NATIONAL BUREAU OF STANDARDS REPORT

4711

A SURVEY OF THE HAZARDS OF

HANDLING LIQUID OXYGEN

by

C. S, McCamy

<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
II. S. DEPARTMENT OF COMMERCE

Sinclair Weeks, Secretary NATIONAL BUREAU OF STANDARDS

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

The scope of activities of the National Bureau of Standards at its headquarters in W ashington,

D. C., and its major field laboratories in 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 by its title. A brief description of

the activities, and of the resultant reports and publications, appears on the inside back cover of

this report.

WASHINGTON, D. C.

Electricity and Electronics. Resistance and Reactance. Electron Tubes. Electrical Instru- ments. Magnetic Measurements. Process Technology. Engineering Electronics. Electronic

Instrumentation. Electrochemistry.

Optics and Metrology. Photometry and Colorimetry. Optical Instruments. Photographic

Technology Length. Engineering Metrology.

H eat and Power. Temperature Measurements. Thermodvnamics. Cryogenic Physics.

Engines and Lubrication. Engine Fuels. Atomic and Radiation Physics. Spectroscopy. Radiometry. Mass Spectrometry. Solid State Physics. Electron Physics. Atomic Physics. Nuclear Physics. Radioactivity. X-rays.

Betatron. Nucleonic Instrumentation. Radiological Equipment. AEC Radiation Instruments. Chemistry. ( )rganic Coatings. Surface Chemistry . Organic Chemistrv . Analy tical Chemistry . Inorganic Chemistry. Electrodeposition. Gas Chemistrv. Phvsical Chemistry. Thermochemistry. Spectrochemistry. Pure Substances.

Mechanics. Sound. Mechanical Instruments. Fluid Mechanics. Engineering Mechanics.

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Mineral Products. Ceramic Engineering. Porcelain and Pottery. Glass. Refractories.

Enameled Metals. Concreting Materials. Constitution and Microstructure.

Building Technology. Structural Engineering. Fire Protection. Heating and Air Conditioning. Floor, Roof, and Wall Coverings. Codes and Specifications.

Applied Mathematics. Numerical Analysis. Computation. Statistical FIngineering. Mathematical Phvsics.

Data Processing Systems. Components and Techniques. Digital Circuitry. Digital Systems.

Analogue Systems. Applications FIngineering. • Office of Basic Instrumentation • Office of Weights and Measures

BOULDER, COLORADO

Cryogenic Engineering. Cry ogenic Equipment. Cry ogenic Processes. Properties of Materials.

Gas Liquefaction.

Radio Propagation Physics. Upper Atmosphere Research. Ionospheric Research. Regular

Propagation Services.

Radio Propagation Engineering. Frequency Utilization Research. Tropospheric Propagation

Research.

Radio Standards. High Frequency Standards Branch: High Frequency Fllectrical Standards.

Radio Broadcast Service. High Frequency Impedance Standards. Microwave Standards Branch:

Extreme High Frequency and Noise. Microwave Frequency and Spectroscopy. Microwave

Circuit Standards.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

0302-10-2604 June 18, 1956 4711

A SURVEY OF THE HAZARDS OF

HANDLING LIQUID OXYGEN

by

C. S. McCamy

Interdivision work order No. 03-2651

<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The publicatiol

unless permi9si

25, D. C. Sue!

cal ly prepared

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 201 5.

e or in part, is prohibited

if Standards, Washington

a report has been specifiar report for its own use.

A SURVEY OF THE HAZARDS OF

HANDLING LIQUID OXYGEN

1 . INTRODUCT ION

Proposed increased use of liquid oxygen has prompted

the following brief review of the characteristics of this

material which determine the hazards involved in its use.

2 0 LIQUID OXYGEN

At normal atmospheric pressure (760 mm of Hg), liquid

oxygen has the following properties (1)*

boiling point

density

heat capacity

heat of vaporization

critical temperature

critical pressure

critical density

-l83o0°C

1.14- gm/cnP

0.394- cal/gm~°C

50.9 cal/gm

-118 . 8 °

C

49 ® 7 atm

0.4-30 gm/cnP

On passing from the liquid state at the boiling point

to the gaseous state at 20° C (both at a pressure of 760 mm Hg)

oxygen expands to about 858 times the initial volume. If

the material were confined to the Initial volume during this

increase in temperature, the pressure would increase to

about 2440 atmospheres, as calculated by the method of

Hirschfelder and co-workers (2) on the basis of the critical

constants given above. Consequently, the pressure rupture

of liquid oxygen containers is likely if proper venting is

not provided.

The properties of most materials are altered considerably when they are cooled from room temperature to the

temperature of liquid oxygen (3, 4, 5? 6, 7). This fact

must be borne in mind in designing equipment for storage

and handling of liquid oxygen. With few exceptions, ferrous

alloys are too brittle for use at these temperatures but the

following metals are useable at the temperature of liquid

oxygen and are listed in order of increasing brittleness

(6); pure nickel, monel metal, inconel, copper, aluminum,

18-8 low carbon stainless steel, and annealed brass.

