NBSIR 76-1054

An Appraisal of Tests and

Standards for the Evaluation of

Electricity Division

Institute for Basic Standards

National Bureau of Standards

Washington, D. C. 20234

May 14, 1976

Final Report

Prepared for Energy Research and Development Administration

Electric Energy Systems Division

Contract No. E(49-18) - 2052

Electrical Fluids

NBSIR 76-1054

AN APPRAISAL OF TESTS AND

STANDARDS FOR THE EVALUATION OF

ELECTRICAL INSULATING FLUIDS

Electricity Division

Institute for Basic Standards

National Bureau of Standards

Washington, D. C. 20234

May 14, 1976

Final Report

Prepared for Energy Research and Development Administration

Electric Energy Systems Division

Contract No. E(49-18) - 2052

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

AW APPRAISAL OF TESTS AND STANDARDS FOR THE EVALUATION OF

ELECTRICAL INSULATING FLUIDS

David B. Miller, Principal Investigator, Purdue University,

Consultant to Electricity Division, NBS; Vincent E. Bower,

F. Ralph Kotter and Oskars Petersons, Electricity Division, NBS;

and Merritt M. Birky, Clayton M. Huggett and Andrej Macek, Fire

Science Division, NBS

Table of Contents

Page

1 . Summary 1

1.1 Introduction ]_ 1.2 Appraisal and Recommendations 2

1.3 Acknowledgments 6

2. Status of Test Techniques and Standards for New 8

Insulating Fluids — A Summary

2.1 "Askarel-class" Transformers 8

2.2 "Askarel-class" Capacitors 10

2.3 Available Insulating Fluids 10

2.3-1 Fluid Characteristics 10

2.3.2 Test Techniques and Standards 11

2.3.3 Flammability 11

2.3. )4 Toxicity 12

2.3-5 Degradability 13

2.1+ The Scope and Influence of Government Regulations ih

2.5 The Scope and Influence of Insurance and Fire Code 15

Regulations

3. Appraisal and Recommendations 17

3.1 Electrical Tests on Fluids 17

3.2 Flammability Tests for New Fluids 19

3.2.1 Flash and Fire Points 20

3-2.2 Oxygen Index 21

3.2.3 Autoignition Tests 21

3.2.U Spray Flammability Tests 21

3.2.5 Arcing Tests 22

3.3 Toxicity Tests on Fluids 22

3.3.1 Appraisal 22

3.3.2 Recommendations 2k

3.1+ Recommendation on Degradability and Biodegradability 25

Tests

3.5 Insulation System Tests and Standards — Transformers 26

3-5.1 Insulation System Tests 26

3.5.2 Standards — Transformers 28

i
Page

3.6 Insulation System Tests and Standards — Capacitors 29

3.6.1 Insulation System Tests 29

3.6.2 Standards — Capacitors 31

3-7 Standards, Regulations, Codes 32

3.8 References 35

Appendix

Status

A.l "Askarel-class" Transformers 36

A. 1.1 Description of the "askarel-class" of 36

Transformers

A.l. 2 Sources and Consequences of Transformer Tank 38

Rupture

A.l. 3 Transformer System Testing ' k2

A.l.h Alternatives to Askarels in "askarel-class" U3

Transformers

A.l. 5 Test Techniques and Standards Used by 1+5 Manufacturers and Users to Evaluate FluidFilled Transformers

A. 1.6 References ^9

A. 2 "Askarel-class" Capacitors 52

A. 2.1 Description of the "askarel-class" of 52

Capacitors

A. 2. 2 Probability and Consequences of Rupture 53

A. 2. 3 Full Capacitor Arc Testing 5^

A.2.U Effect of Alternative Fluids on Design and 55

Testing of the Full Capacitor Unit

A. 2. 5 Test Techniques and Standards Used by 57

Manufacturers and Users to Evaluate FluidFilled Capacitors and Cables

A. 2. 6 References 60

A. 3 Dielectric and Insulating Fluids 6l

A. 3.1 Available Fluids 6l

A. 3.2 Standards Relating to the Testing of Available 73

Fluids

A. 3. 3 Test Techniques By Which Electrical Properties 75 are Evaluated

A.3.U Test Techniques By Which Fluid Flammability is 76

Evaluated

ii
Page

A. 3. 5 Some Test Techniques for the Evaluation of 8l

the Toxicity of Dielectric Fluids

A. 3. 6 Test Techniques By Which Degradability is 97

Evaluated

A. 3-7 References 10U

A.h The Scope and Influence of Government Regulations 108

A.U.I Environmental Regulations 108

A.h. 2 Poisonous Ingredients in Foods 109

A.h. 3 Occupational Health 110

A.U.U Transportation 112

A.U.5 Solid Waste Disposal 115

A. 5 The Scope and Influence of Insurance and Fire-Code ll6

Requirements

iii

Section 1 Summary

1.1 Introduction

Askarels, the principal constituents of which are polychlorinated

biphenyls (PCBs), have been used for over forty years as insulating

fluids in power capacitor and flame proof transformer applications.

However, recently they have come under close scrutiny and criticism

because of suspected toxicity and long persistence in the environment.

Large scale use of PCBs has now been restricted to electrical equipment

applications under stringent controls to prevent accidental spills.

As a result of these concerns and the possibility of further

restrictions being placed on the use of PCBs, alternative fluids are being considered; however, so far none has gained general acceptance.

Among the factors impeding the acceptance of new fluids are the cost

considerations and the excellent electrical properties of PCBs. Besides

these major factors, it was felt that lack of adequate test procedures

and test-related performance standards for the evaluation of new fluids

did present an impediment to their acceptance. For example, the question

was asked: Are the existing flammability performance requirements and

the associated tests realistic in terms of fire risks? Of equal concern

were tests and requirements regarding toxicity and degradability of the

material in the environment. Could one arrive at concisely defined yet

meaningful requirements for these properties coupled with a comprehensive

set of tests and measurements?

In the early part of 197 J the National Bureau of Standards was approached by the Energy Research and Development Administration concerning

standards for testing new nonflammable insulating fluids for transformers

and capacitors. The objective was to detail in a report or position paper

the test methods and standards and the test-related research and development

required to facilitate the evaluation and qualifications of new insulating

fluids for distribution transformers and power capacitors. In the study

leading to this report the authors attempted to find answers to the type of

questions mentioned above and to identify test-related roadblocks to the

acceptance of new insulating fluids.

The material for this report was gathered in literature reviews

and interviews with representatives of the electric utility industry,

manufacturers of insulating fluids and electrical apparatus, Government

regulatory agencies, organizations preparing standards and codes, trade

associations, and independent testing laboratories. The resources and the

time frame of the project were such that not every test for the properties

of insulating fluids could be examined in detail—American Society for

Testing and Materials (ASTM) standards (see Appendix A. 3.2) list about

ho properties—nor do we believe that such an examination would have

been desirable and cost effective. Instead we took the position of

responding to problem areas as brought to our attention by numerous

personal contacts.

The status portions, Section 2 and the Appendix, review the

existing test procedures and standards for insulating fluids. They also

describe the askarel-type transformers and capacitors and stress the

interdependence between the insulating fluid and the rest of the device.

1
To illustrate the properties of insulating fluids and trends in the

fluid development, several existing and proposed insulating fluids

are described. Finally, since a new material introduced in commerce

must meet the requirements of numerous codes and Government regulations,

an outline of these is provided at the end of Section 2, with details

in the Appendix.

The appraisal and recommendations are the authors' considered

opinions. In Section 3 we comment on the entire field of tests and

standards without firm suggestions for a division of the recommended

future work among the industrial, trade organization, or public sectors.

In 1.2, we emphasize those areas which would benefit from public

support. Admittedly, the public and industrial responsibilities cannot

be always clearly delineated.

During this investigation we were frequently close to the PCB

controversy. However, our scope and objectives did not include the

evaluation of merits and deficiencies of PCBs ; we do not pass judgment

in this area. Similarly, although several potential replacement fluids

are mentioned in the report, we offer no firm conclusions regarding the

availability and suitability of replacements. The identification of

commercial materials and their sources in this report is made for

illustrative purposes only. In no case does this identification imply

recommendation by the National Bureau of Standards, nor does it imply that

the materials are the best available.

1.2 Appraisal and Recommendations

In this part of the report we summarize our most important

conclusions, our appraisal, and our recommendations for future action.

Not all our findings are abstracted here; for a complete appraisal

the reader is referred to Section 3 of the report. The flavor of some of the complex aspects of the problem, such as toxicity and Government

regulations, can only be obtained by reading the pertinent parts of the

entire report including the appendix. The summarized recommendations here

are mostly those which we feel warrant the consideration of public support;

they are emphasized for the convenience of the sponsor of this study.

We are now convinced that the problem of impediments to the

acceptance of new fluids is, with only minor exceptions, not associated

with formalized test procedures as prescribed by standards documents

and the associated measurement technology. The U.S. system of voluntary

standards is sufficiently flexible to provide for ad hoc exceptions if

such exceptions are warranted. On the other hand, compulsory codes

and regulations based on the characteristics of specific existing

products rather than on required performance present serious handicaps

to progress.

While simple laboratory tests on the insulating fluids themselves

can be performed using standard procedures, these alone do not suffice

for evaluation of the fluid. Essential tests on models and prototypes

in advanced stages of development are not readily standardized.

2
The latter, however, are essential since ultimately the fluid must be

qualified in the environment imposed by the equipment. Adverse interactions among various components of the equipment, rather than an isolated fluid property, may be the real barrier to the acceptance of

a fluid. The problems with such system tests are threefold: (l) the

test technology and procedures may not be available; (2) the tests may

have to be tailored to individual insulation systems; and (3) the

tests are very costly.

Finally in certain areas such as toxicity, uniform test protocols

may not be desirable because of the complexity of the system and

required responses. One must accept a lengthy set of experiments in

the process of evaluation.

Because of the above concerns, we did not restrict the

investigation to standardized tests and the related measurements,

but considered a broader spectrum of experimental procedures and

regulatory constraints associated with the introduction of new

fluids.

At its conclusion we see this study as having confirmed the

existence of a need for the development of additional tests and

standards. While for meeting some of these needs the course of

action appears clear, for others it does not.

Within the scope of our investigation the most significant roadblocks

appear to be in the flammability area. The problem lies with the

building codes and fire regulations and the lack of a simple procedure

for evaluating the risk in actual fire situations.

Current codes and regulations dealing with the flammability

specifications for insulating fluids refer only to specific chemical

families—mineral oils and askarels and thus tend to exclude new

developments. Furthermore, it appears that in some cases flammability

performance evaluations are being made with greater consideration given

to the properties of the liquids currently in use than to established

criteria of operating and environmental conditions and the fire

risks involved. It is highly probable that replacements, dictated

by environmental considerations, will have poorer fire resistance

properties than the askarels. The problem is to determine how much

relaxation of the flammability requirements may be possible without

introducing undue risk.

It -U> K.e,comm<Lndcd that KeMiaKck bo, conducted In an attempt to

dtveZop filanmabttity p2A{onmanc<L cnJjtoJuja fioh. new ^Imldd. This work

should consider the analysis of past accidents, the environment in which

the equipment operates and the failure modes. This research activity

must have a strong input from the insurance industry, Underwriters

Laboratories, and personnel from the National Electrical Code

Committee. The results, if to be of benefit, must be usable in

preparation of code revisions.

3
The laboratory tests for initial screening of materials—flash

and fire point and autoignition tests—appear generally satisfactory.

However, they are tests of relative flammability and not true indicators

of fire safety involving large scale equipment failures. In the past,

the definitive tests for fire safety have been the arc tests involving

actual prototypes. This is not a satisfactory state for the introduction

of new fluids since the entire fluid and equipment development procedure

must be carried out before the test can be conducted. Besides the

development costs, the test itself is very expensive. It would be

highly desirable to arrive at a realistic fire-safety test procedure

using small models of the insulation systems, not necessarily scaled

down actual devices. Since actual failures follow electrical arcs and

energy releases, arc tests appear promising. They are little explored,

but whatever little has been done in this area has attracted wide

interest

.

ThuA oua A&cond izcomrmndcuLion in thu cviza ofi &Zamma.b<UU£y testing

u> faon. tk<i d&ve.lopmznt ofi a tz6t wlilch woudLd bo. a. n.<iaJLu>tic. <LndLLcatoA.

oft ^aJlh haza/id. The test involving an arc in a simulated insulation

system appears promising. Since any new test has to be implemented in

practice through code revisions, interaction with the previously mentioned

groups is essential.

Questions have been raised about the lack of a quantifiable definition

of flammability; indeed the term is largely used in a qualitative and

relative sense. We believe any improved definition of flammability of

insulating materials, although still relative, must follow the development

of an improved test procedure. Whether or not the insulating fluid passes

the test will qualify it as nonflammable or flammable.

Potential toxicity is of great concern in the introduction of new

fluids. The underlying characteristic of this area revealed in our study

is its extreme complexity. Relatively short tests with well defined

measurements such as those employed to determine physical properties do

not apply here. Instead, lengthy and numerous experiments must be

performed on animals. As examples of the complexity of the subject, a reference work, cited in this report, mentions 27 different organs in

which responses can be specifically identified; 22 different routes of

administration; and finally 23 levels of animal preference.

There are several definitions of toxicity but relatively few

standard experimental procedures for determining the toxicity of a new

chemical. The attempt to develop a standard set of protocols for routine

assessment of the toxicological hazard of a new insulating fluid or any

chemical has several dangers that must be recognized: (l) it may lead

to unnecessary tests for certain substances; (2) it may fail to ask

questions which are of overriding significance; (3) in view of the

multiplicity of possible biological systems, it may be wasteful; (h) in

view of the multiplicity of responses, some of which may require a long

time before the effect can be observed, such testing cannot guarantee

the complete safety of a new chemical.
Two typa o& tc6t6, Amct> tc6t and ckxonic 6tu.dU.QA, axe 6ugg2J>tcd

in tkU> KcpoKt ^OK. Koutinc cahty 6cn.C2.ning ofa matQJxJjxlA. We believe

the early toxicological screening belongs with the development of the

insulating fluid. The fluid manufacturers are either aware of or are studying toxicity of their materials. As the development of the fluid

approaches the time when there is reasonable probability of actual use,

it would be desirable to conduct impartial, critical and in-depth

appraisals of the manufacturer's toxicity data. We 1ZC.omm2.nd that

-Lnde.p2.nd2.nt appKaibaJLb ofi the toxicity data be bponhoKcd. We favor them

since such appraisals will minimize the chances of discovering adverse

effects years after the insulating fluid has been established in

commercial use.

The degradability of insulating materials in the environment is

also a complicated but even a less explored subject than toxicity. The

process by which a substance degrades to naturally occurring compounds

may be biological, chemical, or physical. The subjects of toxicity and

degradability are often interdependent; for example, rapid degradability

implies that the substance is highly reactive and therefore perhaps

toxic. In dealing with the question of degradability, the following

aspects are important: the rate of degradation, toxicity of the

degradation products, and accumulation of the original substance and

intermediate degradation products in living organisms.

There are no standard degradability tests for the electrical

insulating fluids, although individual manufacturers have performed

experiments on their products. One industry group which has been successful

in developing a standardized test for biodegradability , including a definition of what is meant by biodegradable, is the Soap and Detergent

Association. Their success has lead us to believe that an attempt to

develop a similar procedure for insulating fluids would be a worthy

endeavor. ThuA , we K2.comm2.nd KCbcaXch to explore th.2 d2.v2JL0pm2.nt o&

btandaK.di.zcd dcgKadabitlty evahxatLon pK.oc2.duJx.2A.

In the electrical and other areas we see no major deficiencies in

the laboratory type of tests on insulating fluids. There are several

minor problems mentioned in Section 3. These concern the types of cells

used for breakdown tests; possibly inadequate tests for moisture content

of new fluids; specifications and significance of corona inception and

extinction levels.

We feel the situation is different for the tests in the more advanced

stages of equipment development during which insulation models and prototypes are evaluated. Of concern is the stability of the insulation system,

and how it is affected by interactions among various components. Such

interactions may degrade the insulating properties of the fluid and reduce

the life expectancy of the apparatus. An important cause of failure is

corona, but there are other factors contributing to insulation deterioration.

It could be argued that tests at this stage are the sole responsibility

of the developer of a particular apparatus. We believe, however, that

guidelines to uniform system testing would accelerate the introduction

of new fluids. Having well developed and verified guidelines would

5
reduce the cost of insulation system evaluation and would facilitate

the comparison of results of competitive systems, and the availability

of carefully-performed and well-documented results of a validated test

will mitigate user reluctance in accepting a new product. Tests in

accordance with such guidelines would be expected to uncover possible

deficiencies which could cause expensive, unexpected failures at a future date and possible withdrawal of the product. ConAnqu&ntZy, W<L i2.comm&nd n.Qjt>zan.ch leading to tka. dzveZopm&nt ofa fionmal Qul&oJLinQA {on.

thjOLYibfaotimQA and capOLcAXoK. insulation AyAtem t2At&. The long-term

performance of an insulation system is often determined through

accelerated aging procedures. To arrive at a valid accelerated test,

the basic mechanisms of failures must be understood. A study in the

basics of insulation failures, as they affect tests, would be desirable.

Finally, we consider the effect of published voluntary performance

standards, compulsory building codes, and Government agency regulations.

These do slow down the process of introduction of new products, if for

no other reason than because of multiplicity of requirements which must

be considered. Sometimes these requirements are ambiguous and conflicting.

The impediment is very severe if the codes and regulations recognize only

certain specific products.

The process of preparing voluntary standards could be accelerated

by encouraging greater user and third party participation in committees.

This objective could be partly achieved through allocation of a special

fund for these purposes.

A close liaison should be maintained between the Energy Research and

Development Administration and Federal and State regulatory agencies through

flow of information in both directions, participation in meetings, and assistance in project reviews and steering. We mc.0mm2.nd i.nc.K2.aA2.d inX2Ad2.paAtm2.ntoX

cootdincution o{ n.2.QuJLcutony acXiviXy. A task force consisting of members of

concerned agencies charged, with a minimum duty of keeping each other informed

would alleviate problems in this area. If the task force could then become

the focal point for coordinating the specific actions of the agencies which

impinge on the electrical power industry, and thus become a center to which

the industry could look for guidance, it would be of even greater value.

1 . 3 Acknowledgment s

This report is based on information gathered from a large number

of sources, and in particular from meetings with many individuals and

groups who are involved in one way or another with insulating fluids.

We wish to express our appreciation to these groups, listed below, who

very willingly supplied their time, information, and suggestions in order

to best meet the stated objectives of this study:

Government Regulatory Agencies

Environmental Protection Agency (Water and Hazardous Materials Group,

Office of Toxic Substances, Environmental Monitoring Laboratory,

Environmental Research Laboratory); Department of Health, Education and

6
Welfare (Food and Drug Administration, National Institute for Occupational

Safety and Health, Public Health Service); Department of Labor (Occupational

Safety and Health Administration); Department of Transportation (Federal

Railroad Administration, Urban Mass Transit Authority); Department of

Natural Resources, State of Michigan; and Department of Natural Resources,

State of Wisconsin.

Manufacturers

Dow Chemical U.S.A.; Dow Corning Corporation; Electric Utilities

Company; Exxon Research and Development Company, Corporate Research

Laboratories; General Electric Company (Transformer Laboratory Operation,

Capacitor Products Dept., Research and Development Center, Environmental

Protection Operation); McGraw-Edison Company (Power Systems Division);

Monsanto Industrial Chemicals Company (Specialty and Process Chemicals

Division); RTE Corporation; and Westinghouse Electric Corporation

(Transformers Divisions, Research and Development Center).

Electric Utilities

Commonwealth Edison Company; Consolidated Edison Company; Kansas City

Power and Light Company; Potomac Electric Power Company.

Standards Organizations, Trade Associations and Testing Laboratories

American Society for Testing and Materials; Edison Electric Institute;

Electronic Industries Association; Factory Mutual Engineering and Research;

International Association of Electrical Inspectors; Manufacturing Chemists

Association; National Electric Manufacturers Association; and Underwriters

Laboratories, Inc.

The authors thank J. E. Cunningham for typing the manuscript,

including numerous drafts, under tight deadline conditions. We also

acknowledge with thanks the contributions of M. G. Broadhurst

and C. G. Malmberg of the Polymers Division, NBS; F. L. Hermach and

R. S. Turgel of the Electricity Division, NBS; W. H. Kirchhoff of the

Office of Air and Water Measurement, NBS; and G. Carlson, Department

of Toxicology, Purdue University, in critically reviewing sections of

the report

.

7
Section 2 Status of Test Techniques and Standards for New

Insulating Fluids — A Summary

"Askarel" is a generic term for a class of fire-resistant,

synthetic, chlorinated hydrocarbon fluids used by the electric

industry for insulation in capacitors and a certain class of

transformers. Their "fire resistance," good heat-transfer and nonsludging characteristics and their high dielectric constants make these

fluids particularly attractive for these applications. The industry

has grown accustomed to the particular features of the askarels over the UO-odd years they have been available and many standards and

operating guidelines have been developed in the light of their specific

characteristics

.

It is the purpose of Section 2 to review in a summary form the

status of existing standards and test procedures for insulating fluids

as they relate to the new fluids being proposed as replacements for the

askarels (the Appendix contains detailed background material).

In reviewing the available procedures, the reader should keep in

mind not only the applicability of given procedures to new fluids, but

also the adequacy in the face of today's much more complex and stringent

requirements on electrical materials and apparatus. Reliability, fireresistance, nontoxic ity and minimum environmental impact demand far more in

the way of materials and apparatus testing than was required when askarels

were introduced. It is an appropriate time, therefore, that the adequacy

of insulating fluids test techniques and standards be reviewed.

In this section, background on the requirements of askarel-insulated

transformers and capacitors is surveyed in order to identify the

operational requirements which new fluids must fulfill within the

apparatus environment. Fluids characteristics themselves are then

investigated. Finally, existing constraints due to governmental

regulation and fire codes are explored to reveal possible additions and

changes which might be required in this area to accommodate new fluids.

2.1 "Askarel-class" Transformers

Specifications for transformer askarels (proprietary blends of

polychlorinated biphenyls (PCBs) and other ingredients) are given in

ASTM Standard D 2283-73. The fluid is enclosed in a metal tank, and

the transformer windings are completely immersed in the fluid. Askarels

are used as the insulants in transformers where the fire resistant

characteristic is particularly important. These uses include utility

and industrial distribution service, where the transformer serves a heavily concentrated load in an urban, commercial or industrial area and

where the transformer must be in close proximity to populated buildings.

Electric railroads and many electrostatic precipitators also use fireresistant transformers.

8
The fire resistant quality of the askarels is due, in part, to

the nonflammable gas, mostly hydrogen chloride, which is produced when

the fluid is subjected to arcing or high temperature. This gas is

also corrosive, and scavengers must "be used to absorb small amounts of

hydrogen chloride produced in normal operation. Transformer rooms or vaults must he adequately vented to prevent build up of HC1 vapor, and

any leaking or spilled askarel must he contained because of its toxic

and environmental problems.

The transformer fluid could be spilled during manufacture, transport,

processing, filling, normal operation, service failure, repair or disposal

of the transformer. Guidelines have been issued for proper handling

(MSI1 0107.1-197^; IEEE2

7 6-197 M •

Spilling during service most often results from an internal arc causing the transformer tank to rupture. The arc generally starts as a small discharge, and pressure builds up slowly; a pressure relief device,

if present, prevents failure from this type of malfunction. Small

discharges, however, may grow rapidly to high current arcs. The resulting

pressure wave then builds too fast for a pressure relief device to operate.

Although a current -limiting fuse can be used to reduce the magnitude of

the pressure wave, the tank must be made exceptionally rugged to withstand

this condition. Because of intensive preventive programs, users report

very low (0.01 to 0.02%) yearly tank rupturing failures. In spite of the

low failure rate, indoor mineral-oil insulated transformers are installed

in fire-proof vaults in accordance with National Electrical Code

recommendations. Vault requirements apply to all mineral-oil insulated

transformers and to askarel-insulated transformers rated over 35 s OOO volts.

The fire-resistance of a transformer fluid must ultimately be

determined by testing a complete transformer. The askarels were originally

qualified by such tests conducted by Underwriters Laboratory. More

recently, RTE Corporation has run a set of demonstration tests comparing

mineral oil, askarel, silicone fluid, and an RTE proprietary material

"RTemp." In this test, the three newer materials were shown to be less

flammable than mineral oil; this test could form the foundation for a more rigorously controlled and instrumented standard test of transformer

insulating fluids.

When considering alternatives to mineral oils or askarels in

transformers, in addition to the obvious electrical and thermal properties

the following special characteristics will have to be considered before

a new fluid can be considered to qualify: material compatibility, ability

to impregnate the solid insulation used, hydrolytic stability, fire

safety, toxicity and environmental impact.

Standards for external protection of transformers with new fluids

should also be considered; this includes fusing, circuit breakers, and

vault requirements.

A large number of standards exist which guide the selection and

handling of mineral oil and askarel in transformers. These are listed in A. 1.5;

presumably similar standards for new fluids would eventually be required.

American National Standards Institute

Institute of Electrical and Electronics Engineers

9
2.2 "Askarel-class" Capacitors

A large percentage of liquid-filled electrical capacitors use askarels

as the dielectric fluids, primarily because of their relatively high dielectric

constants and the fact that they are approximately equal to the dielectric

constant of readily available paper insulation. Their good electrical

insulating and stability qualities also make them attractive for capacitors.

Although not a prime requirement for large power capacitors, the fireresistant feature of askarels is also a significant advantage. The fire

resistance appears to be important in certain types of smaller ("industrial")

capacitors, such as those used in conjunction with fluorescent lights and

appliance motors. There is an interdependence of the transformer and

capacitor askarel manufacture which should not be overlooked in considering

the economics of substitutes.

Capacitors generally fail by an internal arc destroying the

electrical insulation. The arc will also often rupture the capacitor

tank. Capacitor reliability is generally quite good, with yearly

failure rates being less than one-percent.

In addition to the special characteristics noted as important in

the case of candidate replacement fluids for the askarels used in

transformers, the fluids for use in capacitors must possess high

dielectric constants. The ease with which the solid insulation can be fully impregnated with the liquid is even more important in the

capacitor application.

Existing standards for capacitors are described in A. 2. 5. These

deal with the fluids themselves (specifications, acceptance, handling,

disposal) and with the requirements of the total capacitor.

2.3 Available Insulating Fluids

2.3-1 Fluid Characteristics

We have described several available new fluids in A. 3.1 of the

Appendix. For the sake of completeness, descriptions of mineral oils

and askarels are also included. A listing of these substances including

their principal properties follow.

The askarels are mixtures of polychlorobiphenyls and chlorobenzenes

with additives. These liquids have excellent electrical properties and

are highly stable, but evidence of their toxicity has developed. Their

excellent stability has given them high reliability on the one hand, but

also given them the disadvantage of poor degradability in environment.

Silicone liquids (mixtures of dimethyl siloxane polymers) have good

electrical properties (although the dielectric constant is not as high

as in the case of the askarels). They are useful over a wide temperature

range, but are less fire resistant than the askarels and form solids

during electrical discharge. They are high molecular weight liquids which

appear to be relatively nontoxic.

Mineral oils are mixtures of paraffinic (or naphenic) and aromatic

compounds of petroleum origin with aromatic additives to prevent oxidation and

10
sludging. The electrical properties are satisfactory and the cost is

low. These materials are flammable (see table p. 72). Their toxicity

is low and results largely from the toxicity of additives. However,

the additives are satisfactorily degradable.

Hydrogenated paraffin oils exhibit characteristics similar to those

of mineral oils except for higher flash points and consequently lower

flammability

.

Mixtures containing diaryl sulfones , particularly formulated for

capacitors, possess high dielectric constants. The liquids are somewhat

flammable (see table p. 72). Their toxicity and electrical properties

are now being thoroughly investigated. They appear to be satisfactorily

biodegradable

.

The phthalate esters are readily' available in large quantities since

they are now used extensively in the plastics industry. Their high

dielectric constants (about 5) and other electrical properties make them

more attractive for capacitor than for transformer applications. They

exhibit low toxicity and satisfactory degradability although their

flammability characteristics (see table p. 72) represent some disadvantage.

Butylated monochlorodiphenyl oxides have good electrical properties

(dielectric constant about 5), and are being considered for capacitor

use. They are flammable (see table p. 72 ). The slight toxicity resulting

from a minor component has been investigated. The fact that the offending

component is biodegradable and that its degree of bioaccumulation is also

low permits these to remain as candidate liquids.

2.3.2 Test Techniques and Standards

The standards relating to testing of insulating fluids are summarized

in A. 3.2. These refer to procedures for specific fluids (askarels,

silicone fluids, insulating oils) and to specific test techniques

independent of the particular fluid being tested.

2.3-3 Flammability

Fire and explosion are potential hazards in the operation of transformers

and to a lesser degree capacitors and since one outstanding feature of the

askarels is their low flammability, the flammability or "fire resistance"

of potential replacement fluids must be evaluated. Flash and fire points

are defined as the temperatures at which an ignition source will cause

a transient and a continuing flame in the vapors of the fluid. These are the most widely used measures of flammability. Closed and open cup

methods for measurement of these parameters are described and discussed

more thoroughly in A. 3.^.

11
In the Section A. 3.^ on flammability testing, several other tests

are also described. The Oxygen Index (0.1.) Test is a frequently used

technique in which the lowest combust ion- support ing percent of oxygen

in an oxygen-nitrogen mixture is determined. Some limitations on the use of the 0.1. test are discussed. A heated atomized mist of the

substance is sprayed into an open flame in the Spray Flammability Test;

this is a very severe test and has not been applied to any extent in

evaluating the flammability of insulating fluids. Another flammability

test is the Auto Ignition (A.I.) Test, in which the temperature for

spontaneous ignition is determined. This has been used for insulating

fluids; the A.I. temperatures are generally quite high, well above

normal operating temperatures.

