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Figure 4-3 – BLOWDOWN VALVE
Blowdown Valve (Figure 4-3) - This valve normally is used for control functions, but also serves to
relieve reservoir pressure following a shutdown. The blowdown valve is a two-way solenoid valve which
is piped into the 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 1-4, page 11) - This gauge is located on the oil reservoir and indicates the oil
level. See Section 5 for information on how to correctly read the gauge and proper lubrication.
Figure 4-4 – MINIMUM DISCHARGE PRESSURE/CHECK VALVE
Minimum Discharge Pressure/Check Valve (Figure 4-4) 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.
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