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Flexible Impeller pump max flow 59 GPM max pressure 56 PSI 501M

Flexible Impeller Pump - 501

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.

This pump model is available as a pedestal style-bare shaft, clutch driven or SAE flange mount.

Note, the direction of the shaft rotation will determine inlet and outlet ports.

Pump will operate satisfactorily when mounted in any position. DO NOT RUN DRY. Rubber impellers generate high rubbing friction unless lubricated by liquid pumped and lack of liquid will cause impeller to burn up.


  • Bronze Construction - Corrosion Resistance
  • Machined-in Cam for Reduced Impeller Wear
  • Polytetrafluoroethylene (PTFE) Barrier Seals Protecting Ball Bearings
  • Mechanical Carbon Ring, Ceramic Face Main Pump Seal
  • Two Sealed Ball Bearings Spaced for Maximum Load Ability
  • Large Vent & Drain Openings Separate Seal & Bearing Areas
  • Shaft Slinger for Additional Bearing Protection
  • Neoprene (05) or Nitrile (06) Impellers
  • Stainless Steel Shaft
  • O-Ring Seal Between Body & Cover
  • Impeller easily replaced
  • Option: Flanged Engine Mount SAE ‘B’ Available


Either direct drive with flexible coupling or pulley drive can be used. Make sure both flexible coupling halves are properly aligned. When using pulley, do not over-tighten belt.



Liquids compatible with neoprene (05) can be pumped, including fresh and saltwater solutions and mild chemicals. Nitrile (06) impellers can handle oil-contaminated water. When possible, flush pump with fresh water after each usage.

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 and use methyl alcohol based anti-freeze compounds such as Zerex®, Shell Zone®, Pyro Permanent®, 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 the suction line is recommended.