13-21-616 v00 Page 36
Inlet Valve
(Figure 1-4, page 10 and Figure 4-2 page 34) The Inlet valve restricts the inlet to control delivery
and closes to unload the compressor. At shutdown, the inlet valve closes to prevent the back flow of air.
The inlet valve position is controlled by air pressure in its piston cylinder, which is controlled by the Governor
Controller through solenoid valves IVC and IVO. As Pressure to the piston is increased, the valve closes
to restrict air flow and compressor delivery.
Solenoid Valves IVC and IVO
- These valves control position of the inlet valve in response to signals from
the Governor Controller. With both valves de-energized, the normally open IVC valve allows control
pressure to the inlet piston to close the valve. If IVC only is energized, the inlet valve is held in its current
position. If both valves are energized, control pressure is relieved from the inlet piston to allow the valve to
open.
Pressure Regulator
- The pressure regulator is used to supply a constant and low control pressure to
prevent damage to the inlet valve from “slamming". The regulator should be set for 60 psig.
Shuttle Valve
(Figure 4-2, page 34) Also known as a double check valve, the shuttle valve is a device
which will take two (2) supply signals and allow the one with the highest pressure to pass through. The
shuttle valve is used to provide control air pressure from either the reservoir or plant air system, as required
during different operating conditions.
