Do you happen to know how much is expelled by the antminer s9?
Since the dimensions of the fan are identical to 17/19 series, you 'could' assume 250cfm (500 / 2), however it's just a guestimate.
So I think assuming 270cfm would be a safe number.
Assuming I have this number, for 50 miners that would be 270 x 50 = 13,500cfm.
Assuming every miner burns 1450W, I saw an online calculator to calculate the W to BTU/hr which is 1W=3.412BTU/hr ( I don't know if this is correct.)
So 1450W x 50 x 3.412 = 247,370 btu/hr.
I don't know if this is correct or not.
But if anybody knows how to calculate to get rid of this heat please help me. In the summer the ambient temperature here reaches upto about 49 degree Celsius sometimes.