Water Pump Definitions
Tech Talk 32
With the variety of water pumps available today, selecting the ideal model for your application can be tricky. Following are a few useful definitions, helpful hints and conversion charts to aid in your decision:
Centrifugal Pump: Medium- to moderate-pressure, flooded-suction or self-priming pump. An impeller is used to "sling" water to the outside, pumping by centrifugal force.
Check Valves: Installed on pump outlet to prevent back siphoning when pump is off.
Flooded Suction: Water must enter pump by gravity.
Foot Valve: Installed on a pump inlet to prevent the loss of prime during nonoperational periods.
Freshwater Pumps: Freshwater pumps can be used with salt water for brief periods and experience only minimal corrosion. Rinse with fresh water after use.
Head: The amount of pressure a pump must work against during operation. Total head equals feet of vertical lift plus friction. The amount of head is an important value when sizing a pump correctly. One psi equals 27" of water.
Friction: The loss in pressure and volume that occurs when liquids travel through pipes, fittings and other restrictive elements of a piping system.
Gpm: US gallons per minute.
Pedestal Pump: A self-supporting pump mounted above a long shaft, with the motor above the water level and the intake below.
Pressure Curves: Motor overload can occur if pumps are operated below the lowest pressures depicted by the curves shown in the pumps' specifications. If your application does not have sufficient head pressure to stay within the curve, throttle the outlet with a valve or other restriction. Use an amp meter for guidance.
Propeller Pump: A submersible pump with a propeller, which draws water through a housing. Propeller pumps are usually high-volume, low-head.
Salt Water Compatible: Our salt water compatible pumps are rated for long-term, continuous duty with salt water. Little corrosion should occur within one year.
Spherical Pump: A silent pump that has only one moving part—an induction-driven impeller. Spherical pumps have no motor shaft, seals or bearings, making them virtually maintenance-free.
Trash Pump: A centrifugal pump that can pass large objects, including sand, gravel and mud. Often used for dewatering ponds.
Vertical Pump: A centrifugal pump mounted in a vertical direction. Vertical pumps usually have a long shaft with the motor mounted above water.
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