The energy release during combustion of an insulating fluid is a very pertinent parameter since physical damage to the apparatus and its

surroundings is the thing which one hopes to eliminate if combustion

occurs. Energy release measurements have not been applied to insulating

fluids, but in A.3.U suggestions are made toward this end.

A basic problem related to the flammability issue is the general

lack of a rigorous, quantized definition of "flammability." We have

used this term, and also such terms as "fire resistant" without really

having an operationally useful meaning for them. Standardized,

interpretable tests such as described above will provide the data on which quantitatively meaningful definitions can be based.

Tables in A. 3-1 and A. 3.^ summarize existing flammability data for some of the available insulating fluids.

2.3.k Toxicity

The toxicity of the askarels has recently become a significant

issue, leading to severe restrictions on their present day use, and

creating the intensified search for substitute fluids. The toxicity

of each candidate replacement must therefore be an important parameter

to evaluate before the liquid is put into widespread use in electrical

equipment. Some reference is given to the toxicity of the various

insulating fluids in A. 3.1. In A. 3. 5, toxicity determination techniques

are explored. Perhaps the most important conclusion is that the toxicity

issue is extremely complex.

A variety of definitions of toxicity are presented in A. 3. 5,

emphasizing that a fluid cannot merely be labeled "toxic" but that its

specific toxic actions must be identified. Questions raised include:

At what dose level does any toxic response occur, and what is the

lethal dose? Is the chronic response to long-term, continuous exposure

different from the acute response to a single large dose?

A large variety of responses occur. Table C p. 88 indicates the variety

of organs and systems in which responses can be specifically identified,

12
including such things as skin, blood, nervous system and liver.

Likewise, the response can depend on the route of administration,

e.g., orally or by inhalation; 22 different routes are identified in

Table B p. 86 . Finally, the toxicity of a given substance may differ

from one species to another; 23 levels of specie preference are listed

in Table A p. 85 .

The importance of continually improving chemical analysis techniques

must be recognized in any attempt to establish definitions or protocols

for toxicity. Gas chromatography and mass spectroscopy have, for

instance, greatly advanced analysis, both qualitatively and quantitatively,

in recent years.

The RcQU>Viy ofa Toxic E^tcti ofi Chemical Su.bAta.ncc6, published

by the National Institute of Occupational Safety and Health, is identified

in A. 3. 5 as listing all chemicals which are documented as having shown

any toxic effect in any species. The effect, dose, administration route,

species and reference source are also given. A. 3. 5 also contains further

governmental legislative and regulatory enactments which give operational

definitions of toxicity. These include: The Federal Hazardous Substance

Act, Department of Transportation Regulations, Occupational Safety and

Health Administration Regulations, Food and Drug Administration

Regulations, and Environmental Protection Agency Regulations.

2.3-5 Degradability

Because of the highly stable nature of the polychlorobiphenyl

molecule, the askarels which accidently or upon disposal reach the

environment persist for long times; they are not biologically degraded

in the manner or at the rate of most organic compounds. This persistence

has amplified the toxicity problem and has brought out the need to

investigate the degradability as well as the toxicity of replacement

fluids.

Degradation to more simple, harmless, environmentally compatible

compounds may occur due to natural physical processes or, as in the

case of most organics, by biological processes. New compounds require

testing for both types of processes. Silicones, for instance, do not

biodegrade, but are shown to decompose to basic silica and water in the

presence of solar (ultraviolet) radiation, air and water.

Tests for biodegradability of potential pollutants include the

River-Die Away Test, continuous activated sludge tests and batch activated

sludge tests. The Subcommittee on Biodegradation Test Methods of the

Soap and Detergent Association have promulgated a standard sulfonate

biodegradability test. The Biochemical Oxygen Demand (BOD) and the

Oxygen Electrode tests are identified as useful biodegradation tests

in the EPA Manual of Methods for Chemical Analysis. All of the above

tests are described and referenced in A. 3- 6.

13
2.h The Scope and Influence of Government Regulations

In 2.3 above, Federal legislation and regulations were identified

as one source for definitions of toxicity. We return to these sources now to examine the authority and procedures by which governmental

bodies will influence the acceptance of new insulating fluids. More

detailed examinations and referencing of these various laws and

regulations will be found in A.U.

The Environmental Protection Agency (EPA) has the following

authorities from the Federal Water Pollution Control Act:

1. Prepare a list of toxic pollutants; criteria for selection,

standards for allowed levels.

2. Assign oil and hazardous substance liability; regulations

for reporting and clean-up of spills.

3. Establish pretreatment standards; standards for pretreatment of

pollutants which could enter public treatment works.

k. Establish effluent standards; standards for allowed levels

of discharge of each identified pollutant.

5. Issue pollution discharge permits; EPA may issue permits

limiting the amount of discharge of specific pollutants from

identified sources into navigable waters.

Various versions of a Toxic Substance Control Act are also being con- sidered in Congress. If this Act is passed it is expected that EPA will be

given direct control of the use, as well as the discharge, of toxic substances.

The Federal Food, Drug and Cosmetic Act empowers the Food and Drug

Administration (FDA) to maintain safe levels of food quality in the

United States. Under this authority, the FDA can regulate the use of

poisonous ingredients in agricultural and food processing industries.

In the specific case of the PCBs , the FDA has issued regulations where

PCB-containing materials can and cannot be used. Thus, new insulating

fluids may fall under FDA jurisdiction if used when food contamination

is possible. Currently, PCBs are allowed in sealed electrical transformers

and capacitors; presumably these regulations could be stiffened if and

when replacement fluids come into generally accepted, commercial use.

The Occupational Safety and Health Act directs the Occupational

Safety and Health Administration (OSHA) to assure working persons safe

and healthful working conditions. New insulating fluids could fall

within the jurisdiction of this Act both during manufacture (of the

fluid or the apparatus) and during use of the fluid-filled apparatus in

a working area. The Secretary of Labor (through OSHA) is directed to

issue standards for toxic substances and to inspect working places in

order to enforce these standards. The Secretary of Health, Education

and Welfare (through the National Institute of Occupational Safety and

Health, NIOSH) is to carry out research and develop the criteria for

establishing standards.

Ik
NIOSH regularly updates its "Registry of Toxic Effects of Chemical

Substances" (see Ref. h5 of A. 3). This list, for instance, specifically

cites several "Aroclors" (a manufacturer's tradename for mixtures of PCBs).

The list should he consulted for toxicity information on other candidate

fluids.

OSHA regulations have incorporated the whole of the National

Electrical Code, making this code, and specifically its provisions on transformers and capacitor fluids, part of Federal law. OSHA has also

now issued draft technical standards on chlorobiphenyls

.

Department of Transportation (DOT) regulations would have an impact

on new insulating fluids in two ways:

1. Control of the insulating fluid in transformers of electric

railroad cars; the availability of a sufficiently nonflammable

fluid must be recognized when considering a restriction on askarels in this application.

2. Control of the transportation of fluids; the transportation of

hazardous materials falls within DOT's authority. Class B

poisons are defined in 1+9CFR 173. 3^3.

Finally, we mention that the Department of Health, Education and

Welfare (HEW) has regulatory control of solid waste disposal through

provisions of the Solid Waste Disposal Act. HEW is, for instance, to

publish guidelines on solid waste recovery, collection, separation and

disposal. Federally controlled disposal facilities are obligated to

follow these guidelines.

2.5 The Scope and Influence of Insurance and Fire Code Regulations

The National Electrical Code (NEC) is a guide to the safe

installation of electrical equipment. It has been adopted, as is, or with modifications, as a part of the legal building code by many state

and local authorities. It has also been incorporated into the Federal

Occupational Safety and Health Regulations. The current edition of the

NEC mentions only mineral oils and askarels for use as insulation fluids

in transformers and capacitors.

Independent testing laboratories such as Underwriters Laboratories (UL)

and Factory Mutual Engineering and Research (FM) will carry out testing

of apparatus and issue an approval, indicating that the item meets NEC

standards. UL has also published flammability ratings of materials.

FM will issue an "acceptance" rating, indicating that a particular

installation meets safety standards. These ratings are important in

aiding the insurance companies to decide whether a given installation

should be insured.

15
Fire safety has always been a major concern associated with

electrical apparatus, and it will be particularly important in equipment

using new fluids in place of the "fire-resistant" askarels. For

building code and fire insurance protection, therefore, new fluids must

be acceptable by fire code standards.

Further details regarding insurance and fire code regulations will be

found in the Appendix (A. 5).

16
Section 3 Appraisal and Recommendations

3.1 Electrical Tests on Fluids

It appears that existing specifications, standards and test procedures

are adequate for dealing with the mineral oils and askarels currently in use. While it does not seem feasihle to propose a single specification

which could he applied to old as well as new candidate fluids for all

applications, it does seem quite feasible to use at least most of the

same electrical test procedures for all.

So far as we have been able to determine none of the current standard

electrical test procedures called out for insulating fluids actually act

to impede the acceptance of new fluids except perhaps indirectly. An

example of this indirect impact is the situation with respect to dielectric

breakdown tests dealt with in two ASTM Standards: D 877 "Standard Method

of Test for Dielectric Breakdown Voltage of Insulating Liquids Using

Disk Electrodes" and D l8l6 "Standard Method of Test for Dielectric

Breakdown of Insulating Oils of Petroleum Origin Using VDE Electrodes."

These standards differ in that D 877 calls for a test cell having

a small volume and an electrode geometry which provides a near-uniform

field, whereas D l8l6 requires a substantially larger cell with electrodes

which establish a uniformly decreasing field about a maximum field point.

The liquid in this larger cell is maintained in gentle forced flow between

the electrodes. The D l8l6 procedure provides a test which is more

sensitive to the presence of moisture in the liquid being tested and is

less influenced by the contaminating by-products of previous breakdowns;

however, it requires a significantly larger volume of the test liquid.

Either method can be used for testing the candidate silicone fluids;

because of breakdown by-products, however, the specified alternative D 877

procedure which calls for refilling the test cell with new fluid prior to

each breakdown test must be followed in order to obtain consistent results.

The circulation of the liquid avoids this problem if D l8l6 is used. Thus

with either procedure the volume of liquid required for the test is several

times that required in a mineral oil or askarel test and the higher cost

of the silicone fluid then appears as an indirect deterrent to its use.

It should be noted that poor repeat breakdown strength of a fluid alone

does not necessarily mean poor repeat breakdown strength of the composite

system when the fluid is used as the impregnant of a porous solid.

ASTM Standard D 2^13 applies to such composite systems.

Another indirect deterrent is the obvious requirement that the test

fluid not be contaminated by chemical interaction with the materials used

in construction of the test cells. The commercially available cells which

are inert to the mineral oils and askarels (and not all are inert to both)

are not inert to all new candidate liquids.

Still another indirect deterrent may be the fact that current standard

test procedures for moisture content are not as satisfactory for silicone

fluids or perhaps for other liquids as for mineral oils and askarels.

These can only be considered as temporary impediments to the adoption

of new fluids since prospective widespread use of any new fluid would soon lead to the development of test procedures suitably tailored to its

peculiarities

.

17
A characteristic of askarels which adds to their attractiveness as electrical insulating fluids is the behavior when partial discharges

(corona) occur. With mineral oil and some other insulating fluids, the

partial discharge inception voltage is significantly higher than the

extinction voltage. Thus a temporary voltage excursion which initiates

the partial discharge may lead to a prolonged discharge period with a resultant degradation in the properties of the fluid. With askarels,

the inception and extinction voltages differ very little so that

temporary voltage excursions which lead to partial discharges are inconsequential. This characteristic of an askarel tends to encourage

its being specified as the insulating liquid.

Recommended test procedures relating to this characteristic exist.

However, since acceptable limits may vary from one application to another

and from liquid to liquid, no universally accepted basis for judging

the relative merits of new versus old candidate liquids in this respect

is available. The lack of such a standard may be considered another

"indirect" deterent to the adoption of new fluids.

The stability of an insulating fluid describes the permanence of

its important physical and electrical characteristics in the operating

transformer or capacitor. This is an extremely important characteristic

since these fluids are expected to operate reliably and essentially

unattended in long-service-life apparatus. Although bench tests on the fluids themselves to screen out obviously unsatisfactory candidates

are essential, fluid must finally be qualified in the apparatus

environment. Such tests are described in Sections 3-5 and 3.6. Within

these tests are also included suggestions for developing cleaning and

maintenance procedures for fluids in service.

Finally, guidelines and standards must be developed for proper

disposal of new fluids as they come into use. ANSI C107.1, guidelines

for proper handling of askarels, would serve as a useful example. These

guidelines would have to await quantitative determination of the toxicity

and degradability of each new fluid, and they would have to be cognizant

of changing federal and local waste disposal regulations.

Institute of Electrical & Electronics Engineers (IEEE) Standard

#^5^-1973 "Recommended Practice for the Detection and Measurement of

Partial Discharges (Corona) During Dielectric Tests"

National Electrical Manufacturers Association (NEMA) Standard

#CP-P2-1973 Official Standards Proposal "Test Procedure for Measurement of Internal Partial Discharges in Capacitors"

American Society for Testing and Mat erials (ASTM) Standard D 1868-73

"Detection and Measurement of Discharge (Corona) Pulses in Evaluation

of Insulation Systems"

18
3.2 Flamma"bility Tests for New Fluids

Fire safety tests have been classified in a variety of ways [1,2].

For our purpose, it is convenient to classify them as:

(a) properties of materials tests

(b) system tests

(c) apparatus prototype tests.

Tests of the first class are small scale laboratory tests designed to

measure an intrinsic property of a material which is related to its

fire performance, e.g., flash point or heat of combustion. Such tests

are useful in developing a qualitative picture of the hazards associated

with the use of a material and for purposes of specification and quality

control. They are relatively inexpensive and would be the first tests

to be run on new candidate fluids. They do not necessarily predict the

hazard potential of a material under actual use conditions.

System tests involve the interaction of the material with the

environment and with other elements of the system in which it is intended

to be used. An example is the RTE Arc Tests (A.1.3). System tests attempt

to simulate essential features of the device, and thus are less susceptible

to standardization than property tests. They are usually larger in scale,

require more careful planning and are relatively more costly than tests

of component materials. Thus, they would find use in the latter stages

of the development and qualification of new insulating fluids.

Prototype tests involve the testing of the complete device under

conditions simulating actual use, for example, the Underwriters Laboratories

Tests (A.1.3). Such tests can be very expensive, not only because of the

cost of the test units and test operation but because most of the

development costs of the device will have been incurred before the first

unit is ready for testing. They should be undertaken only after a careful

analysis of the conditions under which the device is intended to function,

the possible failure modes, and the type of information that is to be

sought in the test.

The purpose of flammability tests and standards for insulating fluids

is to reduce the probability of loss from fire incident to the use of

these materials. In order to set realistic performance standards and

select appropriate test methods, it is necessary to know the properties

of the environments in which these fluids will be used, the failure modes

that occur, and the consequences of these failures. We have been unable

to find any systematic compilation of such hazard information in the course of the present study. Consequently, the establishment of suitable

flammability criteria for new candidate insulating fluids will at this

time be based on inadequate knowledge of the nature of the hazards which

may be encountered.

References shown in brackets, are found in 3-8.

19
Recommendation : It is recommended that a systematic survey and

analysis be made of the environmental conditions in which insulating

fluids may be used and incidents involving the use of such fluids which

result in fires or related loss.

Current flammability specifications for insulating fluids apply to

specific chemical families of fluids and vary from one type to another.

This presents a barrier to the introduction of new chemical types since

they do not fit under existing specifications and there are no clear

guidelines for acceptability. It appears that some present performance

specifications have been established with greater consideration given

to performance levels which the fluid in question can readily meet than

to the actual requirements of the application. Setting too high a requirement may result in the elimination of promising candidate fluids

whose properties are entirely adequate for the intended application.

The excellent flammability performance of the askarels has led to a very low incidence of fires involving these materials. It is highly

probable that replacements for these materials, dictated by environmental

considerations, will have poorer fire resistance properties than the

askarels. The problem is to determine how much relaxation of flammability

requirements may be possible without introducing undue risk. This question

cannot be answered by reference to the historical record of the performance

of devices using askarels.

Recommendat ion : It is recommended that flammability performance

requirements for new candidate insulating liquids be based on a consideration

of the environment in which they will be used and on analysis of likely

failure modes, rather than on the properties of the fluids they are designed to replace.

3-2.1 Flash and Fire Points

The measurement of flash and fire points gives important information

on the flammability hazard characteristics of a liquid. The Cleveland

Open Cup method (ASTM D 92) is used for this purpose. A number of other

methods are available for the measurement of flash points. Closed cup

methods generally give somewhat lower values for the flash point than the

open cup method, but the latter has the advantage of permitting the

concurrent determination of the fire point. Since the flash point is a relative rather than absolute measure of flammability hazard, the small

differences in results between the two methods are of little significance

in the present case.

An ASTM ad hoc Committee on Flash Point Methodology and Government

Response is currently considering new test methods with the major

objective of resolving conflicting flash point definitions and test

methods used in different government regulations [3]. The committee

appears to favor a closed cup, equilibrium temperature method.

20
Recommendation : The measurement of flash and fire points using the

Cleveland Open Cup method ( ASTM D 92) should he retained, at least for the

present. Specifications should he set to provide an adequate margin of

safety above the highest anticipated operating temperature for the planned

application. If a new flash point test is adopted for regulatory purposes its use for determining the flash point of insulating fluids should he considered,

hut the determination of the fire point should he retained.

3.2.2 Oxygen Index

No standard method for determining the oxygen index of liquids is

available. The oxygen index is related to the fire point [H,5]. Since

insulating fluids will have high fire points, heat loss to the apparatus

is an important factor and the measurements are extremely apparatus

sensitive. No meaningful interpretation of the oxygen index of liquids

in terms of fire hazard characteristics is available at the present time

Recommendat ion : Since oxygen index measurements, as presently made

and interpreted, do not provide useful information on the fire hazard

characteristics of insulating fluids, they should not be incorporated

into electrical insulating fluid specifications.

3-2.3 Autoignition Tests

Recommendat ion : The autoignition test, ASTM D 2155 and similar tests

do not simulate any hazard mode identified with the use of devices

incorporating, insulating fluids and thus are not appropriate as fire safety

tests. They do provide useful information, in conjunction with other

material property tests, on the general performance properties of

materials, and thus may be useful in the preliminary characterization

of new candidate insulating fluids.

3.2.U Spray Flammability Tests

Recommendation : Inasmuch as our limited survey of the uses and misuses

of insulating fluids has revealed no circumstances which would be Closely

simulated by these droplet combustion tests, there is no reason why they

should be included in the specifications for candidate replacement fluids.

A further survey of accidents and potential accident circumstances may

provide grounds for the further consideration of this type of test in

the future

.

21
3.2.5 Arcing Tests

Arcing appears, at this time, to be the most common failure mode

of devices incorporating insulating fluids. Failure may result from a gradual growth of low level discharges during normal operation or from

sudden overvoltage conditions. Tests which simulate such failures

provide essential information on the fire safety properties of insulating

fluids. Such tests have been conducted on an ad hoc basis [6]. There

is need for a standard procedure to permit evaluation and comparison of

the fire safety properties of new fluids under simulated use failure

conditions. Separate procedures for transformers and capacitors may be

needed. Both gradual and catastrophic failures should be simulated.

The energy release characteristics of the failure should be measured.

Recommendation : A standard test method or methods should be developed

to simulate the arcing failure of devices incorporating insulating fluids

under application conditions. The test method should be based on a careful analysis of the observed or plausible failure modes of such

devices. Further recommendations regarding such a test will be found

in 3-5 and 3.6.

3.3 Toxicity Tests on Fluids

3.3.1 Appraisal

The determination of the toxicological hazard or risk of a chemical

in the environment, whether insulating fluid or otherwise, depends on a large number of factors. The exposure to chemical toxicants can be

divided into two rather broad categories: (l) direct exposure of humans

during the manufacture and handling of fluids including accidental

exposure due to spills, and (2) contamination of the environment that

may ultimately lead to exposure of animals and humans. These two

categories include both the acute (accidental spill) and the chronic

exposures. Both categories, the work environment and environmental

contamination, usually produce chronic exposure situations, that is, low

level sub-lethal exposures that may continue for periods of months and

years. This is particularly true in the industrial environment.

Therefore this type of study should be emphasized.

Both categories require an assessment of the effects of the fluid

on a complex biological system that may respond in a multitude of ways.

A partial list of the biologic responses that the toxicologist must

observe in studies to determine the toxicity of a chemical is given in

Table C, page 88. For example the production of tumors (neoplastigenesis )

,

benign or malignant (carcinogenesis); the production of changes in the

offspring, whether transmissible (mutagenesis) or not (teratogenesis )

;

and the production of death are just a few of the observations that are used as qualifying toxic effects.

22
The observed or measured toxicity will depend on a number of

parameters such as mode of administration (see Table B, page 86),

length of exposure, the animal species used for testing, the period

of observation, etc. Many of these factors have been reviewed for

PCBs by Kimbrough (see A. 3.7, Ref. 11 ) and further illustrate the

diversity of responses to a chemical using a variety of animal species.

This review illustrates the difficulty if not the impossibility of

specifying a comprehensive set of test methods.

Exposure of humans (industrial toxicology): While a number of

agencies have defined toxicity (see A.3.5), there are relatively few

standard tests for determining the toxicity of a new chemical. In the

first category above, protection of the work environment is generally

achieved through the use of a "threshold" limit value (TLV) formerly

known as maximum allowable concentration (MAC). In the United States

the threshold limit values are set by the American Conference of

Governmental Industrial Hygienists and published annually. The TLV may or may not have been arrived at through animal testing to determine "safe"

levels. The levels are constantly undergoing revisions as new information

and experience becomes available. Perhaps the most recent example of this

is the lowering of the threshold limit value for vinyl chloride monomer

due to the finding of liver carcinoma (angiosarcoma) in industrial

workers who were exposed to low sub-lethal levels of vinyl chloride over

a period of 20 to 30 years.

While there is no "one" test method used for determining the toxicity

of a chemical to humans, the most frequently used chronic and acute tests

are: (I) oral LD50; (2) dermal toxicity (skin absorption); (3) irritation

to determine the effect on skin, eyes or mucous membranes; (k) inhalation;

(5) chronic or ingestion studies. These determinations are generally

made on animals and the relationship between human and animal data

continues to raise numerous questions that cannot be resolved here.

Details on performance of most of these tests are given in the text

of the Federal Hazardous Substances Labeling Act (Public Law 86-613,

see A.3.5). It should be emphasized that these tests are recommendations

and not meant to be all-inclusive.

Protection of the environment: The second category referred to

earlier as the hazard to the environment is certainly more complex and

generally represents a chronic exposure. The hazard that a particular

chemical poses to the environment not only depends on its inherent

toxicity but also the chemical and physical properties of the chemical.

For example, the chemical stability, water and lipid solubility,

biodegradability , vapor pressure, etc., will determine the extent to which

the chemical will survive and be distributed throughout the environment.

These factors will determine to a large degree the ability of the chemical

to be involved in bioconcentration as it proceeds along the food chain.

Biodegradation or biotransformation, may itself produce a more toxic

product, more easily assimilated into biological systems than the original

chemical

.

Biological accumulation requires high lipid solubility versus water

solubility, high persistence in the biological system, and a low

23
tendency for complex formation with organic ligands. The degree to

which a chemical affects the environment may lead to chronic exposure

of man by the way of the food chain. Thus the foregoing discussions

regarding the contamination of the environment may ultimately lead

back to human exposure. These factors must be considered in the

evaluation of a new insulating fluid.

3.3.2 Recommendat ions

1. Avoid rigid protocols : Any attempt to develop a standard set

of protocols for routine assessment of the toxicological hazard of an insulating fluid, or any chemical, has several dangers that must be

recognized. Such a course of action may lead to the use of tests that

are unnecessary. In addition, such standard protocols may fail to ask

questions that may be of overriding significance. Given the multiplicity

of the possible biological systems, an all inclusive standardizing test

protocol, which considers all possible reactions, would be wasteful of

resources if not impossible. Furthermore, such testing would not

guarantee the "complete" safety of a new chemical.

2. Multidisciplinary assessment of toxicity requirements : The extent

and nature of tests should reflect (l) the possible level of exposure and

route of administration to be expected in usage, (2) the consequences that can be expected, and (3) a margin of safety between expected environmental

levels and the dose that produces some adverse effect. In terms of

insulating fluids it is important to examine the pattern of usage and

disposal, the chemical and physical properties and the biological effects

of the compound. An understanding of these factors demands that chronic

toxicity evaluations be assessed by a sophisticated multidisciplinary

group which involves chemists, toxicologists , microbiologists, and

biochemists, etc., working together. Anything short of this approach

is likely to lead to a repetition of the present PCB situation.

3. Ames test : It is recommended that all new fluids be screened

for mutagenesis in the Salmonella/microsome test otherwise known as the Ames test [f]. The mutagenicity of the combustion products of new

fluids should also be screened using this procedure. Since this test

is relatively simple and a high correlation has been obtained between

carcinogenicity and mutagenicity with large number of chemicals, it

should be run prior to any other toxicological studies to determine the

mutagenic potency of a new fluid. With data available on the mutagenic

potency of a new fluid, a decision to do more extensive testing or to

terminate the effort can be made at a relatively early stage.

k. Chronic tests for initial screening : While no set of routine

animal investigations will be universally applicable for the definition

of the toxicological properties of all insulating fluids, a screening

procedure is valuable. Since the problem is mainly one of low level

chronic exposure, this type of study should be emphasized but acute

exposure should not be neglected. In fact many toxicological studies

start with acute work even though the exposure is chronic. Since chronic

exposure in the work environment is likely to occur through the respiratory

tract, this mode of administration should be emphasized. Due to the fact

that environmental problems frequently occur by way of water contamination,

avian and fish studies are extremely valuable and should be used.

2k
Acute toxicity studies are frequently used to: (l) determine relative

toxicity in order to determine what type of further studies should be

made (chronic and acute), and (2) delineate the specific toxic effect

and mechanism of action. Such studies aid in identifying target organ

effects which are valuable in the design of chronic exposure studies

which is the primary concern in the evaluation of insulating fluids.

In addition to LD50 data, acute toxicity tests provide information on species variability, sex differences, and signs of intoxication which

include the relationship of the response of primary interest and the

dose response curve.

While a specific protocol is inappropriate, general but detailed

guidelines, as suggested by the National Academy of Science in "Principles

for Evaluating Chemicals in the Environment" ( A. 3 . 7 , Ref. kk) are appropriate.

It is highly recommended that appendix B and D of that document be followed

closely in evaluating the toxicological effects of a new insulating fluid

prior to its introduction into commerce.

5. Combustion product toxicology : The toxicological hazards

associated with the combustion products of an insulating fluid are likely

to represent an acute exposure situation with a single high concentration

of products for a relatively short period of time. The major route of

exposure is by inhalation. The assessment of this hazard is complicated

by the large number of products that are likely to result during accidental

fire. On the other hand, the situation is simplified by the fact that

environmental contamination with toxic combustion products is not likely

to create a problem since accidental fires are expected to be relatively

infrequent

.

At the present time there is no accepted or standardized procedure

for this type of hazard assessment. However, a recommended protocol for

determining the relative toxicological hazard of combustion products

for various synthetic materials is under active development in a number

of laboratories in the world. This is one of the major objectives of

the Program for Toxicology of Combustion Products at the National Bureau

of Standards. The protocol under development would appear to be applicable

with minor modifications to insulating fluids.

3. h Recommendation on Degradability and Biodegradability Tests

Our knowledge of the degradability of the materials of interest as PCB replacements comes mainly from several experiments which were dictated

by the immediate needs of individual organizations. There has been no coordinated, industry-wide effort to study the degradability of the

electrical insulating fluids currently used or proposed for use in

transformers and capacitors.

A standard degradability test, developed by the Soap and Detergent

Association, has been successfully employed in that industry's selfpolicing program. The same test procedure has also proven significant

25
in evaluating the biodegradability of the phthalate esters by that

industry. A need exists for a similar standard test procedure, or set

of procedures, for evaluating the degradability—biological, chemical,

or physical—of electrical insulating fluids.

In view of the urgency and of the almost universal impact of the

decisions to be made it seems appropriate to recommend involvement of

governmental agencies—by initial sponsorship and subsidy—in fostering

the development of such standard test procedures. Initial emphasis should

be on tests applicable to those liquids which appear on other grounds to

be the most promising candidate replacements for the askarels.

Much stress has been placed upon the toxicity of askarels and other

widely used fluids. It is clear, however, that the toxicity of the

intermediate substances in the breakdown processes of the proposed askarel

replacement fluids as well as the fluids themselves should be scrutinized.

The ideal solution may be elusive. Since an increase in degradability

means an increase in reactivity, as new insulating materials for use in

power transformers and capacitors are sought, repeated confrontation with

dilemmas such as the following must be expected:

1. Increased degradability may bring with it intensified

toxicity.

2. Increase in degradability may increase fire risk.

3. Increased degradability may cause a lowering of reliability

of performance of the insulating liquid.

A consideration of all these points will necessitate a comprehensive

examination of all properties of a fluid along with an examination of

all properties of its breakdown products, an immense task. It is

evident that until knowledge accumulates care will have to be exercised

and judgment rendered and compromises accepted for each new class of

insulating liquids.

