Acronyms & Units
RPM
Revolutions Per Minute
RPM stands for revolutions per minute, a measure of engine speed. On the pump it sets how fast the impeller turns, which determines the pressure and flow the pump can produce.
Pushing the throttle raises engine rpm, spinning the impeller faster and moving the pump up its curve toward more pressure. The pressure governor adjusts rpm automatically to hold a set discharge pressure as demand changes.
More rpm is not the same as more water, though. Against a weak supply, raising engine speed cannot conjure flow the source cannot deliver — it only risks overdrawing the intake.