

2 4

1 3

2 1 3

2

2

3

2 1 4

2

2 1 12 1 2 3

2 2

2

2

2 1 3

2

2

1 2

2 1 3

2

2 1 3

2

2 1 2

2

2 1 3

2

2 2

1 2 14 Misc. Industrial & Commercial

2

3

1

1

2

3

2

1 32 1 3

2

2 2 1

1 1 1 2 12

2

2

2 1 2

^2_

1 h 1

1 ! 1

!

1 1

1

2 1 32 2

3

2

1

1

15 General Public

2 1 jl

1

'

i

1 2

1 2

2 1

1 T 21 2

1 ^ 2

1 1 2

\ -t

2 2 It1 2

1

1

KEY TO MATRIX ENTRIES

IMPORTANCE OF TRANSACTIONS

1 = Purely convenience

2 s= Strongly desirable

3 = No real alternatives

4 = Essential

B - RATE OF CHANGE

N = Declining

0 = Stable

2 = Growing

4 = Growing explosively

Unknown, X = Not studied, Blank = 0

USERS

C D SUPPLIERS A-

B

D - (IN)ADEQUACY OF SERVICES

0 = No improvements needed

1 = Could be improved

2 = Marginal

3 = Serious deficiencies

4 = Out of control

MAGNITUDE OF TRANSACTIONS

0 = Trivial

1 = Minor

2 = Moderate

3 = Important

4 = Major

31
N = Declining volume or needs

0 = Stable

2 = Growing

4 = Explosive growth or discontinuity on hand

In the upper left hand corner , a digit indicates the importance or critical ity of the

transaction

1 = Purely a matter of convenience;

transaction not essential;

reasonable alternatives readily

available

2 = Economically important; strongly

desirable

3 = No satisfactory alternate source; legally required

4 = Essential; sole source; matters

of life and death

In the upper right hand corner , another

digit indicates the (in)adequacy of the

transaction goods or services:

0 = No foreseeable improvements

needed or desirable

1 = Under control, but could be

improved

2 = Only marginally O.K.; significantly

inadequate

3 = Seriously deficient

4 = Out of control ; thoroughly un- satisfactory

The general code for a stable field is

a zero. For ease in reading, all zeros

have been suppressed in the table. There

are no intentional omissions, as an "X" would have been used to indicate a factor

deliberately excluded.

Double-lines are used to help subdivide

the large matrix into smaller ones. For instance, double lines are found on either

side of "NBS", and they are also used

between the Department of Defense Sector

and the Regulatory agencies.

Hiqhl iqhts . International Metrologiaal

Organizations and NBS, in the field of

this microstudy , have only a moderate

volume of transactions between them, hence

the "2" in the center of the box. These

transactions are growing -- "2" in the

lower Jeft hand corner -- as the importation

of LN6 increases. The interaction is

essential -- "4" in the upper left corner. They are under control, but could be

improved as the volume and variety of the

transaction increases -- "1" in the upper

right corner. NBS and Other U.S. National Standards

Authorities. A useful example here is our interaction with the'U.S. Coast Guard,

which is indeed a national authority that

sets minimum specification and performance

standards for ships that may use U.S.

ports. We help by supplying technical

information on the properties of LNG,

potential hazards, handling procedures, and

structural materials. The volume of this

transaction is minor at present (1, center);

is growing (2, lower left); is strongly

desirable (3, upper left); and could be

significantly improved (2, upper right).

It appears that the U.S. Coast Guard has

final legal authority to set the standards

required and to define the measurement

codes and practices to test whether or not

the standards are being met. The U.S. Coast Guard may do this without neces- sarily having recourse to the NBS. Accordingly, it appears that this part of the

measurement system is disjointed at the

present time. There is no objective reason

why it should remain so. Item 12, State and Local Government

Agencies, for this microstudy includes: The

New York City Fire Department and similar

jurisdictions concerned with the safety of

LNG.The General Public has little direct

contact with cryogenics, since it is essentially an infrastructure industry. However,

transactions do occur in such diverse areas

as liquid oxygen for breathing therapy,

artificial insemination, cryo-embalming, and

questions of safety regarding the storage and

transportation of cryogenic fluids.

2.5.3 Highlights re Major Users

It has been claimed that cryogenics is

nearly a $2 billion industry, and that there

is widespread interest in it. The discussion

below gives a few indicators leading to these

claims and highlights the major users. 2.5.3.1 Industrial Gases and Equipment

Industrial gases are at present the backbone of this industry, and will continue to be while the liquefied natural gas component

builds up. At some time in the future, LNG

may surpass industrial gases (Carbon Dioxide,

Acetylene, Nitrogen, Oxygen, Argon and Hydrogen --SIC Code 2813), but the value of shipments of industrial gases was $795 million in

1974, produced in 507 establishments employing 9,000 people [26]. A "rule-of-thumb" for

this industry is that it has roughly three

equal components: liquids, gases, and equipment. Therefore, if the liquids and gases

sold were worth about $800 million, then the

cryogenic equipment is worth about half of

this again, $400 million, making the total

about $1.2 billion.

The annual investment in capital equipment is at least 15% of sales [27] or about

32
$280 million. Thus the total expenditure in

cryogenics is about $1.5 billion per year.

These figures exclude LNG, but it is not hard

to imagine the value of LNG bringing the

total close to $2 billion.

In order to be more specific, we have

analyzed the public Annual Reports of a few

of the major corporations engaged in cryogenics. The findings are given below, and we may safely assume that the figures given are realistic, as such reports are carefully

controlled by the Securities and Exchange

Commission (SEC). Not all of the reports are from the same year. One is from 1971, for

instance, but this discrepancy will only

serve to make the figures conservative, as newer figures would be greater due to real

growth, inflation, etc.

Table 2-11. Net sales of major cryogenic

companies in the U.S.

Corporation Net Sales

Chemtron Gases Group, $ 156.4 M formerly National Cylinder

Gas (1972)

Union Carbide, Linde Div. 581.0

Gases and related products

(1973)

Air Products and Chemicals, 209.6

Gases and Equipment Group

(1971)

Airco, Industrial Gases and 240.0

Cryogenics Group, formerly

the AiReduction Co. (1972)

Cryogenic Technology Inc. 33.0

(1974)

Total $1,220.0 M These are not all the companies doing

business in cryogenics, but they are representative of the principal ones.

(Note that this demonstrable figure of

$1.22 billion compares favorably with our previous "rule-of-thumb" estimate of $1.20

bi 1 1 ion.

)

We can still add approximately 15% [27]

for the annual capitalization rate, or $183 million, and thereby get $1,403

billion as the annual size of the cryogenic gases, liquids, and equipment industry.

2.5.3.2 Liquefied Natural Gas (LNG)

The following is a brief summary from

the published literature that tends to establish the dollar value of the LNG industry on an annual basis.

Import-Export . The Minerals Yearbook

[28J states that 2.2615 billion cu. ft. of

natural gas was imported as liquid from

Algeria and Canada in 1972. In addition,

it states that 47.9 billion ft^ of LNG was exported to Japan from Alaska during 1972.

Therefore, 50 billion ft^ of natural gas in

liquid form was involved in import-export

commerce in 1972. By applying a conservative

$1 per thousand std ft\ it is possible to estimate a value of $50 million for the LNG

import-export trade.

LNG Produced for Internal Consumption . We may estimate the value of LNG produced

for internal consumption from the gross

liquefaction capacity of peak shaving and

satellite liquefaction facilities presently

operating. Although LNG is generally not

considered a cormodity in peak shaving

operations, it is nonetheless possible to estimate its value from the size of the

national liquefaction capacity by assuming

the market value of LNG at $1 per thousand

std ft^ equivalent. "Gas Facts" [29]

cites gross liquefaction capacity of 206

million ft^ per day which computes to be 75

billion ft^ per year with a dollar value

of $75 mill ion.

LNG Ship Building Construction . There are presently 16 LNG ships under construction in

the U.S. [30]. It is assumed that these

ships were ordered in the period 1973-1974

for delivery in the five year period 1975 to 1980. We estimate each ship's value at $90

million [31]. Assuming that these 16 ships

will be delivered over the five-year period

mentioned, we thus derive an average yearly

value of $288 million for LNG ship construction.

LNG Storage and Peak Shaving Plant Construction . Hale [32] states that up to 10 or more LNG peak shaving plants will be built

each year for the next 10 years. Further

more, there are 19 applications pending

before the Federal Power Commission for

permission to import LNG or to liquefy and

store it for interstate use alone. These

applications are not trivial. To illustrate,

one peak shaving facility in Iowa is estimated to cost $23 million. The import ter- minals proposed by Western LNG is estimated

to cost $1.7 billion, and the El Paso-Alaska

export terminal to supply part of the west

coast (including 11 ships and a pipeline) is estimated to cost $5.6 billion. Hale [32]

cites a recent Northern Natural Gas Company

plan for a $20 million facility. With his

value as a conservative average, we may

estimate investment in peak shaving facilities to be at a level of $200 million per

annum. The size of the U.S. LNG industry is therefore approximately:

33
Component Value, $ M/yr

1. Import-Export Trade $ 50

2. LNG produced for Internal 75

Consumption

3. LNG Ship Construction 288

4. Peak Shaving Plant 200

Construction

$613 M Therefore, the approximate size of the

cryogenic industry in the United States is $1,403 million plus $613 million or $2,016

bil 1 ion.

2.5.3.3 Research and Development

None of the above includes research and

development, or any estimate of the future.

There are a few indicators in this area: About $26 million per year is spent on superconductivity programs in the U.S. [33].

This total includes: $3 to 4 million for

electrical generators; $3-1/2 to $4 million

for electrical power transmission; $6 million

for electrical propulsion systems; $6-1/2

million for energy storage, magneto-hydrodynamics and controlled thermonuclear re- actors; $7-1/2 million for high energy physics

experiments; and $2-1/2 million for basic

research on superconducting materials.

The importance of helium is noted in

the Energy Research and Development Administration (ERDA) legislation, which directs

the Administrator to conduct a study of

the potential applications of helium, and

to report his recommendations to the

President and the Congress within six

months of enactment. These recommendations

will concern the management of the helium

program from the standpoint of energy R&D

[34].

The Institute of Gas Technology reports

that the natural gas utilities feel the

need to demonstrate to their investors

that they have prospects for participating

in a "perpetual" energy industry, not subject to depletion. They see hydrogen

as a substitute fuel gas to move through

their pipelines [35].

Many feel that cryogenics may be to the

second half of the twentieth century what

high temperature processing was to the

first^half. We at NBS certainly agree

that at least it is an important, large,

growing and dynamic industry.

3. IMPACT, STATUS AND TRENDS OF THE CRYOGENIC MEASUREMENT SYSTEM

3.1 Impact of Measurements

3.1.1 Functional, Technological, and Scientific Appl ications

The impact of cryogenic measurements may

be illustrated by some examples where cryogenics plays a crucial role in the advancement of national programs. In the examples

below, the measurement infrastructure supports the commerce in cryogenic fluids, although measurements per se may be peripheral to the applications listed. They are mentioned primarily because of their inherent interest.

In the area of health: blood for transfusions can be stored at. liquid nitrogen

temperature for extended periods of time,

while storage for over 2 weeks at 4°C is the

maximum allowed with conventional technology.

Recently, the Food and Drug Administration

has approved such blood as a commodity for

interstate commerce.

Biological samples (like tissue, cancer

cells, tumors, cornea, and bone marrow) can

be stored without serious degradation for

study and inter! aboratory comparison. The

National Cancer Institute maintains just such

an archive.

There are several applications in agriculture, but one of the most noteworthy is that more than 50% of all cattle are bred by

artificial means with the bull sperm stored

and transported at liquid nitrogen temperature.Another agriculture related use of liquid

nitrogen is in food freezing, a well established technology--over $50 million worth of

liquid nitrogen is used for this purpose

annually. Since the use of liquid nitrogen

has been so advantageous, developments are underway to extend its use further back into

the food chain. For instance, sweet corn and

sweet peas are being harvested experimentally

with the aid of cryogenics. This process is said to enhance their value by retaining the

"field sweetness" of the produce. Soybeans,

a valuable source of protein, are being

cryogenical ly harvested also. It is said

that the objectionable (to some) flavor of

soybeans is due to the highly perishable

nature of the newly picked beans. Cryogenic

harvesting is said to enhance the value of

this product several times over by helping to retain the highly desirable fresh-picked

flavor.

In transportation there are already a limited number of cars and trucks using LNG

and hydrogen, but the auto industry does use cryotechniques extensively, including oxygen

for steel making, grinding paint pigments,

and deflashing parts at low temperatures.

In addition, float glass is inerted with

gaseous nitrogen. Even the reclamation of

scrap metal from old cars and tires uses cryogenic technology—cooling to low

temperature permits fracturing and component

separation.

34
The aerospace industry is committed to cryogenics and about 40% of the National

Aeronautics and Space Administration's

budget is cryo-related.

In research, the National Accelerator

Laboratory (NAL) has recently purchased

15,000 lbs. of NbTi ingots at a cost of

approximately $500,000 to build a superconducting energy doubler. This amount of

material is enough for only 1/6 of the

magnets around the 4 mile ring, or $3

million worth of raw NbTi. Other scientific applications of cryogenics y/ere discussed extensively in Section 2.2.5.

The Navy is building 3000 HP superconducting motors and generators for ship propulsion and has design studies underway for a 30,000 HP version. These motors could

revolutionize the use of hydrofoils and even conventional ships.

In some of these examples, the NBS role

is rather diffuse and indirect, while in

other cases, our aid is quite explicit.

In all cases, cryogenic measurements are

central to the infrastructure that supports

the technological and scientific applications mentioned.

3.1.2 Economic Impacts--Costs and Benefits

Some examples of the value of cryogenic

measurements were given in Sections 2.2.2.2

and 2.5.2. We shall highlight a few of

these values again below, and conclude

with a specific case study sponsored by

The Instrument Society of America.

•Approximately 2,000 cryogenic flowmeters are in use today with a value of over $3 million, making approximately

400,000 custody transfers per year.

Flowmeters are considerably less numerous

and less widely used than other cryogenic

instruments

•In terms of rate of growth, the

industry as a whole, of which cryogenic

measurements are a part, ranked 59th out

of 130 industries surveyed by the Department of Commerce during 1973-74. The

average growth rate was 7%. The two principal subcodes within this

group are 3821 and 3822. Projections [36]

through 1980 are shown in table 3-1. A specific example of benefit-cost estimation may prove useful at this point and

help bridge the gap between instrument and

user. Our example shall turn around the

cryogenic flowmetering program, especially

the summary report [37] prepared by The

Instrument Society of America Ad Hoc Committee mentioned in Section 2.2.1.1.

As mentioned, NBS contributed to this

report and excerpts are given below:

"The previous section has developed some of the needs for cryogenic fluid flow

measurement and standards. However,

it is one thing to have needs and another

to economically justify the solution of

these needs. Since this was part of the

charge to the Ad Hoc Committee, an attempt

was made to come up with an economic justification. As in many situations such

as this, this economic justification is not easy to prove and verify by actual

numbers because so many intangibles must

be considered as part of the economics of

such a problem. However, using statements

and estimates from various Ad Hoc Committee members and other interested contributors, plus statements and estimates

gathered from technical papers, letters,

and telephone conversations, a brief

report has been prepared in an attempt

to at least demonstrate the economic magnitude of cryogenic fluids. For the purposes of this section of the report, the

cryogens of concern at this time are oxygen, nitrogen, argon, hydrogen, and

liquefied natural gas."