3. 5 Recommended Insulation System Tests and Standards — Transformers

3.5-1 Insulation System Tests

Tests of the separate properties of new transformer fluids, as described in 3.1, 3.2, 3.3, and 3-^, are adequate for screening the

potential usefulness of the fluids, but they must ultimately be

qualified in the true transformer environment. The influences of

winding, tank, and core geometries, and of possible reactions between

the fluids and core, tank and solid insulating materials cannot be

evaluated outside the actual transformer configuration or its realistic

model

.

26
Each transformer manufacturer will, of course, test new fluids

in his own designs, hut it would he additionally helpful to have a standard test configuration developed so that different fluids and

different fluid/solid combinations can he put on a comparative basis.

This would he useful to fluid and transformer manufacturers, transformer

users, and to fire insurance, code and regulatory personnel. Each of

these interests should therefore he represented in planning and guiding

the detailed design, initial testing, and preparation of descriptions

and instructions for this standard transformer test.

As an example, we recommend for consideration the test guidelines

described in the remaining portion of this subsection. We must caution

that this is only our initial concept of such a test based on a limited

exposure to the problem. Firm guidelines for testing can only be

established and validated after considerable experimentation. We recommend

research which could lead to such guidelines.

The following features should be considered for a transformer test:

1. Tank: fixed size, shape (tank material might be considered

to be a variable)

2. Bushings: fixed

3. Sealing and filling techniques: fixed. A provision should

be made for regular sampling of the fluid.

k. Winding; winding insulation; core size, shape, and materials:

fixed

5- Internal supporting structure and electrical connections: fixed

6. The size of the standard model should be large enough for

realistic instrumentation, but not so large that cost and

laboratory size are excessive. A unit in the range of a few

kVA and a few kV might be the right size.

Three types of testing should be carried out for an evaluation

of a new transformer fluid: stability, corona, and arcing testing.

Instrumentation and measurements which might be considered are described

below.

1. Stability tests : The objective of these tests is to

measure the permanence of the fluid, and the degree

of deterioration of solid surfaces in contact with the

fluid. Temperature cycling should occur. The fluid

should be sampled at regular intervals and tested

for changes in electrical (dielectric constant,

dielectric strength, resistivity, loss factor) and

physical (density, viscosity, specific heat, flammability

)

properties. Chemical analysis should be carried on to identify

contaminants. The tank walls, core and wire insulation surfaces

should be inspected regularly for detection of surface reaction.

Standardized procedures should be employed wherever available.

27
2. Corona tests : A standard corona source should be designed

into the standard model transformer, possibly associated with

one of the windings. Corona inception and extinction levels

should be measured, using standard procedures.^ Corona

should persist at a prescribed level for a specified duration.

The fluid should be regularly sampled during this time to

measure changes in electrical and physical properties, and to

detect contaminants. Tank walls, core and conductor insulation

should be regularly inspected for surface reactions. An

attempt should be made to detect and identify any tendency

to convert from corona to a higher current arc. Procedures for

removing contaminants should be considered.

3. Arcing tests : A standard method should be developed for

igniting an arc within the model transformer. Possibly the

standard test could include different arc modes , between

adjacent layers of a winding, between windings and from one winding to the tank. The following parameters should be

controllable variables: source voltage and impedance or arc current, arc duration and initial temperature. The following

phenomena might be measured or observed:

a. Growth of arc current and arc length and position.

b. Pressure wave within the tank and on the tank wall.

c. Conditions to cause tank rupture.

d. Energy release from the fluid.

e. External fire; fire threat to neighboring structures.

f. External blast wave and damage to neighboring structures.

g. Escaping combust ion/explosion products.

After an acceptable insulation model has been developed and thoroughly

tested, the design and testing procedures should be documented for

consideration by standards, codes, insurance groups and regulatory

agencies

.

3-5.2 Standards — Transformers

Several of the ANSI C 57 series of standards dealing with

transformers make reference in the title or elsewhere to the liquid

filling, i.e., "mineral-oil immersed," "mineral-oil filled," etc. These

are probably only intended as restrictions to eliminate dry-type

transformers since ANSI C 57-80 (Terminology) states "the term oil includes

synthetic liquids as well as mineral transformer oil." However it would

seem appropriate that the whole series be studied and necessary modifications

made in future revisions to remove the restrictions where they are not

essential. In those cases where the restrictions are necessary,

corresponding documents which apply to transformers with other insulating

liquids should be prepared.

1A.STM D 1868-73 "Detection and Measurement of Discharge (Corona) Pulses

in Evaluation of Insulation Systems"

28
Some standards and formal guidelines which might he needed for

transformers with new fluids are:

1. Standard sizes and ratings.

2. Guidelines for acceptance testing.

3. Installation and operation codes.

k. Guidelines for maintenance of new fluids in transformers.

5. Guidelines for storage and disposal."1"

6. Guidelines for fusing.

The insulation system tests on transformer models described above

should be designed to- provide the information needed for these new

standards and guidelines. While fusing is strictly outside the scope

of this study, more flammable fluids could be used if higher levels

of fusing were present; the model system tests could place quantitative

requirements for fuse protection of new, more flammable fluids.

3.6 Recommended Insulation System Tests and Standards — Capacitors

3.6.1 Insulation System Tests

Tests of the separate properties of new capacitor fluids, as described in 3.1, 3.2, 3-3, and 3.^-, are adequate for screening the

potential usefulness of the fluids, but they must ultimately be qualified

in the true capacitor environment. The influence of electrode and solid

dielectric geometry and possible reactions with these surfaces are essentially impossible to evaluate outside the actual capacitor

configuration.

Each manufacturer will, of course, test new fluids in his own capacitor designs, but it would be additionally helpful to have a standard test configuration so that different fluids and different

fluid/solid combinations can be put on a comparative basis. This

would be useful to fluids and capacitor manufacturers, to capacitor

users, and to fire insurance, code and regulatory personnel. All of

these interests should, therefore, participate in guiding the detailed

design and use of such a standard capacitor test.

The suggested model tests on capacitor insulation systems are identical in approach to those recommended for transformers in 3.5-1.

Many factors responsible for insulation failures in transformers are present also in capacitors. There are several obvious practical differences

in the components of transformers and capacitors. Because there are

A contributor has suggested that guidelines and standards will also be

needed for the proper substitution of new fluids for askarel in

existing transformers.

29
differences, the entire suggested guideline for capacitor model tests is

described. As for transformers, we again emphasize that the following

guidelines are our initial recommendations for a model test; they point out

a number of details which should be investigated in any model test.

However, they are not firm and verified test procedures. These can only

be established after considerable experimentation.

The following features should be considered for a standard capacitor

model test:

1. Container: fixed size, shape, material.

2. Bushings: fixed.

3. Sealing and filling techniques: fixed; provision should be made

for regular sampling of the fluid, possibly by dismantling one

out of a group of test units at regular intervals.

h. Electrode foil; insulation film size, thicknesses and roll

configuration: fixed.

5. Foil and film materials: variable, so that the reaction of the

test fluid with different foil and film materials can be

measured

.

6. Foil/film roll supporting structure and electrical connections:

fixed.

Three types of tests should be carried out for a complete evaluation

of a given fluid/film/foil combination: for stability, for corona effects,

and for arcing effects. Instrumentation and measurements which might

be made in each test are described below.

1. Stability tests : The objective of these tests is to

measure the permanence of the fluid, and the degree

of deterioration of solid surfaces in contact with

the fluid. Temperature cycling should occur. The

fluid should be sampled at regular intervals and

tested for changes in electrical (dielectric constant,

dielectric strength, resistivity, loss factor) and physical

(density, viscosity, specific heat, flammability ) properties.

Chemical analysis should be carried on to identify contaminants.

The container walls, foil and film should be inspected

regularly for detection of surface reaction. Standardized

procedures should be employed wherever available.

2. Corona tests : A standard corona source should be designed into

the standard capacitor configuration. This might be the foil

itself, or an auxiliary electrode. Corona inception and extinction

levels should be measured, using standard procedures."'" Corona

1

ASTM D 1868-73 "Detection and Measurement of Discharge (Corona) Pulses

in Evaluation of Insulation Systems"

30
should persist at a prescribed level for a specified duration.

The fluid should be regularly sampled during this time to

measure changes in electrical and physical properties and to

detect contaminants. Foil, film and container walls should be

regularly inspected for surface reactions. An attempt should

be made to detect and identify any tendency to convert from a corona to a higher current arc. Procedures for removing

contaminants should be considered.

3. Arcing tests : A standard method should be developed for

igniting an arc within the container. The source voltage and

impedance or arc current, arc duration and initial temperature

should be controllable variables. The following parameters

might be measured or observed:

a. Arc voltage.

b. Pressure wave (intensity and time parameter) within

the container.

c. Pressure on the container wall.

d. Energy release from the fluid.

e. Conditions to cause container rupture.

f. External fire; fire threat to adjacent capacitors.

g. External blast wave and damage to neighboring capacitors

and structures.

h. Escaping arc products.

After a suitable model has been developed and thoroughly tested,

the design and testing procedures should be documented for consideration

by standards, codes, insurance and regulatory agencies.

3.6.2 Standards — Capacitors

Several guidelines and standards will eventually have to be

developed for capacitors with new fluids; these can be grouped in

several categories:

1. Standard sizes and ratings.

2. Guidelines for acceptance testing.

3. Installation and operation codes.

k. Guidelines for maintenance of new fluids in capacitors.

5. Guidelines for storage and disposal.

6. Guidelines for fusing.

31
These would serve capacitors with new fluids much as ANSI C55.2,

NEMA CP1 and EIA RS-392 now serve askarel-filled units. The model system

tests described above should be designed to provide the information needed

for these new standards and guidelines. We should note that EIA is moving

in this direction already with its RS- 392-1 standard (also ANSI C83.6T9)

but that the combination of nonaskarel fluid and nonpaper dielectric has

not yet been covered by EIA standards.

Some brief explanation of the above fusing recommendation is in order.

While fusing is strictly outside the purview of this study, it does

possess a close relationship to the flammability issue and therefore deserves

some mention. A more highly flammable fluid can possibly be tolerated in

a capacitor if the fusing protection is sufficiently good. The system

model tests described above should be designed to quantize this trade off

between flammability and fusing.

3.7 Standards, Regulations, Codes

In previous sections of this report, frequent references have been

made to standards, regulations, and codes, but mostly in the context of

specific test techniques or specific new fluids. In this present section

we will briefly review this same material, not in terms of the techniques

themselves but rather to investigate mechanisms for formal adoption of

the techniques.

It is true that existing codes and standards are such that locations

can be found for initial service testing of capacitors and transformers

with new fluids; however, new or revised standards will be required as new fluids, and new test procedures for these fluids are "proved out" in

field testing and as they approach full-scale commercial use.

Because of the long time required in the preparation of such

standards, the existing standardizing committees in IEEE, ASTM, NEMA,

and EIA should be encouraged to accelerate current efforts and to initiate

new programs where necessary to permit the development of standards to

proceed as nearly as possible in parallel with the field testing phase.

Of concern in a discussion of the need for new, or the revision of

existing, standards documents is the problem of achieving adequate "user"

participation in the technical society committees which prepare them.

It has been called to our attention, for example, that of the near 100

members of the ASTM D 27 committee which is responsible for insulating

fluids standards, only the order of 10% are from utilities, and

participation of Federal Government agencies is at a very much lower level

although the Government through GSA, DoD, Dol, etc., is perhaps the

largest single purchaser of power transformers. It seems evident that

greater participation by the "user" group might significantly expedite

the preparation of needed standards.

32
Concern with the costs of staff participation in standardizing

activities probably is the principal deterrent to greater involvement

both of this "user" group and of the academic community. This concern

no doubt also sets a limit to the level of effort in these activities

by the manufacturing community which currently appears to be making

the greatest contributions.

Recommendation : Establish a fund to pay travel costs incident

to staff participation in the preparation of the most urgently

needed standards, in order to broaden the base of industry and

academic participation and greatly reduce the time required in the

preparation and adoption of new and revised standards.

The National Electrical Code (NEC) plays a key role in commercial

acceptance and usage of new fluids, as has already been pointed out in

earlier sections. It is used by fire insurance companies in judging the

acceptability of installations for insurance coverage, it forms the basis

of many local building codes and ordinances, and it has been incorporated

into federal regulations. It is important, therefore, that the Electrical

Coordinating Committee of NEC be cognizant of, and give counsel on development of new flammability tests such as discussed in Sections 3-2,

3.5, and 3.6. Independent testing laboratories such as Underwriters

Laboratory and Factory Mutual Engineering and Research must also be given

the opportunity to contribute to formulation of these new flammability

test procedures.

Each of the pertinent Government regulatory agencies has its own particular area of concern regarding new insulating fluids, and can contribute from its own special strength in developing new tests, and in

interpreting regulations as they apply to new fluids. In particular,

the following specific comments can be made:

1. OSHA: Consideration should be given to modifying regulations

to allow insulating fluids not yet recognized by the National

Electrical Code. OSHA might also encourage development of airborne

toxicity tests and flammability tests which are particularly

adapted to the work place.

2. FDA and State Departments of Public Health : Early evaluation

of the new candidate fluids is needed, regarding not only

toxicity but also likely avenues of entry into food production

and distribution.

3. DOT : The hazards of new fluids particularly associated with

transportation should be explored; also a determination should

be made whether any new candidate fluids fall within DOT '

s

existing hazardous or toxic substance classifications.

h. HEW : Test procedures will need to be developed for determining

toxicity and degradability of new fluids.

33
5 . EPA, State Departments of Natural Resources and Public Health : Analytic procedures will be needed for measuring presence,

toxicity and degradability of new fluids in the natural

environment; present background levels of the substances should

also be determined for future comparison. An evaluation should

be made of the impact of proposed toxic substance legislation

on the industry if it turns to the new candidate fluids.

Recommendation : Form an interagency task force with representation

from each of the federal (and perhaps from a few of the more active and

involved state) agencies, charged with the task of developing a consistent

governmental approach to solution of the problems imposed by the safety

oncern with electrical insulating fluids. If such a task assignment

lS not feasible, even the minimal assigned responsibility for keeping

each other and the electrical power industry at large well informed as

•-o planned actions would well justify its formation. The task force

could become the focal point for the industry's contacts with the

Government in this area of concern.

3k
3.8 References for Section 3

1. A. F. Robertson, "Test Method Categorization and Fire Hazard

Standards." Standardization News , Vol. 3 (1975), pp. 18-20.

2. H. L. Malhotra, "The Philosophy and Design of Fire Tests."

Proceedings of the International Symposium on Fire Safety of

Combustible Materials , University of Edinburgh, Oct. 1975, p. 1^9-

3. H. A. Wray, "New Flash Point Tester for the Paint Industry."

Journal of Paint Technology , Vol. U5 (1973), pp. hh-^k

.

h. A. F. Roberts, "Extinction Phenomena in Liquids." Proceedings of

the Fifteenth Symposium (international) on Combustion, The Combustion

Institute , 197 1*, pp. 305-313.

5. D. J. Rasbash, "Relevance of Fire Point Theory to the Assessment of

Fire Behavior of Combustible Materials." Proceedings of the

International Symposium on Fire Safety of Combustible Materials , University of Edinburgh, Oct. 1975, p. l69-

6. D. A. Duckett , "Catastrophic Explosion Tests in Insulating Fluids."

Internal Report, RTE Corp., Waukesha, Wisconsin 53186, Nov. 9, 197^.

7- J. McCann, E. Choi, E. Tamasaki and B. Ames, "Detection of Carcinogens

as Mutagens in the Salmonella/Microsome Test: Assay of 300 Chemicals."

Proc. Natl. Acad. Sci. , Vol. 72, Dec. 1975, pp. 5235-5239-

35
APPENDIX

Status

A.l "Askarel-class" Transformers

A. 1.1 Description of the "askarel class" of transformers

Electrical transformers are used to change voltage, current ana- impedance levels in a vide variety of applications in electrical

apparatus. These transformers range from the very smallest types in

solid-state electronic circuitry to very large 60-Hz power transformers.

This study is concerned with the following restricted but important set

of^ t rans formers

:

1. Utility and industrial distribution transformers; these include

a wide variety of applications: uses in utility "network" systems, in

secondary unit substations and factory load centers; they may be underground, within buildings or adjacent to buildings or other occupied

areas. This group is therefore identified by industrial and commercial

use in areas where the load and population densities are high. Typical

ratings are 500-2500 kVA, h-3h kV.

2. High voltage transformers, for electrostatic precipitators which

remove particulate pollutants from furnace exhaust gases.

3. Transformers for multiple-unit type electric railroad cars;

these are located under the flat-bed of the car.

While many precipitator and most railroad transformers are askarelCilled, only 10-15$ of utility and industrial distribution transformers

identified above av e the askarel-type

.

Most power transformers use a liquid insulant which serves two

purposes: electrical insulation and cooling. Compared with air insulation,

the liquid allows much closer spacing (smaller size) for a given voltage,

and compared with air or solid insulation (as used in "dry-type"

transformers), the circulating liquid coolant leads to a much smaller

size for a given power rating. Mineral oil was traditionally used for

this purpose and is still used for most applications. Estimates are that as much as 98% of all liquid-cooled power transformers use mineral

oil, on an MVA or gallon-of-coolant basis.

However, the particular set of applications described above have

critical nonflammability requirements since they are generally located

in heavily populated areas or are used in high-temperature or high firerisk conditions. "Askarel" transformer liquid was developed, using

blends of the polychlorinated biphenyls (PCBs), in the early 1930's to

replace mineral oil in applications where nonflammability was an important requirement. The PCBs for these transformer askarel s are manufactured by Monsanto Industrial Chemicals Company and are sold by

Monsanto under the trade name "Aroclor." Two grades are presently used

(showing percent chlorination and 197 1* domestic sales in thousands of pounds)

Aroclor 12k2 (h2%) 6207

Aroclor 125^ (5k%) 6l85

36
Ten to twenty percent of this production goes into electrostatic

precipitator and railroad transformers"'"; most of the remainder is used

in the utility and industrial transformers. Approximately 5000 askarelfilled transformers are manufactured per year in the U.S., at a value

of about $U5 million.

The term "askarel" which describes a broad class of fire-resistant [l],

synthetic, chlorinated, hydrocarbon insulating liquids is defined more

rigorously in the following standards and guidelines.

IEEE Std. 76-197U; IEEE Guide for Acceptance and Maintenance

of Transformer Askarel in Equipment

ASTM D-22S3-73; (Jhiorirated Aromaf' c Hydrocarbons (Askarels ) for

Transformers (also see D-2233-70)

National Electrica] Code, 1975; Art. 100 ("Definitions"), h^0

(Transformers and Transformer Vaults), U60 (Capacitors).

In addition to the fire-resistant characteristics of the askarels,

their high dielectric strength, low electrical loss, adequate viscosity,

specific heat, and thermal stability, and their nonsludging qualities

have combined to make them increasingly attractive transformer insulants

since their introduction in 1932 [2]. Their high cost relative to mineral

oil has, however, restricted their use to transformers for the abovedescribed fairly well defined set of applications —the "askarel-class"

of transformers.^ It is for this set of uses, then, that alternative

transformer fluids are being offered, and test methods and standards for

these alternative fluids should therefore be responsive to these

specific applications.

The askarels provide fire-resistance by generating inert hydrogen

chloride upon decomposition. Their flash and fire points are also very

high, making them difficult to ignite. Hydrogen chloride is a highly

corrosive material, and so extensive special designing and installation

must be observed. Only particular, corrosion-resistant winding and tank

coating materials can be used, "scavenger" materials must be present in

the fluid to take up any small amounts of hydrogen chloride which are generated in normal operation, and in addition the transformer room or vault must be adequately ventilated to prevent buildup of HC1 vapor.

It should also be noted that askarels are very efficient solvents and that

consequently all solid insulating materials, including gaskets and paints,

must be carefully selected.

These two special uses are growing as mass transportation and air

pollution control programs expand.

Askarel transformers are specifically identified in the National

Electrical Code and in many local fire codes and ordinances.

37
Because of the toxicity and environmental problems of the PCBs

,

drainage from askarel transformer installations must also be adequately

collected so that small or large scale spilling of fluid, during filling,

testing, operation or catastrophic rupture, will be contained and not

reach the ground water or navigable water systems.

These special requirements of existing askarel-trans former designs

and installations are being identified in order to have a clearer

picture of the processes which will be involved in replacing the PCB

fluid with an alternative. Either the new fluid will have to be

compatible with all of the characteristics of the existing askarel

installation, or new installations will have to be designed to

accommodate the new fluid. These constraints will shape the requirements

of testing procedures to evaluate and qualify new fluids and transformers

filled with new fluids.

A. 1.2 Sources and consequences of transformer tank rupture

In the construction of "askarel-class" transformers, the windings

are completely immersed in the fluid, inside a tank which is sealed to

prevent the fluid from escaping.-'- The tank must be heavy walled to withstand the sudden pressure of a high-current electrical fault within the

tank. The tank is generally finned for convective heat transfer to the

surrounding air, and it often has a pressure relief device to bleed off

any small but steady rise of gas pressure within the tank (as from

occasional low-level arcing or corona).

If mineral oil or a new liquid insulant such as a silicone fluid

is to be used as a replacement for askarel in transformers, one can be

sure that containment of this fluid will be a prime objective, for

safety, environmental and economic reasons. In anticipation of requirements for containment tests and standards, it will be the purpose of

this section to review the present state of standards, tests and

understanding in the area of transformer fluid containment.

Although the fluid is held in substantial drums or in the sealed

transformer tank, loss of the fluid can still occasionally occur under

several different circumstances:

a. during transport of the fluid or of the filled transformer,

b. during processing and handling of the fluid by the manufacturer

or user,

The amount of askarel fluid in such a transformer ranges from hO to

1500 gallons, depending on the size and rating of the transformer.

38
c. (luring in-service operation of the transformer, and

d. upon disposal at the end of the unit's life.

Instructions for proper transport of the fluid and of the transformer

are included within the general procedures of the Department of

Transportation [3], (see also Section A.h) . In addition, the following

are cited as examples of the types of guidelines and standards which

could be developed to prevent leakage during acceptance, maintenance,

handling and disposal of transformers and fluids:

a. "Guidelines for handling and disposal of capacitor and

transformer grade askarels containing polychlorinated

biphenyls," ANSI ClOJ.l - 197^; American National Standards

Institute, lU30 Broadway, New York, N.Y. 10018. 1

b. "IEEE guide for acceptance and maintenance of transformer

askarel in equipment," IEEE Std. 76 - 197 h , Institute of

Electrical and Electronics Engineers, 3^5 E. U7 Street,

New York, N.Y. 10017.

These standards are discussed more fully in Section A. 1.5.

The oil spill regulations developed and enforced by the Environmental

Protection Agency [h] also can serve as a model for judging the

restrictions on other fluids leaking into the environment. These are discussed in Section A.h.

A very rugged design is used for transformer tanks in order to

maintain containment under most external or internal stresses likely to be

encountered in service. These tank designs are specified by industry

standards published by ANSI [5]. Tank dimensions, static pressure withstand

capability and corrosion resistance are specified. These standards should

be reviewed for applicability with new fluids.

Rupture of a transformer tank while in service is most often due to

arcing within the tank. This is a very complicated phenomenon which has

been studied for many years. The following paragraphs describe the

phenomenon, its effects, and possible controls as presented in recent

articles by Barkan et_. al. [6], Goodman and Zupon [7], Nettleton [8],

and Ristuccia and Benton [9]-

a. The arc most often starts as a low-current, high-impedance

insulation breakdown between adjacent turns somewhere within

the transformer windings.

Revision of this document is currently under way.

39
b. A "high proportion" [?] of transformer failures result from

the gradual buildup of pressure in the tank due to the gas

evolved by the low current arc. The pressure-relief valve

present on most network transformers could avoid this as a cause of rupture in this important application of "askarelclass" transformers. Some users claim, however, that the

pressure relief valve is more trouble than asset, and therefore

avoid its use. A fuse could also be used to clear these lowlevel faults, although network transformers are generally

operated without primary fusing.

c. The high-impedance arc will grow with time to a high-current

fault as the arc attacks the insulation on more turns.

Because the use of pressure relief valves generally prevents

the type of tank rupture described in part b. above, the high

current arc may be the most prevalent cause of tank failure

in the network transformers. We presume that the final growth

of current is rapid, creating a bubble of high pressure gas

within the fluid. According to Barkan [6], this bubble,

as it expands, drives a "piston" of oil against the tank

wall, momentarily overloading the wall and causing rupture.

d. Techniques for calculating the peak tank wall pressure under

arcing faults are presented in both the Nettleton [8] and the

Barkan [6] articles, but both also point out the difficulty of

this for actual tank geometries. The static pressure relief

valve is of no use here because of the rapid rate of pressure

rise [9], and gas-flame venting techniques are also generally

inapplicable for the same reason [8]. There is apparently a proposed revision to the ANSI transformer standard ( 057 • 12.20-

1971) for a standard transformer arc test to determine the

necessary tank arc pressure withstand capability [9le. Further complicating the pressure calculation are the effects

of energy release by burning of the fluid and of fluid products.

This energy will build up the pressure, and the pressure wave

will have characteristics due to being flame- as well as arc- driven [8].

f . One should not rely purely on tank withstand strength to prevent

tank rupture under arcing, but rather this should be coordinated

with a properly specified current-limiting fuse [6, 9]- The

peculiar impedance characteristics of the arc prevent use of the

familiar I^t type of fuse specifications; rather, the fuse

manufacturers should recommend the proper fuse, based on the

user's known voltage and fault-current level s.l

One user points out that network transformers are often in subways

and must therefore be submersible, and fuses are therefore avoided.

ho
Protection against the high current arc is of great importance,

not only "because it may he the most prevalent source of "askarel-class"

transformer failures, hut also because the arc is a high-temperature

source which can ignite the fluid or the decomposition products due to

the arc. Thus, protective tests and standards must coordinate the

available temperature and energy (as for instance determined by a current

limiting fuse) with the ignition temperature and energy of the fluid and

of flammable components created by the arc. The "transformer system

testing" discussed in A. 1.3 will explore this type of testing in

depth.

It is worth noting at this point that an arc in an insulation fluid

can cause a wide range of decomposition products, depending on the

chemical nature of the fluid, the availability of react ant gases such

as oxygen, and the intensity (temperature) of the arc. Products can be

flammable, explosive, corrosive and toxic. As examples, arcs (or low

level discharges such as corona) can decompose mineral oil into hydrogen

and hydrocarbon gases (and probably water if air is present), while

askarels are known to break down to hydrogen chloride, and some hydrocarbon gases. Nitrogen, carbon monoxide and carbon dioxide are also

said to result [10] but again probably only in the presence of air.-1-

Not only can these products be directly harmful, but they can also

weaken the dielectric strength of the insulating fluid and thereby set

the stage for subsequent high current flashover and tank rupture. One

should, therefore, seek standard procedures by which the fluid can be

cleaned up at regular intervals, or after known arcing, in order to avoid

future equipment failure. As guides in preparing such standards, we should note the following procedures which are now regularly employed.

a. "Scavenger" substances are mixed with askarels to take up the

corrosive hydrogen chloride which is produced by occasional

low level electrical discharges within the fluid.

b. In spite of the presence of scavenger material, users are instructed to bubble nitrogen through the fluid immediately

after known arcing in order to pick up hydrogen chloride

before it can do corrosion damage.

c. The IEEE Standard 76-197^ suggests that moisture content and

dielectric strength of askarel be regularly checked if

electrical discharge is known to be occurring.

Because of the combination of preventive measures outlined above,

manufacturers and users report that present transformers of the network

type experience about a 0.01 to 0.02% yearly rate of tank rupturing

A recent report (National Conference on PCBs, Chicago, Nov. 1975)

indicates that chlorinated dibenzofurans are formed in PCB heat

exchanger fluids.

Hi
failures. Tests, standards, and guidelines must be prepared for new

fluids in order that low failure rates will also be obtained for new transformer fluids.

Even though a low rupture rate is experienced with transformers,

it is still industry practice, generally backed by fire or environmental

code enforcements, in indoor installations to place fluid-insulated

transformers in vaults or special rooms. Mineral oil units must be in

fire-proof vaults [ll]. Low-voltage askarel transformers need not be

in fire-proof vaults but must be installed so that ventilation is adequate

to prevent accumulation of toxic vapors [12]. Drainage facilities should

be such that spilled fluid ... contained

A. 1.3 Transformer system testing

In the early days of askarel usage a short-circuit test and an arcing test were performed by Underwriters' Laboratories, Inc., on actual transformers filled with an askarel (General Electric "Pyranol").

Details of these tests are reported in the ULMH No. 258l Report, dated

September 29, 193^+. More recently, catastrophic explosion (arc) tests

with several insulating fluids were performed by RTE Corporation [13].

1 . Underwriters' Laboratories Tests

The transformers were rated 60 Hz, 5 kVA, 2200-110 volts. One of

these was short-circuited externally. The other was subjected to an arcing test by being connected to a 12,000 kVA generator so as to apply

7,500 volts between the ungrounded 122-volt lead and ground. In both

cases, pressure-tight covers were provided with pressure-relief diaphragms

designed to rupture at not less than 10-12 psig (69-83 kPa gauge).

The results of the two tests were rather similar: no appreciable

change in pressure was noted for approximately 2 minutes after current

was supplied to the transformer. Thereafter, the pressure increased

rather rapidly until the diaphragms ruptured. Large volumes of gases were liberated during the tests, but the gases did not ignite upon

application of a test flame.

2. RTE Arc Tests

Four insulating fluids were tested: mineral oil, DC-200 Silicone

fluid (Dow Corning), hydrogenated paraffin oil "RTemp" (RTE Corporation),

and an askarel (Westinghouse Inerteen 70-30). Approximately four gallons

of each fluid were used, preheated to 150 °C.

