Table of Contents
Advertisement
down valve, and therefore the blowdown valve is
open.
The pneumatic blowdown valve uses a
mechanical spring to keep the valve open if LP pilot
air is not routed to the valve's diaphragm chamber.
Once the controller signals the blowdown solenoid
to close, LP pilot air is routed to the blowdown
valve. Pilot air pressure of . 10 psig exceeds the
mechanical spring force, closing off the flow of HP
discharge process air to the blowdown silencer and
atmosphere.
This
combined
inlet/blowdown
ensures the air compressor defaults to a safe
unloaded condition in the unlikely event of: control
signal loss, a component failure, or loss of external
power. A closed inlet and open blowdown state are
also the conditions for these subsystems during the
UNLOAD MODE.
START MODE: 0 TO ≅ ≅ 30 PSIG (0 TO 2.1 BARG)
When the start button on the control panel is
depressed, the unit starts and ramps up to 1400
RPM. During this mode, the controller maintains its
default "closed" (de-energized) signal to the inlet
control solenoid valve, keeping the inlet butterfly
valve "closed". The same controller signal main-
tains its default "closed" (de-energized) signal to the
blowdown subsystem solenoid valve, resulting in
Figure 4-3A Silencing/Discharge Air and Cooling Systems
COMPRESSOR SYSTEMS
the pneumatic blowdown valve staying open.
FULL LOAD MODE: ≅ ≅ 70 TO 135 PSIG (4.8-9.3
BARG)
After five minutes at 1400 RPM, or the coolant tem-
perature reaches 130°F, the controller will modulate
the engine speed between 1400-1900 RPM until
the
Simultaneously, the controller sends a signal to the
inlet control solenoid, opening (energizing) the sole-
noid valve. The valve directs pressurized oil to the
configuration
actuator, which extends its control rod opening the
butterfly valve to ingest air. The same controller sig-
nal is sent to the blowdown solenoid valve, opening
(energizing) the solenoid and allowing LP pilot air to
be routed to the pneumatic blowdown valve
diaphragm. The pneumatic force overcomes the
spring force and closes the blowdown.
UNLOAD MODE: ≥ 135 PSIG (≥ ≥ 9.3 BARG)
If the demand for compressed air falls below supply,
system line pressure (P2) should increase as the
discharge check valve closes. When P2 exceeds
set point pressure (100 psig) the controller will sig-
nal the inlet control solenoid to close (de-energiz-
ing), routing oil pressure to the actuator retract posi-
tion and closing the inlet butterfly valve. The same
signal will close (de-energize) the blowdown sole-
system
set
pressure
Section 4
is
reached.
15
Advertisement
Table of Contents
