Page 46 - Advanced Mine Ventilation

Air Flow in Mine Airways 29

Figure 2.2 Mine characteristic curve for example problem.

An example: A single fan mine needs a ventilation rate of 250,000 CFM air at 4 in.
of W.G. Calculate and plot the mine characteristic.
Using Eq. (2.18), a set of data is created and plotted in Fig. 2.2.

Mine Q (CFM) Total Pressure (W.G.)
200,000 4
300,000 9
400,000 16
500,000 25

Eq. (2.18) leads to a new term called equivalent orifice (EO). It compares the total
mine resistance to a circular opening in a thin plate that creates the same resistance if
the same ventilation quantity was flowing through it.
McElroy [8] has developed an equation for it.
3.9 × 10 Q
-4
EO = (2.19)
H
2
where EO is in ft , Q is in CFM, and H is in inches of water.