How Do You Calculate Efficiency And Volume Of Screw Compressor?
if it it has a 25 gallon tank, If you trigger a refill cycle by bleeding out air slowly with the relief valve, you could observe on the tank gauge (not the downstream gauge) that the compressor “cuts in” at say 85 psig and “cuts out” again at 102 psig, a difference of 17 psi. It cranks for 35 seconds to build up that pressure. Divide the tank volume in gallons by 7.48 (1 cu-ft = 7.48 gallons) to get the tank volume in cubic feet. Thus the tank volume is 25 gallons / 7.48 gal/cu-ft = 3.34 cubic feet. In units of atmospheres of pressure, since 1 atm = 14.7 psi, the 17 psi of pressure added during the cycle is 17/14.7 = 1.16 atm of pressure during the cycle. When a compressor pumps one “CFM” (cubic foot per minute), that means the intake port inhales one cubic foot of “free air” (air at atmospheric pressure, which is 0 psig) per minute. (Note: A CFM does not mean in any sense the compressed volume.) So the unit really measures the mass of air flowing per minute, not volume per minute, sin
