Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) gd on October 9, 2015.

NATIONAL BUREAU OF STANDARDS REPORT

6807

FUEL POTENTIAL TEST METHOD

by

J. J. Loftus, D. Gross

and

A. F. Robertson

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANOAROS
THE NATIONAL BUREAU OF STANDARDS

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NATIONAL BUREAU OF STANDARDS REPORT

NIBS PROJECT NBS REPORT

1002 - 12-10120 April 6, i960 6807

FUEL POTENTIAL TEST METHOD

by. .

J. J. Loftus, D. Gross

and

A. F. Robertson

IMPORTANT NOTICE

NATIONAL BUREAU OF ' *'• progress accounting documents

the Office of the Director, however, by the Governme

to reproduce additional cc

the Office of the Director, Standards and Technoloev fNISTt ‘ permission is not needed,

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U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

FUEL POTENTIAL TEST METHOD

by

J. J, Loftus, D. Gross

and

A. F, Robertson

ABSTRACT

Modifications have been made to a method,

currently a standard of the French government, for

assessment of the combustible characteristics of

building materials. This method makes use of bomb

combustion calorimetric techniques in which the

combustion of small quantities of combustible in

an otherwise inert material is insured by use of

a combustion accelerator which is added prior to

test. By performing calorimetric measurements

both before and after exposure to a "standardized

fire" (muffle at 750®C with controlled air supply)

the difference may be considered as the fuel

potential. A series of measurements of this property have been made for a variety of building

materials and the results reported. A discussion

is included on the precision of the test method.

1, INTRODUCTION

The extent to which building construction materials

burn and add fuel to fires Involving buildings is considered

of importance by code officials. Because of this, they have

Incorporated in their codes various requirements with respect

to the "noncombustible" properties of materials to be used in

different portions or types of buildings. However, the test

methods which have most frequently been proposed or used for

measuring this property of materials (1, 2, 3? 5) have

been qualitative in nature. The results obtained with their

use have often been a function of the flammable, smouldering,

and heat release characteristics of the material tested with

emphasis varying, depending on the characteristics of the

material tested. As a result, there has been considerable uncertainty as to exactly what material property was being measured.

2

Because of this situation, it has been difficult to select

a method of test which could be considered satisfactory

for standardization on a national level.

Calorimetric test methods of various types have been

considered for measurement of the heat release of materials

on exposure to fires. The Factory Mutual Association (6)

has recently described a calorimetric furnace by means of

which measurements are made of heat release rates for fourfoot square test samples of constructions. This is surely a useful and pertinent test method for this purpose. Bomb

combustion calorimetric measurements have also been considered,

but these have, in the past, been rejected because the cojnbustion characteristics in an oxygen pressurized bomb are much

different from those effective during building fires. The

former results in complete oxidation of many metals which are

relatively unaffected by building fires. However, the French

government (7) has recently standardized a test method making

use of a differential bomb calorimetric method.

The present paper describes the further development of

a similar test procedure and presents the results of measurements of the "fuel potential" of a wide variety of building

materials

.

2. TEST METHOD

The method may, perhaps, be most briefly described by

reference to Figure 1, Two samples are removed from the

material to be tested. One of these is ground, pelletized

and then burned in a high pressure oxygen atmosphere as

described in reference (8)

,

yielding a measure of the higher

heating value of the material. In the case of materials of

low fuel potential, a combustion accelerator is added prior to

pelletizing the specimen for test in the combustion calorimeter.

A second specimen of approximately 1/2- x 3/^- x 3-in. size

is exposed to an oxidizing atmosphere for two hours at a temperature of 750 C (1382 F) . The weight loss of this specimen

is noted and the residue remaining is ground or pulverized.

A portion of this resulting powder corresponding to a known

weight of the original material is mixed with a combustion

accelerator, pelletized, and burned in the combustion calorimeter as previously described. After correcting for the heat

produced by the combustion accelerator, the difference in

heating values of the two specimens is reported as the fuel
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potential. It is evident from this diagram that the fuel

potential measurement is not a direct one but is obtained

by difference measurements. It is indicative of the quantity

of heat released during exposure of the specimen to the heat

of the muffle furnace.

