Atlas Copco PTS 1600 Cud S3A/T3 APP, Instruction Manual

Page: 23 / 128

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3.5 Operation flows
3.5.1 Air flow system
Description
Air drawn through the air intake filters (AF
C
), and
unloader (UA) into LP compressor element (CE
LP
) is
compressed and discharged to the intercooler (IC)
where the heat of first-stage compression is removed
by the cooling air flow.
The cooled air then enters MP compressor element
(CE
MP
) where it is further compressed and
discharged through check valve (CV), aftercooler 1
(AC
1
), aftercooler 2 (AC
2
) and water separator (WS)
to air outlet valves (AOV).
During loaded operation air inlet throttle valve (TV)
is open and unloading valve (UV) closed. These
valves are simultaneously closed and opened
respectively by loading solenoid valve (LSV) through
unloader piston (UP) when the working pressure
reaches its preset maximum. The pressure of the MP
compressor element is then released to the
atmosphere through the unloading valve and the
blow-off silencers (BOS), resulting in closing of the
check valve. The throttle valve leaves an air passage
in the closed position. Thus air remains drawn into the
compressor to maintain a reasonable pressure ratio
over the elements.
An air-operated balancing piston is fitted behind the
male rotor rear thrust bearing of MP compressor
element. The piston decreases the load on the male
rotor front thrust bearing during loaded operation.
During loading the MP compressor element
balancing piston is actuated by working pressure,
while during unloading the pressure on the piston
equals the atmospheric pressure.
Two intercooler relief valves (RV), an electric blow-
off valve (BOV) and a MP safety valve (SV) are
comprised in the system.