Cavitation
The formation of vapor bubbles in the fluid when suction-side pressure drops below the fluid's vapor pressure, and their violent collapse in the pressure zone. It produces a rasping noise resembling gravel and quickly cuts permanent pits into pump surfaces.
The bubble collapses in under a millisecond the moment pressure rises, producing very high local pressure and temperature over a very small area. Microscopic particles are torn from the metal; the detached particles mix into the fluid, increase contamination, and chain damage begins.
- Most common causes: a clogged suction strainer, a suction valve left closed, a crushed or undersized suction hose, low fluid level in the tank.
- Cold fluid struggles to flow on the suction side, so the risk is higher on the first startup in winter; high engine speed should be avoided until the system warms up.
- Exceeding the pump's permitted speed also lowers suction pressure and produces the same result.
Continuing to run the machine once you hear the symptom is the most expensive option; damage accumulates within minutes. Check the fluid level and suction line first. Cavitation is often confused with aeration; although the two sound similar, with aeration you see foam in the tank, with cavitation you do not.
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