The report continues in this realistic

fashion and estimates the value of cryogenic

fluids. It continues:

Table 3-1

Instruments for measurement, analysis and control:

projections 1973-80

(value of shipments in millions of dollars)

SIC Industry 1973 1974 Percent Percent

code increase increase

1973-74 Low High

3821 Measuring and controlling

instruments 1,800 1 ,920 7 4.8 6.0

3822 Automatic temperature

controls 740 780 5 5.2 6.5

35
"A study of this table indicates that if the

custody transfer of these fluids were in error by only one percent (present codes

allow two percent), a billing error could

amount to more than 15 million dollars.

This point is emphasized in the table

below.

Year Possible

Billing Error/Yr

1966 $ 2,158,000

1971 5,705,000

1976 15,372,000

In Section 2.2.2.2, we estimated that

the total value of flowmeters in service

in 1971 was about $3.1 million. One

can choose for himself whether or not

to divide the figures above by one

another. If he does, a ratio of between

2 and 4 to 1 is obtained.

The report continues on another tack:

"Previous discussion has outlined the economic worth of the cryogenic fluids in terms

of custody transfer. However, this is not

the only place where an increased cryogenic fluid meter calibration certainty

would be desirable. For example, in the

aerospace industry an increase in fluid

meter calibration certainty would go a long way to guarantee engine performance.

Present uncertainties in the factors

involved in mixture ratio trim cause approximately a 2% uncertainty in guaranteed engine performance. Accordingly,

guaranteed engine performance is downgraded by 2% in order to insure overall

mission success when engine and vehicle

are mated. Any decrease in this 2% un- certainty would raise the mission capabillity by some corresponding amount.

"In the case of one oxygen-hydrogen engine

under development, the 3a error in flow

measurement is 0.433 and 0.541% for fuel

and oxygen, respectively. The corresponding percent error in mixture ratio

(3o) is 0.727%, which is clearly a substantial portion of the overall 2%

uncertainty.

"If a facility were available that could

reduce the flowmeter calibration

uncertainty to 0.2% each, the corresponding percent error in mixture ratio (3o)

would be reduced from 0.727 to 0.282%.

Hence, the uncertainty in engine perfor- mance is reduced by 0.444%. If the specific impulse of the engine is around 350

seconds, the corresponding increase in

engine performance certainty is (350)

(0.444%) or 1.56 seconds.

"In the special case under consideration, each second of additional guaranteed

performance is equivalent to a 25 lbs increase in payload for a given booster.

Accordingly, the improvement in flowmeter

calibration assumed here reflects an increase in payload capability of (1.56)

(25) = 39 lbs for a given booster.

"The value of increased flowmeter calibration certainty may be reflected in

other ways. The above example indicates

an increased payload capability of nearly

40 lbs. This also means that for a given

payload, the booster has a payload capability of 40 lbs more than necessary, due to flowmeter calibration uncertainty. By

decreasing this uncertainty to the levels

assumed, the booster size can be decreased

by 40 payload-lbs equivalent.

"In a typical system, each pound of payload

requires some 60 lbs of additional

propel lant. Decreasing the flowmeter

uncertainty means that, in this case, the

booster size could be reduced by (40) (60)

= 2,400 lbs of propel lant. Corresponding

reduction in tankage, lines, valves,

engines, launch facilities, personnel,

liquefier capacity, test sites, booster

transportation, etc., occur.

"If the economic worth of cryogenic fluids,

the possible billing error to consumers,

the improved rocket performance, the

improved regulatory agency relations,

the improved customer relations, etc., are considered, it is safe to assume

that the net value of improved flow

, measurements in custody transfer,

diagnostics, and standards is a multimillion dollar per year proposition .

Please recall that all of the above is quoted

from the ISA report.

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

Impacts

We have already mentioned in Section

2.2.5.1 that 15 Nobel prizes in physics were

awarded for work in or related to cryogenics.

While these are hardly "man-on-the-street"

impacts, it must be recognized that cryogenics has had significant impact on basic

research and education, which does affect us all.A much more down-to-earth educational

need involves the plant operators, truck

drivers, police and fire departments. The ' following statements have been collected

to help reinforce this point.

"There is a broad feeling among those

responsible for the measurement of LNG

that much needs to be learned as to the

best methods for measuring and calibrating flowmeters, tank level gauges, and

densimeters. Plans for LNG measurement

techniques and standards, at this

point, are nebulous. It is probably a 36
case in which operating experience is expected to focus attention on the need

for specific programs in this area by

the operating companies." M. H. November,

Potter Aeronautical . "It is a responsibility of the program of

the NBS to train county personnel in

the proper procedures of inspection."

W. Watson, California Bureau of Weights

and Measures . " —that a committee or organization

(possibly such as the CGA) work closely

with the regulatory agencies and cryogen

producers to educate both to the problems and to develop any necessary

guides for product handling and metering." G. C. Nubel , Air Reduction

Company . "The cryogen producers also need more

information for fire prevention codes.

This information is needed by the

public, such as fire department and

police department officials." W. Spencer,

American Cryogenics . To cite educational needs (almost

everyone agrees to education) is one thing, but to meet these needs is another.

These needs are not essentially simple

ones easily met by bulletins, pronouncements, or regulations, but rather they are complex ranging from technical and scientific down to operational. Some of these

complex educational needs include: (1)

study of safety practices; (2) education

of police and fire officials; (3) education of driver-operator in proper procedures -- the why and how of these procedures, and so forth. Measurements are needed to help develop educational programs,

specify codes, etc., which have the direct

human/man-on-the-street impact.

The point of the cryogenic measurement

system is to foster and help develop a new technology, the infrastructure technology

of cryogenics itself. It is generally

accepted that such technological innovation

can help us expand our markets at home and

abroad, strengthen old industries, create

new ones, and generally provide more jobs

in the labor market.

The direction of private technological

activities is determined in large measure by

thousands of private decisions -- and this

should always be the case -- but we cannot

ignore the fact that federal policy, such as undergirding a new technology, also has a profound effect upon what happens in the

private sector.

3.2 Status and Trends of the System

Several special studies have been prepared

to characterize the cryogenic measurement

system (See Section 4.5.1).

The Overview . Two overviews have been

made to document the infrastructure position

of cryogenics in large national programs

(space, health, transportation, etc.) and to identify leading indicators of trends of the

health of cryogenics.

Applications for Specific Customers . Once

the network of cryogenics in technology as a whole had been defined and tested, it was

useful to look at specific functional relationships between terminals in that network,

or the leverage of cryogenics in specific

applications. Such studies were made on the

application of cryogenics in atomic energy

programs, transportation, biology, and water

pollution abatement.

Applications to a Specific National Need - Energy . Technology assessments have been

prepared in three energy areas -- LNG, hydrogen, and superconductivity.

Analysis of Major Technical Threats . Since cryogenics is a rather well bounded and

self contained technology, it is not likely

to be replaced by a competing technology.

The principal threats are from among the

rivals within the technology itself, as from

abroad. Two foreign technology assessments

have been made.

Analysis of Major Technical Barriers . The

question of reliability and cost is always

raised whenever a commercial application of

cryogenics is suggested. Accordingly, a survey of the state-of-the-art of commercial

refrigerators was first published in 1969 and

updated in 1973.

Analysis of Major Technical New

Opportunities . Assessments of cryoelectronics, superconducting engineering and the

commercialization of cryogenics have also

been prepared.

The synthesis of these studies is that the

major developments in cryogenics in the next

few years that will have significant impact

on the technology of the country and its

balance of trade are the widespread international use of liquefied natural gas

potential uses of hydrogen, and applications

of superconductors. These developments

are a result of the national sense of

urgency regarding energy problems and the

established trends toward the uses of: (1)

liquefied natural gas to meet local peak

energy requirements (peak shaving) and to accommodate the transportation of natural

gas in the dense cryogenic form; (2)

liquid hydrogen as a potential synthetic

fuel of the near future; and (3) superconductivity in applications for electric

power generation, transmission, and storage.

The cryogenic measurement system must

respond with design data, metrology, and

related applied cryogenic research.

37
Along with this "commercialization" of

cryogenics comes a new role that gives

even greater leverage to the measurements

and data, and which is one way to assure

the effective transfer of measurements

into the hands of the users. This new

role is a partnership between cryogenics

and the regulatory agencies. For instance, results of the NBS flowmetering

program (e.g., tolerances and basic property data) have been adopted into NBS

Handbook 44 as a result of cooperative

work with the states of California and New

Jersey. The Maritime Administration and

the U.S. Coast Guard are interested in new, inexpensive, but safe materials for

seagoing tankers. The Federal Power

Commission (FPC) needs cryogenic mea- surements and data on the cryogenic safety

and design aspects of current applications

before the FPC for authorization of LNG

terminal and storage facilities. Underlying and supporting each of the specific

technologies of LNG, hydrogen, and superconductivity is the necessity of: (1)

establishing and providing an information

base for cryogenic measurements and properties of materials at low temperatures;

and (2) characterizing the behavior of

materials at low temperatures by definitive

studies involving mechanical, thermal, and

electrical property measurements. Some of

the strengths and weaknesses of the current

cryogenic measurement system are described

below.

Liquefied Natural Gas (LNG) . Over 30

percent of the basic energy supply in the

U.S. is provided by natural gas. The

demand for this relatively inexpensive,

ecologically satisfactory fuel has substantially exceeded the domestic supply.

Even with responsible conservation and

development of alternative sources, large

quantities must be secured not only through

foreign importation, but also from Alaska,

by 1985. Domestically, major facilities

have been established in large population

centers to permit peak shaving and redistribution. These large scale applications re- quire handling the natural gas in liquid

form. New measurements and data are re- quired, to permit the U.S. to participate

successfully in domestic and imported liquefied natural gas programs in order to develop; (1) advanced concepts, (2) environmental impact statements, (3) regulations,

(4) economics, (5) safety, and (6) reliability. Accordingly, a complete and com- prehensive physical measurement system for

LNG needs to be developed.

Today, quantity gaging in storage and

ship tanks is uncertain and requires accuracy statements and traceability yet to be

developed. Flowmetering for commodity

transfer and equity in trade has been developed for more conventional cryogens

(Handbook 44). An equivalent program for

LNG will be unique in conception because

it will require the integration of mass

and heating value measurements. Nonetheless, traceability to national standards

(NBS) is already written into existing international agreements (El Paso Gas-Algeria

and Algonquin Gas-Algeria) with little or

no technical basis in fact.

Basic measurements of the thermal and

mechanical properties of structural materials are the key to realizing the potential

of LNG as a major source of fuel . For

instance, the fatigue crack growth rate and

fracture toughness of many potential con- struction materials have not yet been measured for cryogenic applications. Such

data are essential to ship construction as well as to stationary storage of LNG. Hydrogen . Hydrogen is a prime candidate

to satisfy many long-term national (and

international) fuel requirements. It seems

no longer necessary to justify the relevance

of hydrogen fuel research since hydrogen is

a clear contender for the synthetic fuel

market of the future -- only the time scale

for implementation of this fuel is uncertain. Its use in the period 1985-2000

appears guaranteed. Thus basic measurements

and data are required now. Priority research elements that have been

identified are: (1) improve hydrogen liquefaction efficiency, (2) evaluate methods of

recovering liquefaction energy, and (3)

evaluate hydrogen compatible materials of

construction. Longer term priorities include

the development of improved insulation systems and the establishment of instrumentation

and measurement methodology for commercial

exchange of liquid hydrogen.

Superconductivity . Cryogenic measurements

and data are intimately bound together with

the electrical energy industry through the

application of superconductivity to power

transmission, generation, and storage.

All three applications have at least three

problems in common. First, conductors

tailored to each of the above areas are

still under development, and their performance depends in part upon the rate of heat

transfer to the helium heat sink under

transient conditions. Second, the behavior

of the entire helium refrigerant flow

system, including responsiveness to instabilities must be known (pressure, temperature, and flow rate vs. time). Third,

degradation, or aging, of the superconductor may result from the various different

stresses -- thermal, electrical, or mechanical -- with long term reduction of system

38
capacity. The problem areas -- refrigeration

and superconductor behavior -- are common

to each and every superconducting application and at present represent a weakness

in the cryogenic measurement system.

Helium is, of course, the indispensable

refrigerant for all known superconductivity technology. The importance of helium

was recognized in the bill creating the

Energy Research and Development Administration (ERDA), which directs the Administrator to conduct a study of the potential

energy applications of helium and to report his recommendations to the President

and the Congress within six months after

the enactment of this Act. These recommendations will concern the management of the

helium program from the standpoint of

national energy research and development,

and will undoubtedly have a profound

effect upon the future of the cryogenic

measurement system.

4. SURVEY OF NBS SERVICES

4.1 The Past

Ever since the Federal Government established the Bureau, NBS has been involved in

cryogenic measurement science and has frequently been sought out to settle technical

controversies or to solve problems whose

sophistication lay beyond the capabilities

of other agencies.

In fact, the NBS program in cryogenics

itself dates back to 1904 when Congress

approved the purchase of a hydrogen liquefier exhibited by the British at the St. Louis world's fair. A somewhat larger

facility was established in Boulder in 1952

at the request of the AEC, and ever since

then, the Cryogenics Division of NBS has

participated significantly at the critical

stages of planning and execution of every

major national program using cryogenics. A brief historical background follows:

- Established the National Cryogenic

Engineering Conferences, now in their 20th

year.

- Assisted in the development of the

first large liquid hydrogen bubble chamber,

which won for Dr. Luis Alvarez the Nobel

Prize in Physics in 1968 and also a commendation 'for the NBS team.

- Developed the OP catalyst essential to the long term storage of hydrogen.

- Produced the first text book in cryogenic engineering; co-edited the first

journal of cryogenics and taught the first

college accredited course in cryogenic

engineering.

- Received the DoC Gold Medal for Measurement and Publication of Definitive

Properties of Hydrogen.

- Assisted in 1970 in the investigation

of the cause of the Apollo 13 cryogenic

tankage failure and helped to establish the

basis of safe redesign.

Thus it is apparent that NBS has provided

cryogenic measurements, data, and services

for nearly 70 years. The present holds

every bit as much promise as cryogenics

matures and finds more and more use. 4.2 The Present Scope of NBS Services

The present scope of NBS services to the

cryogenic measurement system is indeed significant. We have already indicated that

cryogenic measurement and data services are offered in nearly every field that NBS as a whole does: conceptual knowledge, instrumentation, reference materials, standard samples,

reference data, and specifications (See

Section 1.). Accordingly, it may be more edifying at this time to illustrate these

services with our case study, the liquid

nitrogen flowmetering program. We shall

attempt to illustrate not only the NBS

services, but also their uses and interactions

through an Input-Output analysis. This

matrix is essentially a four terminal network

to describe the flow of information between

NBS and various users. Block I is "from NBS to NBS", or Internal

Input.

Block II is "from the outside to NBS" or External Input.

Block III is "from NBS to the Outside" or External Output.

And Block IV, since it describes interactions "from the Outside to the Outside"

and does not involve NBS per se, appears

to hold little interest for us at the moment.

4.2.1 Description of NBS Services

A description of NBS services should not only include those services that NBS supplies

to the outside, but to internal users as well. Accordingly, we shall subdivide this

section into two parts: Internal Inputs--

NBS to NBS; and External Outputs--NBS to the outside.

Internal Inputs: NBS to NBS . This block

i ncludes, for instance (Figure 1 )

•The Institute for Basic Standards--

whose statutory responsibility to provide basic measurements and standards

made the program possible.

•The Office of Measurement Services - provided guidance on accuracy statements, and experiences in conducting

round robins.

