With the variety of water pumps available today, selecting the ideal model for your application can be tricky. The following are a few useful definitions, helpful hints to aid you 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
Check Valves: Installed
on pump outlet to prevent back siphoning when off.
Flooded Suction: Water must
enter pump by gravity.
Foot Valve: Installed on
a pump inlet to prevent the loss of prime during
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
that 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 inches 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: U.S. gallons per minute.
Pedestal Pump: A self-supporting
pump mounted above a long shaft with the
motor above water and the intake below the water level.
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 you
should throttle the outlet with a valve or other restriction. Use an amp meter for
Propeller Pump: A submersible
pump with a propeller which draws water
through a housing. Propeller pumps are usually high volume low head.
Saltwater Compatible: Our
saltwater-compatible pumps are rated for long-term
continuous duty with salt water. Little corrosion should occur within 1 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.
As efficiency relates to aquaculture, pumping and aeration are the two biggest consumers of electricity. After feed costs and labor, electricity is probably your next highest overhead expense. Be careful when selecting a pump. Do not compare them by their horse power alone. What is more important is their amp usage. Often, a cheap pump has an undersized motor that must work very hard to do the job volume. This may be an appropriate pump selection for temporary or noncritical applications, but not where the lives of your animals are concerned. Often, pool type pumps when used for low pressure aquaculture applications, work with an overloaded motor.
Operating an undersized motor in the duty range of its service factor is acceptable from the pump manufacturers point of view, but not a fish farmer's point of view. It lowers the pump's cost (which looks good to you), but it increases its energy consumption and operating temperature. Higher operating temperature shortens pump life.
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