How to Control Liquid Ring Vacuum Pumps
Liquid ring vacuum pumps require proper operation and monitoring, however.
This article will address several monitoring and troubleshooting situations involving liquid ring vacuum pumps.
A check valve will prevent a backflow of gases at start-up or shutdown of the system.
When choosing a check valve, a low pressure drop type should be considered to minimize pressure loss in the system. A butterfly style check valve normally has the lowest pressure drop.
For accurate control of suction pressure, an absolute pressure transmitter, a pressure controller and a recycle valve (typically a pneumatic diaphragm operated globe valve) should be considered. This combination will maintain a constant suction pressure by recycling non-condensables from the separator discharge to the vacuum pump suction.
It is a good idea to have a vacuum gauge, typically a bourdon tube type, on the vacuum pump suction.
A level gauge should always be installed on the separator tank. Visible indication of the contents of a closed vessel is good engineering practice.
The vacuum pump requires a certain amount of seal liquid to operate at the design pressure.
Y-type strainers can be used to remove large particles.
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