•Patent Advisor--guidel ines for handling proprietary information on the

performance of specific flow meters.

39
•The Office of Weights and Measures--

publishes Handbook 44 and provides the

secretariat to the National Conference

on Weights and Measures (NCSM). Gave our program the direction and mechanism

to make its results have the effect of

law.

•Applied Math Division--planning experiments for statistical soundness and

analyzing the results.

•Cryogenics Di vision--provided the

essential technical base and resources.

For more detail on these Internal Inputs,

see Section 2.4.1, especially NBS Infrastructure . External Outputs: NBS to the Outside . The analogy has been drawn that basic mea- surements and standards are the "currency"

or medium of exchanges in business. The

analogy may be broadened by recognizing that

a currency has no intrinsic value of its own, but is only as good as the user's

confidence. The same is true for basic

measurements and standards.

Standards as the "currency" of science can

be a revealing analogy, for standards are the

key to the commercialization of science.

Each scientist works within a self contained

system using "his" thermometer, "his" balance,

and "his" meter, which could be the distance

between two marks on a barn door, as far as he is concerned. As long as his measurement

system is internally consistent, he has no need to refer to or compare against an external set of standards. Only when he steps

out of his system to put his work into general

use, to gain general acceptance, to put his

work into circulation, as it were, does he

need to refer to a set of external standards.

Basic standards then are not the analog of

currency, but are the currency of fact, since

they are indeed the medium of exchange that causes the scientific work to become commonly

accepted, used, and repeated. Thus, basic

standards are the transfer agent from which

the benefits of science are derived.

It is a paradox that "basic" has come to mean in the minds of some "undirected" or "exploratory", for indeed the sole need for

standards is to communicate with others. In this sense, standards provide the dictionary

of tedinology and commerce. Standards are the means used to judge

something as authentic, good, or adequate.

They are the measures to determine what a thing should be, or whether it is correct.

Thus, there are standards for measurements

(property data) for performance (tolerance)

and for products (type testing). In this

program, these standards were embodied as "External Outputs" (Figure 2).

•Codes, Standards, and Recommended Practices, such as adopted in Handbook 44.

•Properties Data. The NBS property data

for liquid nitrogen were also adopted in

Handbook 44. See Sections 2.2.1.2 and 2.2.3.

•International Conventions. As mentioned

earlier, the Compressed Gas Association was strongly motivated to deal with one national

laboratory rather than fifty state laboratories. We extended this philosophy on an international scale via the lOLM. See

Section 2.4.1

•Performed type testing of meters of

foreign manufacture as an integral part of

the program. (See Tech. Note 624, "An Evaluation of Several Cryogenic Turbine

Flowmeters" .

)

•Promoted and facilitated many visits by

international observers. The result of one

such visit was the direct translating into

German of NBS Report 9778, "Cryogenic Flow

Research Facility Provisional Accuracy

Statement" to be used as a model by the PTB. For more discussion, see Section 2.4.1.

4.2.2 Users of NBS Services

The principal users of NBS services, in

the representative sample chosen for illustration, can readily be identified by the

inputs they had to the program. This may at

first seem to be a backward approach, but it

is surely the most direct way to identify

those who needed the services the most - namely

those who helped influence and "design"

those services. We call these External

Inputs

External Inputs: Outside to NBS . The

principal external inputs (Figure 3) came from

regulatory agencies, and trade associations.

Their role was fundamental in both initiating and guiding the program and was described in detail in Section 2.2.1.1. These

included the Instrument Society of America

(ISA) Ad Hoc Committee on Cryogenic Flow

Metering, The Compressed Gas Association,

and the State of California. There are three factors in common between NBS and

these groups that bear further comment.

1. The regulatory agencies need a sound

technical basis for their codes so that they

are feasible as well as enforceable. The

NBS, having no regulatory authority (and

desiring none), needs the leverage of regulatory agencies for its basic measurements

and standards to be adopted rapidly and

uniformly.

2. Because the NBS has no regulatory

functions, our basic measurements and standards must stand on their own merit. They

must be the best in the country to be accepted, for they are not promulgated by law.

40
INFORMATION INPUT - OUTPUT MATRIX

NBS To OUTSIDE

OUTSIDE

INTERNAL INPUT

• IBS

• OMS

• Patent Adviser

• OWM

• Applied Math Division • Cryogenics Division

FIGURE 1. Internal input.

NBS To OUTSIDE

NBS

OUTSIDE

INTERNAL INPUT

• IBS

• OMS

• Patent Adviser

• OWM

• Applied Math Division • Cryogenics Division

EXTERNAL OUTPUTS

• Codes

• Standards

• Recommended Practices • Properties • Measurement Techniques

• Correlations • Literature Services

• MAP

• International Conventions

FIGURE 2. External outputs.

41
(The analogy has already been drawn that

basic measurements and standards are the

"currency" or medium of exchanges in business).

3. Because of our unbiased outlook, the

parties involved, each with his own self

interest or view points, feels free to come

to us as the impartial third party. The ISA

specifically recommended recourse to a na- tional laboratory. The State of California

also expressed the need for traceability to

a national standard, since they are obligated

by law to perform type approvals. The CGA

was strongly motivated to come to a central

laboratory, for the alternative was to deal

with fifty state laboratories.

Our responsibility lies not only in

providing the competence in advance of need,

but also making that aompetenae known to our customer's^ and making it easy for him to do business with us. 4.2.3 Alternative Sources

We offer to the Cryogenic Measurement

System essentially every service that NBS as

a whole offers to the entire measurement

system. Therefore, the list of every actual

or potential alternate source is, for all

practical purposes, endless. We have at- tempted to tether such a discussion by

tying it to a specific scenario: namely,

what would happen if NBS were to stop its

cryogenic measurement services tomorrow?

This scenario is developed in Section 4.3

"Impact of NBS Services", especially Section

4.3.1.

Here, we shall limit our discussion to means of identifying user needs possibly not being met, and the NBS role vis-a-vis such

needs. One way to do this is to identify

the Outside-Outside interactions. By definition, these interactions do not involve

NBS, but perhaps they should.

Outside-Outside Interactions . The inputoutput functions of Block IV at first do not appear to interest us, for they do not involve NBS per se . They include, for instance (Figure 4)

Regulatory Agencies - California and New

Jersey state weights and measures officials

collaborating on a model code in order to facilitate trade among their states, as well

as intra-state commerce. Meter Manufacturers--an instrument maker

planning his flow meter design and distribution to conform not only with U.S. convention, but also with that of the PTB, for

instance.

Fluid Producers--especial ly those in

interstate or international commerce. Professional Societies--such as non- technical policy board meetings of the ISA.

Note that these examples are essentially

non-technical policy level determinations,

and accordingly appear not to be the concern

of NBS. But note these common traits.

1. Vantage points of enormous leverage

where the most fundamental decisions are

made.

2. Opportunities of largest possible

economic impact (it is more economical for

everyone concerned to get a code that is feasible in the first place, rather than

testing and re-writing the code after the

fact.)

3. Taken as a whole, they represent the

"Industrial Measurement System", a sub-set

of the National Measurement System. (Figure

5).

This is the arena where decisions are the

most fundamental, and where the opportunities

and problems originate. Accordingly, it is not only in our sphere of responsibility, but

also in our own interest, to consciously and

systematically monitor and influence the course of technology in the political (people),

technical, economic, ecological, and social

environments. If we are to serve the cryogenic measurement system adequately, then we must continuously identify, analyze, evaluate

and participate in the transactions occurring

in this essential, but sometimes overlooked

part of the measurement system.

4.2.4 Funding Sources for NBS Services

In Section 3.1 we identified the impact

of our measurement services, and noted that

in some of the examples given (health,

agriculture) the NBS impact had been rather

diffuse and indirect. In other cases (space

exploration, LNG), the NBS cryogenic measurement services were explicit and direct. So

it is with the funding sources for our

services. Some services result in wide

public benefit, meriting wide public support

(e.g., appropriated funds). On the other

hand, where specific beneficiaries can be

identified, then these beneficiaries have

paid, because "full recovery of costs" is

the rule. A few specific examples may prove

helpful and are given below.

Cryogenic Flowmetering . We have used

this specific case study throughout our microstudy to help illuminate general principles. As discussed in Section 2.2.1.1, the

Compressed Gas Association was a specific

beneficiary, and the member companies most

interested in the problem (see Table 2-2)

contributed funds and helped provide program

definition that allowed the program to proceed to its ultimate technical conclusion.

Reference Data . Accurate density mea- surements and analytical calculation methods

for liquefied natural gas are essential to

42
INFORMATION INPUT

NBS To

OUTPUT MATRIX

OUTSIDE

NBS

From

OUTSIDE

NBS

From

OUTSIDE

INTERNAL INPUT

• IBS

• QMS

• Patent Adviser

• OWM

• Applied Math Division • Cryogenics Division

EXTERNAL OUTPUTS

• Codes

• Standards

• Recommended Practices • Properties • Measurement Techniques

• Correlations • Literature Services

• MAP

• International Conventions

EXTERNAL INPUT

• National Conference on Weights

& Measures

• Federal Agencies

• Trade Associations

(C6A, AGA)

• Regulatory Agencies

(State, National, International)

FIGURE 3. External inputs.

NBS To OUTSIDE

INTERNAL INPUT

• IBS

• QMS

• Patent Adviser

• OWM

• Applied Math Division • Cryogenics Division

EXTERNAL OUTPUTS

• Codes

• Standards

• Recommended Practices • Properties • Measurement Techniques

• Correlations • Literature Services

• MAP

• International Conventions

EXTERNAL INPUT

• National Conference on Weights

& Measures

• Federal Agencies

• Trade Associations

(CGA, AGA)

• Regulatory Agencies

(State, National, International)

• Regulatory Agencies

• Meter Manufacturers

• Fluid Producers

• Consumer

• Professional Societies (ASTM)

FIGURE 4. Outside - outside interactions.

43
INFORMATION INPUT

NBS To

OUTPUT MATRIX

OUTSIDE

NBS

From

OUTSIDE

INTERNAL INPUT

• IBS

• QMS

• Patent Adviser

• OWM

• Applied Math Division • Cryogenics Division

EXTERNAL OUTPUTS

• Codes

• Standards

• Recommended Practices • Properties • Measurement Techniques

• Correlations • Literature Services

• MAP

• International Conventions

EXTERNAL INPUT

• National Conference on Weights

& Measures

• Federal Agencies

• 1 race Associaiions

(CGA, AGA)

• Regulatory Agencies

(State, National, International)

INDUSTRIAL

MEASUREMENT SYSTEM

• Regulatory Agencies

• Meter Manufacturers

• Fluid Producers

• Consumer

• Professional Societies (ASTM)

FIGURE 5. Industrial measurement system.

provide an unequivocal basis for custody

transfer. These same data provide the basis

for mass, density and heating value measurements throughout the fuel gas industry. A technical program to meet these needs is presently underway, funded and guided by a consortium of 18 energy companies (See

Section 2.2.3 for technical description).

Hydrogen-Future Fuel . In the fall of

1972 the NBS Cryogenics Division NAS-NAE-NRC

evaluation panel recommended renewal of a modest effort on hydrogen fuel technology.

The scientific staff responded enthusiastically and a state-of-the-art evaluation was released in the summer of 1973. An economic

analysis of hydrogen-fueled electrical

utility systems was published in March 1974,

and a benchmark literature bibliography was completed in June 1974. The work described

below was initiated in July 1973, and efforts were accelerated by support of management

at all levels of the NBS , e.g.. Institute of

Basic Standards Director's Reserve funds were made available to initiate this study.

The goal of this work is to provide

innovative cryogenic technology so that

hydrogen may be liquefied, stored, and distributed efficiently on an unprecedented

scale and with safety and fairness to the consumer. Specifically, analyses and sum- mary reports were prepared on the following

topics: (1) cost and availability of hydrogen, (2) hydrogen in the electrical utility

industry, (3) applications of hydrogen in

transportation, (4) survey of materials for

hydrogen service, (5) instrumentation for

cryogenic hydrogen fuel, (6) transmission

and distribution of energy, (7) solar energy

liquid hydrogen, (8) industrial applications

of hydrogen, and (9) hydrogen fuel literature

These analyses demonstrated, among other

things, that even now hydrogen appears

attractive as an aircraft and aerospace

fuel, in certain integrated utility systems

(e.g., use of hydrogen to store solar

energy), for transport of energy from nuclear

or solar sea power plants and is already an essential ingredient in a wide variety of

industrial processes (ammonia synthesis,

hydrocracking, hydrotreating, and methanol

synthesis). This example was chosen to illustrate how internal re-direction of

funds by an alert management can quickly

produce results not otherwise possible.

Liquefied Natural Gas . This present

study of the cryogenic measurement system

(now in its second year) has helped document

for us the complete process that must be

undertaken to provide a complete measurement

service. Specifically, our LNG Budget

Initiative submitted in the Spring of 1974

was deliberately constructed to include all

44
three necessary elements: measurement

science, data base, and technology transfer

(includes safety, interstate and international cooperation, effective use of

Office of Weights and Measures and training).

Thanks (in part) to the National Measurement

System study, new work proposals now use the

guidelines so developed to assure a complete

and comprehensive approach.

Even though this particular initiative

did not survive the government budget process,

we are nonetheless pursuing other avenues of

funding, perhaps even multiple sources, but

with the objective of nothing less than a comprehensive program. This example was chosen to illustrate the course of a new budget initiative pf potentially large public

benefit, which could reasonably be assumed

to merit public support (appropriated funds).

Thus the answer to "Sources of Funds for

NBS Services" is: "It depends". Table 4-1 gives a more explicit answer. Table 4-1 Funding by sources

Fiscal Year 1974

NBS Percent

Direct appropriation 31 Postdoctoral s 01 Standard Reference Data 03

Standard Reference Materials 01 NBS TOTAL 36%

OTHER AGENCY R&D

National Aeronautics and

Space Administration 11 Atomic Energy Commission 05

Department of Defense 23

Maratime Administration 05

Navy 01 Federal Power Commission 02

National Science Foundation 01 OTHER AGENCY TOTAL 48%

IN DUSTRIAL ASSOCIATIONS

American Gas Association 11 International Copper

Research Association 01 Other 01 INDUSTRIAL ASSOC. TOTAL 13%

TESTING, CALIBRATION, SERVICES 03

GRAND TOTAL 100%

4.2.5 Mechanism of Supplying Services

Dissemination mechanisms are as varied as the services themselves.

Calibrations, and Maps were described in

Sections 2.2.1.1 and 4.2.1 in conjunction

with the cryogenic flowmetering program.

Reference Data , whether distributed in an unstructured way by individuals, or in a systematic way by the Cryogenic Data Center, were discussed in Section 2.2.3. Publications, special bibliographies. Standard

Reference Data, and several Current Awareness

services were described there.

Reference Materials were described in

section 2.2.4. These included the Standard

Reference Materials incorporated in the NBS

program of that name. Also mentioned was the

importance of corollary reference data and

round robins utilizing "uncertified" reference materials.

National trade associations, other federal

agencies, and international mechanisms were described in Section 2.4, "Dissemination and

Enforcement Network".

These descriptions, while as complete and

comprehensive as possible, nonetheless appear

rather sterile compared to actuality. Supplying services is never "pure". Usually a mix of services, e.g., reference data along

with reference materials, must be supplied to

a mix of users, e.g., several laboratories in

a round robin interchange. The cryogenic

flowmetering program serves well again as an example of the mechanisms required in practice.

