Figure 4-5 - Shuttle Valve - Gardner Denver AUTOSENTRY EAQ99Q Operating And Service Manual

Solenoid Valves IVC and IVO - These valves control position of the inlet valve in response to signals
from the "AutoSentry" 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 25-30 psig.
Figure 4-5 – SHUTTLE VALVE
Shuttle Valve (Figure 4-5) - 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.
Purge Air Valve - The purge valve is a normally closed two-way air actuated valve that admits purge air
from the final discharge manifold to the compressor to counteract the oil knock that occurs in oil-flooded
rotary screw compressors when they are completely unloaded with pressure in the oil reservoir. This
valve is controlled by the same control pressure which controls the inlet valve.
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