The containers were covered before the test, but the rupture pressure

(presumably roughly the same in all four cases) was not specified. In

each test the liquids were subjected to a massive arc discharge: U660

to U820 A, the arc being initiated with U800 volt open circuit. Each

of the four samples showed a violent flash initially and wide spraying

of the liquid as the cover was blown free, but only mineral oil continued

U2
to burn. It is important to note that mineral oils used in transformers

have flash points in the vicinity of 150 °C and fire points about 15 °C

higher. The highly-chlorinated askarels, on the other hand, have no fire

point up to the boiling point. They have no true flash points but so- called pseudo flash points may be observed under conditions of the test.

Silicone fluids have very high flash points at about 300 °C (see the

section on flammability tests). RTemp, bein/?; a high hydrocarbon fract ' "~ , presumably also has a high flash point. Thus the tests were conducted

with initial fluid temperature near- the flash and fire points of mineral

oil, but substantially below the flash points of the other fluids.

3 . Reaction from Industry

The consensus appears to be that both sets of tests (UL and RTE) show

askarels to have very low flammability. The UL rating of 2-3 on the scale

of 100 for flammable fluids reflects this consensus. Furthermore, the

Factory Mutual representatives appear satisfied that the RTE tests show

also the silicone fluids and RTemp to have flammabilit ies in the same,

generally acceptable, range as askarels. UL representatives have not

commented on the RTE tests.

On the other hand, the nature of the initial flash in RTE tests and

of the observed pseudo flashes in flash point testing of askarels does

not appear to be understood; some concern therefore remains. Intense

heating of the decomposition products by the arc may lead to some reaction

of these products with air. Contributors have also suggested that in arc explosion tests of askarels the fluid is electrically heated to decomposition

temperatures, and that decomposition itself is exothermic. As a result,

several representatives from industry and insurance business have commented

that a carefully standardized arcing test should be developed.

Manufacturers, users, and testing laboratory personnel have indicated

a willingness to cooperate in developing such a test.

A.l.h Alternatives to askarels in "askarel-class" transformers;

influence on total transformer tests and standards

We must emphasize again that the purpose of this study is not to

evaluate alternatives to askarels but rather to survey the status of

tests and standards by which such alternatives may be judged. The

characteristics of the available alternatives must be explored, however,

to the extent that unique characteristics will influence the definitions

of tests and standards. This section will emphasize the effect of

alternatives on the total unit, while the Section A.h will look at the

fluids themselves. Many concepts originally brought up in A. 1.2

("Sources and consequences of transformer tank rupture") will be

revisited in terms of the goals of this section.

The characteristics of available alternative fluids are presented

in detail in Section A. 3 and therefore need not be repeated here. It is

important to note, however, that these represent a wide range of density,

h3
viscosity, operating temperature, corrosiveness , volatility, hydrolytic

stability, flammability , etc. Because of the diversity of these values,

we will see that universal fluid performance specifications will be

difficult to write without taking into account the unique characteristics

of each particular insulant. This will be equally true in establishing

performance standards for the total transformer assembly. The important

fluid characteristics which must be accounted for in any future transformer

standards and specifications are listed below:

a. Material compatibility . The chemical activities of the

available insulation fluids differ in kind and degree. Tests

must, therefore, be devised to measure adequacy of the materials

used for protective coating on inside of the tank walls, for

insulation on the wire used for the transformer windings, and

for miscellaneous other components such as disconnects and

fuses which might be in contact with the fluid.

b. Temperature . If the particular insulating fluid requires an unusually high operating temperature, all materials used to

construct the transformer must be compatible with this

temperature, and in addition the location of the operating

transformer must be selected to be acceptable to this higher

operating temperature. Existing standards such as: "General

Principles for Temperature Limits in the Rating of Electric

Equipment," IEEE Std. I-I969, are probably adequate for this

purpose. Standard sampling techniques may also be desired

to insure the stability of the fluids at high operating

temperatures

.

c. Cooling . The fluid in a transformer is used as both an insulating and cooling medium. An economically competitive

transformer must have its cooling system design closely matched

to the characteristics of the coolant fluid; new fluids will

undoubtedly require some redesign of the transformer. This

may necessitate new standards on transformer tanks, cooling

surfaces, circulating equipment, etc., and the user may demand

more thorough cooling specifications on transformers with new

coolant fluids.

d. Hydrolytic stability . Water is generally a problem in transformer

fluid, but the degree of difficulty will probably change from

one fluid to another. Sealing against moisture entry, and

processes for removal of water should, therefore, be specified

for each new insulant

.

e. Containment . The different fluids will have different densities

and required volumes for any given transformer power and voltage

ratings, and space and supporting structure specifications must

be made up for each new fluid. The types of seals will also

have to be correlated with each fluid, since different fluids

have different leakage characteristics. Since rigorous containment of any fluid may be the goal of future regulations,

standards and tests for evaluating containment of each tank/fluid

combination will be of increasing importance.

hh
Standards for external protection should be coordinated with the

particular class of transformers, the fluid and the level of tank

containment security. By external protection, we mean secondary

protection provisions, beyond the tank itself. This includes both

vaults , for extra containment in case of tank failure and protective

circuit elements (such as circuit breakers and fuses) to prevent tank

rupturing arcs from occurring. Much as an electrical system has its

various power and protective elements coordinated with one another, so also might the industry consider more quantitative coordination of the

levels of transformer containment. One might, for instance, consider

that increased speed and redundancy of circuit breaker and fuse

protections could allow a less cumbersome and expensive vault structure.

Extensive probability analyses of actual operating experience would be

required before such a coordination plan could be acceptable for fire

codes and insurance purposes.

Although no new standards or tests may be required, we include, for

completeness, a mention of two other available alternatives, namely drytype and gas-cooled transformers. These transformers depend on ambient

air or special gas insulation. The dry types are available now and are being used extensively in place of askarel transformers. Relative

reliability and overload capability have been questioned by some users

but are quite acceptable to others, which may mean that standardized

tests on these characteristics should be available to resolve such

disagreements

.

Gas cooled transformers are not yet as readily available for

substitution. Tests may be required to establish the harmlessness or the

need for containing products of arcing within the insulation gas.

Development of these tests should be guided by the extensive existing

work on entire gas-insulated substations.

A. 1.5 Test techniques and standards used by manufacturers and users

to evaluate fluid-filled transformers

The transformer manufacturer and user have the following standards

documents available for guidance in selecting and handling the insulating

fluid.

1. ASTM

1

D 2283-7^ "Standard Specification for Chlorinated Aromatic

Hydrocarbons (Askarels) for Transformers."

This document gives detailed specifications of the physical, chemical

and electrical properties of six askarels which have been, or are being

used in transformers and identifies specific test methods.

2. ASTM D 31U6-75 "Standard Specification for Oxidation - Inhibited

Mineral Insulating Oil for Use in Transformers and Circuit

Breakers .

"'"American Society for Testing and Materials, 19l6 Race St.,

Philadelphia, Pa. 19103-

h5
This document gives detailed specifications of the physical, chemical

and electrical properties of the oil together with approved test methods.

3. ASTM D 10U0-73 "Standard Specification for Uninhibited Mineral

Insulating Oil for Use in Transformers and in Oil Circuit

Breakers .

This document gives detailed specifications of the physical, chemical

and electrical properties of the oil together with approved test methods.

k. ANSI

1

C 59.131-1971 "Guide for Acceptance and Maintenance of

Insulating Oil in Equipment" [Also issued as IEEE2 Std. 6U-1969]-

The purpose of this guide is to assist in evaluating the serviceability

of oil received in equipment; oil as received from the refiner for filling new equipment at the installation site, and as processed into such

equipment. It also is intended to assist the operator in maintaining

his oil in serviceable condition. The guide recommends standard oil

tests and evaluation procedures, methods of reconditioning and reclaiming,

the levels at which these become necessary, and the routines for restoring

oxidation resistance where required by the addition of inhibitors.

5. IEEE Std. 76-197^ "Guide for Acceptance and Maintenance of

Transformer Askarel in Equipment."

This guide assists in evaluating askarels as received in transformers,

reactors, and accessory equipment operated at power frequencies and in

efforts to maintain askarels in serviceable condition. It recommends

standardized tests and evaluation procedures. Methods are outlined for

reconditioning and reclaiming askarels whenever necessary.

6. ANSI C 107.1-197**. "Guidelines for Handling and Disposal of

Capacitor- and Transformer-Grade Askarels Containing Polychlorinat ed

Biphenyls .

This document gives typical physical, chemical and electrical

properties of askarels used in insulating fluids in transformer and

capacitor construction, standard methods by which these properties are measured, details methods of shipping and handling, spells out necessary

safety precautions, recommends labeling practices and details approved

disposal techniques. It also lists organizations having facilities for

analysis and for disposal and it describes analytical procedures for

the determination of PCBs in air, water and sediment.

American National Standards Institute, 1930 Broadway, New York, N.Y. 10018.

Institute of Electrical and Electronics Engineers, 3^5 E. U7 Street,

New York, N.Y. 10017-

h6
7. IEEE Draft "Specification for New, Unused. Transformer-type

Askarels .

This specification covers bulk shipment in tank cars and drums of

new, synthetic, nonflammable electrical insulating liquids of the

chlorinated aromatic type known as askarels which are used as insulating and cooling media in liquid-filled transformers. While this

specification is intended to cover the composition and characteristics

of askarels for purchase only and does not apply to liquids in apparatus,

a number of discontinued types are included for purposes of identification

and historical significance.

8. IEEE Std. 283-1968 "Guide for Installation of Oil-Immersed

Transformers .

This document suggests procedures to be followed in filling with oil

those large transformers which are customarily shipped to the point of

installation without the oil.

9. A NEMA"^ Standards Document titled "Proposal for American

National Standard on Mineral Insulating Oil for Use in

Electrical Apparatus" is in the final stages of preparation.

It is intended "to provide a functional industry standard that

will assure a continuing supply of a single mineral insulating

oil that adequately meets the needs of equipment manufacturers

and oil refiners."

It sets functional limits for the essential physical, electrical,

and chemical properties and specifies the ASTM test methods to be used.

Presumably it will ultimately replace items 2 and 3 above.

p

10. FSS-GSA Federal Specification VV-l-530a "Insulating Oil,

Electrical (For Transformers, Switches and Circuit Breakers)."

This standard specifies the physical properties required, establishes

quality assurance provisions, and gives instructions for testing. It

identifies several ASTM documents as forming a part of the specification.

11. FSS-GSA Federal Specification W-l-1219 "Insulating Fluid,

Electrical (Noncombustible) .

This standard applies to "liquid of the chlorinated aromatic

hydrocarbon type (askarels)" with coverage similar to that of W-l-530a.

National Electrical Manufacturers Association, 155 E. hh Street,

New York, New York 10017-

Federal Supply Service, General Services Administration, Washington, D.C. 20^05

hi
The following standards relate to the specifications and

performance of the transformer itself:

1. ANSI C 57.12.00-1973 (also IEEE #U62) "General Requirements for

Distribution, Power, and Regulating Transformers."

This standard specifies (l) service conditions; (2) preferred

ratings; (3) insulation classes and dielectric tests; (h) tolerances

on losses, impedance, ratio, regulation and temperature rise; (5) tests;

(6) such construction details as bushing class, marking of terminals,

nameplate data, etc.; and (7) short circuit characteristics.

2. ANSI C 57-12.90 (also IEEE #262) "Test Code for Distribution,

Power, and Regulating Transformers."

This standard prescribes methods for performing the tests specified

in C 57.12.00-1973 (above) and in the separate transformer standards

of the C 57-12 series. The test methods covered are: (l) resistance

measurements; (2) electrical insulation; (3) losses 'and impedance;

(h) ratio and regulation; (5) temperature rise; (6) insulation power

factor; (7) polarity and phase relation; and (8) short circuit

calculations. C 57-98, an Appendix to C 57-12.90, covers impulse tests.

3. C 57-12.90a-197 1+ (also IEEE #262A) (Draft Standard) "Distribution

and Power Transformer Short-Circuit Test Code."

This code defines a procedure by which the mechanical capability of

a transformer to withstand short-circuit stresses may be demonstrated.

Other standards and guides in the ANSI C 57 series (there are about

30) include such documents as:

C 57 -12. 20-197^ "Requirements for Overhead-Type Distribution

Transformers 67,000 Volts and Below"

C 57 - 12 . 21-1969 "Requirements for Pad-mounted Compartmental-Type

Single-Phase Distribution Transformers"

C 57.12.1+0-1967 "Secondary Network Transformers, Subway and Vault

Type (Liquid Immersed)"

C 57-100-197^ "Thermal Evaluation of Oil-Immersed Distribution

Transformers"

C 57-93 (also NEMA TR-5-1956) "Guide for the Installation and

Maintenance of Oil-Immersed Transformers"

C 57.92 "Guide for Loading Oil-Immersed Distribution and Power

Transformers"

h. NEMA TR1-197U "Transformers, Regulators and Reactors"

This document identifies the ANSI transformer standards which have
been approved as NEMA standards and includes more detailed specifications

regarding such characteristics as audible sound levels, external

clearances "between live parts, accessories, and some test procedures

.

5. NEMA TRll-1967 "Small Power Transformers with 65C Average

Winding Rise and Distribution Characteristics."

This covers electrical characteristics and mechanical features of

this class of transformers.

The above are representative of about ten NEMA standards dealing

with various classes of transformers.

6. UL (Underwriters Laboratories) 506 "Specialty Transformers"

This standard covers requirements for air-cooled transformers and

reactors for general use but does not cover oil-filled units.

7- AAR (Association of American Railroads) SM262 "Specifications

for Impulse Transformer for Coded Systems Control."

8. AAR SMI65 "Specifications for Transformer, Oil-Immersed, SelfCooled."

9- FM (Factory Mutual) 5-27 "Fire Prevention Transformers."

10. FM 5-275 "Arc-Furnace Transformers."

11. FM lh-8 "Inspection and Maintenance of Transformers."

(Note: Items 7-11 above are not in hand and thus no further description

is available )

.

Section A. 3-2 should be consulted for designation of the standards

and techniques used for specifying and measuring the various fluid

material properties identified in the above transformer standards.

A. 1.6 References, Section A.l

Much of the material in this section was obtained through personal

conversations with the manufacturers and users cited in the introduction.

In addition to these personal communications, the following sources were

found to be helpful

:

i. In Re: Proposed Toxic Pollutant Effluent Standards, (EPA)

FR1 Dec. 27, 1973; testimony on behalf of:

Federal Register

^9
a. General Electric Co. , Mr. George B. Farnsworth,

March lU, 197^

b. Westinghouse Electric Corp., Dr. James H. Wright,

March 15, 197 1*.

ii. "The Role of Polychlorinated Biphenyls in Electrical Equipment,"

General Electric Co., Schenectady, N.Y., Feb. k, 1912, (internal

publication )

.

iii. "Study of the Potential Impacts of the Proposed Toxic Substances

Control Act, as Illustrated by Senate Bill S. 776," for

Manufacturing Chemists Association, Washington, D.C., by

Foster D. Snell , Inc., June 26, 1975-

iv. National Conference on Polychlorinated Biphenyls, sponsored by

Environmental Protection Agency, Chicago, Illinois, Nov. 19-21, 1975.

The foil wing specific references have been cited in the text:

L. "Transformer Askarel Inspection and Maintenance Guide,"

Monsanto Company Bulletin No. IC/FF-38R, revised March 1975-

2. R. N. Sillars, Electrical Insulating Materials , IEE Monograph lU,

1973; Section 10.2.1.

3. U9CFR1100-199, revised October 1, 19lh.

U. "Oil Pollution Prevention," Environmental Protection Agency,

38 FR 3^l6U, December 11, 1973.

5- C 57-12.U0; American National Standards Institute.

6. P. Barkan, et_. al_. , "Overpressure Phenomena in Distribution

Transformers with Low Impedance Faults: Experiment and Theory,"

F 75 U6U-8, IEEE PES Summer Meeting, San Francisco, Calif.,

July 1975-

7. E. A. Goodman, L. Zupon, discussion to Barkan paper (F 75 U6U-8).

8. M. A. Nettleton, "Explosions Due to Faults in Electrical Equipment,"

Electrical Review , July 25, 1975, pp. 116-119.

9- D. J. Ristuccia, R. E. Benton, "Ten Most-Asked Questions on Violent

Transformer Failure," Transmission and Distribution , January 1975,

pp. 30-31.

"'"Code of Federal Regulations

50
10. A. E. Knowlton, editor-in-chief, Standard Handbook for Electrical

Engineers , Ninth Edition , McGraw-Hill Book Co., New York, 1957,

U-561, h-510.

11. National Electrical Code, 1975; Sec. U50-2U, "Oil-Insulated

Transformers Installed Indoors," NFPA, Boston, (also see

Ref. 10, Sections 15-102, U-572, lU-300).

12. National Electrical Code, 1975; Sec. ^50-23, "Askarel-Insulated

Transformers Installed Indoors," NFPA, Boston.

13. D. A. Duckett , "Catastrophic Explosion Tests in Insulating

Fluids," RTE Corporation, Waukesha, Wisconsin 53186,

November 9, 197 1*.

51
A. 2 "Askarel-class" Capacitors

A. 2.1 Description of the "askarel class" of capacitors

As in the case of transformers, there is also a wide range in types

and sizes of capacitors which are used in electrical apparatus. These are

used in electronic circuits, for electric energy storage, and for power

factor correction purposes. Their ratings can range from a few picofarads

to many microfarads, with voltages from a few volts to over one-hundred

kilovolt s

.

Although some high-frequency capacitors use air insulation, most

capacitors are made up of multiple, thin layers of metal and solid

insulation. To eliminate any weakening by the presence of air, these

layer assemblies are then totally immersed in a liquid dielectric 1-; often paper is used as one part of the solid insulator, and this paper

is impregnated by the liquid. In addition to being a good electrical

insulator, the liquid should have a high relative permittivity (high dielectric

constant, e/e Q

). The PCBs possess both of these features, and so grades of

capacitor askarels have been used in capacitors since the introduction of

the askarels in the 1930' s. Whereas only a small percentage of transformers

contain askarels, nearly one-hundred percent of power and industrial liquidfilled capacitors use this type of liquid insulant.

Because of the widespread use of PCBs in capacitors, Monsanto in

1971 introduced a more environmentally compatible formulation, Aroclor 10l6,

especially for capacitors. In 197^-, Monsanto sold 21,955 thousand pounds

of this fluid; the capacitor market for PCBs is considerably greater

than the transformer PCB demand. The market value for PCB-insulated

capacitors is in excess of $100 million per year.

Askarel capacitors are often divided into two categories, "power"

and "industrial." The power capacitors are high voltage units which

generally contain several gallons of fluid. They are used for power

factor correction to increase the efficiency of the electric power system.

Additional uses in the "power" category include dc filters, energy storage,

and induction heating capacitors.

"Industrial" capacitors are generally smaller units which serve a large number of purposes including motor start and run, and fluorescent

light starting. They are also used in arc welders and power supply

filters. The industrial class of capacitors is estimated to use one-half

to two-thirds of the demand for capacitor askarels.

Except for a few capacitor types, e.g., mica capacitors, which use only

solid insulation.

52
Capacitors of both categories are generally constructed by winding

alternate sheets of metal foil and paper and/or film dielectric in round or flattened rolls. These rolls are connected together inside a closed metal

housing which is filled with an askarel. The paper dielectric material has

a high permittivity, but it is dried before assembly into the capacitor, and

it contains a large volume percentage of open air space. The askarel

impregnates the paper, filling the air-space voids. Askarels are superior

to mineral oil for this dielectric application because the high permittivity

(e % 6e

<_) ) reasonably matches the paper, and therefore causes less non- uniformity in electrical stress. The net high permittivity and the high

dielectric strength of the askarels also allow for a smaller capacitor for a given power or energy rating.

This combination of high permittivity and high dielectric strength alone

would suffice to make askarels favorable impregnants for capacitors. Our

survey of manufacturers and users indicates that they generally have also come

to depend on the stability and nonflammability performance of askarel capacitor

fluids. Since power capacitors are often out-of-doors or in vaults, however,

it appears that more flammable fluids may in the future be more readily

accepted. This may not be true with the industrial capacitors which are often

installed in potentially flammable environments, for example, fluorescent

light fixtures and appliance motors in buildings. This flammability issue

is further discussed in A. 2. 3.

In considering test techniques for alternate capacitor fluids, then, we can at this time identify the following factors as significant:

dielectric constant (relative permittivity, e/e )

, dielectric strength,

impregnability, flammability, and stability. Toxicity, environmental

degradability and compatibility with other capacitor materials are added to the list in subsequent sections.

There is an important economic interdependence between the capacitor

and transformer fluids markets which should not be overlooked in deciding

on alternatives to PCBs. The capacitor and transformer askarels have

different percentage contents of various PCBs, but they are both formulated

from the same basic stock. They, therefore, aid each other in achieving

the cost advantages of large scale production. Any shift of either

market away from askarels would influence the price of the askarels for the

other use. This factor should be considered in evaluating the relative

cost advantages of substitutes for PCBs.

A. 2. 2 Probability and consequences of rupture

The rate at which the small industrial capacitors experience a tank-rupturing failure is very low; and when one of these small capacitors

fails, there is little loss of fluid. 1 The total amount of fluid in all

small industrial capacitors is, however, large, as was mentioned previously.

In a capacitor containing paper insulation, 80% of the fluid is absorbed

and so will not spill out even if the can does rupture.

53
In the case of the larger, power-type capacitor, the failure

rate has been historically low. Generally, a capacitor will fail

by an internal arc short-circuiting the unit. Each power capacitor

should be individually protected by a current-limiting fuse 1 which

will blow when the capacitor fails, leaving the capacitor-fuse unit

open-circuited. If the industrial capacitors contain more than

3 gallons of "flammable" liquid, the National Electrical Code also

directs that these be enclosed in a vault if indoors or within a fenced enclosure if outdoors (NEC-1975, Art. U60-2).

Often, power capacitors are used in parallel-series connected

groups, or banks, and upon failure of one capacitor in the bank, all

parallel capacitors will try to discharge through the failed unit. A

current-limiting fuse on each unit limits this "in rush" current in

order to protect the other capacitors in the bank.

2

3 NEMA standards exist for identifying the proper fuse to use to

protect any given capacitor. These are somewhat out of date, however,

so a manufacturer will generally provide the necessary information for

his capacitors. There is need, therefore, for a newly created set of

industry-wide standards for protection of new capacitor designs with

new types of impregnant dielectric fluids.

A. 2. 3 Full capacitor arc testing

We have established in Section A.l that nonflammability is an important

characteristic of "askarel-class" transformers and that the insulating

fluid has been in the past and should continue to be qualified by full

transformer arc testing. We have also recognized the importance of

nonflammability of capacitors, but it must be reported that there is

little documented experience or interest in arc or flame testing of

capacitors

.

The apparent justifications for this lack of testing are the low rate

of capacitor failure and the small amount of fluid in any one capacitor.

Fuse protection as described in A. 2. 2 also reduces concern for rupture

and fire.

The National Electrical Code calls for "overcurrent protection" on any

capacitor operating at potentials greater than 600 V (NEC-1975; Art. U60-25).

i Power capacitors on distribution feeders are often group fused.

'CP 1-1971, "Shunt Capacitors," National Electrical Manufacturers

Association, New York. See also ANSI C55-1-1968 (IEEE No. 18), "Shunt

Power Capacitors."

5h
In evaluating the need for full unit flammability testing of

capacitors, one should also keep in mind the following factors:

a. New candidate capacitor dielectric fluids generally are more flammable than askarels.

b. The paper and film, which make up a large percentage of the

bulk material within a capacitor, are generally flammable.

c. Power factor correction capacitors are generally used not

singly but rather in large multiple-unit banks. A study

should therefore be made of the probability of fire spreading

from one faulted unit to other capacitors in the bank.

d. Use of many capacitors in large, closely spaced banks also has

another risk. Unless each capacitor is properly fused, all

parallel branches of a bank can discharge through a single

unit which develops an internal, short-circuit fault. Fusing

requirements of capacitors with new fluids should therefore

not be overlooked.

Manufacturers of fluids and capacitors have privately run occasional

arc tests on capacitors to study flammability effects after a tankrupturing fault. No definitely recommended format for such testing has

been brought to our attention, however, and the indication is that

considerable design and testing would be required before a quantitatively

interpretable and repeatable test could be devised. Several parties

involved in the manufacture and use of capacitors did, however, feel

rather strongly that such a test should be developed, particularly in

light of the increased flammability of the new fluids.

A.2.U Effect of alternative fluids on design and testing of the

full capacitor unit

The dielectric fluid must be compatible with all other materials

with which the fluid makes contact inside the capacitor casing. As in

the transformer situation, the inside coating of the metal capacitor

tank must be nonreactive with the fluid. Since the fluid permeates

directly to the metal foil electrodes, either the metal and fluid must

be compatible or the metal must be treated with a protective coating.

In capacitors, the most serious material coordination problem is

between the fluid and the insulating sheets which separate the foil

electrodes. If this is a paper, then the fluid must be able to

completely impregnate the paper, leaving no voids in which corona

discharges can be initiated. Although certain fluid characteristics such

as molecular weight and viscosity will help to screen out obviously

improper fluids, adequacy of impregnation is best evaluated finally by

testing the impregnant fluid in a true film-electrode capacitor geometry.

55
One should be on the watch not only for immediate corona from

inadequate impregnation, but also for weakening of the dielectric

strength of the fluid, which can result from the fluid dissolving

impurities out of the solid insulation material.

Incompatibility of a new fluid with the existing film and paper

may be solved by selecting new paper and film rather than by rejecting

the new fluid. Thus, tests must be devised so that combinations of

fluid and solid films can be evaluated on a controllable and comparative

basis, and criteria for interpreting these tests must be devised in

order that new fluids are not rejected merely because of inadequacies

in the paper or film. The best practical combinations of fluid and

solid must be compared.

In the previous paragraph, we sought the best combination of

impregnant and paper from a materials compatibility standpoint. It is

important, however, to also coordinate dielectric characteristics.

Severely mismatched dielectric constants will cause very uneven electric

stress which can lead to corona and flashover in the more highly stressed

member. Thus, askarel is a good fluid to use with paper since both have

relatively high dielectric constants. The plastic films which are now

in use in capacitors, such as polypropylene, have lower dielectric

constants, and are therefore more compatible with lower dielectric

constant fluids.

Using lower dielectric constant materials means that the capacitance

per unit area of electrode is less for a given electrode separation.

Larger voltage or size are therefore needed for the same energy storage.

Regardless of what material is selected, its dielectric constant should

be accurately known under actual operating conditions, and its dielectric

constant should be measured with the material in the true operating

electric field. This may suggest that an extension be made in the ASTM

standard test for dielectric constant (D 92U).

The size of the capacitor is influenced not only by the dielectric

constant, but also by the dielectric strength. Decreased capacitance

and energy storage because of decreased dielectric constant can potentially be regained by higher dielectric strength materials which

allow higher fields and voltages. The design of the capacitor is,

therefore, influenced by the dielectric strength (breakdown strength)

of the fluid. The breakdown strength of the fluid itself may be measured

by standard test procedures, as described in Section A. 3. 2. Final

capacitor designs, and test capacitor geometries can be evaluated by

methods outlined in Section A. 2. 5-

The maximum operating" voltage of a capacitor is generally set by

its corona inception and extinction levels, rather than by the flashover

voltage. The low current, but continuous corona discharge causes damage

to solid and liquid dielectric material and therefore leads to short life

and failure of capacitors even though the operating voltage may be well

below the breakdown level. Detection and measurement of corona and

particularly of its inception and extinction points are therefore

56
extremely important in order to specify the maximum safe voltage for

long life. These corona levels are not characteristic of just the

insulating fluid, itself, however, but rather of the fluid in the actual

electrode configuration, including the electrode material, the

microscopic surface conditions, and purity of the electrode/fluid

interface. An absolute measure of corona inception for a pure, isolated

fluid is therefore of little value, and one must instead determine the

inception level for the whole electrode/insulator configuration,

assembled according to routines which would be followed in manufacture.

Corona measurement techniques are specified, for example, in

ASTM D 1868-73.

In addition to corona, losses in capacitors result from resistive

and dielectric properties of the fluid. These can generally be evaluated

for the pure, isolated liquid as described in Section A. 3.2. The

measurement should duplicate operating conditions (frequency, temperature,

electric field) as closely as possible. Generally, higher dielectric

constant materials exhibit higher loss, because of the large and rapid

molecular polarization changes required by high permittivity materials

in ac fields.

A final important characteristic of the capacitor dielectric fluid

is its stability. It must show little change in dielectric, chemical

or physical characteristics under actual electrical and thermal

operating conditions over the many years expected life time of the

capacitors. Frequent comments from fluids manufacturers, capacitor

manufacturers and users brought out (l) the importance of this

characteristic, (2) the difficulty in defining and measuring stability,

and (3) the importance of the measurement being in as realistic an environment as possible, i.e., in a test capacitor configuration.

In conclusion, this section has shown that the particular dielectric

fluid chosen for a capacitor has a major effect on the total capacitor

design. Consequently, and of more major importance to this study, we

can further conclude that all aspects of new capacitor dielectric fluids

finally need to be evaluated in an environment which simulates realistic

operating conditions.

A. 2. 5 Test techniques and standards employed by manufacturers and users to evaluate fluid-filled capacitors

The capacitor manufacturers and users have the following standards

documents available for guidance in selecting and handling the

insulating fluid.

1. ANSI C 59:11 (also ASTM D 2233-7M "Standard Specification for

Chlorinated Aromatic Hydrocarbons (Askarels) for Capacitors."

This document gives detailed specifications of the physical,

chemical and electrical properties of four askarels which have been

used as capacitor impregnants and details test methods.