Figure 6 illustrates the truly staggering

number of mechanisms for supplying services

that came into play. Note for instance:

Regulatory Agencies--State

Regulatory Agencies--Foreign

Professional Societies

Industrial Meter Manufacturers--Domestic

Industrial Meter Manufacturers--Foreign

Industrial Producers--Domestic

Industrial Producers--Foreign.

Specific detail is given in Figure 6. 4.3 Impact of NBS Services

We shall attempt to examine the impact of

NBS services by following a specific scenario

namely, what would happen if NBS were to stop

its cryogenic measurement services tomorrow?

For this approach, we are indebted to Professor Charles Howe, who is Chairman of the

Economics Department at the University of

Colorado. Professor Howe is a consultant to the State Legislature of Colorado and his

specialty is establishing criteria for public

supported programs. He has served as a consultant in this capacity to Ghana, Kenya,

Botswana, and lately to the Cryogenics Division of NBS. We shall try to follow this scenario down

two roads, one leading to the potential

economic impact; the other to the technological impact.

4.3.1 Economic Impact of Major User Classes

One possible scenario is that cryogenics

would simply disappear. We believe, however,

that cryogenics is here to stay; we have

shown that it is an infrastructure technology

45
NBS Institute for Basic Standards

Patent Advisor

Office of Measurement Services

Applied Mathematics

Mechanics

Quantum Electronics

Electromagnetics

Cryogenics Instrument Shops

Plant Division

Office of Weights and Measures Electronics Technology

Regulatory Agencies - State and Federal

Office of Weights and Measures

Federal Power Commission

T"

U. —

H

Federal Agencies

National Aeronautics and Space Administra

United States Air Force Atomic Energy Commission

Industrial Trade Association

Compressed Gas Association

American Gas Association (AGA)

Pipeline Research Committee

Cryogenic Flow Research Facility

NBS Institute for Basic Standards

Patent Advisor

Management and Organization

Cryogenics

Office of Weights and Measures Conference on Weights and Measures Electronics Technology

Regulatory Agencies - State

Cal ifornia

Colorado

Nebraska

Wyoming

Conference on Weights and Measures (50 States)

Regulatory Agencies - Foreign

Physi kal isch-Techni sche Bundesanstal t. West Germany

Ministere de la Consommation et des

Corporations, Canada

Professional Societies

American Inst, of Physics

American Society of Mechanical Engineers Instrument Society of America

—J

1

—I

._L_

Industrial - Meter Manuf. - Domestic

Brooks Inst. Div. Emerson Electric Co. Daniel Industries

Eastech Inc. ITT Barton Foxboro Company

Liquid Controls Corp.

National Cylinder Gas, Division of

Chemetron Corp.

Union Carbide Corp. - Linde Division

Rockwell Meter Co.

Industrial - Meter Manuf. - Foreign

•

I British Oxygen Company - London, England

1 1 Compagnie des Compteurs - Paris, France

Linde, A.G. West Germany

Industrial - Producers - Foreign

British Oxygen Co., London

L'Air Liquide, Paris

Linde, A.G., West Germany

Messer-Griesheim, West Germany

Industrial - Producers - Domestic

Air Products and Chemicals, Inc. Air Reduction Company

American Cryogenics, Inc. Burdette Oxygen Company

National Cylinder Gas, Division of

Chemetron Corp.

Liquid Air, Inc. Liquid Carbonic

Messer-Griesheim

Union Carbide Corp. - Linde Division

FIGURE 6. Liquid nitrogen flow program interactions.

46
that is used wherever it is more economical,

or wherever it permits some higher level of

performance. Accordingly, every user of

cryogenics would create his own in-house

competence a piece at a time. It follows

that:

Such redundant facilities and data

gathering would likely cause expensive and

slow response to national needs, while at the same time wasting national resources . It seems inevitable that such duplicate

efforts would produce inconsistent design

data which would prevent both process opti - mization and safety evaluation . The corrolary

questions are: "Who is right?"; "Where is

the arbiter to judge, and how does he decide?".

It is argued by some that while proprietary data of a basic nature may give its

owner' a slight edge for a short time, keeping

data proprietary may sometimes impede national

technological advancement and hence our ability to compete successfully in international

trade .In the absence of a centralized effort

such as NBS provides, arbitrary or even conflicting standards could be adopted,

leading to questionable practices in custody

transfer and in safety evaluation . If a free enterprise economic system is to survive

in a modern industrial society, buyers and

sellers in the marketplace need to have as much confidence in the quantity and performance

of goods exchanged as they do in the amount

of moneys paid.

The government would find itself in the

conflicting role of trying to regulate the

very technology it is trying to promote . A vague technical base inhibits both

compliance and regulation , no matter how

well-meaning or good intentioned either

party may be. If there were no centralized effort,

both government and commerce would find

themselves with a generally unsatisfactory

basis for decision making and impartial

judgments

The key to impact of NBS services appears

to lie in their centralized, coordinated

nature. Our legislative mandate does indeed

call for us to provide a base for a national

system of measurement, and to furnish essential services. The congress has also wisely

chosen language that calls for us to coordinate that system as well. Perhaps it can best be summed up that "no coordinated

effort" would lead rather shortly to discordant and hence wasteful national programs.

4.3.2 Technological Impact of Services

Let us continue our scenario of:

"What if NBS were not involved? What

would happen if we stopped cryogenic

technology tomorrow?" There would be no

ready acceptance, no preferred alternative,

and no centralized national effort. While

this is true, it is neither very helpful nor very satisfying. We would like to be more

specific and I believe we can be, by looking

at some specific technological examples

illustrating the points made above.

Redundant data/facilities cause expensive

and slow response to national needs . The

cryogenics measurement system is supplied

reference data by many experimental systems.

One of these is our Pressure-Volume-Temperature system for the thermodynamic properties

of fluids, which was built up over many years

by the National Aeronautics and Space Administration and NBS at a cost of approximately

$1.6 million. If it did not exist, something

like it would have to be built up many times over by every user who needs the data; and

operated by scientists relatively "low" on the learning curve. As it is, it is available for any priority work regardless of its

origin. It is, in fact, being employed now

to produce industry wide data on LNG for the

AGA.

Inconsistent design data prevents optimization

and evaluation . Many times NBS has been

called upon by the government to evaluate

efficiency claims and production capacities

projected by "paper studies". A complete and

consistent set of design data is essential to this purpose. The National Aeronautics and

Space Administration, for instance, specifies

that NBS data be used in its proposals to provide a common, sound basis for evaluation.

Similarly, NBS recommendations to the FPC

would be open to question if it were not for our sound foundation of valid, consistent

data.

Arbitrary/confl icting standards : questionable custody transfer and safety evaluation . The State of California, frustrated by their

legal requirement to regulate the sale of

liquid nitrogen, but with no technical backup, were forced to set arbitrary standards.

Specifically, they set the same standard for

liquid nitrogen as was then in force for

gasoline. The suppliers demanded a technical

demonstration of the feasibility of these

standards. This impasse was resolved by the

NBS liquid nitrogen flow program. The producers benefited dealing with one central

laboratory rather than 50 separate state

laboratories. The states benefited by not having to construct 50 times over such a complex cryogenic test facility. The public

benefited by the rapid proof and adoption of

the codes. As mentioned, we feel that this

is a practical realization of the "New Federalism" at work - as NBS competence was directly transferred to the states.

47
Conflicting government role : regulate/pro- mote technology . The federal government has

occassionally found itself in the awkward

position of attempting to regulate and promote a technology at the same time. The

effective and safe use of atomic energy is

perhaps such an example. Recently, the

Atomic Energy Commission as such was abolished the regulatory functions assigned to a new commission, and the technology advancement functions assigned to a separate energy

development agency.

The National Bureau of Standards, having

no regulatory function, is free of this type

of mission conflict.

Vague technical basis inhibits both compli - ance and regulation . A liquefied natural gas

explosion in 1944 was not only the worst

disaster in Cleveland's history, but it also

helped to set back the use of LNG for 20 or

30 years.

One hundred and thirty-one persons were

killed when one of the LNG tanks failed from

low temperature embrittlement/fatigue.

Neither the plant builders and operators nor

the public safety agencies had an adequate

technical basis (the properties of 3-1/2%

nickel steel, in this case), although both were conscientious in their respective

tasks.

Unsatisfactory basis for decision making/ - impartial judgment . Because of the enduring

energy shortage and the great potential of

hydrogen as a future fuel, a large number of

laboratories, both public and private, have

moved speedily to verify the feasibility of

hydrogen as a fuel, e.g., numerous graduate

students have converted automobile internal

combustion engines to run on hydrogen gas. While this has been interesting and has

attracted a great deal of attention, we have

preferred to produce a benchmark study that

will be used as th_e technological base for

all further programs of any agency or university on hydrogen: future fuel. This

report will do much to remove most of the

speculation from this area and to provide a sound and common basis for decision making.

4.3.3 Pay-off from Changes in NBS Services

Services provided to the National Measurement System for cryogenics will always be

embodied in measurements, data, and technology;

but the thrust of the effort may change with

time.As mentioned, major developments in the

field of cryogenics are occurring at three

distinct regions of the cryogenic temperature scale, namely: 110 K (liquefied natural

gas), 20 K (hydrogen: future fuel) and 4 K (superconductivity technology). These

trends are not only valid, but also are taking on added significance in the light of

48

the national commitment and sense of urgency

to achieve a greater degree of national

energy self-sufficiency in the near time

frame.

These trends represent our best informed

judgment of our prime teehniadl opportunities

for service over the next five years. In addition, largely as a result of this present

study of the National Measurement System

operational opportunities are emerging.

The historical role of cryogenics at NBS has

been one of technical problem solving to complement the monolithic mission of other

government agencies (e.g.. Atomic Energy

Commission, National Aeronautics and Space

Administration), and we continue to look

forward to this exciting and mutually beneficial partnership. We now see another role

emerging that gives even greater leverage

to our measurements and data, and which indeed assures the effective transfer of mea- surements into the hands of the users. This

emerging role is a partnership with the re- rulatory agencies. For instance, the results

of the flowmetering program (e.g., toler- ances and basic property data) have been

adopted into NBS Handbook 44 as a result of our cooperation with the states of California and New Jersey. A metals combustion

program resulted from an initial Department

of Transportation request following an oxygen tank truck disaster in Brooklyn.

Much of the present LNG program came from

interests by The Maritime Administration

and the U.S. Coast Guard in new, inexpensive, but safe materials for seagoing

tankers. Consultation and advisory services

are provided to the Federal Power Commission

on the cryogenic safety and other technical

design aspects of several current applications before the Federal Power Commission

for authorization of LNG terminal and storage

facilities.

Table 4-2 shows how the beneficiaries of

our outputs are expected to change as a consequence of the trends mentioned above.

Some of the reasons behind the expected

changes shown in Table 4-2 are: •Services to specific manufacturing

firms will increase, reflecting the fact that

cryogenics in general and superconductivity

in particular are coming of age. More

practical devices and instruments, such as SQUID'S, will be manufactured.

•Interaction with the service industries

will also increase as we interact more with

the public energy utilities (hydrogen fuel,

LNG, applied superconductivity).

•We have little direct measurement

contact with the consumer per se , and expect

no significant change. Contact will con- tinue to be made through service industries

and regulatory agencies.
Beneficiaries of Outputs

directly to specific manufacturing firms

or industries

directly to specific service industries

directly to the individual consumer

to the Defense Department

to Federal regulatory agencies

to State government needs

to other Federal government agencies

to other NBS groups

to university research and other research

at the frontiers of science

Table 4-2. Distribution of effort

Percent of Cryogenics Division Total Effort

Current 5 years from now

8% 10%

5%

n

30%

2%

1%

43%

5%

5%

8%

1%

33%

5%

3%

30%

5%

5%

• Direct support of the Department of

Defense mission will continue, reflecting

the fact that the Department of Defense

supports about half of all research in this

country [38] and that the first practical

applications of superconductivity will

probably be to Department of Defense needs.

•Both federal and state regulatory needs

will grow. The federal interest (Federal

Power Commission, Coast Guard) will be in

the safe and efficient handling of cryogens.

The State's interest lies primarily in

effective metering, sale and taxation of

cryogens.

•Non Department of Defense agencies will

show a decline of the total, primarily due

to the growth of the regulatory agencies.

•"Other" will remain small and constant,

as instruments become standards and as conceptual knowledge is developed to the

point of useful research.

4.4 Evaluation of NBS Program

4.4.1 Evaluation Criteria

Needs for NBS services to the cryogenic

measurement system fall into two major

categories: those determined by our own studies and initiatives, and those brought

to our attention otherwise, such as suggestions from within other units of NBS or requests from other agencies, both federal

and state. In any case, however, a similar

decision process is made, carefully accounting for a balanced program, internal capability and facilities, staff wisdom, and the

promotion of the mission and functions of

Institute for Basic Standards and NBS. Programs in support of these needs, whether

funded by direct appropriation or by transfer

of funds from other agencies, must be chosen

for the same basic reasons. The Congress has

wisely chosen a statement of the Bureau's

mission broad enough to allow the Bureau to respond to changing needs. By the same

token, such a freedom of choice demands of us

a continual appraisal of the most important

problems to tackle. Of the criteria for

choice, and therefore for action, four seem

to be vital to success: •Needs in Relation to Mission (what is the relevance on either a long or short range

basis?)

•Technical Opportunity (is it timely to take on a new program; is there a good idea?)

•Resources (can we bring enough manpower

and money to bear on the problem to ensure an adequate contribution?)

•Leadership (is there an energetic "ballcarrier" who wants to do the job?)

Unless all four criteria are met, any problem

that is tackled is not likely to have striking success. However, there are three characteristics

of our other agency work that do set them

apart from our own, and these evolve in the

following way:

•We wish to promote the efficiency of

government through effective utilization of

federal laboratories. When approached for

help by another agency, we consider what they

would have to spend to achieve our existing

capabil ity.

•The applied measurement programs of

other agencies give our staff practical

experience with problems in the field, and

thereby automatically enhance the relevance

of their work. We give priority to problems

that add to our capabilities to carry out our primary statutory functions.

•We provide technical assistance to agencies that issue regulatory standards.

The appropriateness and fairness of the tests

49
and measurement standards that define such

regulations are critically important to fair

and rational management of the Nation's

technology.

If further consideration is warranted, we proceed through checklists (sometimes formally and documented, sometimes informally)

that include at least the following criteria:

Evaluation Criteria - External

•Appropriate federal role?^

•Match to NBS mission

•Potential high impact

•Leverage of NBS measurement and data

services on given sectors of

the economy

•Importance of these services to fields

other than immediately represented

by measurements and data

•Importance of these fields within the

scope of national priorities

•Absence of alternative institutions who

can provide this information

Evaluation Criteria - Internal

•Utilize unique facilities, competences,

and staff wisdom

•Maintain and strengthen staff competence

•Provide scientific and technical expertise to NBS programs

•Provide Institute for Basic Standards

and NBS programmatic coherence

•Implement long-range strategic plan

Admittedly, these are only qualitative

guidelines, but since the process is iterative

and open to discussion over a period of

time, some arguments begin to take on weight

and become demonstrable while others do not. For instance, a "must" is that the program

be somehow quantifiable -- that it have

milestones for measuring progress versus

plans. The decision is ultimately the line

manager's responsibility, and he must bear

the consequences. We find the above guidelines invaluable and useful. They are especially useful as tie points to tether

the arguments and to make the decision

process open and visible.

^ This is of course, a most vexing question.

Guidance is found in the NBS and Institute

for Basic Standards mission statements,

several NBS internal Policy Guides, and Administration interest. Guidance is also

found in the following statement by a previous administration: "The legitimate

object of government is to do for a community

of people whatever they need to have done,

but cannot do at all, or cannot so well do

for themselves, in their separate and

individual capacities". (A. Lincoln, Springfield, Illinois, July 1, 1854).

