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Piston Section
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S
= section in sq. cm
r = piston radius in cm |
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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.
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Intake air
volume
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Va = air intake in l/min
C = displacement in cu. dm
N = rev. per min. |
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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 |
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Piston speed
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W = speed in m/sec
C = piston stroke in cm
n = rev. per min |
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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 |
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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 |
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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 |
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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 |
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Reference
conditions for compressed air in N cu. m/h
(STANDARD CONDITION = t 0°C = 32°F ---
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 %
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