What is Cavitation and What Causes it?
Cavitation occurs from the formation and resulting collapse of vapors within a hydraulic pump. Excessive vacuum conditions at a pump’s inlet (supply) side create vapor bubbles within hydraulic fluid that are then moved to the discharge (pressure) side, at which point they collapse. The moment of collapse is when the damage of cavitation occurs Eaton hydraulic pump.
Cavitation is especially destructive to metal surfaces, which have little elasticity. The explosive force of cavitation causes friction and wear, which eventually leads to damage, and if left untreated, it will result in pump failure.
Although the leading cause of cavitation is poor plumbing, there are many other ways this destructive force can begin.
Some of these other possible causes of cavitation in a hydraulic pump include:
Flow restrictions
High oil viscosity
Clogged filters
Pipe blockage
Poor piping design
Conditions not meeting NPSH (net positive suction head) requirements
Identifying Cavitation in a Hydraulic Pump
Most often, cavitation is heard – it’s identified by a recognizable sound. There are other visual signals, however, that are accurate clues when a pump is experiencing cavitation.
When you are concerned that cavitation is occurring in a hydraulic pump, pay attention to massage :
The sound: A whining sound from the pump can indicate mild cavitation, while a rattling sound best described at “marbles in a can”, can indicate intense implosions.
The physical evidence: Metallic debris found in the hydraulic oil filter during routine maintenance may indicate cavitation in a pump.
The damage: If the pump and its components are clearly damaged, it may be the result of cavitation and the pump requires immediate inspection.
Troubleshooting and Prevention
If end-users are experiencing cavitation, there are some easy troubleshooting practices that can fix the problem, limit damage, or help avoid the problem entirely.
Here are some troubleshooting and preventative steps that can be taken.
Troubleshooting
Check filters and strainers, looking for metallic debris
Determine the absolute pressure available (NPSHa) and required (NPSHr) for the suction port of the pump
Check oil viscosity and ensure it is appropriate for the application and climate conditions