The final key to our program evaluation

is how well the proposed program fits the

Division strategic plan. This strategic plan

is established by the cooperative action of

senior technical staff. Institute for Basic

Standards and NBS management, and the Evaluation Panel. Planning is, of course, a con- tinuous process, but this strategic plan is

formally documented and articulated annually

in the Division's Planning and Budgeting

Document (usually prepared each fall in

time for the annual Evaluation Panel meeting,

and the initiation of the budget cycle).

In this part of the evaluation process,

it is important to realized that both the

plan and the program are tested. Sometimes

we do modify the plan to fit the program,

but if so, we try to do this consciously and

systematically, to be fully aware of why the

strategic plan needed changing and what the

consequences are. 4.4.2 Evaluation Panel Role

The Evaluation Panel always plays an important role in this evaluation process.

The background and affiliation of the members

are perhaps more germane to this present

discussion than the names of the members

themselves. The affiliations of the Panel

members over the last few years (1975 back

through 1970) are given below:

Department of Physics,

University of Pennsylvania

San Diego Gas & Electric Co. Mechanical Engineering Department,

University of California,

Lawrence Berkeley Laboratory

Department of Physics,

University of Connecticut

Director, Superconductivity and Cryogenics

Programs,

Westinghouse Research Laboratories

Controlled Thermonuclear Reaction,

Lawrence Livermore Laboratory

Department of Chemical Engineering,

University of California

Department of Mechanical Engineering

and Applied Mechanics,

University of Rhode Island

Los Alamos Scientific Laboratory

The Evaluation Panel is charged with both

broad and specific responsibilities. The

Evaluation Panel

•Provides Bureau management assistance

in planning

•Considers importance and relative

priority of projects

50
•Makes recommendations on new program

initiatives

•Identifies areas of redirection

•Provides forum for technical staff

•Identifies barriers to progress

•Provides communication link with scientific and industrial organizations

We find the Panel especially valuable in

evaluating our strategic plan and promoting a certain degree of discipline in exposing our programs to critical review and evaluation.

4.4.3 Why NBS?

In Section 4.3, we discussed the impact of

NBS services and gave some specific examples

of the consequences of not providing those

services. In this Section, we shall examine

some of the factors that help make the NBS

role crucial

Part of the reason is historical. NBS has

supplied data and services to the cryogenic

measurement system for nearly 70 years (see

Section 4.1). As a result, we have developed

unique capabilities -- not just in facilities,

but more importantly, in staff experience --

a resource difficult, if not impossible, to duplicate elsewhere.

Industry values the third party independence and integrity of NBS, i.e., our impartial judgment. Companies and industrial

associations frequently plead with us to establish a first line measurement competence

in their technical area, even though they may

already have competent research laboratories.

Those industries who know they have an excellent product want their customers to be able

to make accurate and objective evaluations of

that product. If their own product claims

are based on measurements traceable to NBS,

customer confidence is enhanced. This is important also in foreign trade, for the

Bureau is regarded as highly abroad as it is at home. We call it neutrality and acceptance;

"neutrality" in the sense of an independent

third party; and "acceptance" in two ways.

Not only does the integrity, competence, and

independence of NBS often lead to the ready,

universal acceptance of our work, but also we

are able to accept proprietary data in con- fidence, which often facilitates the process

of objective technical review and evaluation.

Providing a fast and timely response is

possible in part to this ready acceptance.

NBS is also able to respond rapidly and

credibly because of the experienced staff,

having diverse backgrounds, which is available to assist in problem solutions requiring

many technical disciplines (as in the Apollo

13 and Staten Island LNG incidents).

NBS alone has the charter to provide both

national standards and international standards

through the aegis of the Treaty of the Meter.

The federal role of NBS is to provide the

basic measurements, data, and standards that

are required to support and enhance a diverse

national technology --the infrastructure

technology of cryogenics itself. NBS does

this in part by providing a sound technical

basis for regulations that will stand up in court. NBS was established by the Congress to be helpful, and this assigned function is a critical link between the basic research

community and those who have to put science

to work.

The coordination of such a nationwide

effort as this is best centralized so that

the Nation can have a strategic and integrated program rather than a piecemeal one, and can further benefit from the synergism

that naturally occurs in a centralized,

coordinated effort.

These principles are the lifeblood of the

National Bureau of Standards and are strongly

and deeply felt by each and every one of the

Cryogenics Division's professional staff

members, just as they are by every member of

the NBS as a whole.

Table 4-3 summarizes the crucial role of

NBS. (See page 53).

4.4.4 Program Evaluation

"We judge ourselves by what we feel capable

of doing; others judge us by what we have

done." Henry Wadsworth Longfellow.

The previous sections have described the

evaluation process; the following gives the

results of that process, in particular, the

judgment of the Evaluation Panel appointed

by the National Academy of Sciences/National

Academy of Engineering/National Research

Counci 1

The members of the Evaluation Panel are chosen by the above associations for re- cognized scholarly competance. The members

of the 1973-74 panel were: Donald N. Langenberg, Chairman , University of Pennsylvania; Paul L. Hathaway, San Diego Gas and

Electric Co.; H. Paul Hernandez, University

of California; John L. Mason, The Garrett

Corporation; John M. Prausnitz, University

of California; Clyde E. Taylor, Lawrence

Livermore Laboratory.

The following material quotes the summary

and general conclusions of the 1973-1974

report.

"Summary

"The Cryogenics Division's coupling with

outside client agencies, industries, and

associations is good, though more effort

should be made to achieve visibility at

the highest managerial levels of these

organizations

51
"The Panel believes that all three of

the Division's new program initiatives

are timely, relevant, compatible with

the Division mission and goals, and

worthy of support. On the basis of the

irmediaay of the problems being

addressed, rather than long-term importance or quality, the Panel ranked the

initiatives as follows: (1) Liquefied

Natural Gas Technology, (2) Cryotechnology for Superconducting Equipment,

and (3) Hydrogen: Future Fuel. Within

each initiative, portions of relatively

higher or lower priority were identified and discussed.

"General Comments

"The Division's technical and managerial

competence remains high. With the

possible exception of certain aspects

of its Liquefied Natural Gas (LNG)

Program, it maintains a good balance

between work related to its essential

basic-standards mission and work that

responds to national problems, such as the energy crisis. Even in the latter

area, the proposals and activities are clearly within the basic mission of

the Division.

"The Division effectively maintains

close coupling with its counterpart

industries and industrial associations.

Because these interactions are essential

and contribute to the Division's

success, they must be continued and

enhanced. The Division is well-known

at the operational level in industry.

However, the Panel does not believe that

U.S. industrial leadership at the vicepresidential level is aware enough of

the Division's capabilities in troubleshooting and contributions to engineering research. It is to the

Division's advantage to ensure that

those individuals who are in a position

to influence policy in government and

in industrial research foundations know

about its industrially important activities and well-earned international

reputation. Accordingly, the Panel strongly

recormends that the Cryogenics Division

consider ways to increase its visibility

in general and especially in high-level

industrial management circles.

"An important Division contribution

outside NBS has been its consultative

services to industry and other governmen.t agencies. The Panel urges that as many permanent technical staff,

including its younger members, as possible participate in this activity

as a means of ensuring continued

effectiveness and achieving more general

recognition of the importance of this

facet of its work."

The 1974-1975 panel members were Donald

N. Langenberg, Chairman , University of

Pennsylvania, Paul L. Hathaway, San Diego

Gas & Electric Co., H. Paul Hernandez,

Lawrence Berkeley Laboratory, Paul G. Klemens, University of Connecticut, James

H. Parker, Jr., Westinghouse Research

Laboratories, Clyde E. Taylor, Lawrence

Livermore Laboratory.

The following sections are quoted directly

from the panel's 1974-1975 report:

"THE ROLE OF NBS IN CRYOGENIC TECHNOLOGY

"The Panel was informed that the involvement

of NBS (primarily through the Cryogenics

Division) in cryogenic technology is sometimes questioned. The rationale for such

questions is apparently that, since cryogenic technology is a primary concern of

a variety of private-sector institutions,

many of the cryogenic programs currently

in progress within NBS might better be

carried out in these institutions.

"It is the view of the Panel that the current

activities of the Cryogenics Division in

the area of cryogenic technology are en- tirely consistent with the goals and

purposes of NBS and should not (and in

many instances could not) be left to private sector institutions, particularly when the independent position and

the high quality of the Division's work

is recognized.

"Let us consider some examples:

"A. Liquefied Natural Gas (LNG). The Cryogenics Division is studying the thermophysical properties of pure components

and of mixtures of the components of

LNG. The purpose of this work is to develop the basic reference data and

measurement techniques required to assure equity in the handling and transfer of

LNG, an activity which is rapidly becoming a major factor (billions of

dollars) in our fuel importation industry. The assurance of equity in

trade and certifiable measurement of

trade quantities is sel f-evidently an NBS function. If the LNG industry were

to assume responsibility for this program,

it could do so only be replicating,

probably several -fold and at considerable cost in time and money, the unique

facilities and expertise already in

existence in the Cryogenics Division.

We would then have one party to commercial transactions specifying reliability

of the measurements involved, or two

52
parties in conflict over the applicability

of different measurement systems. This

is just the sort of thing it is NBS's

function to avoid. That all of this is fully recognized by the LN6 industry is evidenced by the fact that it is providing

major funding for the NBS program through

its trade organization, the American Gas

Association.

"B. Cryogenic Materials. The Cryogenics

Division is studying the mechanical and

electrical properties of a wide variety

of materials for use in cryogenic en- vironments. The purpose here is to develop bench mark data for use in design,

a function which could be carried out

elsewhere only at considerable cost in

duplication and general credibility

and acceptability. Here again, the

special capabilities of the Cryogenics

Division are recognized in funding

supplied by the Advanced Research Projects

Agency and the U.S. Maritime Administration.

"C. Cryoelectronics. Several divisions of

NBS are engaged in developing applications of superconducting electronics.

Here the primary and immediate import

will be on the Bureau's own needs for

precision measurements and standards.

There simply is no other institution

which is in a position to supply the

technology needed for these special needs.

"D. Properties of Cryogenic Fluids. The

Cryogenic Division has provided a unique

public service in acquiring available

physical properties data, in performing

experimental measurements, and in formulating these data for use in thermal

computations for such fluids as helium,

hydrogen, nitrogen, methane and the like.

The integrity of their work is recognized

worldwide and has led to the broad acceptance of this basic data."

Evaluation Summary . Each year, the

Panel is charged with specific responsibilities in addition to its overall duty,

and accordingly, the response each year

centers about a different theme. Nonetheless, some general conclusions may be

drawn from the above reports. Others judge

us as having good coupling with our outside clients; having a timely, relevant and

balanced program; maintaining high technical

and managerial competence; and making an important contribution through our consultation services. Our special capabilities

are recognized in funding supplied by

counterpart institutions. We ai^e criticized

for having poor visibility at high level

management circles. Correcting the latter

deficiency could add leverage to our work.

On the whole, this outside review of our program is rather favorable.

Table 4-3. The crucial role of NBS

• Federal Role

- Need for data and services to accomplish a specific government function,

such as health and safety regulation

- Importance of these data and services

within the scope of national priorities

- Leverage of NBS data and services on

a given sector of the economy

•Diverse National Need

- Lack of direct incentives to a single

organization to perform the "services"

needed

- Diffuse benefit--high risk, low gain

- Multiple beneficiaries

•Provide National Standards

- Model established: measurement development, plus transfer of technology

•Impartial Judgment

- Neutrality

- Acceptance

•Unique Capability

- Unique NBS capability in equipment,

facilities, personnel, or experience

- Past success; acceptance

- Experience in related fields

•Fast Response Time

- Ability to respond rapidly and credibly

to a recognized need

•Technology Transfer

- Needs identified by cryogenic community;

well identified needs; well documented

successes •Preferred Alternative

- Absence of alternative institutions who

can provide this information

- Mission orientation

•Acceptance

- De facto standards of measurement, of

quality, of performance, and of practices

•Coordinated National Effort

- Importance of these data and services

to fields other than those requesting

the data

- Other agencies conjoined; synergism

4.5 The Future

We have indicated that cryogenics is

largely an infrastructure technology. It is

by and large hidden from the casual observer,

while at the same time occupying a central

position of great potential leverage on the

Nation's essential science and industry. The

53
cryogenic measurement system is in turn, an infrastructure of cryogenic technology.

Therefore, to anticipate the needs of the

future, it is necessary to assess the state

of cryogenic technology itself and the state

of the measurement system within that technology. Such assessments are carried out

periodically and systematically. The framework of the studies is discussed below.

4.5.1 Technology Assessments in Cryogenics

Overview . As mentioned briefly in Section

3,2, two overviews were made at the divisionas-a-whole level to document the infrastructure position of cryogenics in large national

programs (space, health, transportation,

etc.) and to identify leading indicators of

trends of the health of cryogenics.

The first, "Cryogenics and National Goals",

[39] was in 1968. At the height of the space

effort, it predicted the demise of that

program, its need for hydrogen technology,

and foresaw the growing importance of a practical helium technology and LNG as a fuel. It is perhaps interesting to note that

the Oil and Gas Journal at that time said

that "The U.S. is not generally regarded as an energy starved nation, and imports of LNG

will never be significant."

The motivation for the second overview,

"Trends in Cryogenic Fluid Production in the

U.S." [40], was to verify and update the

findings of the first. It seemed important

to let a little time pass, and then test the

structure and underlying assumptions of the

first benchmark study. It was an experimental check of the 1968 study and did

document the critical supporting role cryogenics plays in essential national industries.

Applications for Specific Customers . Once

the network of cryogenics in technology as a whole had been defined and tested, it was

useful to look at specific functional relationships between terminals in that network,

or the leverage of cryogenics in specific

customer applications. Four such studies were formally done and published.

"Superconductivity Programs of the AEC"

[41], predicted the need for efficient

cooling of long lines to helium temperatures

for power transmission. There are now four

major research groups involved in the development of just such superconducting power

transmission lines in the U.S. Precise

measurements (especially pressure measurements) are crucial to achieving the effective

cool-down of such long lines.

"Superconducting Levitation of High Speed

Vehicles" [42], was prompted by need of the

Department of Transportation to decide between

competing levitation technologies, such as

the floating of trains above a track on an air cushion, or supporting it on magnetic

cushions that may or may not use superconducting magnets. This study documented the

precise role of cryogenics in high speed

ground transportation and proposed several

possible ways to anticipate and resolve

potential cryogenic measurement problems.

"Current Developments in Cryomedicine"

[43] was meant to define what role, if any,

NBS should play in the field of cryo-medicine.

There did not appear to be a unique opportunity for NBS in the field of measurement

science in cryo-biology . Accordingly, no particular course of action was deemed to have a striking chance of success. A con- scious decision was made not to enter this

field.

"Water Pollution Abatement" (internal

study by Chelton) was the Cryogenics Division's first systematic look at environmental

problems. Again, a program was deliberately

not recommended, although both the need and

the technical opportunity (but for others) were present. Two technical conclusions were

reached: (1) The most extensive potential

application of cryogenics is that of supplying (liquid) oxygen instead of air to secondary waste water treatment plants to accelerate

decomposition, and thus upgrade present

plants and facilities; and (2) the most

sophisticated application of cryogenics is

the use of superconducting magnets for

colloidal filtration of river water. Nonetheless, criteria for NBS entering the field were missing. Specifically, the first case

was not really a cryogenic research problem,

for the handling of liquid oxygen is a well

established business. Neither was the second,

necessarily, since the construction of large

superconducting magnets has been accomplished

at the national laboratories.