3. PROCEDURAL DETAILS

The detailed techniques which have been developed for

standardizatioh of the test method are described in the

appendix. A brief discussion will be presented in this

section of the reasons for selection of these details.

3.1 MUFFLE CONDITIONS

The conditions under which the specimen is heated in

the muffle furnace have an influence on the measurements

made. The temperature of 750*C (1382°F) was selected

because of its long use in this and other countries for exposure of the specimen in combustibility test methods. The

temperature is lower than the maximum which would be expected

in fires of even brief duration, It is, J^owever, high

enough to permit the ignition of magnesium. Aluminum, on

the other hand, will melt and not become inflamed. These

results are believed typical of actual fire experience. The

specimen size, air feed rate, and duration of high temperature exposure were selected to insure complete combustion,

if possible, -of fuel in cinder concrete specimens and oxidation of carbon resulting from pyrolysis of wooden specimens.

3.2 COMBUSTION ACCELERATOR

The use of a fuel additive to the specimen prior to

burning in the bomb is intended to insure that combustion

of fuel content is complete even when present in small

quantities. The additive used was benzoic acid of known

heating value (9)

•

Determination of the quantity of acid

required was made by measurement of the percentage of fuel

consumed when mixtures of benzoic acid and aluminum oxide

were fired in the combustion calorimeter. The results are

shown in Figure 2, It is evident that when the quantity of

acid in the sample is less than about 30 per cent, combustion

may be incomplete and reliable results should not be expected.

Because of this, materials suspected or known to have low

fuel potential are only burned after addition of about

50 per cent benzoic acid. Such large acid additions are not

required with materials such as woods and some plastics involving high combustible content.

3-3 SPECIMEN PREPARATION

The material to be tested was pulverized to permit incorporation of the fuel additive prior to pelletizing. This

was accomplished by means of a hand mill for all but the

hardest materials. A mortar and pestle as well as files or

rasps have been found useful for some otherwise difficult

materials

.

RESULTS

As a means for demonstrating the sensitivity and usefulness of this method of measuring the heat release potential

of building materials, a series of tests were performed with

the use of plaster of Paris specimens to which various additions of charcoal had been made. The mixtures of dry plaster

and charcoal were made in the dry state. These were then

hydrated and the hardened mixtures used for fuel potential

determinations. From analysis of the plaster the hemihydrate

content was determined as equal to 9^ per cent. On the

basis of this and the assumption of high accuracy in the

preparation of the specimens, computed values of the fuel

potential were prepared and are presented in Table Table I.

Comparison of these with the experimentally determined valuep

of fuel potential show' very close agreement. It is therefore

evident that when benzoic acid was used in weight concentrations of 50 per cent complete combustion was achieved in the

calorimeter even for mixtures showing very low fuel potential.

Table II presents the results of fuel potential measurements made on a variety of building materials. The materials

listed here were selected largely to provide an indication

of the manner in which the test method would classify

materials. It should not be assumed that all materials which

conform to the brief descriptions given will show the same

fuel potential. Fuel potential is tabulated here as heat

release per unit weight and unit volume, or unit area for

Impermeable materials subject only to surface reactions. For

discussion purposes. Table II also presents the flame spread

index of those materials which have been tested by the radiant

panel method (10)

,

Examination of this table shows that, for the materials

studied, fuel potential varies from about -300 BTU/lb to

17,000 BTU/lb. Materials such as brick, asbestos-cement

board, some concretes and the gypsum plasters showed very low

fuel potentials while cork, polystyrene, and asphalt impregnated building paper showed very high values . Expanded metal

lath, gypsum lath and wall board exhibited quite similar fuel

potentials which were low but not zero.
V
- 5

Some materials such as woods and plastics exhibited so

low a residue after muffling that it seemed unnecessary to

run a second calorimeter experiment. In cases such as

these, the fuel potential reported was considered equivalent

to the higher heating value of the material.