57
2. ANSI C 59-123-1970 (also ASTM D 2297-68) "Standard

Specification for Continuity of Quality of Electrical Insulating

Mineral Oil for Capacitors and Cable Accessories."

This document provides detailed specifications of the physical,

chemical and electrical properties of the oil.

3. ANSI C 59-122-1970 (also ASTM D 2296) "Standard Specification

for Continuity of Quality of Electrical Insulating Polybutene

Oil for Capacitors."

This document provides detailed specifications of the physical,

chemical and electrical properties of the oil and details test methods.

k. ANSI C 107- 1-197^ "Guidelines for Handling and Disposal of

Capacitor- and Transformer-Grade Askarels Containing Polychlorinated

Biphenyls

.

11

This document gives the typical physical, chemical and electrical

properties of askarels used as capacitor impregnants, details methods

of shipping and handling, spells out necessary safety precautions,

recommends labeling practices and details approved disposal techniques.

It also lists organizations having facilities for analysis and for

disposal and details an analytical procedure for the determination of

airborne PCBs.

The following standards relate to the specification and performance

of the capacitor itself:

1. ANSI C 55.1-1968 (IEEE No. 18) "Shunt Power Capacitors"

Definition of terms, ratings, tolerance, operation, production and

design testing, fusing. Such characteristics as stability, corona

start, radio influence voltage, overvoltage, capacitance, leakage, loss

and dielectric withstand are identified, but the specific detailed test

techniques are not described, nor are appropriate ASTM procedures cited.

This standard is for shunt power capacitors without reference to the

dielectric fluid; with nonaskarel fluids, certain specified values and

limits might possibly have to change, and specific test procedures may

not be the same as have been traditionally used for askarel capacitors.

58
2. ANSI C 55.2-1973 "Series Capacitors for Transmission and

Distribution-line Compensation"

This standard includes requirements for safety, rating, and gap

settings; functional requirements for protective equipment, alarm

devices, servicing, type, and routine tests and a guide for operation.

3. NEMA CP1-1971 "Shunt Capacitors"

This standard is similar in coverage to ANSI C 55-1.

k. EIA

1 RS-392 "Fixed Paper Dielectric Capacitors for Alternating

Current Applications"

This standard covers the requirements for oil-paper dielectric

capacitors hermetically sealed in metal cases for general purpose

application on ac voltages. It specifies (l) standard designations,

(2) standard test conditions, (3) marking, (U) quality assurance test

programs, (5) tests, and (6) applications suggestions. Although the

term "oil" is used, this standard is meant to apply to askarel-filled

capacitors

.

5. EIA RS-392-1 (ANSI C83 . 67a-197^ ) "Fixed Paper Dielectric

Capacitors with Non-PCB Impregnant for Alternating Current

Application"

This standard applies to capacitors with paper dielectric impregnated

with non-PCB fluid. Note that there is no existing EIA standard covering

non-PCB capacitor fluids with plastic film dielectric.

6. EIA RS-U01 "Paper, Paper/Film, Film Dielectric Capacitors for

Power Semiconductor Applications"

The coverage of this standard is similar to RS-392 above.

2

7. UL 810 "Capacitors" (power factor correction capacitors up

to 15 kVar or 600 V)

This standard does not cover capacitors intended for use as parts

of appliances, motors, transformers or electric-discharge-lamp ballasts.

It does not specify that the liquid used be nonflammable, but does require

that the capacitor be marked to "indicate whether the liquid is combustible

or nonflammable. If the liquid is combustible, the amount of the liquid

in gallons shall be indicated."

Electronic Industries Association, 2001 Eye Street, Washington, D.C. 20006.

Underwriters Laboratories, 333 Pfingsten Road, Northbrook, Illinois 60062.

59
A. 2. 6 References, Section A.

2

Much of the material in this section was obtained, through personal

conversations with the manufacturers and users cited in the introduction.

In addition to these personal communications, the following publications

and reports were found to be helpful:

1. R. H. Munch, "New Capacitor Impregnants ," Conference paper

presented at IEEE Power Engineering Society Meeting, New York,

New York, Jan. 30, 1975-

2. B. H. Goldy, W. 0. Solberg, "A New Liquid Dielectric for

Capacitors," Insulation/ Circuits , Jan. 1975-

3. John Lapp, "Concepts in Systems Testing of Dielectrics in

Capacitors," IEEE Trans, on Power Apparatus and Systems , Vol. PAS

Jan/Feb. 1975, pp. 68-71.

h. J. H. Wright, "Comments of Westinghouse Electric Corporation."

Testimony at hearings regarding "Proposed Toxic Pollutant

Effluent Standards" (EPA) (FR Dec. 27, 1973) given March 15, 191 h

.

5. L. L. Jackson, "Industrial Organic Chemicals as Alternative

Dielectric Fluids," Conference paper presented at IEEE Power

Engineering Society Meeting, New York, New York, Jan. 197^.

6. Statement of Electronics Industries Association, to EPA,

concerning Proposed Toxic Pollutant Effluent Standards, in a letter to the Honorable Russell Train, Administrator,

June 25, 1975.

60
A. 3 Dielectric and Insulating Fluids

A. 3.1 Available Fluids

In this section we shall treat the major materials available at

the present time or potentially available to the electric power industry

as transformer and capacitor fluids. The power industry in general has

viewed with reluctance any change from the use of askarels in certain

transformer and capacitor applications because the askarels possessed

outstanding electrical characteristics. Furthermore, the askarels have

low flammability, and, while not inexpensive, their cost has been at a level the industry could manage. It must be emphasized that there is no other fluid now available which has quite so broad a range of application

and usefulness in the electric power industry.

The major fluids proposed as substitutes for the askarels in power

transformer and capacitor applications are for transformers: (a) silicone

liquids, (b) mineral oils, (c) highly saturated paraffin oils. For

capacitors, the fluids are (d) diaryl sulfones and mixtures, (e) long chain

esters of phthalic acid and (f) alkylated monochlorodiphenyl oxides. The

Japanese are reported to be working on a diarylalkane substitute, and

the French on "Chloralkylene ," an isopropyl chlorinated biphenyl.^

There are other fluids which have high dielectric strength and

excellent electrical properties such as the fluorocarbons and the

perfluoroalkyl furans. These are marketed for use in small devices.

Their cost ($25 per liter, and up) probably prohibits their use

at the present time in large installations such as those that interest

us here.

A table listing the properties of interest of the fluids described

here is appended at the end of this section (page 72).

Before proceeding to the consideration of the nonaskarel fluids a few remarks on the askarels themselves may not be amiss.

Reported at the National Conference on Polychlorinated Biphenyls,

Environmental Protection Agency, Chicago, Illinois, November 19-21, 1975.

61
The Askarels ( Polychlorobiphenyls

)

The askarels are proprietary mixtures of chlorinated "biphenyls and

chlorinated benzenes, the empirical formulas of which are C _ H, „ CI

12 10-n n (where n_ may run from 1 to 10) and Cg Hg_

n CI (where n_ may run from

1 to 6) respectively. These compounds may be represented by the general

structural formula:

chlorobiphenyl chlorobenzene

The proprietary mixtures mentioned above usually are designated

as having an effective percentage of chlorine and this percentage usually

appears somewhere in their trade numerical designation. The singly

chlorinated biphenyls are light oils and the completely chlorinated

(n = 10) biphenyls usually assume the character of a resin or wax.

Although first synthesized nearly a century ago [l]\ it was not

until the third and fourth decades of this century that they were produced in considerable quantities [2]. It was during these decades

that the superior electrical properties of these materials became

apparent. Within a few years, large scale manufacture of the askarels

was undertaken [3]. Besides the excellent electrical properties and the

low flammability of the askarels, it was observed that with the somewhat

higher dielectric constant over, say, transformer oils, the capacitor

dimensions could be reduced [k]

.

The askarel fluids have been used in a wide variety of applications

outside the electric power industry, mostly as heat transfer fluids,

additives to petroleum oils, in textile coatings and in surface coatings

and paints [5]. Applications to sealing compounds, printing inks and

papers, and casting waxes are all well attested [5].

The variety and successfulness of application of the askarel mixtures

has led to widespread use and unfortunately to their widespread occurrence

in the environment. Most of the areas where the polychlorobiphenyls

occur in the environment are, of course, associated with eminently

intense industrial activity. However, the high chemical stability of

the askarels insures their persistence wherever they are transported.

References for Section A. 3, shown in brackets, will be found in

A. 3.7.

62
The result is that they are found at some polluting level in a great

many places around the world. The polychlorobiphenyls have been

documented as existing in North and South America in both marine and

freshwater environments [6-10]. A detailed discussion of these findings

may be found in Kimbrough's comprehensive review paper [ll].

There would seem to be little point in expatiating upon the toxicity

of the polychlorobiphenyls in this brief resume since this report concerns the adequacy of tests of prospective replacements for these

very fluids. Suffice it to say that the polychlorobiphenyls accumulate in,

persist in, and are destructive to animal tissues. There is in fact a large body of literature supporting the toxicity of PCBs [see for

example 11-15]. More recent reevaluation of poisoning incidents seem

to indicate, however, that another substance, polychlorinated

dibenzofuran (PCDF, formed by oxidation of PCBs during thermal aging) was also present and may have significantly contributed to the toxic

action [l6 ]

.

Silicone Liquids

Probably the foremost contenders among the silicone liquids as a substitute for the askarels are mixtures of the dimethyl siloxane

polymers. These mixtures can be made up in a variety of viscosities.

One of the most important properties of the dimethylsilicone liquids

is their low temperature coefficient of viscosity [17]. They are also

mechanically resistant to high shear rates [l8, 19]. These compounds

are generally inert and are resistant to oxidative and thermal

degradation [20, 21].

The dimethylsilicone liquids may be compounded to have viscosities

running from 1 to well beyond 30,000 centistokes. The dielectric

constants for all such mixtures remain in the neighborhood of 2.7 over many orders of magnitude in frequency [22] and over a broad range of

voltages [25]. The flammability of the various mixtures exhibiting this

viscosity range may be gauged by the range of the open cup flash points

from about 37 °C for a 1-centi stoke fluid to about 320 °C for a 200-centistoke fluid [22, 23].

The solid-liquid transitions for the methylsiloxane liquids that

interest us here, occur for the most part in the neighborhood of -80

to -hO °C [22]. The dielectric strength of these fluids is in the

neighborhood of Uo kV/0.25 cm [22]. The dissipation factor is about

0.0003 at 100 Hz. All in all, these fluids are nearly ideal as power

transformer fluids. They do not sludge or oxidize easily and with proper

design one obtains good heat transfer. They offer good resistance to

acid and alkaline contaminants in a transformer. Offsetting these

virtues somewhat is the fact that when these fluids are subjected to

arcs their dielectric strength may be reduced by the formation of

solid SiOg filamentary bridging. In addition there seems to be a possibility of silicon carbide, SiC, being formed in an arc in these

63
liquids. Silicone r article is conductive and refractory, and provides

another impediment lo the self-healing of the dielectric liquid [2k].

However, it is claimed that self-healing does occur if the liquid is

impregnated into kraft paper.

These drawbacks are much more detrimental to applications in capacitors

than in transformers and explain why the liquids are proposed mostly for

transformer use.

Since the breakdown products of the silicones resemble the products

from which they are synthesized, a few words should perhaps be added

here about the chemistry of silicone liquids. What is given below is

not meant to represent current proprietary methods of silicone liquid

production but to give elementary background material for discussions

elsewhere in the report.

Early expectations that silicon would possess a structural chemistry

analogous to carbon organic chemistry were never fulfilled. Saturated

silicon chains analogous to the paraffins can indeed be formed but the

silicon-silicon bond is relatively weak. At the beginning of the century

Alfred Stock prepared the first few members of the silicon hydride series

by dropping [see 26] acid on magnesium silicide:

He found that the hydrides were unstable and he was not able to

prepare any compound in pure state higher than Si^H „ [see 26]. The

modern silicon compounds which are of interest here do not rely on the

Si-Si bond which is subject to oxidation but upon the stable Si-O-Si

bond. From this bond true polymers may be constructed as was evidenced

by the thorough investigation of compounds of this class by Kipping in

the first half of the century [see for instance, 27]. We might pursue

one possible path to synthesis of a dimethyl silicone. If we treat

sand (SiOg) at about 1000 °C with chlorine gas and a reducing agent

(carbon) an important product will be silicon tetrachloride, a corrosive

liquid at room temperature (SiCl^). Use of a methyl Grignard reagent

(CH MgCl) will allow attachment of methyl groups to the silicon atom:

SiCl^ + 2 CH MgC.1 * (CH

3

) 2

SiCl

2 + 2 MgCl

2

.

This last step is performed commercially by causing silicon to

react with methyl chloride at 250°-300°C with a metal catalyst

Si + 2(CH„C1) 2_50°C

* (CH

3

) 2 - Si - Cl

cat 2

.

6k
The dimethyl silicon dichloride is most useful because we simply allow

it to react with water:

CH CH

I

i CI - Si - CI + 2H

2

0 -> HO - Si - OH + 2 HCl

i i CH

3

CH

3

This product is called dimethyl disilanol and will undergo a dehydrative

condensation, thus:

CH CH CH CH

I l

i 5

I HO C - OH + HO Si - OH + HO - Si - 0 - Si - OH + HO

|

I I l 2

CH CH CH CH

giving us a primitive dimethyl silicone. A glance at the equation will

suggest to the reader that longer chains and cyclic compounds can be

built up from our simple silicone, and such is the case. Of course the

last reaction may be reversed by altering the conditions, i.e., may

yield silanols from silicones, a point of interest in the study of the manner in which these compounds may degrade in the environment.

These compounds are considered combustible but they have no true

combustion points. Combustion can be sustained if the heat supplied to

the compound is sufficient to cause depolymerization or decomposition.

Thus, only the short chain polymers really burn [25, 28].

The low toxicity of the silicone liquids is claimed as an advantage

of their use in the applications which concern us here. Indeed there is

little in the literature to refute the contention that the material

has extremely low toxicity, and numerous toxicity studies have been

conducted at the behest of the manufacturers of the silicones.

Mineral Oils

Most of the oils used as transformer fluids are complex mixtures of

paraffinic and aromatic compounds (as inhibitors) of mineral origin. Many

these paraffinic compounds are both saturated and cyclic. Such cyclic

compounds are designated as "naphthenic" by the petroleum industry.

65
The oils are nearly always the result of a process where the refining

method is tailored to the final use of the product. The aromatic content

of the oil must be controlled in order to prevent sludging or oxidation

of the paraffin components; but some aromatics are added as oxidation

inhibitors. A typical additive which is compounded with the oil as an antioxidant is ditertiary butyl paracresol (DTBP or DBPC) which

frequently is added to the extent of a few tenths of a percent [2U].

Such antioxidants are largely confined to distribution transformer

applications. The use of such compounds is largely avoided in power

transformers where the fluid is hermetically sealed into the transformer

under a blanket of nitrogen gas. The addition of aromatic compounds is

also designed to inhibit gassing in an oil under the operating conditions

of a transformer.

The low cost and self-healing properties of mineral oils coupled

with their satisfactory electrical properties have contributed to their

widespread use. These oils have a dielectric constant of about 2. The

dissipation factor is about 0.001 at 60 Hz. The dielectric strength of

mineral oils is generally greater than 30 kV/0.25 cm, and 10^ ohm-cm is a typical value for the resistivity of a fresh oil. The toxicity of oils

composed entirely of saturated paraffins is very low. Highly saturated

oils find perennial use in cosmetic products. Some of the highly refined

oils are pharmacopoeal . The presence or addition of aromatic inhibitors

increases the toxicity of the oils.

The degradation of a pure oil in a normal atmosphere probably follows

the course of oxidation of alkanes to, ultimately, carbon dioxide and

water. Such a process would require high-energy radiation (ultraviolet)

for initiation of the reaction. The mechanism of this process is not

yet clearly understood because of the paucity of knowledge of slow

reactions [ 31 ] . All paraffins are to some slight extent soluble in

water and can therefore in time react with compounds present in natural

waters. Furthermore, volatile fractions of an oil may escape into the

atmosphere where if they are excited by energetic radiation they may form

free radicals which readily react with atmospheric components. Whatever

the details of the case, it is believed that the degradation products

whether produced by physical or biological means are not highly damaging

to the environment.

The flammability of the mineral oils is considered high since they

are hydrocarbons with no quenching atoms (such as halides). If the oil

is to be suitable for transformer use it must be both insulating and

non-viscous at operating temperatures since it will be used as a convective heat transfer fluid. However in general, the less viscous

an oil, the closer it is to its flash point so that a compromise

between hazard of fire and efficiency as a heat exchanger is required.

These considerations have led power companies to the use of oil in

transformers almost exclusively in exterior installations.

If a transformer operates with the insulating liquid at a temperature

far below its flash point the hazard from fire would seem to be minimal.

66
There is some advocacy (see for example Duckett RTE Corp., [30]) of

using high-purity high- flash-point paraffin oils in inside installations,

much as askarels are used at present. The test used to suggest the

suitability of oils is discussed in the next section.

Hydrogenated Paraffin Oils

One suggested fluid for transformer use is a product which the RTE

Corporation of Waukesha, Wisconsin is proposing as a substitute for askarels

in transformers in locations proximate to or inside buildings. The firm

maintains that the high flash point and consequent low flammability of

this oil so much reduces hazard from fire in interior installations

that the fluid should qualify for service in such installations.

This fluid is not produced by the RTE Corporation itself. The supplier

is a large oil company [29] and the fluid was designed, or expected to be

used, in transformers which operate at temperatures high enough to reduce its

viscosity to an acceptable level. The product is marketed as "RTemp." The

composition does not appear to be anything unusual in the way of petroleum

oils. It is a high-viscosity (800 cs at 25 °C), high- flash-point (296 °C)

oil with a dielectric strength of about 37 kV/0.25 cm, (ASTM D877), and high

resistivity, 10 ohm-cm. The oil is a petroleum product twice subjected

to a hydrogenation process, thereby acquiring its saturated paraffinic

properties. RTemp is therefore a highly stable mineral oil which is claimed

to be of food grade [30]. It is presumed that the environmental characteristics

of this highly saturated oil would be similar to the pharmacopoeal mineral

oils [30]. The general physical and electrical properties of this oil

resemble the ordinary transformer oils. The flammability properties

of RTemp transformer oil are better than most transformer oils as would

be indicated by its high flash point. The expected lower flammability

is confirmed in a general way by the surge-cell tests conducted at RTE

Corporation by Duckett [30]. The surge of electric energy into the

oil caused vaporization of the oil and dispersal of the oil outside

the test apparatus. No fire resulted, however, because the temperature

of the liquid oil was well below the combustion point. This behavior

was in marked contrast to an ordinary transformer oil subjected to the

same test which ignited immediately and did not extinguish, possibly

because the transformer oil was initially closer to its flash point

than the RTemp and considerably less energy was required to bring the

transformer oil to combustion temperature.

Oils of the highly saturated type are used in cable and underground

applications. In spite of the high viscosity of such oils they are acceptable

at the common operating temperatures of transformers in temperate, or even moderately cold, weather. But in the severest cold these oils require

the protection of enclosure or burial to maintain their fluidity. Although

the RTE surge tests show, and the combustion data predict, that these

highly saturated oils are probably safer than ordinary transformer oils,

the National Electrical Code Committee will probably need independent

testing before explicit acceptance of this fluid.

67
Mixtures Containing Diaryl Sulfones

These compounds are proposed by one of the major chemical companies

of the country as substitutes for the askarels in capacitor use. The

basic chemical structure is:

where the R is an alkyl group with probably 1-8 carbon atoms, n runs from 1 to 3 and is a phenyl, naphthyl or indan group. All these

compounds are halogen free [35]. The actual product is presumably a proprietary mixture of such compounds and other ingredients such as non-chlorinated biphenyls. Cited as an example in German and U.S.

Patent disclosures [32] is a mixture of tolyl xylyl sulfone,

isopropylbiphenyl and minor ingredients. It is presumed that in use further ingredients will be added to these compounds as antioxidants.

The mixtures as proposed have a dielectric constant of about 6.

No dielectric strength figures are available at present, but life-tests

of capacitors are continually being run by the manufacturer of the

fluid [33]. The fluid is tested in ballast-capacitor use at 1000 volts

at 90 °C working temperature. The flash point of the mixtures now

advocated by the manufacturer is about 150 °C, combustion is sustained

at about 165 °C and the fluid will auto-ignite in the region of U50 °C.

The terminal-to-case resistance is listed as ~3 x 10^ ohm, the

dissipation factor as about 0.003 [3M> No pourpoint figure is available

but the capacitors function well at -50 °C [33]. Some toxicity studies

have been conducted by the manufacturer. These studies indicate that

irritation can be induced by intense or prolonged contact of the mixture

with eye or skin of rodents. The manufacturer recommends that normal

industrial hygienic precautions be taken (attainable, in the main, with

soap and water) in order to assure safe handling.

These materials when fed to rodents broke down into excretable

metabolites according to studies conducted by, or on order of, the

manufacturer. Polychlorobiphenyls fed under similar conditions persist

in the animal body after the sulfone mixtures in the tissue have become

undetectable. A toxicity statement is available from the medical

department of the manufacturer [35]

n r

68
The Phthalate Esters

The phthalates can "be offered immediately as products for use in

the capacitor industry because they are already supplied by the

petroleum industry as plasticizers for polyvinyl chloride plastics in

tonnage quantities. In 1972, about 1 billion pounds of some 20 different

phthalate esters were manufactured [36].

The generally excellent electrical characteristics of the esters

of phthalic acid make them natural candidates as substitutes for the

askarels in selected capacitor use should the substitution become

necessary. They must be limited to low voltage applications, however,

because of the problem of corona extinction in the phthalate esters.

The phthalic anhydride is typically manufactured from naphthalene

which is oxidized in the presence of vanadium oxide to phthalic

anhydride

or alternatively from o-xylene by a similar oxidation process to the

same end product

The phthalate esters supplied as insulating liquids are mostly diisononyl

phthalate (DINP) and dioctyl phthalate (DOP) [37] • One major manufacturer

prefers DINP over DOP because of the expected resistance to hydrolysis

bestowed by steric hindrance.

The chemical and petroleum companies use various methods for

producing the alcohols from which DOP and DIOP are formed, all of which

start from petroleum refinery products. They may be typified by the

one reaction for 2 ethyl-hexanol which begins with propylene to form a aldehyde which in turn, by aldol condensation, yields a Cg aldehyde.

The On aldehyde is hydrogenated to 2 ethyl-hexanol.

69
CLHx- ^->- C, aldehyde aldol

^ aldehyde — 2 ethylhexanol

.

3 6 U condensation 8

The 2-ethylhexanol then esterifies the phthalic acid

producing the well-known plasticizer 2-diethylhexyl phthalate. The

octanols and isononanols used in the manufacture of insulating fluids

will use the same or similar reactions their preparation.

The aromatic dibasic phthalate esters typified by diisononyl and

dioctyl phthalate have specific resistances in the neighborhood of

lO^ ohm-cm. In applications as capacitor fluids they offer a dielectric

constant of about 5. The voltage breakdown point occurs at around

30 kV/0.25 cm. The boiling point at reduced pressure (5 mm Hg) is about

250 °C, and yet the pourpoint is in the neighborhood of -50 °C. The

flash point as determined by the Cleveland Open Cup Method for these

fluids is in the neighborhood of 220 °C; fire point is determined by

showing that combustion is sustained at 250 °C or thereabout [38].

The dibasic phthalate esters are available on the market,

apparently in any quantity desired and are marketed by at least two

major chemical companies. At least one equipment manufacturer has

modified the design of his capacitors to accommodate the phthalates

as capacitor fluids [37]. Engineers from another capacitor manufacturer

report that their commercial use of the phthalate esters has been in

low voltage electronic units for the export market.

The report by Rutkowski and Forster [38] presents a summary of

toxicity studies indicating low toxicity and there is work supportive

of the harmlessness of the phthalates [39, ho] . For detailed studies

of the toxicity of the phthalates see [Ulj.

TO
Butylated Monochlorodiphenyl Oxides

One of the largest chemical companies in the country has for some years been engaged in a joint effort with an electrical power equipment

manufacturer in the electrical and environmental evaluation of butylated

monochlorodiphenyl oxides. This effort has resulted in the offering

of a product to the electrical industry which may be used in high

voltage power capacitors [U2].

The butylated monochlorodiphenyl oxides are offered as direct replacements for PCBs, i.e., no change in capacitor dimensions is required. The

electric properties are similar to other dielectric fluids offered. The

dielectric constant is about 5 and the dielectric strength about 35 kV/0.25 cm. The resistivity is about lof ohm-cm; the vapor pressure is low. At room temperature it is about 10" torr. The viscosity is about 10 centistokes

at room temperature. The pourpoint is about -1+5 °C. The flash and

fire points are considerably (about 100 °C) above the operating temperature,

and the flash point is above that of some of the lower-chlorinated

askarels. The values of flash and fire point are listed as 17^- °C and

199 °C respectively by the manufacturer.

Prolonged reliability tests have been performed, and the manufacturer

has indicated a willingness to produce the material at the million poundper-annum level [h2] . Safety and performance tests were, as of

December 2, 1975, still being assessed.

The manufacturer states that the major constituent of the fluid is

known to be nontoxic to fish. The minor constituent is slightly toxic

to fish but is also the more biodegradable. Solubility is low as is

bioaccumulation. An environmental impact statement may be obtained

from the manufacturer [^3].

71
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72
A. 3. 2 Standards Relating to the Testing of Available Fluids

Three compilations of ASTM test procedures relating to the

performance of electrical insulating liquids have been issued:

1. ANSI C 59.2 (also ASTM D 117) "Standard Methods of Testing

Electrical Insulating Oils"

2. ANSI C 59-62 (also ASTM D 901) "Standard Methods of Testing

Askarels"

3. ANSI C 59.118 (also ASTM D 2225) "Standard Methods of Testing

Silicone Fluids for Electrical Insulation."

ASTM test procedures called out in these documents are listed on the next page.

The above standards deal with the fluids currently in common use. Initial testing of a new candidate liquid would logically be done using

the procedures already proven appropriate for existing liquids; however,

it is to be expected that some procedures would not be satisfactory and

that new procedures perhaps unique to a particular fluid would have to

be developed. As illustrations of this situation note (l) that a different

test procedure is required for the detection of inorganic chlorides in

askarels than in oils and (2) that the test procedure for determining

the water content of askarels and oils is not acceptable for silicones.

In fact, the tabulation indicates that agreement within ASTM on standard

test procedures for several important characteristics of silicones has

not yet been reached.

73
ASKARELS

(D901)

ELECT . INS,

OILS

(BUT)

SILICONE

FLUIDS

(D2225)

Acidity, Approximate

Acidity, Approximate, and

Polar Contamination

Coefficient of Thermal Expansion

Color

Chlorides, Inorganic

Chlorine Compounds,

Hydrolyzable

Dielectric Constant

Dielectric Strength Using

Metal Disk Electrodes

Dielectric Strength Using

VDE Electrodes

2,6 Ditertiary-Butyl ParaCresol Content

Examination, Visual

Flash Point

Fire Point

Gas Content

Gas Content (Nonacidic)

Inorganic Chlorides and

Sulfates

Interfacial Tension

Neutralization Value

(Neutralization Number)

Oxidation Stability

Peroxide Number

Pourpoint

Power Factor

Refractive Index (and Specific

Optical Dispersion)

Resistivity

Sampling

Saponification Number

Scavenger Content

Sediment and Soluble Sludge

Sludge

Specific Gravity

Sulfur, Corrosive

Thermal Stability

Viscosity

Visual Examination

Volume of Oil

Water Content

D1903

D2129

D1821

D1820, D2UU1

D92U

D877

D92

D9T^, D66U

D9T

D92U

D1807

DII69

D923

D1701

D1810

D1936

D88, Vhh5

D1702

D1808

D1533

D153U

D1902

D1903

D1500

D878

D877

Dl8l6

D1U73

D152U

D92

D831

D1827

D878

D971

D66U, D97^

V2kh0*

D1563

D97

D92U

D1807

D1169

D923

D9i+

DI698

D1313, D131U

D1298

D1275

D88, DUU5, D2161

D1315, D1533

D2129

W2h

D92

D97 1*

D97

D92U

D1807

DII69

D1298

D^U5, D2l6l

D9^3, D1931*, and D2112 also deal with oxidation stability. D3lU6 is called out

in "Standard Specification for Oxidation — Inhibited Mineral Oil for Use in

Transformers and Circuit Breakers."

Ik
The following related ASTM Standards have recently appeared:

D 3300 "Standard Method of Test for Dielectric Breakdown Voltage

of Insulating Oils of Petroleum Origin Under Impulse

Conditions"

D 3303 "Standard Method for Rapid Gas Chromatographic Estimation of

Higher Boiling Homologues of Chlorinated Biphenyls for

Capacitor Askarels"

D 330U "Standard Method for Analysis of Environmental Materials for

Polychlorinated Biphenyls" (This document is a modified

version of Appendix B of ANSI C 107-1-197*0.

