The weight of one cubic foot of air will obviously be the reciprocal of its volume, that is, 1/v pounds.
VOLUME AND WEIGHT OF AIR AT ATMOSPHERIC PRESSURE AT VARIOUS TEMPERATURES _______________________________________ | | | | | | Volume | | | Temperature | One Pound | Weight One | | Degrees | in | Cubic Foot | | Fahrenheit | Cubic Feet | in Pounds | |_____________|____________|____________| | | | | | 32 | 12.390 | .080710 | | 50 | 12.843 | .077863 | | 55 | 12.969 | .077107 | | 60 | 13.095 | .076365 | | 65 | 13.221 | .075637 | | 70 | 13.347 | .074923 | | 75 | 13.473 | .074223 | | 80 | 13.599 | .073535 | | 85 | 13.725 | .072860 | | 90 | 13.851 | .072197 | | 95 | 13.977 | .071546 | | 100 | 14.103 | .070907 | | 110 | 14.355 | .069662 | | 120 | 14.607 | .068460 | | 130 | 14.859 | .067299 | | 140 | 15.111 | .066177 | | 150 | 15.363 | .065092 | | 160 | 15.615 | .064041 | | 170 | 15.867 | .063024 | | 180 | 16.119 | .062039 | | 190 | 16.371 | .061084 | | 200 | 16.623 | .060158 | | 210 | 16.875 | .059259 | | 212 | 16.925 | .059084 | | 220 | 17.127 | .058388 | | 230 | 17.379 | .057541 | | 240 | 17.631 | .056718 | | 250 | 17.883 | .055919 | | 260 | 18.135 | .055142 | | 270 | 18.387 | .054386 | | 280 | 18.639 | .053651 | | 290 | 18.891 | .052935 | | 300 | 19.143 | .052238 | | 320 | 19.647 | .050898 | | 340 | 20.151 | .049625 | | 360 | 20.655 | .048414 | | 380 | 21.159 | .047261 | | 400 | 21.663 | .046162 | | 425 | 22.293 | .044857 | | 450 | 22.923 | .043624 | | 475 | 23.554 | .042456 | | 500 | 24.184 | .041350 | | 525 | 24.814 | .040300 | | 550 | 25.444 | .039302 | | 575 | 26.074 | .038352 | | 600 | 26.704 | .037448 | | 650 | 27.964 | .035760 | | 700 | 29.224 | .034219 | | 750 | 30.484 | .032804 | | 800 | 31.744 | .031502 | | 850 | 33.004 | .030299 | |_____________|____________|____________|
Example: Required the volume of air in cubic feet under 60.3 pounds gauge pressure per square inch at 115 degrees Fahrenheit.
53.33 × 575 Hence v = ----------- = 2.84 cubic feet, and 10,800
1 1 Weight per cubic foot = - = ---- = 0.352 pounds. v 2.84
Table 27 gives the weights and volumes of air under atmospheric pressure at varying temperatures.
Formula (9) holds good for other gases with the change in the value of the constant as follows: