Piston Section |
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S = section in sq. cm r = piston radius in cm |
Displacement |
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V = displacement in cu. cm S = piston section in sq. cm C = piston stroke in cm
Total displacement derives from the addition of the displacement of every cylinder. Two-stages compressor displacement derives only from low-pressure cylinders displacement. |
Intake air volume |
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Va = air intake in l/min C = displacement in cu. dm N = rev. per min. |
Output air volume |
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Vr = air output in l/min at 7 bar Va = air intake in l/min
Volumetric efficiency (0.62) single stage Volumetric efficiency (0.72) two stages |
Piston speed |
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W = speed in m/sec C = piston stroke in cm n = rev. per min |
Air speed when passing through valves |
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w = air speed in m/sec S = piston section in sq. m s = valve section in sq. m W = piston speed in m/sec |
Air speed through a duct |
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V = air speed in m/sec Q = air quantity in m/sec S = duct section in sq. m |
Pressure increase when temperature changes |
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P2 = Gauge pressure derived from temperature increase (bar) P1 = measured pressure (bar) T1 = Starting temp. + 273 T2 = Final temp. + 273 |
Compressed air consumption in a system with a tank of known capacity |
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C = air consumption in l/min P2 = starting pressure (bar) P1 = final pressure (bar) Vs = tank volume in l t = time needed in sec |
Reference conditions for compressed air in N cu. m/h (STANDARD CONDITION = t 0¡ãC = 32¡ãF --- p 1 bar = 14.5 PSI) |
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trif e prif = reference temperature and pressure T e p = temp. & press. of volume to be conv Pvs = saturated steam pressure (see table) ç = relative humidity % |