Cavitation is what happens when the pressure inside a pump drops so low that the liquid boils into vapour bubbles, which then collapse violently as they reach higher-pressure regions. Each collapse is a tiny implosion, and together they erode the impeller, wreck efficiency and can destroy a pump in weeks. It sounds like the pump is passing gravel.
Liquid boils not only when it gets hot but also when its pressure falls to its vapour pressure. At the eye of a pump impeller the pressure is at its lowest, so if the suction margin is too small the liquid flashes into vapour bubbles there. As those bubbles move into the higher-pressure parts of the impeller they collapse almost instantly, firing microscopic jets of liquid at the metal surface.
Most cavitation traces back to insufficient NPSH: a suction lift that is too high, a long or clogged suction line, a hot liquid with high vapour pressure, or a blocked strainer. Running a pump far past its best efficiency point makes it worse, because the required NPSH climbs with flow, and pushing a pump out on its curve rather than respecting the affinity laws is a common trigger.
The fix is to restore suction margin: raise the source level or lower the pump, shorten and enlarge the suction pipe, clean the strainer, or cool the liquid. Reducing demand so the pump runs nearer its best efficiency point also helps. Where the duty genuinely needs it, an inducer or a low-NPSH pump is the design answer.
Cavitation announces itself through vibration and acoustics well before the impeller is destroyed, so it is very catchable. A monitoring platform that trends pump vibration and performance turns that early signature into a work order rather than a failure. Fabrico reads the signal from the line and routes the job automatically. Book a Fabrico demo to see it.
Insufficient suction pressure margin, or NPSH, so the liquid boils at the impeller eye. High suction lift, hot liquid, clogged strainers and running far off the best efficiency point are the usual causes.
Like the pump is pumping gravel or marbles, a rattling crackle caused by vapour bubbles collapsing against the impeller.
Low NPSH is the usual cause; cavitation is the result. When NPSH available falls below NPSH required, the liquid vaporises and cavitation begins.
Restore suction margin: raise the source level, shorten and widen the suction line, clean strainers, cool the liquid, or reduce flow toward the pump's best efficiency point.
Connexion
Blog