A. 3- 3 Test Techniques By Which Electrical Properties Are Evaluated

a. Dielectric constant and power factor. Techniques for measurement

of the dielectric constant of insulating fluids are well documented and

pose no problems if applied with care. ASTM Standard D 92U "Standard

Method of Test for Power Factor and Dielectric Constant of Electrical

Insulating Liquids" outlines test procedures and specifies suitable test

cells and ASTM Standard D 150 "Standard Methods of Test for A-C Loss

Characteristics and Dielectric Constant (Permittivity) of Solid Electric

Insulating Materials" outlines the theory and describes typical measuring

circuits

.

b. Dielectric Strength. While not suitable for determinations of

intrinsic dielectric strength, two designs of test cells have gained

acceptance for ac measurements of the dielectric breakdown characteristics

of insulating fluids. ASTM Standard D 877 "Standard Method of Test for

Dielectric Breakdown Voltage of Insulating Liquids Using Disc Electrodes"

specifies a cell using 25. h mm flat disc electrodes (with square edges)

spaced 2.5 mm and outlines acceptable test procedures. ASTM Standard D l8l6

"Standard Method of Test for Dielectric Breakdown Voltage of Insulating

Oils of Petroleum Origin Using VDE Electrodes" specifies a cell with a propeller for circulating the liquid and having brass electrodes, the

opposing surfaces of which are spherical in shape and separated 2.0h mm

(with an optional spacing of 1.02 mm if the voltage limitation of the

test transformer requires it).

A third cell and test procedure is specified in ASTM Standard D 3300

"Standard Method of Test for Dielectric Breakdown Voltage of Insulating

Oils of Petroleum Origin Under Impulse Conditions." Alternate electrode

configurations are specified as follows: (l) sphere-to-sphere, using

12.7 mm brass or steel spheres and (2) point-to-sphere, using a 12.7 mm

brass or steel sphere and a steel point, with a 0.06 mm radius of curvature.

While concern has been expressed by some users regarding the

desirability of placing greater emphasis on cleaning the test cell, on care in sample preparation, and on the fact that the electrode material

75
may slightly influence the results, these standards are generally

considered satisfactory for the purpose.

c. Resistivity. ASTM Standard D 1169 "Standard Method of Test

for Specific Resistance (Resistivity) of Electrical Insulating Liquids"

specifies the test cells and procedures for measurement of resistivity

using direct voltage. The theory and measuring equipment to be used is

specified in ASTM Standard D 257 "Test for DC Resistance or Conductance

of Insulating Materials." These standards appear adequate for the

purpose

.

d. Partial Discharges (Corona). ASTM Standard D 1868 "Detection

and Measurement of Discharge (Corona) Pulses in Evaluation of Insulation

Systems"; IEEE Standard h^h "Recommended Practice for the Detection

and Measurement of Partial Discharges (Corona) During Dielectric Tests";

and NEMA CP-P2-1973 "Test Procedure for Measurement of Internal Partial

Discharges in Capacitors" are similar documents. They deal with a phenomenon which relates to the total system rather than to the fluid

alone; however, the corona characteristics of different fluids are often

compared independent of their operating environment in particular

apparatus

.

A. 3.1+ Test Techniques By Which Fluid Flammability Is Evaluated

Most would agree that the concepts of combustion and flammability

of a material are qualitatively clear and easily understood. The

quantitative definition of flammability of the material, that is,

whether it will ignite and then continue to burn under specified

temperature, pressure and ambient atmosphere conditions is not, however,

as easily achieved. What is required is a flammability test in which

all relevant parameters are rigorously controlled and in which the

results are unequivocally interpretable , and this has been difficult to

develop to everyone's satisfaction. The various tests which are recognized

and in common use are described below, along with comments on their

applicability and shortcomings:

a. Flash and Fire Points

The only test specified by the standards-setting agencies (ASTM,

ANSI, NFPA1

, IEEE) for insulating fluids, mineral oils and askarels,

is the Cleveland Open Cup test for flash and fire points (ASTM D 92).

The specifications are:

Mineral oil: flash point of lh6 °C (in some areas 130 °C);

Askarel : no fire point up to boiling point.

Beside the D 92 test, ASTM recognizes several other variants for

determining the flash point, which, however, are not prescribed for

insulating fluids: the Tag Open Cup tester (D 1310), the Tag Closed

National Fire Protection Association, 60 Batterymarch St., Boston, Mass. 02110

76
Tester (D 56), and the Pensky-Martens Closed Tester (D 93). In all

experimental arrangements the flash point is determined by slowly

increasing the temperature of the cup containing the liquid sample.

An ignition source, placed above the surface of the liquid, is actuated

at specified intervals. The flash point, by definition, is the lowest

temperature of the cup at which the vapors above the liquid surface

flash. The flashes are transient, because only the vapor phase burns,

not the liquid. In addition to the determination of the flash point,

the D 92 test specifies the procedure of increasing the temperature

beyond the flash point up to the temperature at which transient

application of the ignition source causes continued burning of the

liquid. The lowest temperature at which this happens is the fire point.

Determinations of flash and fire points give valuable indications of

flammability hazards, and should continue to be used. However, it must

be recognized that developments in recent years have progressed

significantly beyond the stage at which the standards for insulating

fluids were set, and also beyond the state-of-the-art prescribed by

officially adopted ASTM standards. The following items should be

considered before flash and fire point standards are recommended for

replacement fluids:

(1) There has been a general trend toward closed-cup methods

(e.g., D 93). In particular, Underwriters' Laboratories have favored

closed-cup tests for some time now. These generally give lower flash

points than the open-cup variants. For example, the flash points

of the Dow Corning 50CS (silicone) fluid are 30U °C and 277 °C as determined by D 92 and D 93 tests respectively.

(2) The ASTM Flash Point Committee is moving toward recommending

international adoption of an "equilibrium" method. Equilibrium methods

specify Flash-No Flash determination at a series of constant (rather

than continually increasing) temperatures. Since in equilibrium methods

the entire system, sample and container, is at the same temperature,

complications associated with heat transfer between the sample and the

container are eliminated. Therefore sample size is arbitrary and much

smaller samples can be used. In addition, these methods do not depend

on viscosity because convective currents within the sample are also

eliminated.

(3) Scientific analyses of fire-point determination are poorly

developed. Therefore, the significance of the test is not clearly

understood. This point will be further discussed in connection with the

Oxygen Index test.l

b. The Oxygen Index Test

In the Oxygen Index (01) test the test sample is placed inside a tube

containing a mixture of oxygen and nitrogen gases. The gas mixture,

normally at room temperature, flows gently upward. The sample is

ignited and the percentage of oxygen in the gas mixture is decreased.

01, by definition, is the percentage of oxygen in the oxygen/nitrogen

mixture at which extinction occurs.

A reviewer points out that in any event fire point is of less importance

if the more conservative flash noint is used in specifications.

77
The specified ASTM 01 technique applies to solid samples only

(D 2863)- Various laboratories have made their own modifications of

the test to apply it also to liquids, and have reported the resulting

data, but there is no uniformity of procedure.

Sharply divided opinions exist as to the value of the 01 test

toward a definition of flammability . For example, a limited polling of

the industrial opinions in this survey shows that some manufacturers use

the test for practical purposes, while others consider it "worthless."

The reasons for this division are not difficult to see. On one hand, it

is recognized that the burning of a small laboratory sample (a few grams)

in room-temperature environments in no way simulates the behavior of

large amounts of combustible materials in a well-developed fire. On the

other hand, there are reasons why the 01 test should not be discounted

in the context of this survey. Fundamentally, the test is the prototype

of extinction of a diffusion flame, and it bears roughly the same relationship to practical fire-point determinations that the fundamental

flammability-limit data do to practical flash-point determinations. As was discussed earlier, both flash and fire points are specified standards

for definitions of flammability of insulating fluids. The problem is,

however, that fundamentally meaningful fire point, or 01, tests are more difficult to design than the meaningful flash point tests.

To obtain consistent extinction data one would have to develop an

01 test for liquids and a fire point tester in such a way that an 01

value of 21 (i.e., air) is obtained at the experimental fire point.

Recent work at the NBS Center for Fire Research shows that such

development would require very careful design of the test geometry.

Therefore, an 01 test for insulating fluids should be recommended only

after some additional study, allowing specifications of the testing

arrangement

.

c. Spray Flammability Tests

The ASTM Mist Spray Flammability of Hydraulic Fluids test

(D 3119-T2T) could be applied al so to electric insulating fluids, but

we have no evidence that anyone has done that. The test is a very

severe one, entailing the spraying of a preheated atomized mist into an open flame. Underwriters' Laboratories consider it too severe and use one of their own variants in its stead (UL File MH 01^66, p. Tl-6). The

UL test consists of applying drops of the liquid to the surface of a heated

steel plate, and observing the "behavior." Factory Mutual Research

Corporation has its own spray flammability test, akin to D 3119. It is

also a very severe one. Most hydraulic fluids do not pass it. Factory

Mutual is currently using the results of their spray flammability test

to establish acceptable operating temperatures for askarel substitutes.

d. Autoignition Temperature (AIT)

Several techniques exist for the heating of liquids in air until

they ignite. ASTM D 2155 is a specified procedure for liquid petroleum

products. Underwriters' Laboratories use a similar test of their own.

78
As one should expect, auto ignition temperatures of electric insulating

fluids are quite high. Some reported values are: 332 °C for a mineral

oil and 393 °C for Dow Corning 50CS fluid, both by the D 2155 test;

662-670 °C for askarels by the UL test.

As in the case of the spray flammability tests, operational

conditions, normal or abnormal, are unlikely to give rise to these

temperatures in the case of insulating fluids. The AIT test, therefore,

does not appear particularly pertinent. (At this point, it should be

mentioned that Underwriters' Laboratories does not evaluate liquids only

on the basis of tests which simulate some aspects of actual operations,

but also on the basis of the total information about stability and

flammability of the liquid. If this philosophy is adopted, then of course the AIT test and any other reproducible test which can be tied

to some property of the liquid, becomes pertinent. In fact, UL did use

the AIT test among others, to arrive at a numerical flammability rating

of askarels )

.

e. Energy-Release Tests

Hazards tests designed to evaluate the amount of explosive energy

released in an accident apparently have not been used in connection with

insulating fluids, but there are good reasons why they should be. Such

tests almost invariably give a measure of energy release by the effect

on the surroundings: damage to a target, displacement of a target, or generation of a blast wave in air. Since the hazard of an arc-initiated

fire in a transformer or capacitor tank may be due to the blast wave

damage as well as the subsequent fire, a measure of the explosive energy

release capability of an insulating fluid would appear to be useful.

Such a test would be particularly important if it could be shown to be

a useful screening mechanism before going to the more expensive, full-unit

tests discussed in Sections A. 2. 3 and A. 3-3 (see also Sections 3-5 and 3.6).

Direct measurement of the blast wave intensity may be the most valid

energy release test, as described more fully in Section 3-

The table on page 80 summarizes presently accepted flammability

data on several insulating fluids.

Fluid flammability measurement, by whatever test procedure is

adopted, should be carried out under conditions as closely approaching

operation as reasonably possible. In particular, pressure and temperature

conditions are known and should be duplicated. Thus, power transformers

of the "askarel class" have a temperature increase of about 65 °C under

full load, so that bulk fluid temperatures will probably not exceed

100 °C even on hot days. Local temperatures near the transformer winding

may be ten to twenty degrees higher. Most utilities operate their askarel

transformers with a pressure relief device as prescribed by the National

Electrical Code (Section U50-23); the relief pressure is usually only

a few psi (20-i+0 kPa)

.

Power capacitor tanks rupture at low pressures but small industrial

type capacitors generally are sealed to U0-50 psi (280-3^0 kPa). The

fluid temperatures within capacitors would not be much above the ambient,

which itself might vary widely depending on location.

79
FLAMMAr.ri.ITY [/ATA

Info. Souro

e

Liquid Description

Flash

Point (°C) FirePoint (°C) Autolgnltion Oxygen Temperature {"O Index

ASTM D 10U0 t 31>»< Mineral Oil

Mineral Oils

lU6 (130)

Bureau of Mines Report 1 Min. Oil, parafflnic

( deep waxed

)

196 221 371

Dow Corning

197U IEEE-PES , Symposium Paper'

Transformer Oil

(ASTM D92) ASTM D2155 ASTM D2863 (modified)

150 165 332

15.1

ASTM D 2283 "Askarels"

Askarels and PCB Blends

Hone to Boiling

UL ReportBureau of Mines Report1

Aroclor 1016

Aroclor 12U2 (Trichlorobiphenyl

)

Aroclor 125U (Tetrachlorobiphenyl

)

IJk (closed cup)

177

193

670

33U

Hone

Dow Corning

197U IEEE-PES Symposium Paper^

UL Report"

50 CS (Polydimethyl)

Dow C 50CS closed cup

XF-1-U701

Sillconea

305

277

360 393

UU5

Dow Corning

1973 Doble

u Conference Paper

Phenylmethyl (Si) Dimethyl (hi vise.)

Dimethyl (low vise.)

300

315 135

Bureau of Mines Report 1 Methyl phenyl

Polymethyl (low vise.)

271

X2U 138

UL Classified Products Index also gives the following information on the combustibility: Dow Corning 50CS: Moderate

in air 257 °C; XF-l-UjOl: Moderate in air 256 °C (Compare with flash point open cup: 30U °C, closed cup: 277 °C); Aroclor 1016: Moderate in air ihh °C.

The Dow Corning, 197 1* IEEE Conference Paper gives:

Relative burning rate

(gm/sec, 10 gm sample)

Transformer Oil

0.0267

50 CS Silicone

0.0060

Mist spray (D3119) Violent Spasmodic

1. J. M. Kuchta ar.i R. J. Cato, "Ignition and Flammability Properties of Lubricants," SAE Transactions . Vol. 77 (1963).

2. R. F. Burow ani G. A. Vincent, "Silicone Fluids vs. Hydrocarbon Oils..." Conference Paper C7I1-258-O, 197U Winter

Meeting, IEEE Pcver Engineering Society, New York, New York, January 31, 197U.

3. Underwriters Laboratory, Classified Products Index . July 197U.

I». R. F. Burns and T. Orbeck, "Silicone- fluid Filled Transformers..." Conference Paper, 1973 Doble Engineering Client

Conference, Bo--.on, Massachusetts, April 9-13, 1973.

80
For a new fluid, with different loss and heat transfer characteristics,

these typical values may have to be revised.

A. 3. 5 Some Test Techniques For The Evaluation Of The Toxicity Of

Dielectric Fluids

In the past, toxicalegists have not only made the laboratory assessments of toxicity, bat in many instances they have made. the. final judgment

a& to the. social course to be. taken on the. basis of a particular set of

findings. Instead, the. te.chntc.al expert* *hould be charged with *ecuring

an obje.cti.ve. inde.pe.nde.nt determination of the, extent, nature, and frequency

ofa adverse effect*. They should be. asked to explain the relative gravity

of these effect* {on. the. target *y*tem, be. it human* oh. wildlife. Similarity,

otheA qualified te.chni.cal expert* *hould be. requested to make, an objective.

a**e**ment of the. benefit* of use and of alternative material* on processes

.

However, the. final judgment a* to a trade-off between an advent e health

effect and a defined benefit is a social decision and should be made with

the participation of those who one affected. This is not to s ay that technical

expert* u*ing theJji technical expertise will not participate, but it does

state that they should not be the sole judge* of determining the balance

between the benefit and the risk.

"Terms such a* ' toxicalogical insignificance, ' 'safie, ' ' zero tolerance, ' 'no effect level,' and 'negligible risk' have been in rather

common use. All of these contain in one way or another value judgment*

or technical implication* which have no place in an objective assessment

of ri*k. There is no substance which, under certain circumstance* , could

not be dangerou* and un*afe. There i* no batt.ery of test*, however

elaborate, which can prove beyond challenge the complete *afety of a

chemical, for the tjoxicologi*t to apply the term* ' toxicalogically

insignificant' or 'negligible risk.' to a *et of observation* make* a premature judgment in the wrong arena by the wrong per*on a* to

insignificance or acceptability. Attempt ha* been made to eliminate

*uch term* from tki* report.

Another common term of wide usage i* the 'no-effect level. ' Thi*

t* statistically meaningly* and therefore of limited value *ince it

merely mean* that no effect wa* ob*erved in *tudie* using a group of

animal* of particular *ize. Such an ob*ervation i* completely compatible

with the presence of an adverse effect, which in further *tudie* with

larger *ample *ize* or with different type* of ob*ervation might lead

to a positive outcome. We prefer the usage of the term 'no ob*erved

effect, ' which *hould always carry with it a qualifying *tatement a* to

*ize of the group in which no adverse effect was observed."

We have opened this section with quotations from the report of the

National Academy of Sciences, "Principles for the Evaluation of Chemicals

in the Environment" [UU], as a forewarning of the complexities and

difficulties we may anticipate in looking at the field of toxicology.

81
Our knowledge of the toxicity of insulating fluids results, in

the main, from two sources. The first source is clinical observation.

In this instance the observer, generally a physician, is confronted with

a victim of a toxic condition with which he may have had no prior

experience, and even if he is successful in treating the condition, the

one event may well remain an isolated one to him. A more informative

kind of clinical event (and more costly in human terms) occurs when there

is a mass poisoning such as the now famous Yusho outbreak of 1968 in

Fukuoka, Japan. Here there were a sufficient number of cases for a local

medical school to mount a full scale epidemiological study. The study

group was successful in determining the origin of the poisoning,

polychlorobiphe^yl heat transfer liquid which had leaked into a food

preparation vat ~[ll]. It is evident that the clinician or epidemiologist

must seize his opportunity and extract as much information as possible

from the case at hand before the opportunity is lost.

The second source of our knowledge of toxicity comes from animal

experimentation. In contrast to clinical studies, animal experimentation

provides the kind of systematic data which may be acquired by independent

observers and confirmed at will. This kind of experiment constitutes

the main source of information that a developer of a dielectric fluid

submits to government regulatory agencies. It will be mainly this

type of experiment which will be dealt with in what follows.

It is possible to develop a definition of toxicity through the use

of populations of animals as is done in the Federal Hazardous Substances

Act [PL 86-613 and amendments, 15 U.S.C., CH. 30] where the definitions

under Section 2 paragraphs (g) through (k) read:

" [g] The term 'toxic' shall apply to any substance [other than, a radioactive substance) which hat, the capacity to pn.od.acc personal injury

on. illness to man through ingestion, inhalation, on. absorption thn.ou.gh

any body Surface.

[h] (J) The term 'highly toxic' means any substance which falls

within any of the following categories: [a) produces death within

fourteen days in half on. more than half of a group of ten on. more

laboratory white nats each weighing between two hundned and thn.ee

hundred grams, at a single dote of fifty milligrams on. less pen. kilogram

of body weight, when orally administered on. (b) pn.odu.cet> death within

fourteen days in half on more than half of a group of ten on. more

laboratory white rats each weighing between two hu.ndn.ed and thn.ee hu.ndn.ed

grams, when inhaled continuously {on. a period of one hour on. less at an atmospheric concentration of two hundred parts per million by volume or less of gai> or vapor of two milligrams per titer by volume or less of

mist and dust, provided such concentration is likely to be encountered

by man when the substance is used in any reasonably foreseeable manner)

or (c) produces death within fourteen days in half or more than half of a group of ten or more rabbits tested in a dosage of two hundred

milligrams or less per kilogram of body weight, when administered by

continuous contact with the bare skin for twenty- four hours or less. (2) If

the Secretary finds that available data on human experience with any

A more recent evaluation [l6] suggests that a contaminant of the PCB

rather than the PCB itself may have caused the poisoning.

82
bubbtance indicate. results different {tiara thobe obtained on animals in

the above-named dobages or concentrations, the human data bhall take,

precedence.

[I] The term ' corroblve' means any bu.bbtn.no.ti which in contact with

living tisbue wilt cause dcbtA.uctt.on of tisbue by chemical action; but

bhall not refer to action on inanimate burfaceb.

[j] The term ' Irritant' means any bubbtance not corroblve within

the meaning of bubparagraph [i) which on immediate, prolonged, on repeated contact with nofunal living tlbbue will induce a local Inflammatory

reaction.

[k) The term 'btrong benbltlzer' meanb a bubbtance which will, caube

on normal Living tisbue through an allergic or photodynamic procebb a hypersensitivity which becomeb evident on reapplication of the borne

bubbtance and which ib designated ab buch by the Secretary. Before

debignating any bubbtance ab a btrong benbitizer, the Secretary , upon

consideration of the frequency of occurrence and beverity of the reaction,

bhall find that the bubbtance hob a bignificant potential for causing

hypersensitivity .

From the operational definitions provided above one can by means

of a few modifications, define other operational definitions such as are found in the Registry of Toxic Effects of Chemical Substances [U5]

of the National Institute for Occupational Safety and Health:

"TVLo-Toxlc Vobe Low - the lowebt dobe of a bubbtance, ab published

or made available to publish, introduced by any route other than

inhalation over any given period of time and reported to produce any toxic

effect In man or to produce carcinogenic, teratogenic, mutagenic, or neoplastlgenlc effects In humans or animal.

TCLo-Toxlc Concentration Low - any concentration of a bubbtance In

air to which man or animals have been expobed for any given period of

time and that has been reported to produce any toxic effect In man, or to produce a carcinogenic, teratogenic, mutagenic, or neoplastlgenlc

toxic effect In animals or humans.

LVLo- Lethal Vobe Low - the lowebt dobe of a bubbtance other than

LVSO Introduced by any route other than Inhalation over any given period

of tone and reported to have caused death in man or the lowebt bingle

dobe Introduced In one or more divided portions and reported to have

caused death In animals. Entries for lethal dobes administered to

animals for the qualifying toxic dobe, TX.VS, were made In accordance

with the dobe limits of Table I

J

See Ref. 45, p. xvilA.

83
LV50- Lethal Vase. fifty - a calculated dose of a chemical substance

which is expected to cause the death of 50% of an entire population of an experimental animal species, as> determined from the exposure to the

substance, by any route other than inhalation, of a significant number

from that population."

Other lethal dose percentages, such as LD1 , LD10, LD30, LD99, as well as others, may be published in the scientific literature for the

specific purposes of the author. Such data would be published in the

list if these figures, in the absence of an LD50, were the lowest

published in the article. A substance may qualify by an LDLo published

value even though a higher LD50 value, which may also exceed the limits

of Table I-*- was reported in the same publication.

" LCLo-Lethal Concentration Lou) - the lowest concentration of a substance, other than an LC50, in atr which has been reported to have

caused death in man or. to have caused death in animate when they have

been exposed for. 24 hours or less. Entries for lethal concentrations

for animals for the qualifying toxic dose, TKVS, were made in accordance

with the dose limits of Table I.'

LC50- Lethal Concentration Tifty - a calculated concentration of a substance in air, exposure to which for 24 houKS or. less would cause

the death of 50% of an entire population of an experimental animal

species, as determined fr.om the exposure to the substance of a significant number, from that population. These entires qualified in

accordance with the dose limits set forth in Table I.' See LV50 above

for other parameters which may similarly apply to entries for. the list. 1 '

It has also come to our- attention that a scale developed by

Hodge is frequently used by toxicologist s [56].

The complexity of the whole environmental system requires the

examination of the effect of pollutants on more than one type of animal.

It is generally considered desirable to include experiments on birds,

amphibians, and fish as well as mammals, in order to obtain an idea of

the total impact of a substance upon the environment. The more

responsible the concern for the environment, the more detailed will be

the experiments, for we are trying to extract from a few telling

experiments information applicable to virtually the whole of nature.

To acquaint himself with just the first notions of the complexity

of the subject before us here, the reader might refer to a list of

experimental animals used in toxicity experiments. Such a list is

given herewith as Table A. It is taken from the Registry of Toxic

Effects of Chemical Substances [h5 Table III pxx]. The list runs the

gamut from amphibians to man and will doubtless be expanded still

further as toxicological studies proceed through the years.

In addition to the range of animals to be considered, there is also

a variety of methods of administration as given in Table B, taken from

[U5 Table II p. xix] . This list may also be expanded as experimentation

continues, "intraocular" for example which does not appear on the list

See Ref. U5, p. xviii

Qk
TABLE A

SPECIES

Species

bird — any domestic or laboratory bird

reported but not otherwise identified bird —wild bird species

cat

cattle chicken

child

dog

domestic animals: goat, sheep, horse

duck (domestic)

frog

gerbil

guinea pig

hamster

human

infant

mammal — species unspecified in reference man

monkey

mouse

Pig

pigeon

quail (laboratory)

rabbit

rat

squirrel

toad

turkey

woman

Order of Preference Designation

for Data Acquisition

22 brd

23 bdw

7 cat 11 ctl 17 ckn

1 chd

4 dog

12 dom

19 dck

20 frg

13 erb

9 fere 10 ham

1 hmn

J.1 inf 15 mam

1 man

6 mky

3 mus

8 Pig

16 Pgn

18 qal

5 rbt 2 rat 14 sql

20 tod

21 trk

I wmn

85
TABLE B

ROUTES OF ADMINISTRATION TO, OR EXPOSURE OF,

ANIMAL SPECIES TO TOXIC SUBSTANCES

Route Abbreviation Definition

Intraarterial iat administration into the artery

Intraaural ial administration into the ear

Intracerebral ipp nHminictrfitinn into trip rprphrnm

Intracervical icv administration into the cervix

Intradermal idr administration within the dermis by hypodermic

UvvUlv tippHIp

Intraduodenal idu administration into the duodenum

Inhalation ihl inhalation in chamber, by cannulation, or through 1111 UUlJI ma^k" UluofV

lUipialll imp r\] UlaCCU q rf*(\ ciiT*oir*5*H\/ bUl^lCdliy witnin Wlllilli thp UiC- honv UKJyjy lnpstion lU^aUUU

described in reference

Intramuscular ims administration of dose into the muscle by

hypodermic needle

Intraplacental ipc administration into the placenta

Intrapleural ipl administration of dose into the pleural cavity by

hypodermic needle

Intraperitoneal ipr administration into the peritoneal cavity Intrarenal irn administration into the kidney

Intratracheal itr administration into the trachea

Intravaginal ivg administration into the vagina

Intravenous ivn administration of dose directly into the vein by

hypodermic needle

Ocular ocu administration directly onto the surface of the eye

or into the conjunctival sac Oral orl per os, intragastric, feeding introduction with

drinking water

Parenteral par administration into the body through the skin. Reference cited is not specific concerning the route

used. Could be ipr, scu, ivn, ipl, ims, irn, or ice Rectal rec administration of dose by way of rectum to the rectum or colon in form of enema, suppository

Skin skn application to the intact skin, dermal, cutaneous Subcutaneous scu administration under the skin

Unreported unk dose, but not route, is specified in the reference

86
in this year's edition, "but probably will soon as there already are such studies for silicones [U6]. Another list of the effects observed

(extracted from the same document) given here as Table C [k5 Table VI

p. xxiv] shows the almost endless variety of observations to be met

with in the field of toxicology.

In addition to the foregoing variables and constraints there are to be considered, age, sex, and periods of exposure and observation.

The imporatance of considering these last two parameters may be judged

from the National Academy Report [UU].

"Acute toxicity can be defined as expos ure to a test agent {oft 24

hours on. less. This definition wilZ provide Ion. the 24-houA exposure

period often used In dermal procedures and the 7 to S-hour periods often

uAed In tke Inhalation pn.ocedun.eA.

Tke tenm ' acute toxicity' has often been ut>ed to define the

Immediate [usually 14 hours on. less) effects of an agent on the animal;

it Is mone appropriate to ut>e longer periods of observation after, the

single exposure In order to detect any delayed effects arising over an extended period of time. Ike 24-hour period of observation may detect

primarily pharmacodynamic activity, although other biological mechanisms

might be so altered as to cause death or other effects within a longer

penjjod of observation. A prolonged observation period would also

permit detection of effects that might be related to anatomical,

biochemical, or hematological changes that Mould not cause immediate

death.

Acute toxicity studies are needed In safety evaluation for two

distinctly different reasons: one is as a screening procedure to old

In Identifying compounds of such low toxicity that, when considered In

relation to a proposed use of low exposure, extensive Investigations

to make a judgment of safety are not justified. The other Is as a type

of acute toxicity procedure designed to delineate the specific toxic

effect, and mechanism thereof, which might be associated with a massive exposure or a normal use associated with a high level of

exposure to a compound. This latter type of study is designed to assist

in the development of an appropriate clinical management program for

Individuals Involved In a misuse or accident and to assist In appraisal

of the safety of a particular use Involving significant human exposure, even though that exposure might be chronic In nature. Such studies can old In Identifying target organ effects which may be valuable In the

proper design of chronic studies.

In the screening type of acute toxicity procedure, the amount of

material to which an animal Is exposed is so massive that it generally

bears no practical relationship to the expected human exposure. It is

reasonable to establish maximum exposure levels [e.g., S000 mg/kg

orally, 3000 mg/kg dermalZy, etc.) for each acute procedure, which can

be used to predict that the agent is essentially acutely nontoxic If no adverse effects are detected.

87
TABLE C

NOTATIONS DESCRIPTIVE OF THE TOXICOLOGY

Abbreviations Definitions (not limited to effects listed)

AT R ...... Allergenic-systemic reaction such as might be experienced by individuals sensitized

to penicillin.

DL.M Blood clotting mechanism — any effect which increases or decreases clotting time.

BLD Blood effects — effect on all blood elements, electrolytes, pH, protein, oxygencarrying or releasing capacity.

BPR Blood pressure effects — any effect which changes any aspect of blood pressure away from normal — increased or decreased.

PAR Carcinogenic — producing cancer —- a cellular tumor, the nature of which is fatal or is associated with the formation of secondary tumors (metastasis).

Central nervous system — includes effects such as headaches, tremor, drowsiness,

convulsions, hypnosis, anesthesia.

COR Corrosive effects — burns, desquamation.

CUM Cumulative effect — where substance is retained by the body in greater quantities

than is excreted, or the toxic effect is increased in severity by repeated bodily insult. CVS Cardiovascular effects — such as when heart activity is increased or decreased

through an effect on ventricle or auricle; fibrillation; or when the arterial or venous

system is dilated or constricted.

DDP Drug dependence — any indication of addiction or dependence.

EYE Eye effects — irritation, diploplia, cataracts, eye ground, blindness by affecting the

eye or the optic nerve. GIT Gastrointestinal tract effects diarrhea, constipation, ulceration.

