User manual Pomac PLP Lobe pump
14 CE/PLP (1406) EN-12
3.6. Safety valve (optional)
3.6.1. Safety valve types
The PLP can be supplied with a spring-loaded or air-operated safety valve. The opening
pressure is adjustable by means of a setscrew.
The following types can be provided with a safety valve:
3.6.2. Description of the safety valve
The Pomac safety valve is mounted directly to the pump cover. This facilitates maintenance and
guarantees optimal hygienic conditions. When the valve opens a direct by-pass is created
between pressure side and suction side of the pump.
The valve covers almost completely the front side of the rotors and the spaces on suction side
and pressure side partially. At pump side the valve is submitted to the differential pressure
inside the pump; the air pressure or spring load exerts the external force on the valve. Because
fluid characteristics, pressure division, process factors, etc. all can influence the load
characteristic on the valve, the load must be adjusted on-site.
When the differential pressure inside the pump exceeds the closing pressure, exerted by the
load set, the valve will open. Dimensions of valve and valve housing are such, that a part of the
pump capacity can be by-passed from pressure side to suction side.
3.6.3. Connections of the air-loaded safety valve
Connection A : Air pressure
Connection B : Valve vent (always has to be open)
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