The high fuel potential of woods was not noticeably

affected by impregnation with fire retardant treatments

for which studies were made. The apparent reduction of

fuel potential on a weight basis may be largely attributed

to an increase in density resulting from the treatment process.

Fire endurance tests of laminated panels (11) have shown only

minor increase in the time to burn through treated panels as

compared with that for untreated specimens. In one pair of

panels of 2-1/2 in. overall thickness built up with tongue

and gro oved core and 3/16 in. veneer crossbanding, the times

to flamethrough were 72.1 and 69.2 minutes for retardant

treated and untreated specimens, respectively. Other studies

on built-up wood partitions of ^ and 6- in. thicknesses have

shown up to 33 per cent improvement in fire endurance resulting from complete impregnation.

While one plastic, polystyrene, showed the highest fuel

potential measured during the study, two others showed fuel

potentials similar to that of woods when compared on a weight basis.

The so-called noncombustible Insulation materials tested

exhibited fuel potentials which, while low, were not negligible.

That for glass fiber material resulted from the phenolic

binder used for bonding the material. In the case of the rock

wool insulation, the specimens tested included the paper

package enclosure.

The concretes in general exhibited low fuel potentials.

Those for expanded slag, shale, and the sillcious aggregates

were nearly zero. The fuel potential for the concrete incorporating a calcareous aggregate was found to be slightly

negative. This latter effect would be expected as a result

of the heat absorption required for calcination of the

aggregate. The negative value shown seems to imply that some

calcination does take place during the brief high temperature

exposure within the bomb. The cinder aggregate concrete

specimens tested exhibited significantly positive values of

fuel potential. The effect of the unburned coah contributing

to the severity of building fires has been noted during burnout tests at the National Bureau of Standards. Studies by

6

Menzel in which he performed fire endurance tests on walls

of concrete masonry units have also shown the effect of

varying addition of solid fuels to cinder aggregates in

reducing the gas requirement for performance of the fire

endurance test (13). This latter effect would, of course,

be indicative of heat release by the specimen since control of the gas feed is such as to maintain a fixed time

temperature exposure relationship.

The plaster specimens tested showed low or negative

fuel potentials. The gypsum wallboard specimens tested

showed higher fuel potentials than were observed for the

plasters. This resulted from combustion of the paper facing

and any finish which was applied.

The laths studied Included both gypsum board and expanded

metal lath. The fuel potential of the gypsum product was quite

similar to that of gypsum wall boards of the same thickness.

That for the metal lath was largely due to the paint which

had been applied and the surface oxidation of the metal.

Of the metals tested, only steel, copper, and brass did

not melt at the muffle temperature. Magnesium burned and

was completely oxidized; its fuel potential was considered

equivalent to the heat of combustion. The fuel potential,

values reported for the other materials which melted were

computed on the basis of the weight change during muffling

and the assumption that an oxidation reaction was involved.

For those metals which did not melt in the muffle, it seemed

proper to report fuel potential on the basis of the exposed

surface of the material. In making these measurements, thin

sheets of the metals involved were exposed to the muffle

conditions. With the single exception of magnesium, the

oxidation of the metals studied was not severe and fuel potentials should be considered low but not zero,

h.l Precision and Accuracy of Method

Standard combustion calorimetric techniques would be expected to yield highly precise measurements of the heating

values of fuels. Perhaps precisions as great as + 30 BTU/lb

would be normal for good quality work with standard laboratory

equipment and specimen weights on the order of one gram.

Such precisions cannot be expected with the test procedure

described here since not only are differences of two measurements reported, but the method involves mixing combustion

accelerators with the specimen as well as the additional

complexity of accounting for weight changes resulting from the
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specimen exposure within the muffle furnace. As a result,

errors of somewhat greater magnitude are to be expected.

The data presented in Table I provide some indication

of the magnitude of errors in both precision and accuracy.

