Boat engine cooling pump
JPR-G Series JMP Corporation

Flexible impeller pumps provide an efficient solution to most marine pumping needs. The primary advantage of a flexible impeller pump is its self-priming capability. As the blades of the impeller are depressed and rebound, they create their own vacuum drawing fluid into the pumps (see operating principle)

Pumps instantly with dry suction lifts up to 3 meters, up to 9.5 meters when wetted. Thus a flexible impeller pump being used in bilge, deck wash, or engine cooling need not be located below the water line or manually primed. An added feature of flexible impeller pumps is that they can pass fairly large particles without clogging or damaging the pump. This reduces the need for filtering the incoming fluid.

A common feature of all flexible impeller pumps is that they cannot be permitted to run dry for more than 30 seconds. Both the impeller and the seals depend upon the water for lubrication and will soon burn out if run dry.