GLN Glandular effects — any effect on the endocrine glandular system.

IRR Irritant effect — any irritant effect on the skin, eye, or mucous membrane.

MMI Mucous membrane effects — irritation, hyperplasia, ciliary activity changed.

MSK Musculoskeletal effects — such as osteoporosis, muscular degeneration.

MUT Mutation or mutagenic — transmissible changes produced in the offspring.

NEO Neoplastic effect — the production of tumors. PNS Peripheral nervous system effects. PUL Pulmonary system effects —effects on respiration and respiratory pathology.

RBC Red blood cell effects — includes the several anemias.

SKN Skin effects such as ervthema rash sensitization of skin oetechial hemorrhage cvc Systemic effects — effects on the metabolic and excretory function of the liver or

kidneys.

TER Xpratneenir pfFerts nontransmissihle changes nroduced in the offsDrint? TFX Toxic effects used to introduce the orincioal orean svstem affected as reDorted or the pathology.

UNS Unspecified effects — the toxic effects were unspecified in source. WBC White blood cell effects — effects on any of the cellular units other than erythrocytes, including any change in number or form.

Editorial note: Death is, of course, another definable response.

88
A decision process based on both parameters oft experimentally

derived toxic eftftect* and estimated exposure levels should be developed

through Subchronlc sludte* In an eftftort to Identlfty those compound* and

use* which merit chronic Studies. In other word* , a* the knowledge oft expo*ure level change* and toxicity Inftonmatlon become* available,

fturther testing may not only be desirable bat necessary . However, that

there may be circumstances other than those which warrant chronic studies

I* recognized. Structural characteristics may Indicate the need oft a carcinogenic bloassay. No *hort-term on subchronlc test* one known that

can give assurance oft the presence oft possible carcinogenic activity.

When a new chemical I* presented ftor evaluation oft toxicologic

hazard, the chemical and physical characteristic* oft the material must

be considered so that appropriate steps can be taken to assure adequate

exposure oft the animal to the chemical In the various procedures . The

chemical stability oft the agent, vapor pressure, solubltlty, particle

size, etc., can be oft Importance.

Beftore any judgment regarding health hazard can be made, 11 Is

necessary to know the Intended use and the anticipated route, ftrequency,

and level oft exposure to man. The type oft exposure being considered Is

generally that likely to result ftrom the normal usage oft chemicals

rather than ftrom an abnormal situation such as would result ftrom a spltt" - [1+1+ , p. 99].

A further complication is the requirement that adequate analytical

chemical techniques should exist (for every conceivable compound and

metabolite) to determine the administered quantity of a toxic substance,

to identify the type and quantity of any contaminants in the substance,

and also to determine the amount and presence in the biological system.

Analytical techniques, such as gas chromatography combined with mass

spectrometry, which can measure trace materials in water down to levels

of 1-10 parts per trillion are available [1+7.].

Finally, the overall complexity of the subject can be inferred from

the criteria for inclusion of a substance in the Registry of Toxic Effects

of Chemical Substances [1+5, p. xvi]: "Quatlftylng Toxic Vose [TX.VS] . All

toxic doses appearing In the Registry were derived ftrom reports oft the

toxic eftftects produced by Individual substances. A toxic eftftect Is

deftlned as any bodily Injury -- reversible or Irreversible; any tumor -- benign or malignant', any mutagenic or teratogenic eftftect; or death

which has been reported to have resulted ftrom exposure to a chemical

substance via the respiratory tract, skin, eye, mouth, or any other

route.

For humans the toxic eftftect Is any toxic eftftect that was reported

In the source refterence. There Is no quatlftylng Limitation to the

duration oft exposure nor to the quantity oft concentration oft the substance,

nor Is there a quatlftylng limitation oft the circumstances that resulted

In the exposure. Regardless oft the absurdity oft the circumstances that

were Involved In a toxic exposure, It Is assumed that the same

circumstances could recur.

89
For animal* the toxic dose must be Limited, in order that the.

Registry uxWt have, practical usefulness as a guide to hazardousness

to humane. The qualifying symptomatology for animate cannot be

elucidated with any practicality; therefore, more objective signs of

toxic ejects must be relied upon. The production of tumors

{neoplastigenesijy) , benign on. malignant (carcinogenesis); the

production of changes in the offspring , whether transmissible

[mutagenesis) or not [teratogenesis) ; and the production of death are

the criteria that are used as the qualifying toxic ejects* for animal

data. Tor a substance to be included, there is no limitations as to

the time of exposure, nor the quantity or concentration of the dose of

the substance reported to have caused mutagenic, teratogenic, neoplastigenic,

or carcinogenic effects in animals. This is because the dose-effect

relationship has not been correlated for animals and man. It ts presumed

that there is some potential for the occurrence in man of effects stmilar

to those noted in animats, if man ts exposed to these substance* ."

We have now come to the point where we have seen the possibility

of defining an experimental protocol in terms of populations of animals

and we have seen a few of the effects which are looked for in the tables.

It might be well for the interested reader to consult a review such as that of Kimbrough [ll], where an overview of the toxicity of a large

number of polychlorinated polycyclic compounds is given.

We see from Kimbrough [ll]. and from the Interdepartmental Task

Force on PCBs [U8] the following general results for the particular

case of the PCBs.

1. Response depends on route of application: inhalation, skin and

oral techniques have been usual in PCB studies.

2. Response depends on species; a large number of animals have

been used, and data also exist on human response.

3. A wide variety of specific reactions occur including liver:

size, action, enzyme production; skin: chloracne, edema;

reproduction; embryonic effects, gastrointentinal lesions,

chemical porphyrogenic effects, neurotoxicity, immune response,

death, with sufficiently large dose.

h. Response time; because of the stability of the PCBs, they tend

to accumulate in specific body tissues and their effects are therefore generally slow to appear and are long lasting.

5. Analytic techniques; sources indicate the problem of identifying

contaminants which probably accompanied the PCBs in controlled

exposure tests. Because of the accumulation phenomenon, toxic

level concentrations may be very low. In addition, regulatory

personnel have suggested PCB standards as low as 1 ppt (l part

in 10 ). Analyses at this level are routinely available in

special situations [1+7].

A citation here of three paragraphs of Kimbrough' s review should

indicate something of the methods, the range, and the vastness of the

90
difficulty of this type of study. From page U55 of Kimbrough [ll] we

see

:

102 103

"In a pheasant reproduction *tudy with Aroclor 1254, ' a *lgnlflcantly greater dl^eAznce. In the. number of egg* that, were

pipped but not hatched was found In the group of kin*, that received

50 mg of PCB* weekly. Egg production and hatchabllity wa* lower -in this

group, the, *urvival of chicken* that did hatch at *lx week* of age was reduced, and the one* that did *urvlve were *lgniflcantly tighter than

the controls.

• r , OA

In another rat reproduction *tudy the lowest do*e of Aroclor 1254

that affected reproduction was 20 ppm [15 mg/kg/day) which manifested

itself In a decreased number of Litter* and le** pup* per titter.

Hetther 1 ppm nor 5 ppm of Aroclor 1254 had an effect on reproduction

in the Sherman * train rat; however, an expo*ure of the dam* to the

Aroclor* at 5 ppm or higher Increased the liver-to-body weight ratio*

in weanling rati of both *exes. At 1 ppm the increase in liver weight

wa* ob*erved only in Fla and Tib weanling male rat*. The dietary levels

of 100, 20, and 5 ppm of Aroclor 1260 did not affect reproduction;

however, the liver-to-body weight ratio of 21-day-old pup* wa* Increased

at all expo*ure levels.

Wink axe highly *u*ceptible to the toxic ejects of PCB*. A daily

dietary intake of 30 ppm re*ulted In death In about 6 month*. Expo*ure

to 5 ppm Aroclor 1254 In the daily diet *everely affected reproduction.^^

Unfortunately, it i* often very difficult to compare the variou*

dietary level* that affect different *pecle* , *lnce the food con*umption

may vary decisively from one animal *pecie* to another and the daily food

Intake In g/kg body weight I* often not Included In the *cientlflc report.

Some mice *trains, for Instance will be expo*ed to a* much of a given

*ub*tance that i* pre*ent In the diet at the concentration of 300 ppm a*

rat* on a diet containing 600 ppm or more. With *ome *pecie* it I* of course difficult or almo*t impo**lble to mea*ure the food consumption,

but a greater effort in establishing these very basic facts would be

helpful for the Interpretation of toxic effects In different *pecies."

A number of additional U.S. Government Regulations exist giving

further operational definitions of toxicity. Among them are:

1. Department of Transportation - From CFR Title h9 "Transportation"

Part 173. 3^3.

Class B poison ("less dangerous") sec. 173.3^3 liquid or solid

substance "known to be *o toxic to man as to afford a hazard to health

91
during transport, or which, in the absence of data, on human

toxicity... fall within any one of the fallowing categories1 :

/) Oral toxicity: produce death within 48 hours in kali oh. more 0^ a group of 10 on. more white laboratory rats

w&lghing 200 to 300 gramb at a tingle dobe of 50 miliigramb

on. lesb per kilogram of body weight when administered

orally.

2) Toxicity on inhalation: thot><t which pn.odu.cn death within

48 hours in kali on. more than half of a group of 10 on. mono, white laboratory note weighing 200 to 300 gramb, when

inhaled continuously {on. a period of one houA on. lesb at a concentration of 2 mWLi.gn.amb on. let* pen. liter of vapor,

mist, on. dust, provided bach concentration is likeJLy to

be encou.nten.ed by man when the chemical pn.odu.ct ib used in

any reasonable foreseeable manner.

3) Toxicity by bkin abborption: thobe which pn.odu.ee death within

48 houAS in half on. more than half of, a group of 10 on. more

rabbits tested at a dobage of 200 milligramb on. lesb pen. kilogram body weight, when administered by continuous

contact with the bare bkin {on. 24 houns on. lesb.

The foregoing categoni.es bhall not apply if the phybicat characteribticb

of the probable hazards to humans as bhown by experience indicate that

the bubbtances will, not cause berious bicknesb or death. Neither the

display of danger or warning labels pertaining to use nor the toxicity

tests bet forth, above bhall prejudice or prohibit the exemption of any

bubbtances from the provisions of Varts 170- 189 of this chapter..

(29 FR 18753, Vec. 29, 1968, as amended by Amdt. 173-3, 33 FR 14922,

Oct. 4, 1968; 33 FR 19823, Vec. 27, 1968)."

2. Occupational Safety and Health Administration: Air contamination

standards (CFR 29 1910.93) cites: "Threshold Limit Values of Airborne

Contaminants for 1968," Amer. Conf. on Govn. Industrial Hygienists.

3- Food and Drug Administration (FDA): FDA relies on EPA to establish

tolerances. FDA also will act on any legitimately verifiable

indication of toxicity of a substance; rather than having its own specific regulatory definitions of toxicity or lists of toxic substances.

Tolerance levels for specific substances may, however, be established,

as was done for PCBs on July 6, 1973 (38 FR 18095; also see 21 CFR 122.10):

milk 2.5 ppm

manufactured dairy products 2.5

poultry 5 eggs 0.5

animal feed 0.2

animal feed components 2

fish 5 infant foods 0.2

The reader will note the similarity between these definitions and those

used in the Federal Hazardous Substance Act (15 U.S.C., Ch 30) discussed

earlier.

92
k. Environmental Protection Agency (EPA): A Federal Water Pollution

Control Act, Amendments of 1972 (Public Law 92-500 86 Stat. 8l6);

the term "toxic pollutants" is defined in section 502(13):

502(13) "The term 'toxic pollutant 1 mean* tho*e pollutant* , on combination* of pollutants, Including disease- causing agent* , which

after discharge and upon exposure, ingestion, inhalation or a**imilatlon into any organism, either directly from the. environment

on. indirectly by ingestion thn.ou.gh food chain*, will, on the. ba*i*

of information available, to the Administrator, cause death, di*ea*e,

behavonlal abnonmalitle* , cancer, genetic mutation* , physiological

malfunction* (including malfunction* in reproduction) oh physical

defonmatlon*, in *uch 0Hgani*m* on. theln off*pnlng."

Section 304(g) directs the Administrator of EPA to publish test

procedure guidelines:

"304[g) The. kdminlt>tnalon shall within one hundred and eighty days

from the. date of enactment of this title., promulgate guideline*

e*tabli*hlng te*t procedure* fon the. analysis of pollutants that

shall include, the. facton* which must be. pnovided in any certification

punsuant to * action 401 of this kct on permit application punsuant

to section 402 of this Act."

Test procedures for 30U(g) were published in 38FR 28758 Oct. l6, 1973;

for "chlorinated organic compounds (except pesticides)," gas

chromatography is the approved test procedure.

Section 307 directs the Administration to establish a list of

toxic pollutants:

"307(e) (a) (7) The. Adminlstnaton shall, within ninety days aften

the date of enactment of this tille, publish (and fnom time to time

theneaften nevise) a list which includes any toxic pollutant on combination of such pollutants fon which an effluent standand

(which may include a pnohibitlon of the dischang e of such pollutants

on combination of such pollutant*) will be established unden this

section. The Adminlstnaton in publishing such a list shall take

into account the toxicity of the pollutant, it* persistence,

degnadability, the usual on potential pnesence of the affected

onganl*m* in any waten*, the imponlance of the affected onganlsm*

and the natune and extent of the effect of the toxic pollutant on *uch onganlsm*.

(2) Within one hundred and eighty day* aften the date of publication

of any Ust, on nevision thereof, containing toxic pollutant* on combination of pollutant* unden panagnaph (1) of this *ub*ectlon,

the Adminlstnaton, in accondance with section 553 of title 5 of the

United States Code, shall publish a pnoposed effluent standard

(on a pnohibilion) fon such pollutant on combination of pollutants

which shall take into account the toxicity of the pollutant, it*

persistence, degnadabUlty, the usual on potential pnesence of the

93
affected organisms in any waters, the importance of the affected

organisms and the nature and extent of the. effect of the toxic

pollutant on Such organisms, and he A halt publish a notice for a public he.aAA.na on such proposed standard to be. held within thirty

days. As boon as possible after such he.aKA.nq, bat not later than

six month* after publication of the proposed effluent standard

[oa prohibition) , unless the. Administrator finds, on the. record,

that a modification of i>uch proposed standard [on. prohibition) is

justified based upon a pAepondeAance of evidence adduced at such

hearings, such standard [oa pAohibition) shall be promulgated.

(3) If afteA a public hearing the. Administrator find* that a modification of such proposed standard {oa prohibition) is justified,

a revised effluent standard [oa prohibition) foA such pollutant oa combination of pollutants Shalt be promulgated immediately. Such

standard [oa pAohibition) shall be. reviewed and, if appropriate,

revised at least eveAy three. years.

(4) Any effluent standard pAomulgated undejt this section shall be. at that level which the Administrator determines provide* an ample

margin of safety.

(5) W/ien proposing or promulgating any effluent standard [or

prohibition) undeA this he.ctA.on, the. AdministrateA shalZ designate

the. category oa categories of sources to which the effluent standard

[oa pAohibition) shall apply. Any disposal of dredged mateAial may

be. included in such a categoAy of sources afteA consultation with

the. Secretary of the. Army.

(6) Any effluent standard [oa pAohibition) established pursuant to

this section shall take. effect on such date, oa dates* as specified

in the. oAdeA pAomulgating such standard, but in no case. moAe than

one. year from the. date, of such pAomulgation.

(7) Prior to publishing any regulations pursuant to this section the.

AdministratoA shaU, to the maximum extent practicable within the

time provided, consult with appropriate advisory committees. States,

independent experts, and Federal departments and agencies."

The "List" was published according to proposed criteria in 38FR 180UU,

July 6, 1973 "Proposed Criteria "

"Pollutants weAe chosen for inclusion on the initial list in light

of the following criteria:

7 . Vata from laboratory or field studies indicate that the pollutant

could, if discharged into water, constitute a serious enviAonmental

threat. The types of data examined in making this judgment are set forth in Part I beZow.

1. The pollutant is discharged, or has the potential to be discharged,

from point sources and constitutes a veAy serious enviAonmental

thAeat.

9h
3. Vata are available, to establish effluent standards meeting the

requirements of the Act.

4. Standard setting under Section 307 [a) is appropriate, and is

necessary because the prospective timing and effectiveness oft abatement actions under other provisions of the Act are not

commensurate with the nature and seriousness of the problems

identified by the above criteria."

I. Explanation of Criteria.

"The first criterion concerns the actual or potential damage that

a Miter discharge of these materials may create by virtue of certain

toxicalogical properties.

detailed toxicalogical data are examined to determine whether one

or more of these types of effects are known: bioaccumulation,

carcinogenic, mutagenic and teratogenic effects, and high acute toxicity.

Specifically, the following types of data are reviewed:

1 . Available data concerning whether a substance or its chemical

or biological transformation product is bioaccumulated through

an aquatic mechanism to the extent that they result in:

[a] Reproductive impairment in any important species, or

(b) Concentrations in food sources in excess of applicable

federally established tolerance levels.

2. Data concerning carcinogenic, mutagenic, and teratogenic effects.

Materials likely to be carcinogenic, mutagenic, or teratogenic

to man are further evaluated as to their chemical, biological,

and physical stability in water.

3. Data concerning high order of toxicity as measured by short-term

lethality tests. In this connection a classification of a substance as 'highly toxic' to man according to classifications

established by the Department of Transportation and the

Environmental Protection Agency [36 FZ 2934, February 12, 1971,

40 CFR 162.8) and the Environmental Protection Agency and the

Food and Drug Administration testing procedures [40 CFR 162. 8 and 21 CFR 191.10) is particularly relevant. According to the

references cited above, substances which have an oral LVBO of

50 mg/kg of body weight or less or have a dermal LVBO of 200 mg/kg

of body weight or less are defined as highly toxic to mammals

and are examined further. The term 'oral LVBO' means that

single oral dose which is lethal to one-half of the test

population within 14 days. The term 'dermal LVBO' means that

dose dermally absorbed in 24 hours which is lethal to one-half

of the test population witltin 14 days.

95
For the protection of aquatic Life, &u.b&tances proposed to be

classified a* 'highly toxic 1 according to the National

Academy of ScA.mc.zt> water pollution ranking system may be

considered {on Inclusion In the list. Such substance* are those which axe toxic to aquatic life a* measured by a 96

hour LC50 of 10 mg/1 oh. les*. The torn 1 LC50' means that

concentration of a substance -in water which Is lethal to

one-half of the test population In the specified time period*,

letting methods such a* those hound in 'Standard Methods {oh.

the Examination of Water and Wastewater, ' 13th Edition, part. 231

,

1971, oh. their equivalent Mill be considered adequate."

"The second criterion concern* the seriousness of discharge* oh. potential discharge* of the pollutant from point bouA.ce*>. Relevant

here axe t>uch factors ai> the natuxe and extent of toxic effects associated

with the pollutant, the extent to which discharges of the pollutant have

been Identified and the production, distribution, and use pattern of the

pollutant. Vata mut>t be available from well documented field studies

showing damage to Important organism* from discharge* of the compound

Into waters, oh. technically sufficient to show the material ha* the

potential to be environmentally harmful after, being discharged from point

source* to the water."

"The third criterion concern* betting effluent standard* for

pollutant* on the List. The following axe representative of the categories

of data useful In standard setting for each material.

1. Toxicity to man and other organisms;

2. Carcinogenicity, mutagenicity, and teratogenicity data;

3. Transport paths of the material In the environment;

4. Bioaccumulation and bio concentration;

5. Chemical, physical, and biological transformations In the

environment;

6. Reliability and accuracy of analytical procedures;

7. Chemical characteristics;

S. Production and Industrial or commercial- utilization;

9. Source* of the pollutant to water;

10. Environmental Incidents attributed to the material [fish kills,

etc

.

) ; 11. Presence of the material In the environment, residue levels

In various organisms , ambient concentrations In rivers, lake*, etc.;

12. State and Federal regulatory requirement* concerning the

material;

13. Classes and characteristics of waters Into which the material

Is discharged."

96
"The. iounth cnlXenlon concerns the oveAall envlAovunzvital e^ect

o{ the control meaiun.es available, Including the oie 0(J Substitute

pn.odu.cjtb, and possible ejects upon ground waten. on. othen. envlnonmental

media.

Section 311(b) deals with regulating the discharge of oil and

hazardous substances:

"37 7 (6) (7) The Congress hereby declanes that it Is the. policy o^

the United Statu that thene should be no discharges o{ oil on hazardous

substances Into on upon the navigable watens o{ the United State*,

adjoining shorelines , on Into on upon the waters o^ the contiguous

zone.

There is at the writing of this report no Toxic Substances Act

administered by the authority of the Environmental Protection Agency which

defines the tests which should be adhered to by manufacturers of

polychlorylbiphenyl replacements. The Agency is now developing guidelines

for such tests and is consulting with industry on the matter.

A. 3.6 Test Techniques By Which Degradability Is Evaluated

In this section we are concerned with the standards and tests which

might apply to degradability of a compound in the absence of living

organisms (physical or chemical degradation) or in their presence

(biodegradability )

.

We are not aware of standard tests for the evaluation of the purely

physical or chemical degradation of transformer and capacitor fluids.

One must seek such information on a piecemeal basis and either design

one's own experiment or make inferences from experiments in the physicochemical literature. Inference is the source of much of our estimate

of the safety of certain products.

An example of the kind of experiment which is relied upon to

provide information on nonbiological degradation is the study by Siegel

and Stewart on the degradation products of silicones when exposed to

high energy radiation [U9]. The technique used by the authors was the

exposure of a dimethyl silicone polymer to vacuum-ultraviolet radiation

in a photolysis tube. At the conclusion of the photolysis the products

were drawn off into a mass spectrometer where analysis was made, and

thence the quantum yields in ethane and methane and the energy transfer

were calculated. These results when coupled with knowledge of the

chemistry of formation of the silicones give a clue to the effect of

sunlight upon silicones, namely that the silicones yield degradable

products

.

In a similar fundamental study of photolysis in the near ultraviolet

of dimethysilicones , Delman, Landy and Simms [50] found from the use of

two different activating lamps that if the ultraviolet radiation is

energetic enough and if oxygen is present, silanes are formed. These

findings were made under carefully controlled physical and chemical

conditions. The conclusion of these results is that in sunshine and air

the silicones will degrade to silanols (Si-OH structures) and thence to

silica and water. In the environment there is also water present, and

one would expect all the more the formation of silanols.

Q7
Attempts are under way in industry to provide more direct

environmental testing of the dimethyl silicones to determine with

certainty the degradation of these products but the studies will be

long and difficult.

There are, however, several standard methods of biodegradability

measurement. Most of these depend upon the degradative activity of

sewage sludge or selected bacteria. Processes range from the simple

so-called River Die-Away test to the difficult continuous-activatedsludge test [51]. This last is specified by the law of at least one European nation for detergent degradability tests [52]. The river

die-away test consists of mixing a quantity of natural river water

with a known amount of the substance under study. Periodic sampling

allows the investigator to follow the rate at which the original

substance decays.

There is also a well known, often used, batch activated-sludge

test. It is similar to the river die-away test except that a prescribed

amount of activated sludge is added. The sludge or culture used may

be made highly uniform and is commercially obtainable [53]. Semicontinuous

methods of sludge addition have also been devised [5l]« These are more

likely to involve pilot-plant scale equipment than the Mason jars

called for in the River Die-Away and batch tests.

So far as we are aware the only test for biodegradability which has

the stamp of approval of an industry-wide committee, is that for

sulfonate biodegradability promulgated by the Subcommittee on Biodegradation

Test Methods of the Soap and Detergent Association [53]. This test,

which defines what is meant by "biodegradable" for the purposes of the

soap and detergent industry, is a detailed procedure for testing sulfones

by a modified semicontinuous activated-sludge method. Defined in the

test are solutions and vessels to be used, design of aerator, source

of uniform bacterial culture, and directions for sampling and rate

of aeration. The Soap and Detergent Association test has been applied

to the phthalate esters with results that were gratifying to producers

of the phthalates [55].

Appended to this section are two tests selected from the EPA

Manual of Methods for Chemical Analysis of Waters and Wastes 197^ [5^].

These tests were culled to illustrate common tests in the field.

98
BIOCHEMICAL OXYGEN DEMAND

(5 Days, 20°C)

STORET NO. 00310

Scope and Application

1.1 The biochemical oxygen demand test (BOD) is used for determining the relative

oxygen requirements of municipal and industrial wastewaters. Application of the

test to organic waste discharges allows calculation of the effect of the discharges on the oxygen resources of the receiving water. Data from BOD tests are used for

the development of engineering criteria for the design of wastewater treatment

plants.

1.2 The BOD test is an empirical bioassay-type procedure which measures the

dissolved oxygen consumed by microbial life while assimilating and oxidizing the

organic matter present. The standard test conditions include dark incubation at 20°C for a specified time period (often 5 days). The actual environmental

conditions of temperature, biological population, water movement, sunlight, and

oxygen concentration cannot be accurately reproduced in the laboratory. Results

obtained must take into account the above factors when relating BOD results to stream oxygen demands.

Summary of Method

2.1 The sample of waste, or an appropriate dilution, is incubated for 5 days at 20°C

in the dark. The reduction in dissolved oxygen concentration during the

incubation period yields a measure of the biochemical oxygen demand.

Comments

3.1 Determination of dissolved oxygen in the BOD test may be made by use of either

the Modified Winkler with Full-Bottle Technique or the Probe Method in this

manual.

3.2 Additional information relating to oxygen demanding characteristics of wastewaters can be gained by applying the Total Organic Carbon and Chemical Oxygen

Demand tests (also found in this manual).

Precision and Accuracy

4.1 Eighty-six analysts in fifty-eight laboratories analyzed natural water samples plus

an exact increment of biodegradable organic compounds. At a mean value of 2.1 and 175 mg/1 BOD, the standard deviation was ±0.7 and ±26 mg/1, respectively.

(EPA Method Research Study 3).

4.2 There is no acceptable procedure for determining the accuracy of the BOD test.

99
5. References

5.1 The procedure to be used for this determination is found in: Standard Methods for the Examination of Water and Wastewater, 13th Edition, p

489, Method 219 (1971).

100
DISSOLVED OXYGEN

(Electrode)

STORET NO. 00299

Scope and Application

1.1 The probe method for dissolved oxygen is recommended for those samples

containing materials which interfere with the modified Winkler procedure such as

sulfite, thiosulfate, polythionate, mercaptans, free chlorine or hypochlorite,

organic substances readily hydrolyzed in alkaline solutions, free iodine, intense

color or turbidity, biological floes, etc.

1.2 The probe method is recommended as a substitute for the modified Winkler

procedure in monitoring of streams, lakes, outfalls, etc., where it is desired to

obtain a continuous record of the dissolved oxygen content of the water under

observation.

1.3 The probe method may be used as a substitute for the modified Winkler

procedure in BOD determinations where it is desired to perform nondestructive

DO measurements on a sample.

1.4 The probe method may be used under any circumstances as a substitute for the

modified Winkler procedure provided that the probe itself is standardized against

the Winkler method on samples free of interfering materials.

1.5 The electronic readout meter for the output from dissolved oxygen probes is normally calibrated in convenient scale (0 to 10, 0 to 15, 0 to 20 mg/1 for

example) with a sensitivity of approximately 0.05 mg/liter.

Summary of Method

2.1 The most common instrumental probes for determination of dissolved oxygen in

water are dependent upon electrochemical reactions. Under steady-state conditions, the current or potential can be correlated with DO concentrations.

Interfacial dynamics at the probe-sample interface are a factor in probe response

and a significant degree of interfacial turbulence is necessary. For precision

performance, turbulence should be constant.

Sample Handling and Preservation

3.1 See 4.1, 4.2, 4.3, 4.4 under Modified Winkler Method.

Interferences

4.1 Dissolved organic materials are not known to interfere in the output from

dissolved oxygen probes.

101
4.2 Dissolved inorganic salts are a factor in the performance of dissolved oxygen

probe.

4.2.1 Probes with membranes respond to partial pressure of oxygen which in

turn is a function of dissolved inorganic salts. Conversion factors for

seawater and brackish waters may be calculated from dissolved oxygen

saturation versus salinity data. Conversion factors for specific inorganic

salts may be developed experimentally. Broad variations in the kinds and

concentrations of salts in samples can make the use of a membrane probe

difficult.

4.2.2 The thallium probe requires the presence of salts in concentrations which

provide a minimum conductivity of approximately 200 micromhos.

4.3 Reactive compounds can interfere with the output or the performance of

dissolved oxygen probes.

4.3. 1 Reactive gases which pass through the membrane probes may interfere.

For example, chlorine will depolarize the cathode and cause a high

probe-output. Long-term exposures to chlorine will coat the anode with

the chloride of the anode metal and eventually desensitize the probe.

Alkaline samples in which free chlorine does not exist will not interfere.

Hydrogen sulfide will interfere with membrane probes if the applied

potential is greater than the half-wave potential of the sulfide ion. If the

applied potential is less than the half-wave potential, an interfering

reaction will not occur, but coating of the anode with the sulfide of the

anode metal can take place.

4.3.2 Sulfur compounds (hydrogen sulfide, sulfur dioxide and mercaptans, for

example) cause interfering outputs from the thallium probe. Halogens do

not interfere with the thallium probe.

4.4 At low dissolved oxygen concentrations, pH variation below pH 5 and above pH 9

interfere with the performance of the thallium probe (approximately ±0.05 mg/1

DO per pH unit). The performance of membranes is not affected by pH changes.

4.5 Dissolved oxygen probes are temperature sensitive, and temperature compensation is normally provided by the manufacturer. The thallium probe has a temperature coefficient of 1.0 mv/°C. Membrane probes have a temperature

coefficient of 4 to 6 percent/°C dependent upon the membrane employed.

