What Causes Cavitation in Hydraulic Pumps?

Two leading causes why hydraulic pumps usually fail are: (1) contamination and (2) cavitation. In order to prevent any potential damage to your entire hydraulic system, it’s imperative to understand cavitation, the indications or symptoms from your system it is occurring, as well as the preventive measures.

How does cavitation happen exactly? It starts when vapor bubbles in the oil are created due to high vacuum. When these vapor bubbles are carried and collapsed on the pump outlet (discharge side), cavitation happens.

Causes of Hydraulic Pump Cavitation

Poor Plumbing

Incorrect fittings or hose size
The path from pump to reservoir is not vertical or straight. Creating restricted flow.

Flow Restrictions

Accumulation in the strainer
Incorrect hose length or valve (not fully open)
Restrictive undersized fittings

High Oil Viscosity

Oil is too viscous
Oil viscosity is not appropriate for application and climate where the hydraulic pump is used

Preventive Measures

Make Sure Oil flow Paths are Straight – Hydraulic pumps are being supplied via atmospheric pressure and gravity, so it’s ideal to place the reservoir above it. Make sure that the path is as straight and vertical as possible. Keep an eye on bent or twisted supply hose.
Make Sure the Valve is Fully Open – If the supply line shut-off valve is equipped, make sure that it’s fully open without restrictions. This must be a “full flow” ball valve with the same inside diameter as your supply hose.
Inspect your Strainer – If your reservoir has strainer, be sure to inspect it regularly. Remove any buildup that can restrict supply flow.
Check Laminar Flow – If you’re hearing turbulence or noise in pump inlet, make sure that the supply hose length is the correct ratio to its diameter. A flange-style, flared fitting in the pump inlet can also help in eliminating pump noise.
Check Proper Viscosity – It's important to choose the hydraulic fluid with appropriate viscosity for your application and climate. Consult with your supplier for professional help in choosing the optimal fluid viscosity.

With regular maintenance, keeping an eye on symptoms, and taking preventive measures, you’d be able to avoid cavitation and expect efficient operation from your hydraulic pumps.