Quote:
Originally Posted by solidsnake11
Bubbles take up volume so if your pumping gas bubbles and oil then you collapse the bubbles you have lost volume.(pressure). Somewhat like air in your brake system.
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You haven't lost volume though - the volume of gas (air for arguments sake) entrained in the fluid doesn't change - it was always there, always being pumped, down the line, evenly distributed. Nor does the volume of liquid in the system change. It's the drop below vapor pressure for the liquid that allows the gas to dissociate from the liquid into clumps (bubbles) that collapse as soon as the pressure on the fluid rises back above vapor pressure. That bubble collapse causes the damage to adjacent surfaces.
You'll see more of an effect on discharge pressure from a centrifugal pump due to cavitation than you will from a PD type pump due to the fixed relationship between RPM to volume moved in a PD (reciprocating piston, gear, lobe vane, peristaltic, etc) pump.