L&W SC-300 E, Operating Instructions Manual, Page: 63 / 89

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LW SC-300 E / LW SC-350 E
Version: 06.12.2022
M A I N T E N A N C E A N D S E R V I C E
Pressure maintaining / non return valve
The pressure maintaining / non return valve combination is
placed in the flow direction after the final filter housing.
Pressure maintaining valve
The pressure maintaining valve drains a large part of the
water content of the compressed air mechanically by
ensuring the minimum outlet pressure. This guarantees
optimal drying and purification of the breathing air.
After starting the compressor, the pressure inside the final
filter housing constantly increases. The pressure maintaining
the valve prevents the compressed air from blowing off (final
pressure gauge = 0 bar).
When the adjusted opening pressure is reached (160 bar), the purified compressed air flows via
pressure maintaining and non return valve to the filling valve.
The value of the opening pressure of the pressure maintaining valve can be read at the final
pressure gauge. When opening pressure is reached, the pressure gauge value increases within a few
seconds.
Adjust pressure maintaining valve see next page.
Non return valve
The non return valve which is placed after the pressure maintaining valve, prevents the purified
breathing air from flowing back into the filter housing / condensate drain valves.
After compressor stop, the indicated filling pressure remains constant, if the non return valve is
working correctly.
.
Fig. - Pressure maintaining / non return
valve in the filter base and HP-outlet