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Flexible Impeller pump max flow 15.3 GPM max pressure 34.6 PSI

Flexible Impeller Pump - N305M

These Flexible Impeller pumps are made of high quality bronze of maximum corrosion resistance. All shafts consist of stainless steel grade 303. Top of the line models have ball bearings and mechanical seals while others have bronze or carbon bearings and lip type seals. Impellers are made of Neoprene Rubber. Nitrile impellers are available as an option. Flexible blades on the periphery of the impeller provide the pumping action. While the impeller rotates the liquid between the blades is continuously squeezed out into the discharge port by a machined in cam located inside the pump chamber. Pump will operate when mounted in any position.

Impeller and seals should be replaced under the following conditions:

The impeller must be replaced if it is worn out or has been damaged by debris or by running the pump dry. Symptoms of a defective impeller are low pumping pressure and low flow. To replace the impeller remove screws and cover pull out the impeller with needle nose pliers or two screwdrivers. Be careful not to dent the pumping chamber with these tools. When inserting new impeller, line up key slot in impeller with the key in the shaft. Use oil on shaft and avoid forcing the impeller onto the shaft. The impeller should also be removed for storage periods to prevent the blades from taking a permanent set.

If water drips from the weep hole or from the area where the shaft exits the pump, the seal is defective and must be replaced. Prolonged running of the pump with a leaky seal can destroy the motor bearings resulting in catastrophic pump failure. For seal replacement, the pump must be removed from the motor and disassembled in order to gain access to the seal area. Where mechanical seals are used, both components (stationary and rotating member) must be replaced at the same time. Refer to exploded view drawings for seal location and part numbers for ordering purposes.


Performance is based on full voltage supply. Use direct lines. Do not drain voltage with other electrical equipment on same circuit. Lower voltage reduces performance and overloads motor. Use adequate wires size and length to maintain supply voltage.


  • Bronze construction - Corrosion resistant
  • Reversible wear plate
  • Nitrile mechanical seal
  • Portable
  • Slotted motor base
  • Neoprene Impeller STD (Nitrile optional 305M-02)
  • Stainless Steel Shaft
  • Nitrile O-ring seal between body and cover eliminates gasket problems
  • Impeller and cam easily replaced
  • Available with AC or DC motors


The pump is driven directly from the electric motor shaft. An aluminum adapter connects the pump to the motor. Reversing supply leads to motor terminals reverses motor rotation. “In” and “Out” pump ports are also reversed.

DO NOT RUN DRY - Flexible impellers generate high rubbing friction unless lubricated by liquid pumped. Lack of liquid will cause impeller to burn up.


Liquids compatible with neoprene can be pumped including fresh and salt water solutions and mild chemicals. Do not pump severe solvents or acids. When possible flush pump with fresh water after each use.

Extremes of cold and heat will affect impeller life. Limits of 40°F to 180°F should be observed. Do not allow liquid in pump to freeze. Drain pump by loosening cover screws. Use methyl alcohol based anti-freeze compounds such as Zerex, Shell Zone, Pyro Permagard, or Dowgard.


Suction lift of 15 feet is possible when impeller is wet. Suction lines must be air tight in order for pump to self prime. A foot valve at the beginning of suction line is recommended.