Page 411 - Advanced Mine Ventilation

380 Advanced Mine Ventilation

Figure 23.1 Flammability curve for methaneeair mixture [3].

It defines the various regions in Fig. 23.2. Thus area A 1 has a value of R equal to
1.00 and has only methane in it. Area A 2 has an R value of 0.8 and so on. The gas
analysis data can be used to find the composition point on the diagram and determine
if the atmosphere is explosive.
An example:
The following gas analysis was received from a mine on fire.

Gas Concentration (Volume %)
CO 2 12
O 2 8
CH 4 3 27%
CO 3

H 2 1
N 2 (100e27) 73