ustible portion of gaseous fuels is ordinarily composed of hydrogen,
carbon monoxide and certain hydrocarbons, a determination of the
calorific value is much more readily obtained by a separation into their
constituent gases and a computation of the calorific value from a table
of such values of the constituents. Table 37 gives the calorific value
of the more common combustible gases, together with the theoretical
amount of air required for their combustion.

TABLE 37

WEIGHT AND CALORIFIC VALUE OF VARIOUS GASES
AT 32 DEGREES FAHRENHEIT AND ATMOSPHERIC PRESSURE
WITH THEORETICAL AMOUNT OF AIR REQUIRED FOR COMBUSTION

+---------------+----------+------+-----+------+----------+-----------+
| Gas | Symbol |Cubic |B.t.u|B.t.u.|Cubic Feet|Cubic Feet |
| | | Feet | per | per | of Air | of Air |
| | |of Gas|Pound|Cubic | Required | Required |
| | | per | | Foot |per Pound | Per Cubic |
| | |Pound | | | of Gas |Foot of Gas|
+---------------+----------+------+-----+------+----------+-----------+
|Hydrogen | H |177.90|62000| 349 | 428.25 | 2.41 |
|Carbon Monoxide| CO | 12.81| 4450| 347 | 30.60 | 2.39 |
|Methane |CH_{4} | 22.37|23550| 1053 | 214.00 | 9.57 |
|Acetylene |C_{2}H_{2}| 13.79|21465| 1556 | 164.87 | 11.93 |
|Olefiant Gas |C_{2}H_{4}| 12.80|21440| 1675 | 183.60 | 14.33 |
|Ethane |C_{2}H_{6}| 11.94|22230| 1862 | 199.88 | 16.74 |
+---------------+----------+------+-----+------+----------+-----------+

In applying this table, as gas analyses may be reported either by weight
or volume, there is given in Table 33[36] a method of changing from
volumetric analysis to analysis by weight.

Examples:

1st. Assume a blast furnace gas, the analysis of which in percentages by
weight is, oxygen = 2.7, carbon monoxide = 19.5, carbon dioxide = 18.7,
nitrogen = 59.1. Here the only combustible gas is the carbon monoxide,
and the heat value will be,

0.195 x 4450 = 867.75 B. t. u. per pound.

The _net_ volume of air required to burn one pound of this gas will be,

0.195 x 30.6 = 5.967 cubic feet.

2nd. Assume a natural gas, the analysis of which in percentages by
volume is oxygen = 0.40, carbon monoxide = 0.95, carbon dioxide = 0.34,
olefiant gas (C_{2}