Here, the apparent error in measurement is reported as the

deviation of the experimentally determined value from the

computed value of fuel potential. These errors, while in

some instances larger than appears desirable, appear to be

of a random nature.

Another method of exploring the precision of the method

is to compare the difference between duplicate measurements

of the individual calorimetric determinations with the

heating value observed during the measurement. This was

done for the data on the unmuffled specimens. It was found

that the differences between duplicates were essentially

independent of the fuel potential of the material being

tested and assumed an average value of 100 BTU/lb. Similar

treatment of the muffled specimens yielded an average of

3^ BTU/lb. These averages correspond to standard deviations

of 89 and 30 BTU/lb for individual unmuffled specimens or

about 63 and 21 BTU/lb for the average of two determinata,Dns

.

The precision of the fuel potential measurement would then

be the root of the sum of the squares of these two or about 9^

for one and 66 BTU/lb for the average of two determinations.

5 . DISCUSSION

Experience with the test procedure described Indicates

that it is applicable to a wide variety of building materials.

It appears to provide a useful tool for measuring the fuel

potential or that portion cf the heat of combustion which

will be liberated during prolonged exposure in an oxidizing

atmosphere at 750®C. The method has the advantage over previously used combustibility test methods of providing a quantitative measurement of the heat release during such

exposure

«

The only remotely similar technique known to be used in

this country at the present time is the FM Construction

Materials Calorimeter (6)

,

This method requires a large

specimen A x A ft in size and representative in thickness

and construction of the building structure to be simulated.

- 8 -

It provides a useful means for measuring the rate at which

the structure will liberate heat during fire exposure on

one surface. Also, by integration techniques, it can provide an indication of the heat release for fires of various

durations. However, because of the problems associated

with heat losses through the specimen, it seems doubtful

whether this method is suitable for total heat release

measurements. Heat losses through the specimen may present

a considerable problem for proper analysis of results. It

seems likely that for the case of very thin panels of translucent combustible materials, such as plastics, such losses

could very well exceed the heat of combustion,.

Probably the two methods should be considered as complimentary, one providing a laboratory method for measurement of total heat release with small specimens while the

other makes possible the measurement of the rate at which

heat generation by the large specimen exceeds the losses

through it. Certainly, studies performed with the use of

this large-scale test method would prove useful in showing

the appropriate manner to be used in application of the

laboratory test results.

During the studies performed, only one material,

graphite, was observed to fail to burn in the bomb, but

was consumed in the muffle. The problems of calorimetric

measurements with graphite have been reported in the literature (l4). Accordingly, when the presence of graphite is

suspected, the residue from the bomb should be examined,

and, if necessary, muffled to determine the amount of unconsumed carbon by weight loss measurements. Charcoal which

comprises carbon with chemically bonded hydrogen was not

subject to this difficulty and was readily burned in the

bomb

.

Some brief mention should be made of the fact that the

calorimetric methods used, result in the condensation of

water formed as a product of combustion. Because of this,

the heats reported are representative of the higher heating

value of the materials and, as such. Include the heat liberated on condensation of the water vapor. It appears beyond

the scope of this paper to present a complete discussion of

this aspect of the procedure. However, the data in Table III

are presented for the purpose of estimating the raagniture of

this effect. The heat of vaporization data presented here

was computed on the assumption of steam table data for change

of heat content of water on heating from 20‘*C to 750“* C at

atmospheric temperature. It was further assumed that the

- 9 -

combined and free water initially present in the material

remained in the form of water. Actually this latter

assumption appears likely to be proper for all materials

listed with the single exception of gypsufn* The negative

fuel potential listed in Table II for gypsum appears to

result from at least partial chemical reduction of the

water present. Because of this, the measured fuel potential

of gypsum shows very close agreement with the estimate of

the correction which would apply to the material. For the

other materials listed, the applicable correction is but

a small fraction of the value of the fuel potential.

Table III is presented here only for discussion purposes.

It appears inadvisable to attempt correction of experimental

fuel potential data for the purpose of compensation of these

heat of vaporization effects.

