Figure 4-2 - Blowdown Valve; Figure 4-3 - Minimum Discharge Pressure/Check Valve - Gardner Denver AUTO SENTRY EAU99P Operating And Service Manual

Figure 4-2 – BLOWDOWN VALVE
Blowdown Valve (Figure 4-2) - The blowdown valve is a two-way solenoid valve which is piped into the
air/oil reservoir outlet ahead of the minimum pressure valve. When the solenoid is de-energized, the
valve opens and the coolant system is blown down. When the solenoid is energized, the valve closes to
allow the coolant system to pressurize. A control air check valve is provided to ensure that the inlet valve
is closed during blowdown.
Oil Level Gauge (Figure 1-2, page 10 and Figure 5-6, page 49) - This gauge is located on the oil
reservoir and indicates the oil level.
Minimum Discharge Pressure/Check Valve (Figure 4-3) - An internal spring-loaded minimum pressure
valve is used in the final discharge line to provide a positive pressure on the coolant system of the
compressor even if the air service valve is fully open to atmospheric pressure. This valve also functions
as a check valve to prevent back flow of air from the shop air line when the unit stops, unloads, or is shut
down.
The valve incorporates a spring-loaded piston which maintains approximately 65 psig in the oil reservoir.
When the air pressure on the upstream (reservoir) side of the valve rises above 65 psig, the spring is
overridden and the valve opens to full porting.
The valve does not require maintenance or adjustment. If the valve fails to function, check the valve stem
O-ring for sealing, valve orifices for restriction, or valve and valve seat for burrs and dirt.
To service the valve make sure all pressure is relieved, disconnect the unit from the power supply, lockout
and tagout, then unscrew the valve cap from the body. The internal parts will come out after the cap has
been removed. Repair kits are available from your local authorized Gardner Denver distributor.
Figure 4-3 – MINIMUM DISCHARGE PRESSURE/CHECK VALVE
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