| II. | Volume × absolute temp. + acquired temp. | = heated volume. |
| Absolute temp. + initial temp. |
In applying this formula to the foregoing example, the figures become:
| I. × | 460.66° + 2000° | = 4.72604 volumes. |
| 460.66 + 60° |
From this last term the gauge pressure may be obtained as follows:
III. 4.72604 × 14.7 = 69.47 lbs. absolute - 14.7 lbs. atmospheric pressure = 54.77 lbs. gauge pressure; which is the theoretical pressure due to heating air in a confined space, or at constant volume from 60° to 2000° F.
By inversion of the heat formula for absolute pressure we have the formula for the acquired heat, derived from combustion at constant volume from atmospheric pressure to gauge pressure plus atmospheric pressure as derived from Example I., by which the expression
| absolute pressure × absolute temp. + initial temp. |
| initial absolute pressure |
= absolute temperature + temperature of combustion, from which the acquired temperature is obtained by subtracting the absolute temperature.
Then, for example,
| 69.47 × 460.66 + 60 | = 2460.66, and 2460.66 - 460.66 = 2000°, |
| 14.7 |