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Flexible Impeller Pumps

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 vanes of the impeller are depressed and rebound, they create their own vacuum drawing fluid into the pumps (see operating principle).

A dry pump can lift water up to as much as 3 meters. 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 liquid 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. Wearing parts are easily replaceable, and service kits are available for all models.


Operating principle



After the blades leave the cam, the blades pop up. The action creates a vacuum, which draws liquid into the pump


Each blade draws in liquid and carries it to the outlet port


When the blades compress, they expel the remainder of the liquid. The flow is continuous and uniform.


Determining Inlet and Outlet Port depending on Rotating Direction




When the rotating direction is counterclockwise, the right port is inlet, the left port is outlet



When the rotating direction is clockwise, the let port is inlet, the right port is outlet


All flexible impeller pumps manufactured by JMP corporation are counterclockwise at the point of view with endcover ( impeller cover).

For good pumping

Pipe runs should always be kept as short and straight as possible, avoiding rising and dipping over obstructions, as this can lead air-locks. Pipework should always be reinforced, non-collapsible hose of the recommended size.

Flexible impeller pumps must not be run dry (more than 30 seconds). Bilge pumps and water pumps in particular should always be fitted with a filter or strainer on the inlet pipework to protect them from debris. These should be fastened to the boat structure to ensure their permanent location. Mount flexible impeller pumps so that some water is left in the pumpbody when the pump is shut off. This will prolong impeller life and speed priming. Pumps must be installed with the overboard to avoid water siphoning back into the vessel.

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