Borehole, booster, high-pressure, low-pressure, peripheral, self-priming, swimming pool, pond, submersible, portable, solar, hydraulic, chemical and trash. These are all types of pumps commonly found in non-industrial or domestic usage with different applications. No wonder newcomers to the wonderful world of moving liquids are sometimes confused.

Borehole pumps

These are submersible, cylindrical pumps that lift water out of a borehole. Commonly they are made in two diameters: 4” and 6”, and are either single-phase or three-phase mains-driven, or solar powered. They comprise two distinct parts, a pump, which because of the nature of the work it is intended to perform, namely lifting water out of the ground from great depth, and the structures of the diameter of the borehole, is in reality a number of small pumps joined together (called a multi-stage pump), with a waterproof motor mounted on top.

Booster pumps

These are electrically-driven low-pressure fixed pumps that are commonly found in domestic situations to ensure a constant flow of water through a house’s taps, at a decent pressure. They are also used to drive irrigation systems. Usually they are fitted with some form of automatic pressure switch designed to activate the pump when pressure in the system drops below a predetermined point (ie, when a tap is opened) and to stop pumping when the pressure in the switch reaches a certain level again (ie, when the tap is closed).

Modern pressure switches are microprocessor controlled and open and close a valve as necessary as the pressure in the system varies, for example when an additional tap is opened or a toilet is flushed. This ensures that somebody standing under a shower, for example, isn’t scalded by a change in pressure when a kitchen tap is opened.

High-pressure vs low-pressure

The former delivers a small volume very far and fast, commonly used in HP washers, fire-fighting applications etc. The latter delivers a large volume of water, commonly at pressures of only a few bars. Borehole, booster, pool pumps, etc, are all low-pressure.

Peripheral pumps

These are very small low-pressure pumps, delivering small volumes of water and commonly used for, eg, small irrigation or hydroponic set-ups.

Self-priming

Nowadays modern pumps are all self-priming, meaning that they have the ability to fill themselves with fluid on start-up, air being the killer of all manner of pumping characteristics. Before the advent of self-priming pumps one would have to fill the pump chamber with fluid before starting the pump, lest the pump just spin fruitlessly in air.

Swimming pool pumps

In reality simply a booster pump fitted with a leaf trap.

Pond pumps

Very small submersible pumps used for filling filters and driving fountains and water features in ponds.

Submersible

A blanket term for waterproof pumps that are immersed in the fluid they handle. Thus, borehole or pond pumps are submersible. Most commonly, however, the term applies to pumps immersed in underground sumps or tanks, when the term dewatering pump is sometimes used. Electrically-driven they are switched on and off by a float switch.

Portable pump

A centrifugal (usually low-pressure) usually pump attached to a petrol or diesel engine and fitted into a frame enabling the unit to be carried to the side of a dam, pond, pool or stream. Used ad hoc to move water or other fluids from one place to another.

Solar

Simply a pump driven by electricity derived from a photovoltaic panel rather than from a mains supply.

Hydraulic

Sometimes called a ram pump, a very simple non-powered device that uses a large volume of water to pump a small volume of water over some distance. A typical application would be to place a ram pump in the bed of a fast-flowing stream where the water pressure from the stream will constantly pump a small volume into a tank some distance from the river.

Chemical

Typically a low-pressure pump manufactured from stainless steel for pumping corrosive fluids and chemicals.

Trash

Pump with a specially adapted pump chamber and impeller which can handle small solids and semi-solids, ie a dirty water pump.

This is Part One in a five-part series on Pumps. Check back throughout the week to read the series or subscribe to receive all five parts at the end of the series.

Part Two: Pump Terminology Explained

Part Three: Solar Pumps: A Good Alternative for Smallholdings

Part Four: In Praise of Silent Pumps

Part Five: A borehole can determine your success as a smallholder

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