Applications to a Specific National Need- - Energy . We have prepared technology assessments in three energy areas: LNG, hydrogen,

and superconductivity. Measurement services

and data to support these three technologies

promise to be the main enterprise of the

Cryogenics Division for the foreseeable

future.

Liquefied Natural Gas was addressed

at two levels — simply its peculiarities as

a cryogenic fluid, and as a commodity.

"LNG as a Cryogenic Fluid" [44] assumed

that the Nation is just now entering an era of the large scale use of liquid natural gas. This report then predicted potential LNG

problems, based on similar experience gained

when the Nation just began handling liquid

hydrogen as a commodity. It predicted specific

instrumentation problems in measuring pressure, temperature, liquid level, and flow.

It also predicted specific problems from

54
property data that are insufficient, have had

insufficient analysis, or are internally

inconsistent. This study documented the

practical utility of basic measurements and

launched the American Gas Association program

on LNG. Since LNG was a significant commodity in

trade, "Measurements of LNG in Commerce"

[45] examined the measurement basis for

purchase of LNG. This study found a six-step

measurement process which has, at present, no quality control or quality assurance built

in, and which is based essentially on a bid

and barter system. For instance, tank volumes

are fixed at room temperature by "strapping"

the tank with a tape measure, and then establishing some functional relationship between

liquid level and volume. This paper documents the advantage of basing the commercial

custody transfer on modern mass flowmetering

and property data instead. The goal is to establish an orderly, systematic, and scientific basis for LNG trade.

"Hydrogen: Future Fuel" [46] showed the

many technical, economical, and ecological

advantages that make hydrogen a prime candidate as a substitute chemical fuel of the

future. It was the first step in documenting

the needs for the present technical program.

"Superconducting Electrical Power Systems"

[47] was an effort to accelerate the application of this technology to an old, established,

and reliable industry. It found, among other

things, that:

•Technological leadership in superconducting machinery in the United States

can help to reduce generator imports

by up to 50%.

•Technological leadership by foreign

companies can help them to capture a larger share of the U.S. market.

•Superconducting generators may be

essential to realizing the full advantage of the large fast breeder reactors.

Specific technical program plans were

drawn to enable the development of superconducting electrical generators, in cooperation

with the large electrical machinery manufacturers. This effort helped stimulate

the development of applied superconductivity

in this country, made public much privately

held information, and has led to major new thrusts to provide adequate measurement

services in support of this field.

Analysis of Major Technical Threats . Since cryogenics is a rather well -bounded

and self-contained technology, it is not

likely to be replaced by a competing technology, such as electrical measurements re- placing mechanical or optical measurements,

or TV phones replacing business commuting.

The principal threats are from among the

rivals within the technology itself, es- pecially from abroad. Since cryogenics was "invented" abroad, we have never suffered

the delusion of thinking that NBS has the

world's supply. Instead, world-wide awareness is central to our supplying timely and

essential measurement and data services to the U.S. cryogenics community.

The most recent systematic foreign technology assessment was the monitoring of

applications of superconductivity in the USSR,

Switzerland, W. Germany, France, England, and

Japan (internal study). For instance, NBS

staff visited the Fawley (U.K.) power station

to inspect the 3250 HP superconducting motor;

discussed national funding of private enterprise with the U.K. - National Research

Development Council; discussed the German

superconducting levitated train in Munich;

and witnessed the Japanese 4-passenger

demonstration superconducting train. We found foreign efforts to be aggressive, well

ahead of our own, and funded in cooperation

with their national governments. This study

documented the magnitude of the foreign

exploitation of U.S. technology and helped

provide a sound basis for designing our own measurements and data program.

Analysis of Major Technical Barriers . The question of reliability and cost is

always raised whenever a commercial application of cryogenics is suggested. Helium

supply, management, and control lie at the

heart of realizing practical superconducting

systems

Strobridge [48] documented that enough

experience has been accumulated in the design

and operation of low temperature refrigerators

and liquefiers to safely assume that any

cooling requirement can be met. This study

frequently obviates proposals for new refrigeration surveys, or, in some cases, re- frigeration development programs, and provides a common data base for refrigeration

dependent technologies (e.g., accelerators

and transportation).

We have seen that cryogenics is an infrastructure industry, serving in an indispensable way the needs of other industries. Similarly, the science of cryogenics

is an infrastructure science. Seldom are

the low temperatures themselves of interest,

except perhaps to establish some record.

Rather, their real importance lies in

enabling the basic understanding of other

phenomena, i.e., increasing conceptual

understanding.

The essential point is that here, too,

cryogenics plays an essential but invisible

role. It is usually not the cryogenics per

se under study, but rather that the ultra

low temperatures cause basic physical

55
phenomena to be greatly simplified and thus

be more susceptible to understanding and

use.Accordingly, we conducted in 1969 an internal planning study to define needs in

millikelvin research and propose specific

action to meet those needs. This study

recommended specific measurement and data

needs in the millikelvin and sub-mi 1 1 i kelvin

range. These plans included the development

and improvement of standards and measurement

techniques, as well as techniques for

obtaining and maintaining low temperatures.

Analysis of Major Technical New Opportunities . The studies above have in common

the motivation of need in relation to mission. A parallel requirement of a sound

program is the existence of a timely technical

opportunity, and our formal technology

assessments have not been without this

component as wel 1

Cryoelectronics has been addressed in

this fashion twice, in harmony with the

notion of reviewing and checking our predictions periodically. The first was an internal planning study which documented

developments in superconducting devices in

d.c. voltage, direct current, magnetic

field, RF current, RF power, pulse technology,

RF noise, and temperature (internal study).

It articulated a measurement role for NBS and

formed a new organization to consolidate an NBS program in cryoelectronics.

"Developments in Cryoelectronics" [49] was published to document the development of new electronic instrument, s taking advantage

of the unique properties of superconductors.

It found that commercial activity has been in

the nature of an investment in the future:

very few devices have actually been sold yet.

It suggested that computers, information

transmission lines and magnetocardiography

may become commercially significant applications of superconductivity.

It suggested that many other superconducting devices also perform specialized

functions uniquely, and would repay the

cost of development without necessarily

generating a large market. This study is

helping to provide the basis for future

measurement and data programs.

An intense and in-depth effort on superconductivity was conducted at the request

of the President's Science Advisory Committee (PSAC), which required the participation of many experts outside of NBS.

In a sense, it was a conference-style Delphi

exercise. The result was an oral briefing to PSAC on the current status and future promise

of superconductivity. It covered such topics

as new superconductors; magnets and their

application to transportation, ore benefication, and water pollution; electric power

generation and distribution; and cryoelectronics. As a result, the President's

Science Advisor formally requested the

Department of Commerce to take a leadership

position for the exploitation of cryogenics

and the creation of new industries.

As a result of this briefing, a plan was developed to help assure the successful

commercial exploitation of cryogenics. The

goal was to assist the Department of Commerce

to create its own policy for the effective

application of cryogenic technology for

public benefit.

Summary of Cryogenic Technology Assessments . These studies have given visibility

to our decision making, and invited staff

participation by those most likely to be

affected by the decisions. A stronger, more

timely program has been the result.

4.5.2 Driving Forces

The overall goal of the National Bureau

of Standards is to strengthen and advance

the Nation's science and technology and to facilitate their effective application for

public benefit. Accordingly, it is not

surprising that we find both technical and

societal driving forces at work, influencing

the trends of our program.

Technical driving forces (applied superconductivity, hydrogen fuel, LNG imports,

etc.) were noted in the specific technical

sections above. In addition, as implied in

the NBS Goal, we must continually give

special attention to the public and private

institutions through which our measurement

and data services benefit people. Some

noteworthy trends in such societal driving

forces and our expected response to them

follow below:

•Services influencing the manufacturing

sector will increase, reflecting the

fact that cryogenics in general, and

superconductivity in particular, are coming of age.

•Interaction with the service industries

will also increase as the interaction

with the public energy utilities and

the Energy Research and Development

Administration increase.

•There is little direct contact with

the consumer per se, and no significant

change is expected. Contact will

continue to be made through service

industries and regulatory agencies.

•Both federal and state regulatory

needs will grow. The federal interest

will be in the safe handling of cryogens.

The state's interest lies in effective

metering, sale, and taxation of cryogens.

As a result, we shall have to maintain a balanced program supplying both measurement

services and data to the cryogenic measurement system.
4.5.3 Emerging Technologies

We have seen that the major developments

in cryogenics in the next few years that will

have significant impact on the technology of

the country and its balance of trade are the

widespread international use of liquefied

natural gas, applications of superconductors,

and potential uses of hydrogen. Cryogenic

measurement and data services are essential

to meet the developing needs for metrology,

design data and applied cryogenic research.

Figure 7 shows these technological trends

and our response to them. The check marks are

a qualitative representation of our present

emphasis, which is in harmony with the timeliness (or urgency) of the technological

trends. LNG is upon us now; superconductivity is a technology that is finding wider

use; while the most pressing need for hydrogen -- Future Fuel is data for decisions.

These emerging technologies will demand

continued NBS support for the foreseeable

future. See Section 5. for specific re-

^ commended actions.

4.5.4 Impacts of the National Measurement

System Study

This study of the National Measurement

System documented for us the complete

process that must be undertaken to provide

a complete measurement service. For instance, our LNG budget initiative submitted in the

spring of 1974 was deliberately constructed

to include all three necessary elements:

measurement science, data base, and technology

transfer (includes safety, interstate and

international cooperation, effective use of

the Office of Weights and Measures, and

training). Thanks (in part) to the NMS study, new programs now use the guidelines so developed to assure a complete and comprehensive approach.

In addition, we have become more sensitive

to the measurement system concept in all our programs, not just the LNG program.

For instance, we are making an inventory of

all of our measurement services. We also

are documenting our operations throughout

the dissemination network, e.g., regulatory

agencies, state offices, central standard

authorities, and education programs.

Left to our own devices, we would most

likely have conducted a technological

impact study (the science and technology

profile of the cryogenics industry needs

updating) and not an examination of our part of the National Measurement System.

Left on our own, we would have benefited by

documenting new and other needs and developing programs accordingly. We would have

lost the understanding we now have of a "complete" program, and our role in the

infrastructure of the National Measurement

System.

5. SUMMARY AND CONCLUSIONS

5.1 Key Developments

This study has shown that there are three

emerging technologies within the broad field

Cryogenics with a need for a complete and

TECHNOLOGY TRENDS |

OUTPUTS Liquefied

Natural Gas

Superconductivity

Hydrogen:

Future Fuel

Physical Measurement

Materials Data Base

Cryoengineering Services

FIGURE 7. Emerging technologies in cryogenics.

57
consistent system of measurements and data.

Specifical ly:

Liquefied Natural Gas . A complete and com- prehensive measurement system for the liquefied natural gas industry needs to be developed, with special emphasis on quantity

gaging in storage and ship tanks, flowmetering for determination of both mass and

heating value, and basic measurements of

thermal and mechanical properties of structural materials.

Hydrogen . Basic measurements and data are required now to support the development of

hydrogen as a fuel, in such areas as improvement of hydrogen liquefaction efficiency,

evaluation of methods of recovering liquefaction energy, of hydrogen-compatible ma- terials of construction, and development

of improved insulation materials and an instrumentation and measurement methodology

for the commercial exchange of liquid hydrogen. Superconducti vi ty . Superconductivity con- nects cryogenics measurements and data to the electrical power industry, for power

transmission, generation, and storage.

Knowledge needed includes heat transfer

rates, behavior of helium refrigerant

flow systems (including the response to instabilities), and the degradation of the

superconductors with time and stress.

Superconductivity is also a means of

employing cryogenics to develop new or improved measurement techniques in fields

outside of cryogenics. The SQUID (Superconducting Quantum Interference Device) is

demonstrating promising applications in

magnetocardiography , geothermal prospecting, determining molecular constants, and

spectroscopy of all kinds. Indeed, the

SQUID appears to be as versatile as the

Laser as a measurement technique, and is,

of course, fundamentally a cryogenic device.

Some of the needs of each of these parts

of the National Measurement System for

Cryogenics are illustrated below.

5.2 Liquefied Natural Gas (LNG)

LNG is a Cryogenic Fluid (NBP 110-140 K)

but unlike the simple fluids of our usual

experience it is:

•A non-ideal mixture of five or more hydrocarbon fluids and nitrogen;

no known mixing rules exist at this

time, and therefore the mixture properties are not yet predictable; all

must be measured.

•Furthermore, the mixture fraction varies

with source-time-and storage treatment.

•LNG is primarily an energy storage

media, because its energy content is

about 600 times that of natural gas at atmospheric conditions.

Peak shaving accounts for the largest

number of LNG facilities with 106 being

completed within the U.S. This number includes

55 actual peak shaving plants (which include

liquefaction, storage and gasification equipment), and 51 satellite facilities (which

comprise a total storage capacity of approximately sixty-five billion cubic feet (equivalent gas volume) and a total liquefaction

capacity of approximately 295 million cubic

feet per day.

LNG presents not only a nationwide problem,

but an international one. Contrary to popular opinion, the U.S. is not dependent

upon just one source. Imports are planned

from Malaysia, Australia and South America,

for instance. We will also "import" from

Alaska. In fact, the U.S. is presently a net exporter of LNG (to Japan) due to con- tracts signed in 1968.

Industry desires NBS assistance in this

national problem. For instance, the president

of the American Gas Association has written

the Secretary of Commerce, requesting mea- surements and data assistance from the

Department of Commerce and the NBS. The Secretary gets many such letters, to be sure, but our study has shown that the

Department of Commerce and NBS have been

earmarked as the international and interstate connection agency. International

contracts call out NBS as the measurement

authority. In addition, we also have an inter-state responsibility to provide LNG

assistance to a variety of federal, state

and local authorities on the inter-state

transfer of LNG. LNG has grown so fast and to such a size

and complexity that our NMS study revealed

that it is now timely for the Department

of Commerce to take steps to assure quality

control and continuity in this part of the

NMS.

The overall measurement and data needs

for LNG identified in the course of this study

include:

•Heating Value (Energy) metering for

national and international trade

•Quantity gaging

•Thermophysical properties

•Properties of structural materials

•Instrumentation and data for Energy

Conservation

• Safety Criteria

The needs for the safe and effective

utilization of liquefied natural gas are

58
most urgent. They include both tools and

techniques for physical measurements as well

as a data base for materials selection and

use. 5.3 Hydrogen

With respect to hydrogen, there seems

to be little doubt that it will become a major source of fuel for the future. Needs

are centered about providing an adequate

data base--reference data, reference materials and performance standards--to give

a rational basis for decision making in this

field.

Candidate Markets for cryogenic hydrogen,

without regard to priority or imminency,

are:•Transportation--to fuel aircraft, autos

and ships;

•Aerospace--rocket and spacecraft fuel;

•Energy storage and transmission--carrier

of nuclear or solar energy from sea-toshore or overland;

•Utilities--fuel for integrated gaselectric utility operations and a portable fuel for rural communities;

and to a lesser extent:

•Superconducting and cryoresistive

electrical power cables--to be used as

a closed-loop coolant (electricity

and hydrogen are del i vered)

•Industrial processes--to provide high

purity hydrogen gas upon demand.

Assuming that a future market exists for

liquid hydrogen we must dispense the fuel in an efficient, fair and safe manner.

