Submersible pump motors are designed to have water flowing up past them.
Submersible motors normally hang beneath the pump or more correctly the “wet-end” inside the appropriate size bore casing. Between these two is the pump inlet. Most Perth submersible bores are in 4′ bore casing.
If a submersible pump is to be used in a static body of water such as a dam or a lake or in bore casing of a diameter that exceeds the specifications then some method of inducing flow past the motor should ideally be employed. This keeps the motor cooler and extends life.
A common method is to make a pump shroud. What is referred to as a 4″ pump is designed for four inch (100mm) casing. A 6′ inch pump for six inch casing etc. etc. Typically the submersible pump is installed in plain casing of the correct diameter just above the slotted casing so water rushes up past the motor. Pump specs often stipulate the flow/velocity required past the motor. Water flow up past the motor can also be limited when water is cascading from above. For whatever reason, when enough flow to dissipate sufficient heat is not normally happening, consider a shroud. (A shroud can also be called for if for some reason sand is entering the bore casing from above the pump. It will provide some initial protection.) Certainly it protects the pump from direct lateral ingress of water.
Making a shroud for a submersible pump to induce flow past motor.
In the accompanying pics Adam has made up a shroud to go over a 4″ motor that will be hung in an 8″ borehole. Now water can only enter the pump inlet after first being drawn past the motor.A short length of 4″ bore casing was cut and with the assistance of heat adapted to create the shroud.
Call Virgin Bores on 9246 0111 if you need a submersible pump installed or replaced anywhere in the greater Perth metropolitan area. Do it properly and do it once!