23.
Using the following data, calculate the NVP in a mine
Depth of mine = 400 m;
Barometer reading in DC shaft 750 mm of Hg;
Average temperature in DC shaft 28°C;
Average temperature in UC shaft 38°C.

25.
Calculate the wg. produced by 3 m dia fan running at 250 rpm and deliver 6000 m3/min of air, if the blades are radial in mm w.g of the blade tip speed is 39.3 m/sec.

28.
The formula for finding the of air flow in m3/min.