*Numbers in parenthesis correspond to the references at the

end of this report.
.
2

The differences in thermal coefficients of expansion

of materials may give trouble where close dimensional

tolerances must be maintained*

Exposure of the flesh to materials at the temperature

of liquid oxygen for more than a. few seconds can cause

tissue damage similar to that produced by severe burns*

Protective clothing made of asbestos or degreased chrome

leather lined with relatively impermeable materials such

as polyvinyl chloride, polyethylene , or neoprene has been

recommended (5,7)

.

Violent boiling and splashing usually occurs if liquid

oxygen is poured into a wide mouthed container at or above

room temperature or if any warm object is placed in contact with the liquid*

3. LIQUID OXYGEN WITH OTHER MATERIALS

The oxygen concentration, in weight per unit of volume, of 98% pure liquid oxygen is about 4-000 times that

in dry air at 20°C and 760 mm Hg, therefore oxidation reactions, once initiated, proceed at very high rates in

the presence of the liquid. Though it might seem that

such a cold liquid would extinguish a burning match, the

actual effect of such a combination is deflagration of

nearly explosive violence (4). Finely divided charcoal

saturated with liquid oxygen may comprise an explosive

similar in many respects to 40 - percent nitroglycerine

dynamite and this combination is used as an industrial

explosive (8, 9, 10) . Other materials that have been

used in this way are wood pulp, cotton, lampblack, carbon

black, various chars, hydrocarbons, metal powders, sulfur, and coal dust (10). Mixtures of any of these materials and liquid oxygen detonate so readily that it seems

likely that an intimate mixture of liquid oxygen and almost any combustible material might detonate under certain

conditions. The following incident illustrates this point.

A leak developed in a pipe joint in a liquid oxygen line

and the liquid flowed onto an asphalt -paved surface directly below. When a workman attempting to repair the

leak struck the joint, the impact was transmitted by the

joint to the pavement below and the pavement detonated.

Among the materials considered particularly hazardous in

the presence of liquid oxygen are sulfur, hydrocarbons

,

alcohols, ethers, fuels of all kinds, oils, greases, waxes,

tars, asphalt, starches, sugars, soaps, powdered metals,

wood, cork, paper, textiles, rope, paints, and some

'plastics (3, 4, 5, 8, 9, 10, 11, 12, 13, l4). Since

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liquid oxygen is denser than water and most liquid petroleum products, it will sink in such materials and boil

violently, producing an intimate mixture® Porous materials may retain a large concentration of gaseous oxygen

long after the liquid has vaporized® It appears that the

hazard represented by a small sample of a given material

when soaked in liquid oxvgen does not differ appreciably

between samples soaked 24- hours and those immersed for

2 or 3 minutes (l4). Thermal insulating materials for

use around oxygen containers must be chosen with due regard for the conditions which would result from a leak.

Inorganic materials such as glass wool or magnesium carbonate may be used if they contain no flammable additives.

Ordinarily, to avoid the flammability hazard of paint,

pipe lines carrying liquid oxygen are not painted.

4. GASEOUS OXYGEN

In the gaseous state, at 0°C and 760 mm Hg, oxygen

has a density of 1.429 g/£ # Oxygen constitutes about 21$

by volume or about 23$ by weight of the earth's normal

atmosphere- at sea level. Wherever liquid oxygen is handled or stored, the continual release of gas is required

to maintain normal pressure. Besides the precautions

necessary to prevent the pressure rupture of containers,

it is necessary to provide sufficient ventilation to prevent excessive concentration of gaseous oxygen in confined spaces. In general, combustible materials burn

violently in an atmosphere of oxygen. Glowing or smoldering materials, including metals, burst into flame or

brilliant candescence when introduced into oxygen. Mixtures of flammable vapors or dusts with gaseous oxygen

may be explosive (10).

Although the human body can tolerate rather wide

variations in the oxygen concentration In the atmosphere,

prolonged exposure to an atmosphere containing 80 percent or more of oxygen can induce a pneumonia (15)

5. IGNITION

The prevention of ignition is a matter of greatest

importance wherever liquid oxygen is handled.
.

»*
Friction in itself may be regarded as a possible

source of ignition where oxygen is in contact with combustibles (10). An incident is reported in which liquid

oxygen had been spilled on a gravelled surface and detonation occurred, presumably in asphalt beneath the gravel,

when a man walked across the gravelled surface.

A large number of materials may be placed in liquid

oxygen for a few minutes and detonated by impact (lh).

On the basis of two experiments with a vegetable base

fiberboard in an adiabatic furnace at the National Bureau

of Standards, it appears that the rate of self -heating

was not greatly affected by increased oxygen concentration

in the atmosphere at temperatures below 200° C but the

change in rate with respect to temperature was somewhat

increased. Above 200° C the rate of self heating was considerably higher in the enriched atmosphere than it was

in air. Materials containing unsaturated hydrocarbons

should be considered particularly hazardous in this respect. It appears that heaters and steam lines which

would not otherwise be considered potentially hazardous

heat sources might become so in the presence of an oxygenrich atmosphere.

