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.