6. CONCLUSIONS

The following conclusions seem justified on the basis

of the work reported:

1. Techniques have been developed for measurement

of the fuel potential of materials during exposure to an

oxidizing atmosphere at 750®C.

2. The test methods developed have been used for

measurement of the fuel potential of a variety of building

materials

,

3. For gypsum, the chemical reduction reactions which

occur during combustion in the bomb result in a fuel potential for this material which appears to partially account

for endothermic losses during fire exposure. This effect

was not observed for other materials in which fuel potential

values measured should be considered indicative of the

combined heat of combustion and heat of condensation of water

vapor

.
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.

REFERENCES

1. National Board of Fire Underwriters. "National Building

Code" 1955 Edition, I 7 -I 8 . National Board of Fire

Underwriters, 85 John Street, New York 38 , N. Y.

2. National Fire Protection Association Committee on Building

Construction. "Standard Types of Building ConstructionDefinition of Noncombustibility." NFPA No. 22C-1959.

National Fire Codes, Vol III.

3 . American Society for Testing Materials Committee E-5-

"Tentative Method of Test for Determining Noncombustibility of Elementary Materials" ASTM E-136-59T.

ASTM Standards 1959

»

A. British Standards Institution "Fire Tests on Building

Materials and Structures - Combustibility Test of

Materials" British Standard ^76:53? 6-7*

5 . N. P. Setchkin and S. H. Ingberg. "Test Criterion for an

Incombustible Material" Proc ASTM V 45, 866-877 (1945)

6. N. J. Thompson and E. W. Cousins. "The FM Construction

Materials Calorimeter," Quarterly of the National

Fire Protection Association, V 52, No. 3, Jan 1959,

186 - 192 .

7 . Anon. "Securite Contre L'Incendle" Classification des

matl'riaux et e^lements de construction. Journal Officiel

de la Republlque Francaise. No. 59-23-8 (Janvier 1959)

8. American Society for Testing Materials Designation D271-48

"Laboratory Sampling and Analysis of Coal and Coke."

ASTM Standards I 96C.

9 . Benzoic Acid Calorimetric Standard. National Bureau of

Standards Sample 39H. October 6, 1959-

1C, General Services Administration. Interim Federal Standard

"Flame Spread Properties of Materials" FS CCI36

July 31 , 1959 .

11. C. R, Brown. "Fire Tests of Treated and Untreated Wood

Partitions." J Res NBS V 20 217-239 Feb 1938.
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•

. X.

. :k

b if''

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•- r
11

12. N. D. Mitchell. "Fire Tests of Treated and Untreated

Wood Walls" Proc . 43rd Annual Meeting of the American

Wood Preservers Institute. V 43 (1947)

13 . C. A. Menzel. "Tests of the Fire Resistance and Strength

of Walls of Concrete Masonry Units." Portland Cement

Association. January 1934.

14. R. S. Jessup. "Heats of Combustion of Diamond and of

Graphite." J Res. NBS V 21. 477 (1938)

12

APPENDIX

Experimental Procedure

The following paragraphs describe the procedures used in

performing the measurements reported in this paper. These

procedures are suitable for non-metallic or mixtures of metallic and non-metallic materials in which the metallic component

is not a major constituent.*

Magnesium was the only metallic material found to burn

when exposed to the conditions of the muffle furnace. The

other metals were subject to surface oxidation, and thus,

fuel potential data were computed from weight changes and

heat of formation data of the oxide on the assumption of no

volatile loss of the metallic component.

*Caution should be observed when performing bomb

calorimetric measurements containing significant

proportions of metallic materials. Apart from

the high reaction temperatures which may occur

with the resulting possible Involvement of portions

of the bomb, another difficulty involves the possibility of electrical shorts in the ignition system.

Specimen ; Two air-dry test samples are required for each determination, both must be truly representative of the material or

assembly involved. Treatment of these two samples will be

described separately:

A . Specimen for Direct Bomb Test

1.

All or a truly representative portion of this

specimen was pulverized into a form suitable to pass a 60-mesh

screen

.