The lower dilution limit of flammability of combustible gases is generally very little different in

oxygen than in air ( 16 )

Tests have shown that the liquid -oxygen explosives

in use in industry were rather insensitive to ordinary

electrostatic discharges and that the discharge energy

required to constitute a hazard was considerably greater

than would ordinarily be encountered, except where

lightning or electric power line sparking are involved

( 10 ).
•

s

<
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REFERENCES

1, Handbook of Chemistry and Physics, Chemical Rubber

Publishing Co., Cleveland, Ohio (1954-).

2. Hirschfelder , J. 0®, et al, A Generalized Equation

of State for Both Gases and Liquids® University of

Wisconsin Naval Research Laboratory, Tech® Rept.

Wis - 00R-12 , March 22, 1956®

3® Hardin, W® L®, The Rise and Development of the

Liquefaction of Gases® The Macmillan Co®, N® Y. (1.899)®

4* Claude, G® , Air Liquide, Oxygene, Azote, H® Dunod

et E® Pinat, Paris (1909)®

5® Liquid Oxygen, Data Sheet D-283, National Safety

Council, Chicago (1955)®

6. Kanarek, I® A® , Properties and Handling and Storage

Characteristics of Ethyl Alcohol and Liquid Oxygen,

North American Aviation, Inc®, Aerophysics Laboratory, Report AL-128®

7 * Liquid and Gaseous Oxygen, Safety Information

Bulletin 2-53? Redstone Arsenal, Huntsville, Alabama,

May 5, 1953®

8® Perrott, G. S®, and Tolch, N® A®, Liquid-oxygen

Explosives, Bureau of Mines Bulletin 3*+9 (1932).

9® Denues, A. R® T®, Fire-retardant Treatments of Liquidoxygen Explosives, Bureau of Mines Bulletin 4-29 (194-0).

10. Tournay, W® E», Bower, F® M® , and Brown, F® W.

,

Safety and Performance Characteristics of Liquidoxygen Explosives. Bureau of Mines Bulletin 4-72

(194-9)®

11. Sloane, T® 0®, Liquid Air and the Liquefaction of

Gases, N® W. Henley, New York (1920).

12. Rice, G. S®, Development of Liquid-oxygen Explosives

During the War, Bureau of Mines TP 24-3 (1920).
.
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13 „ Howell, S.-P., Paul, J. W,, and Sherrick, J. L.,

Progress of Investigations on Liquid-oxygen Explosives, Bureau of Mines Technical Paper 294 (1923).

14. Carter, T. J. , A Procedure for Testing Materials in

Liquid Oxygen, Technical Note 1-30? Engineering

Materials Section, Redstone Arsenal, Huntsville,

Alabama, March 24, 1956.

15. Karsner, H. T«, The Pathological Effects of Atmospheres Rich in Oxygen, J. Exper. Med* 23:149 (1916).

16. Coward, H. F. , and Jones, G, W., Limits of Flammability of Gases and Vapors, Bureau of Mines Bulletin

279 (1939)o
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THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

The functions of the National Bureau of Standards are set forth in the Act of Congress, March

3, 1901, as amended by Congress in Public Law 619, 1950. These include the development and

maintenance of the national standards of measurement and the provision of means and methods

for making measurements consistent with these standards; the determination of physical constants and properties of materials; the development of methods and instruments for testing materials,

devices, and structures; advisory services to Government Agencies on scientific and technical

problems; invention and development of devices to serve special needs of the Government; and the

development of standard practices, codes, and specifications. The work includes basic and applied

research, development, engineering, instrumentation, testing, evaluation, calibration services, and

various consultation and information services. A major portion of the Bureau’s work is performed

for other Government Agencies, particularly the Department of Defense and the Atomic Energy

Commission. The scope of activities is suggested by the listing of divisions and sections on the

inside of the front cover.

Reports and Publications

The results of the Bureau’s work take the form of either actual equipment and devices or published papers and reports. Reports are issued to the sponsoring agency of a particular project or program. Published papers appear either in the Bureau’s own series of publications or in the

journals of professional and scientific societies. The Bureau itself publishes three monthly periodicals, available from the Government Printing Office: The Journal of Research, which presents

complete papers reporting technical investigations; the Technical News Bulletin, which presents

summary and preliminary reports on work in progress; and Basic Radio Propagation Predictions,

which provides data for determining the best frequencies to use for radio communications throughout

the world. There are also five series of nonperiodical publications: The Applied Mathematics

Series, Circulars, Handbooks, Building Materials and Structures Reports, and Miscellaneous

Publications.

Information on the Bureau’s publications can be found in NBS Circular 460, Publications of

the National Bureau of Standards ($1.25) and its Supplement ($0.75), available from the Superintendent of Documents, Government Printing Office. Inquiries regarding the Bureau’s reports and

publications should be addressed to the Office of Scientific Publications, National Bureau of

Standards, Washington 25, D. C.