Cavitate?

What exactly does it mean to cavitate a pump?

I'm trying to revive an old pressure system that is fed from a city line. The current input to the system only flows at about 4 GPM.

Cavitation is the pulling apart of water in the pump housing. There are more technical answers than the one above but what causes it is the pump wanting far more water than is available. The vacuum in the pump housing causes little voids in the water which can damage the metal parts in the pump.

bob...

Cavitation occurs when the input water flow is insufficient for the outgo of the pump and the impeller spins uselessly and the cavitation causes damage to the impeller. To get a pump to work on your 4 gpm flow, you need it to fill a tank and then suck/pump from the tank; then you'd have a flooded suction.

Gary
Quality Water Associates

cavitation

Cavitation is basically steam caused by the lack of water flow and very little pressure, or more precisely a negative pressure. Under those conditions the water will burst into small droplets of steam and the process of creating those steam "bubbles" and their subsequent collapse back into water creates a pitting action on the metal parts they contact. That is the reason that any valve to reduce flow has to be on the outlet of a pump so that the flow into the pump is not reduced which would cause that cavitation.

Cavitation is the vaporizing of water and its explosion therein. If the city water supply line only provides 4 gpm, then that is all you should try to pump with your pump. Your pump has the ability to provide some suction—dependent on pump design and elevation, however this suction will most likely not help to create more flow. The most that you can hope to accomplish with this pump is to boost the pressure. Install a 4 gpm flow control and your cavitation problems should be eliminate—if the pump has not been permanently damaged. As someone else state the flow control should be on the pressure side of the pump, not the suction side.

Oh, also, cavitation often sounds like you are pumping gravel.