B - Regulation Principles - Chicago Pneumatic CPF 175 Instruction Manual

B - Regulation principles

1 - "On/off Load" regulation (see Fig. 11)
standard version
The CPF 175-200 units are fitted with an automatic regulation
system, enabling the machine to be stopped after it has run
unloaded for a given (adjustable) period of time. This period of
unloaded running is necessary to avoid excessively close start-
ups in highly varied periods of compressed air consumption.
When the compressor reaches maximum pressure, the pressure
sensor (Item. 45) closes the solenoid valve (Item. 22). The
compressed air on the suction housing piston and the vacuum
piston are depressurised; the housing is closed and complete
drainage of the tank is carried out.
The compressor draws in air via a by-pass valve (Item. 25).
The low pressure obtained in the oil tank enables the compressor
to be lubricated and cooled during the whole unloaded running
period.
If the compressed air pressure of the user network drops to the
minimum value at which the pressure sensor trips back in before
the end of the "no-load running" time-out, the pressure sensor
(Item. 45) controls closure of the solenoid valve (Item. 22),
opening the intake check valve and closing the opening to
atmosphere. The compressor again runs on full throughput.
When the compressor stops, the solenoid valve (Item. 22) is no
longer powered and closes; the suction housing closes and the
oil tank is evacuated. The tank is thus vented to atmospheric
pressure, for the next time the unit is started up.
23
25
Chicago Pneumatic Compressors
62 305 799 65
Fig. 11 - "On/off Load" regulation
36
38
64
35
21
46 47
20
20 Compressor
21 Suction housing
22 Solenoid-valve
23 Air filter
25 By-pass valve
26 Oil filter
34 Minimum pressure valve
36 Pneumatic pump out
37 Safety valve
38 Oil return solenoid valve
41 Ventilation
45 Regulation pressure switch
46 Safety temperature sensor
47 Ventilation regulation temperature sensor
49 Oil separator
51 A Air cooler
51 H Oil cooler
57 Oil tank
64 Oil return filter
2 - Speed regulator
( see chapter 6)
22
37
49
57
26
Key fig. 11
41
34
51A
51H
45
11/2008
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