The efficiency of liquid hydrogen fueled

systems can be improved on three fronts:

(1) lightweight, efficient and inexpensive

insulation materials are needed, together with

national insulation transfer-standards;

(2) data are needed on advanced construction materials that are lightweight, strong,

inexpensive, resistant to hydrogen em- brittlement and brittle fracture, and having low heat capacity and thermal conductivity.

(3) liquid hydrogen handling procedures,

though highly developed and successful in

the aerospace program, will have to be re- vised for commercial applications.

Liquid hydrogen enjoys an enviable safety

record in the aerospace industry. However,

the safe use of hydrogen in commerce will

require thorough re-evaluation of: 1) com- patible materials of construction, 2) handling procedures and regulations, and 3) ex- plosion hazards.

We must also be able to guarantee equity

in hydrogen commerce. Thus, traceable

measurement standards are required for mass

flow, pressure, temperature, and quantitygaging. Liquid hydrogen instrumentation

has not significantly advanced in the past

ten years since the peak of the space program. Major efforts will be required to meet the needs of a commercial cryogenic

hydrogen fuel market. Instruments suitable

for aerospace applications are not usually

appropriate for commerce and vice versa. Measurement standards are needed to bring

all aspects of hydrogen instrumentation into

quality control within the National Measurement System.

5.4 Superconductivity

Superconductivity was discovered at about

the same time as the Wright brothers first

flight, yet remains largely an undeveloped

technology. This is indeed curious since

the potential practical applications of super

conductivity are staggering. For instance,

it is widely held that superconductors could

be used to advantage to transmit electrical

power with almost no loss, to make magnets

of a size not heretofore possible for energy

storage; to upgrade low quality iron ore in

magnetic mineral processing; to improve the

quality of kaolin; to purify water via

colloidal filtration; or to float high speed

trains on a magnetic cushion.

Yet none of these possibilities are approaching commercial realization in the

United States. The problem does not appear

to lie with the superconducting wires themselves, as over 500 materials are already

known to be superconductors. Furthermore,

a dozen manufacturers here and abroad are producing superconducting wire and cables

in nearly commercial quantities at prices

approximately one- tenth that of copper wire

for the same current carrying capacity.

The problem appears to lie instead in

providing a reliable, safe and convenient

supporting cryogenic environment. We need

to provide the helium measurements and

data base essential to the successful develop

ment of superconductivity. NBS need not address the applications of superconductors

mentioned above, but does need to provide

the supporting measurements and data on:

1) helium heat transfer and fluid dynamics;

2) instrumentation and measurement systems

for helium management, and 3) data on the

degradation of superconductors.

Since heat transfer and fluid dynamics

are strongly interrelated, a thorough understanding of the fluid dynamic aspects is

essential. The important consideration is

that all flow irreversibilities ultimately

show up in the form of heat, thus reducing

the capacity of the helium to absorb other

losses. We need to provide basic data and

understanding on the properties and behavior

59
of helium to provide engineering and process

designs, predictions, and scaling of equipment.Effective helium management will require,

at least, sensors for pressure, temperature,

quantity and flow rate. We need to provide

such instruments through developments which

take advantage of the low temperatures and

optimize the instrument output. For instance,

superconductors themselves may be used for

thermometers and level gages. We need a new generation of instruments and measurement

techniques tailored to liquid helium as a technical fluid.

The third consideration arises from the

fact that practical superconducting systems

will not operate under ideal laboratory

conditions. They will be subjected to mechanical stresses during shop and fieldsite fabrication; they will, at least

occasionally, be subjected to unduly rough

handling; they will have unprogrammed ex- cursions in current, temperature, and mechanical stress during fault conditions. Even more fundamentally, they will certainly

show typical manufacturing variabilities

and may show time dependent deterioration

of their desired design properties.

The foregoing discussion has focused on the physical measurements, units, standards

and essential technical data needed to support the needs of the National Measurement System for cryogenics. In addition,

cryogenics itself may be used to advantage

to develop new or improved measurement

technology outside of the field of cryogenics.

Specifically, the SQUID is being used to improve technology transfer from our physical

measurements program to other federal agencies

and industry; and to extend the impact area

of the measurement program. Since physical

measurements are almost always reduced to electrical measurements, the list of cryoelectronic applications is almost endless.

Accordingly, it is particularly timely to open up the way for extensive new applications of cryogenics to physical measurements

units and standards.

5.5 Summary

Our study of the National Measurement

System for Cryogenics has shown that major

developments in the next few years will occur in cryoelectronics, the widespread

international use of liquefied natural gas,

potential uses of hydrogen, and applications of superconductors. Major other

federal agencies will doubtlessly continue

to solve their specific cryogenic technological problems through a variety of means, including, but not limited to,

soliciting the services of the Cryogenics

Division. We regard this constituent of our total program as a necessity to maintaining our institutional health, and our sustaining a current awareness of national

needs and goals.

However, no other instrument of the government has the prime responsibility to assure

the proper functioning of the Nation's system

of cryogenic measurement. The needs as discussed briefly above and documented within

the body of this study, demonstrate that

now, more than ever, it is time for a central,

coordinated, coherent national effort on the

part of NBS to bring and keep the cryogenic

part of the National Measurement System into

qual ity control

60
METHODOLOGY OF THE STUDY

APPENDIX A. One purpose of the Cryogenics Division

study of the National Measurement System was

to clarify and understand what is necessary

to provide a "complete" measurement service,

and to identify the role cryogenic measurements in the infrastructure of the National

Measurement System.

We hoped by this process to document the

way information was gathered, how conclusions

were reached, and how the results were validated. Such hindsight could then be applied

to the systematic development of new mea- surement services in the future, as well as to improving present services. In the following material, we shall examine our particular

methodology in four categories:

1. Mechanism for Selection of Data

Sources;

2. Transmission Mechanics, the means by

which the desired data was conveyed;

3. Contact Mechanisms, used to obtain

the desired data;

4. Sources of Information or Validation,

Table A-1 is a matrix designed by Dr. R.

C. Sangster, National Measurement System

Coordinator, that conveys at a glance much

about the study. The blocks in the matrix are divided by a diagonal. The upper left corner

refers to the process of obtaining results;

the one in the lower right deals with the

process of val idating the results. "0-L-M-H"

gives a rough quantitative estimate of the

importance (to this study) of the results in

terms of zero, low, medium, or high.

The following narrative describes each

of the four tactical means listed above.

1. Mechanism for Seclection of Data

Sources.

An analysis of NBS clientele was very

important to obtaining data. Many of the

clientele (state weights and measures officials and compressed gas suppliers) played an essential role in validating our results. In the case study cited in this report, our

results were crucial to the commerce between

many of our clientele. They were profoundly

affected (by law) by the results, and therefore had a vested interest in promoting valid

results.

The NCSL membership, per se, was not used because the Instrument Society of

America (ISA) had already formed an Ad Hoc committee on a specific measurement, namely

cryogenic flow measurement. This committee

provided an extensive review and definition

of the national needs for cryogenic flow

measurements and standards, and we used this resource extensively to illustrate the practical realization of general principles.

Invaluable help was obtained from the

Compressed Gas Association (CGA). The CGA is

a nonprofit corporation which represents all

segments of the compressed gas industry in

the United States, Canada, and Mexico. They

also have associate members in European and

Asian countries. Among its membership are over 250 companies, including North America's

largest firms, devoted primarily to producing

and distributing compressed, liquefied, and

cryogenic gases, as well as leading chemical

industry corporations that have compressed

and liquefied gas divisions. They contributed valuable insights to the mechanics of

the National Conference on Weights and Measures, especially as to how a code is developed and promulgated through the documentary

system. Perhaps prompted by the interest of

the CGA and the states in "type approval" of

meters, members of the instrumentation industry were very helpful.

The U.S. Department of Commerce (DoC)

compiled and published many statistical

summaries that were invaluable to this type

of study. For instance, the SIC codes lead

immediately to the "Current Industrial

Reports", in our case Series M28C, which

gives frequent and accurate summaries of the

production of cryogens. The "Alphabetic

Index of Manufactured Products" is a com- panion to the better known "Standard In- dustrial Classification Manual " . Other

useful Department of Commerce publications

include "Industry Profiles", and the annual

"U.S. Industrial Outlook". The latter is

especially useful, for it not only summarizes

statistical data, but also forecasts growth

and the reasons (e.g., new uses for old

products) for this growth. "Mineral Facts

and Problems", published by the U.S. Department of the Interior, provides a resource

similar to the "U.S. Industrial Outlook", but

is even more exhaustive in its treatment of

cryogenic gases.

Private compilations, such as the Dunn

and Bradstreet's "Million Dollar Directory",

while giving a brief overview of a particular

company, also gives the SIC codes for the

products manufactured by that company. For

instance, "Cryostats" do not appear in the

SIC Manual, but can be found in a roundabout

way from Dunn and Bradstreet, if one knows even the name of only one firm in the cryostat business. Once the SIC code is found

for a particular product, then this resource

lists al

firms reporting under that code.

In this way, every firm in that business is

A-1
TABLE A-1. Means used to obtain and validate data.

1. MECHANISM FOR SELECTION OF SOURCES

OBTAIN ^^^^-^^

^-^'"^

/ALIDATE

Analyses of NBS Clientele

Analyses of NCSL Membership

Analyses of Instrumentation Industry 1

^^""^

Analyses of Other, Similar List _IL-'--^''h

Use of SIC Codes for Analyses

Staff Judgment/Wisdom

Analyses of Statistical Compilations

2. TRANSMISSION MECHANICS

Published Literature

Ul — ^

^^-^^ H Formal Meeting Presentation

LI

" ^ ^-—^

H Organizational Statement

Ul — ' ^^'^^ H Personal Statement

1L — ^-^^ H Advertisements M ^

— 0

Clientele Customer Lists

1L _^

^—-""^

0

3. CONTACT MECHANISM

Literature Search

u —-

—-—^—

H Retention of Consultants

Mfl — — h Conversation - Visitor to NBS

u ^—-

n

H

- At off-site location

u ^—

n ^—

h

- By telephone

rt _^ ^ h

- By visit to source's site

Ul —

—

^^-^^ H Correspondence

M ——

rn - ^ M Formal Pol 1 ing/Canvass/Questionnaire

n

0 Delphi Studies

1 -

L —

L Other Formal Forecasting Techniques

Ul ^—'

' ^-"-^""^ 0 Special Conferences (NBS Sponsorship)

u

n^ H Trade Show Exhibits by NBS

U ^

^--^^^

0

Round-Robin/Inter Comparison ^^-^^'^ U ^ H Training Courses ^^^^

0

Construction of New Institution 0^-^^^

0

A-2
TABLE A-1. Means used to obtain and validate data (continued)

OBTAIN ^^^^'^ ^--^^

/ALIDATE

Attendance at Conferences & Meetings

Statistical Compilations

4. SOURCE OF INFORMATION OR VALIDATION

Academic People & Institutions L —

M Prof., Tech. Soc, & Publishers H ^—

H International & Foreign Organizations

^^^^^^^^

Documentary Standards Bodies

^L — ^H Ref. Data & Mat' Is Organizations H ^^^^^ H Instrumentation Industry

H ^^^^^ H NBS Evaluation Panels

L M Other NBS Units H — ^—-"""''^

H Nat'l Conf. WTs & Meas/St. etc. OWM's ^^"'^ H Nat'l Conf. of Standards Laboratories 0 ^^^-^

^^—^ 0 Stds & Testing Labs & Services M^-——"^'^ H Governmental Regulatory Agencies 0 "

0 Other Federal Government Agencies ^---^^

State and Local Governmental Agencies H ^

^H Trade Associations H ^—

^-^^^^ H Trade Press ^M —

0 Private Companies H —

— H Consumer Organizations L ^

^^^^^ 0 Popular Press

0 ^

^--^^ 0 Other (See Text)

H —

—'— H Staff Wisdom/Previous Studies H ^^^--^ — —^ H

A-3
revealed with certain of its vital statistics.

The use of these statistical resources

led us immediately to corporate Annual Re- ports, which are required annually by the

SEC, and whose accuracy must be unquestionable. We gathered a number of such reports,

and they proved to be one of our most valuable resources of specific, fine-grained

information, plus giving projections for the

future. We plan to keep a comprehensive and

current set of corporate Annual Reports as a ready reference to answer "who needs it", and

"what are they doing with it?"

2. Transmission Mechanisms

When the State of California began

public hearings on a code for fluid metering

of cryogens, it was suggested that the Cryogenics Division of NBS provide "best values"

data for inclusion in the California Code.

The gases under consideration were limited to oxygen, nitrogen, argon, and hydrogen. At

the request of both the Compressed Gas Association and the State of California, we generated skeleton tables, which were published in the California Code. In addition,

the Cryogenics Division provided a source

document, NBS Technical Note 361 "Saturated

Liquid Densities of Oxygen, Nitrogen, Argon,

and Parahydrogen" [1]. The latter document

was produced specifically to allow traceability of the selected values. It was revised in 1972 to include compressed liquid

densities, and again in 1974 in a metric

format. These NBS property data are specifically called out in the California Code

and accordingly have the same weight of law

as the flowmeter calibrations and tolerances

themselves.

Other transmission mechanisms include:

•Codes, Standards, and Recommended

Practices, such as adopted in Handbook

44;

•Properties Data. NBS property data for

several cryogens were adopted in Handbook 44. In addition, there is no doubt

that the wide dissemination and knowledge of the NBS cryogenic fluid property work was the original factor

leading the regulatory agencies and

the CGA to come to NBS in the first

place.

•International Conventions. At one time

or another, we have cooperated with

the International Organization of Legal

Metrology (OILM) to facilitate the

adoption of international codes; performed type testing of instruments of

foreign manufacture as part of the

program; and promoted and facilitated

visits by many representatives from

other nations, including Germany,

France, and the United Kingdom.

•Steering Committee. In the case history used for illustration, the

Compressed Gas Association formed a steering committee to help provide

a degree of quality control to the

program, but especially to help substantially by providing guidance and

advice at critical stages of planning

and implementation of the program.

This committee met three to four times

a year during the nearly eight-year

life of the program. In addition,

state weights and measures officials

routinely attended these meetings,

which provided an invaluable forum

for the cooperative solution of vexing

problems.

Advertisements and other trade literature were of moderate importance in locating

meter manufacturers and documenting accuracy

claims. They played no role in validating

the results, unless one cares to note any

changes in advertising copy that might have

occurred after the program.

3. Contact Mechanism

Contact mechanisms may be viewed as the

terminals of the transmission mechanics

described above, and accordingly will not be

re-addressed at any length here. Only a few

observations may be in order:

•Conversations - especially face-to-face

meetings, such as described under "Steering

Committee" above were a prime source of

really useful data.

•Forecasting plays a major role. For instance "Normative" forecasting was performed by the ISA Ad Hoc committee mentioned

in the study. Goals, needs, and desires were

specified, and the Ad Hoc committee then

worked backwards to the (then) present to define what capabilities either existed or could be extrapolated to meet the goals.

Section 4.5 described the major role forecasting plays in developing the Division's

total program of measurement and data ser- vices . •Round-robin intercomparisons are at the

heart of transferring the NBS measurement

capability to the states, producers, and

meter manufacturers. For instance, the State

of California has now calibrated no less than

58 out of the 60 meters used there in liquid

nitrogen commerce by this means. To further

facilitate such intercomparisons, NBS has

built and is currently proving a transfer

A-4
standard of its own. Similar round-robins

have been conducted for years on thermocouple

materials. Section 2.4 describes other

inter-comparisons accomplished through the

use of other reference materials.

Numerous contacts were made within the NBS

and described in Section 2.4.1, under

NBS Infrastructure .

