II






DEPARTMENT OF COMMERCE miscellaneous publication of the

bureau OF standards BUREAU OF STANDARDS

George K. Burgess, Director No. 7

1

(Issued November 21, 1925)

Price per copy, 10 cents COMPRESSIBILITIES OF GASES 1

Graphs for Computing the Compressibilities of Air, Argon, Helium, Hydrogen, Methane, Neon, Nitrogen, and Oxygen,

and for Computing the Volumes Delivered from Cylinders Containing Argon, Helium, Hydrogen, Nitrogen, and

Oxygen at High Pressures

The following graphs from Circular No. 279, The Relations Between the Temperatures, Pressures, and Densities of Gases, have been reproduced on a larger scale in order that they may be used for obtaining numerical values. The

graphs showing the factors for computing the compressibilities of gases up to pressures of 200 atmospheres contain

nearly all of the published data covering this range of temperature and pressure, and the curves are drawn according

to what appear to be the most probable values. The graphs

indicating the volume of gas delivered from a cylinder containing the gas at high pressure have been computed for cylinders having a volume of 1.528 cubic feet, which is the volume of the so-called "200-foot" cylinder. For a cylinder

of any other capacity the volume delivered would be proportional to the volume of the cylinder. In other words,

the figure obtained from the graph should be multiplied by —^—, where V is the volume (in cubic feet) of the cylinder

1.528

in question.

CONTENTS

Graphs 1 to 8. Values of the factor —jr~ pv plotted against the

pressure, where T is the absolute temperature (°C), p the

pressure in atmospheres, and v the volume, which is unity at

0° C. and 1 atmosphere of pressure Graph 1. Air Graph 2. Argon

Graph 3. Helium

Graph 4. Hydrogen

Graph 5. Methane

Graph 6. Neon

Graph 7. Nitrogen 8 Graph 8. Oxygen 9 Graphs 9 to 13. Volume (measured at 68° F. and 1 atmosphere)

of gas delivered from a cylinder containing the gas at high

pressure 10-14 Graph 9. Argon 10 Graph 10. Helium 11 Graph 11. Hydrogen 12 Graph 12. Nitrogen 13 Graph 13. Oxygen 14

i Prepared by S. F. Pickering, Associate Chemist. 60339°—2Jf
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Fig. 9.

Volume of argon (measured at 1 atmosphere and 6S° F.) delivered from a cylinder u hnse volume is 1.528 euhi







VDLUMUE OF DXYGEin

of oxygen (measured at 1 atmosphere and SS°

230 240 25D 260 270 2BD 290 30D 3 cuvcnco [cubic Fllt]

P.) delivered from a cylin>lcr whose volume is 1.533 cubic Jeet
10 CENTS 1'Ell (