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.
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 causing overheating of the boat engine. Poor pump performance can also be caused by slippage of V-belts, so belts should be checked for tightness. 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. While the Polytetrafluoroethylene (PTFE) barrier seal provides a first line of defense, prolonged running of the pump with a leaky seal can destroy the ball bearings resulting in catastrophic pump failure and engine shut-down. For seal replacement, the pump must be removed from the engine 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. Lip seals must be pushed out of their press-fitted position and new seals pressed into place, using a sealant on the outside of the lip seal housing. Refer to exploded view drawings for seal location and part numbers for ordering purposes.
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.
Direction of shaft rotation determines inlet and outlet ports. (see line drawing)
Pump will operate satisfactorily when mounted in any position. DO NOT RUN DRY. Rubber impeller pumps 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 the pump with fresh water after each usage. Nitrile impellers can handle oil-contaminated water and kerosene at reduced impeller service life.
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 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 beginning of suction line is recommended.