Many pump people are familiar with cavitation as it is commonly known in the centrifugal pump world but you may or may not know the same phenomenon can cause devastating damage to your liquid ring vacuum pump.
1. What is cavitation?
Cavitation in layman's terms are micro bubbles or voids that are created in areas of rapid pressure change which implode causing shock waves which can cause severe erosion to the internal components of your vacuum pump. Cavitation causes damage similar to what you might expect if you allowed someone to take a small pick to the inside of your pump. Over time this can lead to the total failure of your pump and the prospect of expensive repairs or even complete replacement. Many times cavitation sounds like marbles inside the pump and many people mistake it for a mechanical problem.
2. When does cavitation occur in a Liquid Ring Vacuum Pump?
In a liquid ring vacuum pump cavitation occurs generally when you are exceeding the maximum vacuum capability of the vacuum pump. This is effected by temperature and altitude among other things but the quick answer is the vacuum level you are running at is usually too high. This typically happens when the vacuum pump is over sized for the application or the desired vacuum level is too high for the selected pump.
3. How can I prevent cavitation in my liquid ring pump?
There are two solutions depending on the desired outcome. One can select a pump that has a higher vacuum capability like a two-stage pump, or one can lower the running vacuum level. If the later option is selected then one can add vacuum process controls such as a vacuum breaker, automatic air bleed line, or even a fixed orifice to protect the pump. These controls are commonly recommended but often overlooked as key methods for protecting your liquid ring vacuum pump.