4. Sources of Information or Validation

Many sources of information were of

necessity described in the previous three

sections. Accordingly, the purpose of this

section will be to summarize the above, and

to comment in a general way on the utility of

some of the sources.

For this particular study, the Popular

Press, Consumer Organization per se the Trade

Press, Federal Agencies (regulatory and

otherwise), the National Conference of

Standards Laboratories (NCSL) and academic

institutions did not constitute a major

resource, although they surely would in other

types of studies.

Some groups ranked low as input sources,

but were virtually indispensable to validating the results. Such groups include international and foreign organizations and documentary standards bodies (the NCWM provided

little input, but was essential to codifying

the results); the main contribution of the

NBS Evaluation Panel was in providing an overview of the study as a whole and aiding

in the technical quality control.

A third group could be ranked as "medium"

on the input side, but "high" in terms of

validation. For instance, especially in the

earlier stages of the physical evaluation of

our flow system, round-robins were conducted

with industrial testing laboratories. This

cooperation not only gave us a head start in our own facility, but also opened the door

for eventual international agreement (via the

OILM, for instance).

The fourth group ranks "high" on both

input and validation, and accordingly was included in the previous sections. For completeness, they may be listed as: professional and technical societies (e.g..

Instrument Society of America, Compressed

Gas Association); reference data organizations (e.g., the National Conference of

Weights and Measures for Handbook 44; and our own Tech. Note No. 361); the instrument industry (via the Instrument Society

of America and instrument manufacturers).

Other NBS units were invaluable in helping

design the experiments (e.g., Applied Math

Division), in codifying the results (e.g..

Office of Weights and Measures) and in

furnishing other essential services (patent

advice). The role of state agencies, trade

associations (Compressed Gas Association)

and private companies (cryogen producers,

instrument makers) have already been mentioned. The Annual Reports of these private companies have proven to be gold mines

of documented needs and opportunities.

Finally, we come to "staff wisdom".

This study of the National Measurement

System is based on 20 years of work by

literally hundreds of men and women in the

Cryogenics Division of NBS. This resource,

especially in terms of accumulated experience, would be impossible to duplicate

elsewhere. Accordingly, "staff wisdom" was

of inestimable value throughout the study.

A-5

REFERENCES

[I] Roder, H. M., Standard Liquid Densities

of Oxygen, Nitrogen, Argon and Para Hydrogen, Nat. Bur. Stds. (U.S.) Tech.

Note No. 361 (1968) (Revised-1972; Metric

Supplement-1974)

[2] Arvidson, J. M., and Brennan, J. A.,

Pressure Measurement, ASRDI Technology

Survey, (to be published).

[3] Measurements and Data 1_, No. 2, 101-112

(Mar-Apr 1973).

[4] Cruz, J. E., Rogers, E. H., and Heister,

A. E., Continuous Liquid Level Measurements with Time-Domain Reflectometry. Book, Advances in Cryogenic

Engineering, 18, 323-(Ed.) K. D. Timmerhaus (Plenum Press, Inc., New

York, N.Y., 1973).

[5] Willis, W. L., Disturbance of Capacitive

Liquid Level Gauges by Nuclear Radiation, Book, Advances in Cryogenic

Engineering, 12^, 665-72, (Ed.) K. D. Timmerhaus (Plenum Press, Inc., New

York, N.Y., 1967): See also, Willis, W. L., and Taylor, J. F., Time Domain

Ref lectometry for Liquid Hydrogen Level

Detection, Unclass. Rept. LA-3473-MS,

Los Alamos Scientific Laboratory, Los Alamos, New Mexico (Feb. 1966).

[6] ASME, Fluid Meters, Their Theory and

Applications, 6th Edition (ASME, New

York, N.Y., 1971).

[7] ISA, Standard Practices for Instrumentation, Instrument Society of

America, Pittsburgh, PA. (1970).

[8] ISO Recommendation R541 , Measurement of

Fluid Flow by Means of Orifice Plates

and Nozzles (Jan. 1967).

[9] Richards, R. J., Jacobs, R. B., and

Pestalozzi, W. J., Measurement of the

Flow of Liquefied Gases with Sharp-edged

Orifices, Book, Advances in Cryogenic

Engineering, 4, 272-285 (Ed.) K. D. Timmerhaus, (Plenum Press, Inc., New

York, N.Y., 1960).

[10] Rodeley, A. E., Vortex Shedding Flowmeter, Measurements and Data, No. 18,

(Nov. -Dec. 1969).

[II] Wyle Laboratories, Final Report, Contract No. NASB-1526, Liquid Hydrogen

Mass Flowmeter Evaluation (Jan. 1965).

[12] Mann, D. B., ASRDI Oxygen Technology

Survey, Flow Measurement Instrumentation, NASA SP-3084 (1974). (For sale

by the National Technical Information

Service, Springfield, VA 22151, Price

$4.50).

[13] Sparks, L. L., Low Temperature Measurement, ASRDI Oxygen Technology

Survey, Volume IV, NASA SP-3073 (1974).

(For sale by the National Technical

Information Service, Springfield, VA 22151, Price $3.75).

[14] Roder, H. M., ASRDI Oxygen Technology

Survey, Volume V: Density and Liquid

Level Measurement Instrumentation

for the Cryogenic Fluids Oxygen,

Hydrogen and Nitrogen, NASA SP-3083

(1974). (For sale by the National

Technical Information Service, Springfield, VA 22151, Price $3.75).

[15] Zudkevitch, D., and Gray, R. D., Jr.,

Impact of Fluid Properties on Design

of Equipment for Handling LNG, Ad- vances in Cryogenic Engineering, 20,

(Ed.) K. D. Timmerhaus (Plenum Press,

Inc., New York, N.Y., 1967).

[16] Olien, N. A., The Cryogenic Data Center,

An Information Service in the Field of

Cryogenics, Cryogenics Vol. 11, No. 1,

11-8 (Feb. 1971).

[17] Mendenhall, J. R., Johnson, V. J., and

Olien, N. A,, Publications and Services

of the National Bureau of Standards,

Cryogenics Division, Institute for

Basic Standards, Boulder, Colorado

80302 1953-1972, Nat. Bur. Stand.

(U.S.) Tech. Note No. 639 (Aug. 1973).

[18] Hust, J. G., and Sparks, L. L., Thermal

Conductivity of Electrolytic Iron,

SRM 734, from 4 to 300 K, NBS SP 260-31

(1971). This work has been extended

to include temperatures from 4 to 1000 K by J. G. Hust and P. J. Giarratano

(In press).

[19] Hust, J. G., and Sparks, L. L., Thermal

Conductivity of Austenitic Stainless

Steel, SRM 735, from 5 to 280 K, NBS

SP 260-35 (1972). This work has been

extended to include temperatures from

4 to 1200 K by J. G. Hust and P. J. Giarratano (In press).

R-1
[20] Must, J. G., Electrical Resistivity of

Electrolytic Iron, SRM 797, and Austenitic Stainless Steel, SRM 798, from 5 to 280 K, NBS SP 260-47 (1973). This

work has been extended to include tem- peratures up to 1200 K by J. G. Must

and P. J. Giarratano (In press).

[21] Hust, J. G., and Giarratano, P. J.,

Thermal Conductivity and Electrical

Resistivity Standard Reference Materials:

Arc cast and Sintered Tungsten, SRM's

730 and 799, from 4 to 3000 K, NBS

SP-260-XX (In review).

[22] Schooley, J. F., et al . , Preparation and

Use of Superconductive Fixed Point

Devices, SRM 767, NBS SP 260-44 (1972).

[23] Standard Reference Materials 1973

Catalog, National Bureau of Standards

Special publication No. 260 (available

from the U.S. Government Printing

Office, Washington, D.C. 20402, Price

$1.25 ; or through the Office of

Standard Reference Materials, National

Bureau of Standards, Washington, D.C. 20234).

[24] Curto, J. M., Growth of the Compressed

Gas Industry, Paper presented at 55th

Annual Meeting, Compressed Gas Assoc.,

5-21 (Jan. 1968).

[25] Lofstrom, J., Uses of LNG for the Future,

Pipe Line Industry 29, No. 4, 95-97

(Oct. 1968).

[26] U. S. Industrial Outlook 1974, U.S. Dept.

of Commerce (available from USGPO,

Stock No. 0325-0004).

[27] Industry Profiles, U.S. Dept. of

Commerce (available from the USGPO).

[28] Minerals Yearbook - 1972, Vol. I, Metals,

Minerals, and Fuels, Dept. of the

Interior, Bur. of Mines, p. 807 (1974).

[29] Gas Facts - A Statistical Record of

the Gas Utility Industry, 1972 data,

p. 58, table 53 (The American Gas

Association, 1973).

[30] Hale, D., Editor, World LNG Carrier Fleet

Growing, Pipeline and Gas Journal,

pp. 42-44 (June 1974).

[31] National Gas Survey, Federal Power

Commission, Vol. II, Supply Task Force

Reports, p. 390; Federal Power Commission, 1973).

[32] Hale, D., Editor, LNG Growth Continues

to Escalate, Pipeline and Gas Journal,

pp. 27-32 (June 1974).

[33] Programs on Large Scale Applications

of Superconductivity in the United

States, by Powell, Fickett and

Birmingham. Appears in Superconducting

Machines and Devices, Proc. NATO Advanced Study Institute, Plenum Press

(1974).

[34] Weekly Energy Report, Vol. 2, No. 41 (October 14, 1974).

[35] Weekly Energy Report, Vol. 2, No. 48

(Dec. 2, 1974).

[36] U.S. Industrial Outlook 1974, with

Projections to 1980 (for sale by the

Superintendent of Documents, U.S. Government Printing Office, Washington

D.C. 20234, Price $3.40).

[37] Instrument Society of America Ad Hoc

Committee Report on Cryogenic Flow

Measurement, prepared under the Sponsorship of the ISA Technical Department,

T. J. Kehoe, Vice President (June

1967).

[38] Federal Funds for Research, Development

and other Scientific Activities,

Fiscal Years 1972, 1973 and 1974,

(the National Science Foundation,

NSF-74-300, Vol. 22, Dec. 1973).

[39] Flynn, T. M., Cryogenics and National

Goals, paper A-1 in Advances in Cryogenic Engineering, (Proc. 1968 Cryogenic Engineering Conf.), Vol. 14,

1-12. Plenum Press, New York (1969).

[40] Flynn, T. M., and Smith, C. N., Trends

in Cryogenic Fluid Production in the

United States, Bull. Inst. Int. Froid,

Annexe 1970-2 (Proc. Comm. I, Conf.

on Cryophysics and Cryoengineering,

Tokyo, Japan, Sept. 11-12, 1970)

p. 241-7.

[41] Birmingham, B. W., Superconductivity

Programs of the AEC, Special Publication of the AEC, WASH-1081 (June 1967).

[42] Arp, V. C, Clark, A. F., and Flynn,

T. M., Superconducting Levitation of

High Speed Vehicles, Transp. Eng. J.,

Vol. 99, No. TE4, 873-85 (Nov. 1973).

R-2
[43] Smith, R. V., Current Developments in

Cryomedicine, Cryogenics, 7_, No. 2,

84-9 (April 1969).

[44] Mann, D. B., and Roder, H. M. , Liquefied

Natural Gas as a Cryogenic Fluid--

Instrumentation and Properties, Proc. Transmission Conf. of AGA, New Orleans,

La., (May 26-27, 1969).

[45] Mann, D. B., Diller, D. E., and Olien,

N. A., Measurements of Liquefied Natural Gas in Commerce, Proc. Distribution Conf. of AGA, Washington, D.C.,

(May 1973).

[46] Hord, J. (Ed.), Selected Topics on Hydrogen Fuel, Nat. Bur. Stds. (U.S.)

Spec. Publ. No. 419 (May 1975). Available from the USGPO, Stock No. C-13.

410:419, $2.80.

[47] Flynn, T. M. , et al.. Superconducting

Electrical Generators of Central Power

Station Use, Advances in Cryogenic

Engineering, j[9, (Ed.) K. D. Timmerhaus (Plenum Press, Inc., New

York, N.Y., 1974).

[48] Strobridge, T. R., Cryogenic Refrigerators

--An Updated Survey, Nat. Bur. Stand.

(U.S.), Tech. Note No. 655, (June 1974).

Available from the USGPO Stock No. C13. 46:655, $0.30.

[49] Kamper, R. A., and Sullivan, D. B.,

Developments in Cryoelectronics,

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

No. 630, (Nov. 1972). Available from

the USGPO, Stock No. C13. 46:630,

$0.70.

R-3 ISCOHX - IRL
NBS 1 UA IRE V 7 73)

U.S. DEPT. OF COMM

BIBLIOGRAPHIC DATA

SHEET

15. SI PHI, I- MI N 1 AK> NO I I- S

1. IM IM |i A 1 ION DK Kl I'DK 1 Nil. iJBSIR 75 -825

2. C MIV 't .\i I ( s s uill 3. H ( ( 1 picnl ' ^ .Ai I ( X V ion \o .

5. Tubh, ,11, on I). I!. October 1975

6. I '( r t lU rii 1 II ^ ( H>;an 1 / .H ii 111 < .ivl' 275.00

8. i 'r r 1 1 ir ni 1 11^ Uri;.in. Ki'pitrt N-t. NBSIR 75-825

10. Hro|. , 1 1 .isk Work I nit No. 2750900

11. ' onl r .u t (. ir ,int No

13. I vpi ol Koport & I', no.l

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14. Spon.sorin^ A^iciu \ ( o>i(

4. 11 I LI- .AN!) sr h 1 II 1 1

The National Measurement System for Cryogenics

7. Al l llOKis) T. M. Flynn

9. PI I<I (.)KM1NC. ORCANI/A I ION NA.Ml ANH ADDHr.Ss NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

12. Spou'-onni; t Vj; .in i / ,it i on N.imo .inJ < oniplcu AJi|ris>. (Sfrevt. City, Stale. /.IP)

Same as Item 9.

16. .AHs'l KA( r (A 200-\\ord or /e.s.s- factual nummary ol mo.s ( >,i^ilicanl in lorwd tton. U doLunn-n I includt.-s j .^i^nitnonl

bibl lofiraphy or literature survey, mention it here.) The Cryogenics Division of NBS has evolved as the nation's central laboratory for

cryogenics, much as NBS itself has evolved as the nation's central laboratory with both

broad and specific responsibilities. Cryogenic measurement and data outputs provide

the common foundation for all the institutions and agencies throughout the nation

employing cryogenics to solve their problems.

This Study of the National Measurement System showed that the Cryogenics Division

of NBS provides almost every category of measurement and data service that NBS itself

provides: not just an instrumentation system (including, for example, pressure, temperature, density, liquid level, flow rate, etc.), but also properties of fluids (both

thermodynamic and transport properties); properties of solids (thermal, mechanical and

electrical); an interface with the users through systems integration and advisory and

consulting services; and a dissemination network through the Cryogenic Data Center.

This study documents the impact, status and trends of the cryogenic measurement

system and specifically illustrates these characteristics wherever possible with a specific case study, a recently completed measurements and data program for the flowTietering of liquid nitrogen.

17. Kl > WORDS (.SIX to twelve entries; alphabetic al order, capitalize only the first letter of the first key uord unless a proper nawe; separated by semicolons )

Cryogenics; data; flowmeter; instrumentation; measurements; National Measurement System.

18. AVAII AHII.I 1 V 1 X Unlimited 19. SlX URllV CLASS

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* a.shinKton Sup. of Hoc, U.S. Government

n.( . 20 102. SI) ( .It. No. ( 1 ^

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j USCOMM- DC ^- _i 4. -'' .'4

YEARS

1901-1376