2. A one-gram pellet of a representative sample of

the powder formed in step 1 was prepared.

3. This pellet Vas used as the test specimen

following the procedures for determination of calorific value

recommended in reference (8).

4 . The fuel capsule was examined after firing the

bomb. If the pellet burned completely, leaving no significant

amount of ash, the calorific value computed on an air-dry

basis was recorded and steps 4 through 7 were omitted.
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- 13 -

5. If the pellet did not burn or a significant

amount of ash remained after step 4, a second one-gram

pellet was prepared with an intimate mixture of the

powdered sample and a standard sample of benzoic acid in

equal weight proportions.

6. The pellet prepared under step 5 was used as

the test specimen following the same procedures as for

item 3 above.

7. A correction for the heat content of the

benzoic acid present in the pellet was applied to the

measured heat released by the specimen. The calorific value

was then computed on an air-dry basis.

B . Specimen for Muffle and Bomb Test

1. A truly representative air-dry specimen of the

material, or assembly, was cut in the form of a rectangular

prism having dimensions of 1/2 x 3/4 x 3 in. In the case of

sheet materials, folded or laminated assemblies were formed

to these dimensions.

2. The weighed specimen was supported in a fused

silica container of 1-1/4 in. inside diameter by 4-ln.

length. The specimen and container cap and a tube for

supply of air to the bottom of the container were then fitted.

The assembly was then placed in an electric muffle furnace

operated at 750^0. Air was supplied at a rate of 0.1 cu ft/min.

measured under laboratory conditions, to assist in oxidation

of the specimen. In cases where ignition occurred immediately,

application of air was delayed until initial flaming had

stopped. Heating of the specimen was continued for two hours.

3. The silica container with specimen was removed

and placed in a desiccator to cool. Measurements were then

made to determine the weight loss of the specimen.

4. If the residue from the muffle procedure was

less than ten per cent of the initial specimen weight, the

following steps were omitted and the calorific value determined

under paragraph A, Section 3 or 7 was reported as the fuel

potential of the material.
mm
14

5. If the residue from step 4 was in excess of

ten per cent of the specimen weight, this residue was pulverized and the same procedures used as for steps 5 through

7, under paragraph A. The resulting calorific value was

reported as that of the residue.

6. The calorific value of the residue was multiplied by the ratio of the residue weight to the original

specimen weight.

7. The fuel potential of the material was then

determined by subtracting the calorific value resulting from

step 6 from that obtained under paragraph A, Section 7* The

resulting difference in calorific values represented the

heat released rurlng specimen exposure in the muffle and was

reported as the fuel potential.

USCOMM-NBS-DC

Table I

Comparison of Computed* and Measured** Fuel Potential

of

Mixtures of Plaster and Charcoal

Charcoal in mixture Fuel Potential Apparent

error in

Measurement

Dry

Plaster

Basis

Hydrated

Plaster

Basis

Computed Measured

% BTU/lb BTU/lb BTU/lb

0 0 -288 -288 -

1 0.852 -170 -172 -2

2 1.705 -47 -29 + 18

5 4.28 +318 +357 +39

10 8 . 6^- 833 -101

30 26.7 3 , 5-89 3,320 -169

50 45.^ 6,142 6 ,l40 -2

100 100.0 13,873 13,873 -

*Computatlons were made on the assumption of exact specimen

preparation and fuel potentials for charcoal and hydrated

plaster of 13,873 BTU/lb and -288 BTU/lb respectively.

*Measured valves are averages of two determinations with

combustion acceleration in concentrations of 50 per cent.

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Table III

Estimated Corrections to Fuel Potential Measurements

for

Heat of Vaporization Effect^t

Water present or

resulting from Fuel Potential

Material combustion Correction

% by weight BTU/lb

Douglas Fir 66 -1130

Styrene 69 -1180

Vinyl chloride 82 -I4l0

Gypsum plaster (neat)

. i21 - 360

Concrete 6 - 102

Based on enthalpy difference at atmospheric pressure

between that of water at 20 ®C and steam at 750®C.