5. Apparatus

5. 1 No specific probe or accessory is especially recommended as superior. However,

probes which have been evaluated or are in use and found to be reliable are the

102
Weston &. Stack DO Analyzer Model 30, the Yellow Springs Instrument (YSI)

Model 54. and the Bcckman Fieldlab Oxygen Analyzer.

6. Calibration

Follow manufacturer instructions.

7. Procedure

Follow manufacturer instructions.

8. Calculation

Follow manufacturer instructions.

9. Precision and Accuracy

Manufacturer's specification claim 0.1 mg/1 repeatability with ±1% accuracy.

£03
A. 3-7 References for Section A.

3

1. Schmidt, H. , and Schultze, G. , (Liebig's) Annalen , l88l , p. 207,

p. 238.

2. Penning, C. H. , "Physical Characteristics and Commerical Possibilities

of Chlorinated Diphenyl ," Ind. Eng. Chem. 1930, Vol. 22, p. Il80.

3- Clark, F. M. , "Nonflammable Dielectric Organic Compounds ," Ind . Eng.

Chem. 1937, Vol. 29, p. 698.

h. Clark, F. M. , Trans. Elect rochem. Soc

.

193^, Vol. 65, p. 59.

5. Broadhurst , M. G.,"Use and Replaceability of Polychlorinated

Biphenyls," Environ. Health Perspect. 1972, Vol. 2, pp. 81-102.

6. Holden, A. V. , "Source of Polychlorinated Biphenyl Contamination in

the Marine Environment," Nature 1970, Vol. 228, pp. 1220-1221.

7- Koeman, J. H. , Ten Noever De Brauw, M. C, and Devos, R. H. , "Chlorinated Biphenyls in Fish, Mussels, Birds from the River Rhine

and the Netherlands Coastal Area," Nature 1969, Vol. 221, pp. 1126-1128.

8. Jensen, S. , Johnels, A. G. , Olsson, M. , and Otterlind, G. , "DDT and PCB

in Marine Animals from Swedish Waters ," Nature 19&9, Vol. 22h , pp. 21+7-250.

9. Zitko, V., Bull. Environ. Contam. Toxicol. 1970, Vol. 6, p. h6k.

10. Veith, G. D., "Recent Fluctuations of Chlorobiphenyls (PCBs) in

Green Bay, Wisconsin Region," Environ. Health Perspect. 1972, Vol. 1,

pp. 51-62.

11. Kimbrough, R. , CRC Reviews of Toxicology , Jan. 197^, p. UU8

,

Chemical Rubber Company, Cleveland.

12. Schweitzer, G. E. , statement at the Wisconsin State Hearings on PCBs, Madison, Wisconsin, August 1975-

13- Stallings, D. L., and Mayer, F. L.

, "Toxicities of PCBs to Fish and

Environmental Residues ," Environ . Health Perspect. 1972, Vol. 1,

pp. 159-16);

.

lU. Hansen, D. J., Parrish, P. R. , Lowe, J. J., Wilson, A. J,, Jr., and

Wilson, P. D., "Chronic Toxicity, Uptake and Retention of Aroclor 125^

in Two Estuarine Fishes ," Bull . Environ. Contam. Toxicol. 1971,

Vol. 6, pp. 113-119.

15. "PCBs and the Environment," Interdepartmental Task Force on PCBs,

Com-72-10Ul9 , National Technical Information Service, U.S. Department

of Commerce, March 1972.

16. Kuratsune, M. , "Yusho ; Characteristics and Long-term Effects,"

National Conference on Polychlorinated Biphenyls, Environmental

Protection Agency, Chicago, November 19-21, 1975-

10l*
IT. Dauppi, T. A., and Currie, C. C, Product Engineering , 191+9,

Vol. 20, p. 108.

18. Currie, C. C. , and Smith, B. F.,"Flow Characteristics of

Organopolysiloxane Fluids and Greases ," Ind. Eng. Chem. 1950,

Vol. 1+2, p. 21+57-

19. Fit z simmons, V. G. , Pickett, D. L. , Militz, R. 0., and Zisman, W. A.,

Trans. A.S.M.E. (19^6), Vol. 68, p. 365.

20. Scott, D. W. , J. Am. Chem. Soc

.

19U6 . Vol. 68, 356.

21. Patnode, W. , and Wilcock, D. F. , ibid., p. 358.

22. Fordham, S. , The Silicones . The Philosophical Library, New York,

196l, also Noll, W. , Chemistry and Technology of the Silicones,

Academic Press, New York, 1968.

23. ASTM Standard Method D 92, Annual Book of Standard Methods Part ho

American Society for Testing and Materials, Philadelphia, Pa., 1975-

2k. Clark, F. M. , Insulating Materials for Design and Practice , John Wiley & Sons, New York, 1962, pp. 136 and 320.

25. See for example "Dielectric Properties of Dow Corning Silicone

Liquids," issued by Dow Corning Corporation, Midland, Michigan.

26. Stock, A., and Somieski, C, Ber. 19l6. Vol. 1+9, p. 111.

27. Kipping, F. S., Proc. Roy. Soc. 1937, Vol. 159A, p. 131.

28. McGregor, R. R. , Silicones and Their Uses , McGraw-Hill Book Company,

New York, 195*+.

29. Link, E. , RTE Corporation — personal communication.

30. Duckett , D. A., Paper before the General Meeting of the Edison

Electric Institute, Transmission and Distribution Committee,

Minneapolis, Minnesota, May 8, 1975.

31. Morrison, R. T. , and Boyd, R. N. , Organic Chemistry , Allyn & Bacon,

New York, 1966.

32. Munch, R. H., German Patent Disclosure No. 2,310,807,13, Sept. 1973,

U.S. Patent No. 3,796,931+.

33. Munch, R. H. , Monsanto Chemical Company, St. Louis, Mo. — personal

communication.

3l+. Munch, R. H., "New Capacitor Impregnants ," Conference Paper presented

at IEEE Power Eng. Soc. 1975 Winter Meeting Session.

35. Report on MCS 1238, Obtainable from Corporate Medical Dept.,

Monsanto Chemical Company, St. Louis, Mo. 6 31 66.

36. Graham, P. R.

, "Phthalate Ester Plasticizers - Why and How They

Are Used," Environ . Health Perspect. 1973, Vol. 3, pp. 3-15-

105
37- Forster, E. 0. — personal communication.

38. Rutkowski , A. J., and Forster, E. 0., Presented at American Power

Society (IEEE) Winter Power Meeting, New York, 1975, also Proc

.

VII Int. Conf. on Electrical Insulating Materials, Inst. Elec

.

Eng., Tokyo, Japan, 197^.

39- Moffitt, A. E., Jr., Clary, J. J., Lewis, T. R . , Blank, M. D.

,

Perone, V. B. , J. Am. Ind. Hyg. Assoc

.

, 1975, Vol. 36, p. 633.

hO. Tanaka, A., Adachi, T. , Takahashi , T. , Yamaha, T., Toxicology 1975.

Vol. h, pp. 253-26U.

Ul. Peters, J. W. , Cook, R. M. , Environ. Health Perspect. 1973, Vol. 3,

pp. 91-91+. See also Rubin, R. J., and Jaeger, R. J., ibid., 1973,

Vol. 3, pp. 53-59, and other papers from N.I.E.H. Sciences Conference

on Phthalic Acid Esters, Sept. 6-7, 1972 in Environ. Health Perspect.

1973, Vol. 3, passim.

h2. Capacitor Fluid XFS-U169L statement on development of fluid by Dow

Chemical Company and McGraw-Edison Company, Dec. 2, 1975, Dow

Chemical Company, Midland, Michigan.

U3. Environmental Impact Statement on XFS-U169L Capacitor Fluid. Dow

Chemical Company, Midland, Michigan.

hh . National Academy of Sciences report on the Principles for Evaluating

Chemicals in the Environment. National Academy of Sciences,

Washington, D.C. , 1975.

i+5. Registry of Toxic Effects of Chemical Substances, 1975 ed. , U.S. Dept.

of Health, Education and Welfare, National Institute for Occupational

Safety and Health, Rockville, Maryland 20852.

h6. Mukai, N. , Lee, P. F. , Oguri , M. , Schepens , C. L., Can. J. Ophthalmol 1975. Vol. 10 (3), p. 391.

hf . Perkin-Elmer Chromatography Newsletter, 197^-, Vol. 3, p. 15-

hd. "Polychlorobiphenyls and the Environment." Interdepartmental Task

Force on PCBs . Com. -72-10i+19 National Technical Information

Service, U.S. Dept. of Commerce, Springfield, Virginia 22151.

U9. Siegel, S., and Stewart, T.

, "Vacuum Ultraviolet Photolysis of

Polydimethylsiloxane Gas Yields and Energy Transfer," J. Phys.

Chem. 1969, Vol. 73, p. 823.

50. Delman, A. D. , Landy, M. , and Sims, B. B. , J. Polymer Sci. 1969,

Vol. 7, p. 3375.

51. Weaver, P. J., and Coughlin, F. J. , "Measurement of Biodegradability ," Amer. Oil Chem. Soc

.

196U . Vol. hi, p. 738.

52. Publication 253/62 of the Federal Council of the German Federal

Republic, 1962.

106
53. Soap and Detergent Association, Amer. Oil Chem. Soc

.

19&5,

Vol. k2, p. 986.

5h. Published by U.S. Environmental Protection Agency, Office of

Technology Transfer, Washington, D.C. 20U60.

55- Saeger, V. W. , Tucker, E. S. Ill , 'Phthalate Esters Undergo Ready

Biodegradation," Plastics Eng. 1973, Vol. 29 (8), pp. 1+6-U8.

56. Gleason, M. N. , ed. Clinical Toxicology of Commercial Products , Uth Ed., Williams and Wilkins , Baltimore, 1975-

107
A.U The Scope and Influence of Government Regulations

The purpose of this section is to identify the several government

agencies which have potential regulatory power over new insulating

fluids, to describe the particular area of concern over which each

exercises regulatory power, and to define what criteria and procedures

are used to determine whether a new fluid falls within the purview of

each particular agency or regulation. The emphasis will, therefore,

he on the regulations themselves; criteria and testing procedures which

support or are cited in these regulations will be briefly identified.

In Section A. 3.2, these test techniques are more thoroughly explored.

A.U.I Environmental Regulations"*"

Environmental protection regulations are developed and enforced by

the Environmental Protection Agency (EPA) and by the various state

departments of natural resources. The state agencies generally follow

the Federal regulations, and they may in fact have operational

responsibility for enforcing the Federal environmental regulations.

Being more closely in touch with the local issues and being under less

complex operating constraints, the states can often act more rapidly than

the Federal enforcement agencies. It is important, therefore, that the

state and Federal environment regulatory bodies act under rigorous,

quantitatively definable criteria in establishing and enforcing their

regulations. We will review the existing and pending Federal regulations,

recognizing that these will also probably be reflected in any state acts.

Insulating and dielectric fluids are typically very stable compounds

which have low vapor pressures and which, therefore, do not represent a significant air pollution problem.^ The primary environmental effect is

in water, and so the primary source of environmental regulation of such

fluids is:

Public Law 92-500 (86 Stat. 8l6)

"Federal Water Pollution Control Act Amendments of 1972"

Three sections in this act are of particular importance for evaluating

the impact of regulations:

1. Sec. 307a "Toxic effluents." A proposed list and a final list

of toxic substances were published by EPA in the Federal

Register on July 6, 1973 (38FRl8oUUP and on September 7, 1973

( 38FR2U3U2 ) , respectively. Criteria for selecting these

substances were included, thereby indicating the standards by

Section A.3.h also contains discussions of Federal environmental

regulations in terms of definitions of test techniques and criteria.

i See Section A.U. 3 "Occupational health," for air quality criteria in

the working place.

>'Federal Register (FR), vol. 38, page 180UU.

108
which new substances can be evaluated. The toxic substance

list is not enforceable, however, until standards for

allowable levels of these toxic substances are finally

promulgated. Although standards were proposed on December 27, 1973,

these have not yet reached final legal status.

2. Sec. 307b "Pretreatment standards." The Administrator of EPA

is authorized and directed to publish and promulgate standards

for pretreatment of pollutants which could be introduced into

publically owned treatment works.

3. Sec. 311 "Oil and Hazardous Substance Liability." (spills,

leakage, pouring hazardous substances into navigable waters of

the U.S.). On August 22, 197^+, an advanced notice was issued:

"Designation and deteAmination o^ n.emovabiliXy ofi hazaAdouA

Aubttances ^Kom u)ateA" (39FR30U66). In response to this advance

notice, written comments were received and were incorporated

into a proposed set of rules issued on December 30, 1975

(UOFR59960). When promulgated, these rules will provide the

basis of the hazardous chemical (including PCBs) spill control

program. Key elements activated by these regulations will

probably include mandatory reporting of discharges, clean-up

and damage mitigation, and civil penalties which may be assessed

by both the Environmental Protection Agency and the Coast Guard.

h. Sec. h02 "Pollution discharge permits." This section empowers

the regional offices of EPA to issue permits limiting the

allowable levels of pollutants in effluent discharges.

Limitations on polychlorinated biphenyls have already been

included in several permits. "Pollutant" is defined (in

Sec. 302) as effluents which "would inteA^eAe. with the.

attai.nme.nt on. maintenance. o& that wateA quality in a i>pe,ci.^ic

ponXion ol the, navigable. watcns which i>haZZ ai>6un,e. pn.ote.cti.on

o{j public wateA Supplies, agnA.QjuJLX.uAai. and induitnXal ui>eJ>,

and the pnote.cti.on and propagation o{, a balanced population oft i>heZll<Uh, &iAh and wildlife., and allow n.e.cn.eRtional activities

in and on the. wateA, "

In addition to the existing legislation cited above, Congress is

in the process of working on a Toxic Substances Control Act, which if

passed would give EPA more direct control on production and use of

identified toxic substances.

A.U.2 Poisonous Ingredients in Foods

The Food and Drug Administration (FDA), an agency of the Federal

Department of Health, Education and Welfare, has the responsibility for

administering the consumer protection standards established by the Federal

Food, Drug, and Cosmetics Act of 1938 with amendments (FFDCA) (U.S. Code,

Title 21). The various state departments of public health cooperate in

109
maintaining proper food standards, under authority of state public

health legislation. Whereas FDA enforcement authority concerns only

foods involved in interstate commerce (Sec. 703 and TOU of FFDCA), the

state may, of course, take local action.

"Poisonous substances" include all substances documented to be harmful

to human health. Thus, they may be specifically identified in FDA

regulations (as in the case of PCBs ; see 38FRI8096, July 6, 1973) or known to be poisonous from other reliable sources such as "The Toxic

Substances List" published by the National Institute for Occupational

Safety and Health (see Section A.h.3 below). Likewise, tolerance levels

are not specifically identified by FDA for each known poison, but rather

this is judged on a case-by-case basis, as specified in Sec. U06 of

FFDCA. 1

Any new insulating or dielectric fluid which is identified by any

Federal agency to be poisonous would thus come within FDA jurisdiction.

In relation to this, it should be noted that the FDA regulations on PCBs (38FRI8096) specifically exempt PCB transformers and capacitors;

their being in sealed containers was an influential factor in this

decision.

In enforcing its regulations, FDA can request a manufacturer to

recall an adulterated product, under threat of prosecution. It can,

under court authority, seize a shipment of adulterated food. And it can legally prosecute manufacturers of illegally adulterated foods. Actions

are reported in:

"FDA Weekly report of seizures, prosecutions, injunctions, field

corrections and recalls," published weekly by the FDA Press

Office, Rockville, Maryland 20852.

A.U.3 Occupational Health

The Occupational Safety and Health Administration (OSHA), a part

of the Department of Labor, has the responsibility "to 066UA2. £0 faoJi <u possible nvexy walking man and woman in the Nation sa^z and keaZth^uZ

working conditions ... ." as stipulated in:

Public Law 91-596 (8U Stat. 1590)

"Occupational Safety and Health Act of 1970"

Dielectric and insulating fluids could come within the scope of

OSHA regulations in two ways:

1. During processing of the material by the capacitor and

transformer manufacturers.

Although levels were set for PCBs, in the July 6, 1973 regulations.

110
2. By use of the capacitors and transformers in or closely

adjacent to work areas.

In the Act cited ahove , the following responsibilities are defined:

1. The Secretary of Labor (i.e., OSHA) is to promulgate standards

for toxic substances (Sec. 6).

2. The Secretary of Labor also is empowered to inspect working

places (Sec. 8) and to enforce the standards (Sec. 10, IT).

3. The Secretary of Health, Education and Welfare, through its

agency, The National Institute of Occupational Safety and

Health (NIOSH) is to carry out research, develop criteria, and

carry on training concerning health and safety in the working

place (Sec. 20, 21, 22).

Thus, NIOSH establishes standards, while OSHA promulgates and enforces

these standards. The following publications and standards have resulted

regarding toxic substances:

"Registry of Toxic Effects of Chemical Substances," 1975 Edition,

NIOSH, Rockville, Md. 20852, June 1975.

In this publication, a large number of toxic substances are listed,

along with toxic dose levels, and the reference sources for these toxic

doses. Four PCBs are included.

"Occupational Safety and Health Standards," 39FR23502, June 27, 197^.

Table Gl lists contaminants, including chlorodiphenyl {h2% Cl);

skin 8-hour time weighted average exposure not to exceed 1.0 mg/m3 , and

chlorodiphenyl Cl), 8-hour time weighted average skin exposure not

to exceed 0.5 mg/m3

. (These are currently listed in 29CFR 1910. 1000).

OSHA has developed draft technical standards establishing requirements for monitoring employee exposure, medical surveillance, handling

and use, training, record keeping, sanitation and housekeeping. These

are now available for comment ( UOFR51+033 , November 20, 1975).

The source of these standards is UlCFR 50-20U.50 which cites:

"Threshold Limit Values of Airborne Contaminants for 1968," Amer. Conf.

of Govn. Industr. Hygienists.

The National Electrical Code (NEC) - 1971 (ANSI Cl-1971) has been

incorporated within OSHA regulations (29CFR 1910.308; see 39FR23502,

June 27, 197^). Dielectric fluids for transformers and capacitors

111
therefore fall within OSHA regulations insofar as use of these fluids

is affected by the NEC. (See Section A. 5 of this report for further

discussion of the NEC).

A.U.U Transportation

The Department of Transportation (DOT) is involved in "both the use

and the control of insulating fluids in these two ways:

1. Use . High speed mass transit systems employ electric traction.

The electric transformer is a key item. It must be small

because of the size limitations on the transit cars, and

fireproof in the event of an accident. Askarel transformers

are therefore universally used in present ground electric

transit systems.^- Thus, DOT may become a significant participant

in the move toward both safe and reliable techniques for continued

use of PCBs and for substitutional use of new insulating fluids;

however, no documentation regarding efforts by this agency to

encourage development of improved transformers has yet come to our attention.

2. Control . The transportation of hazardous materials falls within

DOT's regulatory power, as identified in:

U9CFR Parts 100-199 Transportation ; revised as of

October 1, 1975-

The following sections are particularly pertinent to the insulating

fluids question:

1. List of Hazardous Materials ; sec. 172.5

a. None of the PCBs, by any of their chemical or trade

names, is on the list.

b. Any substance which qualifies for the list under

definitions given in other sections must be treated

as if on the list.

2. Dielectric and insulating fluids would be identified as Class B poisons if they were found to be toxic. (See

Sec. 173. 3U3, quoted on pp. 91, 92).

The Japanese retained askarel in their electric rail cars even after

their otherwise complete ban on PCBs; they apparently are now

experimenting with a silicone substitute.

112
3. Effect of list . Proper procedures for the transport of

hazardous materials are stated in the following sections:

Pt. 173 Shippers

"173.344 Packing far class B poisons, liquid

a) Closing and cushioning. All containers must be tightly

and securely closed. Inside containers must be

cushioned ah prescribed, or in any case when necessary

to prevent bn.mk.age. on. leakage

.

b) Outage.. Outage, fan. container ofi liquid poison fan

transportation by carriers by rail, freight, nail

express, highway, on. water mut>t be. as fallows:

1) Containers must not be. entirely filled. Su^icient

interior space must be. le{t vacant to pn.eve.nt

leakage on distortion ofi container due to the.

expansion o^ the. contents faom increase ofi temperature duning transit.

2) T/ie proper vacant space [outage.) in a tank. can. on. otheA shipping container de.pe.nd6 on the. coe.Hicie.nt

ofi expansion o£ the. liquid and the. maximum increase

ol tempexatune. to which it will be. Subjected in

transit. Outage, must be. calculated to the. total

capacity o£ the. container.

3) liquid potion mui>t not be. loaded into domes ofi tank

com .

4) In tank cars, outage, must be, calculated to percentage

o& the total capacity o£ the tank, i.e., shell and

dome capacity combined. 1 6 the dome o{\ the tank can

doe* not provide su^icient outage, then vacant

space muit be lefit in the shell, to make up the

required outage.

5) The outage far tank can, must not be lea than 1 percent.

6) Mo cargo tank or compartment thereof used far the

transportation ol any liquid poison shall be

completely jilted; su^icient space shall be le^t

vacant in every case to prevent leakage faom or

dtstortJjon 0() any such cargo tank by expansion o^

the contents due to rise in temperature in transit,

and such ^ree space [outage) shall be su^icient in

every case so that such cargo tank shall not

become entirely filled with the Liquid at 130 °F.

113
173.345 Exemption* {ok poi*onou* Liquids, Cla** B.

a) Voi*onou* Liquid*, cla** B, a* denned -cn 173.343,

except tho*e {ok which no exemption* aKe provided a*

indicated by the "No exemption" statement in J 72. 5 o{

thi* chapteK, ok a* pKovided {ok In /73.359(c), -in tightly clo*ed inside containeK* , *ecuKely cushioned

when nece**aKy to pKevent bKeakage and packed a*

{ollow*, aKe exempt {Kom *peci{ication packaging,

maKking, and labeling KequiKement* , except that

maKking name o{ contents on outbtde containeK i*

KequiAed {ok *hipment* via coKKieK by wateK. Shipment*

{ok tKan*poKtation by highway coKKieK* aKe exempt al*o

{Kom PaKt 177 o I thi* chapteK, except 17 7. SI 7, and

VaKt 397 oh thi* title.

1 ) In gla** ok eahXhenwaKe container not oveK 1 quaKt

capacity each, ok in metal containeK* ok polyethylene

bottle* not oveK 1 gallon capaciXy each, packed in

*tKong outride wooden boxe* ok boKKel*.

1) In gla** ok eoKthenwaKe containeK* not oveK 1 pint

capaciXy each, ok in metal ok polyethylene containeK^

not oveK 1 quaKt capaciXy each, packed in *tKong

outride {ibeKbooKd boxe*."

The following sections are also of some relevance:

173.^1^ Poisons material labels

Pt. 17U Rail Freight

17^-532 Loading other hazardous materials

17^.538 Rail freight; loading and storage chart of

hazardous material

17^.586 Handling hazardous materials, by carriers by

rail freight

Pt . 175 Carriers by Rail Express

Pt . 176 Rail Carriers in Baggage Service

176.702 Hazardous materials

Pt . 177 Public highway carriers

177.821 Hazardous materials forbidden or limited for

transportation

177 . 8Ul Loading; poisons

177-8U8 Loading and storage chart of hazardous materials

177.860 Accidents or leakage; poisons

Pt . 178 Shipping container specifications

Pt. 179 Specifications for Tank Cars

llU
A.U.5 Solid waste disposal

The Department of Health, Education and Welfare (HEW) has certain

regulatory control on solid waste disposal through the authority of the

Solid Waste Disposal Act (PL 89-272 and amendments; see 1+2 N.S.C., Ch. 39).

In particular, HEW is to recommend and publish guidelines and information

on solid waste recovery, collection, separation and disposal. Facilities

owned or controlled by the Federal Government must comply with these

published guidelines.

The disposal of the PCBs and of solids contaminated by askarels is

becoming increasingly difficult. Problems associated with disposal of new fluids should be anticipated at an early stage in their development;

the Federal solid waste disposal regulations form one set of criteria

by which disposability of new fluids can be judged.

115
A. 5 The Scope and Influence of Insurance and Fire Code Requirements

In addition to the various federal and state governmental regulations

which might restrict the use of fluids in electrical equipment, one must

also make sure that such equipment does not conflict with insurance and

fire code regulations. The two are closely related and therefore can he

most easily discussed together.

The National Electrical Code (NEC ) is one part (volume 6) of the

1975 National Fire Codes, issued hy the National Fire Protection

Association (NFPA). This code is developed and continually updated by a set of committees which is sponsored by NFPA and is composed of

representatives from manufacturers, users, fire insurance companies,

independent testing laboratories, and municipal and state fire safety

and regulatory agencies. As such, it is an authoritative work universally

recognized as a standard statement of safe electrical fire practice.

Although the NEC is not in itself law, it is usually adopted with

various levels of modification as the legal electrical building code.

Equipment to be legally installed within the jurisdiction of such a code

must therefore conform to NEC.

A further note on the NEC is that it has been adopted in whole by OSHA

("Occupational Safety and Health Standards," 29CFR 1910.308 - See 39FR23502,

June 27, 197 M and it therefore has a very broad legal importance in

industrial facilities. OSHA regulations are discussed more extensively

in Section A. h . 3.

As presently written, the NEC specifically refers only to mineral oils

and askarels as insulating fluids. Since no more general descriptions or definitions are given, one is led to infer that other fluids are excluded

unless specifically identified in future editions. To get a new material

listed in the NEC, the manufacturer must propose the desired inclusion

to the Electrical Coordinating Committee of NEC, along with evidence

substantiating the fire safety of the material. Before approval, however,

the committee would probably require testing and safety verification

by an independent laboratory such as Underwriters Laboratory (UL) or Factory Mutual Engineering and Research (FMER).

UL is an independent not-for-profit testing laboratory which carries

out tests on products for manufacturers and makes "listing" or "classification" judgment based on these tests:

"Listing" - the product is deemed to meet the requirements of

the NEC.

"Classification" - a material will be given a flammability classification, based on a scale between 0 (water)

and 100 (diethyl ether); the procedure is

outlined in: "Tests for Comparative Flammability

of Liquids," UL Standard No. 3^0.

116
Whereas NEC is an installation guide, local ordinances will often look

to the UL listing to verify that the product meets NEC standards and

therefore can "be installed as directed by the code.

FMER is a service arm of the Factory Mutual System of insurance

companies. It carries out testing of equipment and issues "approvals"

or "acceptances" based on these tests:

"Approval" - the product is deemed to be safe and suitable for

general applications.

"Acceptance" - a particular installation of equipment and materials

meets fire safety standards.

Such a safety test could be initiated upon request by a manufacturer or by one of the FM insurance companies.

An installation of electrical equipment must not only meet fire ordinances

but also must be covered by fire insurance. The insurance rates are generally set by the State Insurance Commission, but an insurance company

must have verification of the safety of the installation before agreeing

to write insurance coverage. The insurance inspector will therefore

generally look for UL or FM acceptance, or to some other indication that

the installation meets NEC requirements. The inspector might also base

his decisions on his company's rating of the requesting company and

possibly on the users or manufacturer's own tests.

An experimental unit with a new insulating fluid might for

instance be accepted for further field testing under this latter situation.

If one unit within a larger installation does not meet standards, temporary

approval may be granted with the understanding that the substandard unit

be upgraded to an acceptable level within a specified period.

It should be noted that utilities are often self insured and are granted exclusion from the local codes based on NEC. It is the general

practice of utilities to comply with NEC, however, and they usually work

closely with local fire protection people to make electrical installations

safe. When utility owned equipment is installed in users buildings, often

the local code or insurance requirements would necessitate that NEC

practice be followed.

USCOMM-NBS-DC 117
NBS-1 <4A 1REV. 7-73)

U .S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OK REPORT NO. NBSIR 76-105U2. Gov 't Acce ssion No.

3. Recipient's Accession No.

4. TITLK AND SUBTITLE

An Appraisal of Tests and Standards for the Evaluation

of Electrical Insulating Fluids

5. Publication Date May 14, 1976

6. Performing Organization (-ode

7. AUTHOR(S) 8. Performing Organ. Report No. NBSIR 76-105U

9. PERFORMING ORGANIZATION NAMF AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 2110506

11. Contract /Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Energy Research and Development Administration

20 Massachusetts Avenue

Washington, D.C. 20S1+5

13. Type of Report & Period Covered

Final

14. Sponsoring Agency Code

15. SUPPLK MFNTA RY NOTES

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

bibliography or literature survey, mention it here.)

Based on a literature study and interviews with representatives of the electric utility

industry, manufacturers of insulating fluids and electrical apparatus, government

regulatory agencies, organizations preparing standards and codes, trade associations

and independent testing laboratories, the status of existing standards and test

procedures for insulating fluids is reviewed. Askarel-type transformers and capacitors

are described and the characteristics of several currently-used as well as new

candidate insulating fluids are given. The possible impact of codes and government

regulations on the introduction of new fluids into use is reviewed. Needs for new or revised test procedures and standards are noted and recommendations made for research

and development efforts as well as administrative actions to facilitate the

qualifying of new insulating fluids as acceptable replacements for the askarels

currently in use in a certain class of transformers and capacitors.

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

)

Askarel; capacitors; insulating fluids; liquid insulators; polychlorinated biphenyls;

transformers

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

21. NO. OF PAGES

122

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

22. Price

$5.00

18. AVAILABILITY {T Unlimited

I For Official Distribution. Do Not Release to NTIS

I

1 Order From Sup. of Doc, U.S. Government Printing Office Washington, D.C. 20402, SD Cat. No. CH

^2 Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151 USCOMM-DC 29042-P74