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U.S. DEPARTMENT OF COMMERCE

Frederick H. Mueller, Secretary NATIONAL BUREAU OF STANDARDS

A. V. Astih, Director THE NATIONAL BUREAU OF STANDARDS

Tlie scope of activities of the National Burenii of Stamlanis at its major laboratories in Washington, D.C., and

Boulder, Colorado, is suggested in the following listing of the divisions and sections engaged in technical work.

In general, each section carries out specialized research, development, and engineering in the field indicated hv

its title. A brief description of the activities, and of the resultant publications, appears on the inside of the front cover. WASHINGTON, D.C.

Electricity and Electronics. Resistance and Reactance. Electron Devices. Electrical Instruments. Magnetic Measurements. Dielectrics. Engineering Electronics. Electronic Instrumentation. Electrochemistry.

Optics and Metrology. Photometry and Colorimetry. Photographic Technology. l,ength. Engineering

Metrology.

Heat. Temperature Physics. Thermodynamics. Cryogenic Physics. Rheology. Molecular Kinetics. Free

Radicals Research. Atomic and Radiation Physics. Spectroscopy. Radiometry. Mass Spectrometrv. Solid Stale Physics. Electron Physics. Atomic Physics. Neutron Physics. Radiation Theory. Radioactivity'. X-rays. High

Energy Radiation. Nucleonic Instrumentation. Radiological Equipment.

Chemistry. Organic Coatings. Surface Chemistry. Organic Chemistry. Analytical Chetnistry. Inorganic

Chemistry. Electrodeposition. Molecular Structure and Properties of Gases. Physical Chemistry. Thermochemistry. Spectrochemistry. Pure Substances.

Mechanics, Sound. Mechanical Instruments. Fluid Mechanics, i'mgineering Mechanics. Mass and Scale. Capacity, Density, and Fluid Meters. Combustion Controls.

Organic and Fibrous Materials. Rubber. Textiles. Paper. Leather. Testing and Specifications. Poly- mer Structure. Plastics. Dental Research. MetaUurgy. Thermal Metallurgy. Chemical Metallurgy. Mechanical Metallurgy. Corrosion. Meta!

. Physics.

Mineral Products. Engineering Ceramics. Glass. Refractories. Enameled Metals. Conslilnlion and Microstructure.

Building Technology. Structural Engineering. Fire Protection. Air Conditioning, Heating, and Refrigeration. Floor, Roof, and Wall Coverings. Codes and Safely Standards. Heat Transfer. Concreting Materials.

Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Mathematical Physios.

Data Processing Systems. SEAC Fmgineering Group. Components and Techniques. Digital Circuitry.

Digital Systems. Analog Systems. Application Engineering.

• Office of Basic Instrumentation. » Office of Weights and Measures. BOULDER, COLORADO

Cryogenic Engineering. Cryogenic Equipment. Cryogenic Processes. Properties of Materials. Gas Liquefaction. Radio Propagation Physics. Upper Atmosphere Research. Ionospheric Research. Regular Propagation

Services. Sun-Earth Relationships. VII F Research. Radio Warning Services. Airglow and Aurora. Radio

Astronomy and Arctic Propagation.

Radio Propagation Engineering. Data Reduction Instrumentation. Modulation Research. Radio Noise. Tropospheric Measurements. Tropospheric Analysis. Propagation Obstacles I'mginecring. Kadio-Mctcorology. Lower Atmosphere Physics.

Radio Standards. High Frequency Electrical Standards. Radio Broadcast Service. High Frequency Impedance .Standards. Electronic Calibration Center. Microwave Physics. Microwave? Circuit Standards.

Ratlin Commujiicution and Systems. Low FrcHpicncy and Very Low Freipicncy Research. High Fre- quency anrl Very High Frequency Research. Ultra High I'Visqucncy and .Super High Frequency Research. Modulation Re.scarch. Antenna Bcsearch. Navigation Systems. Systems Analysis. Field Operations.