Water Pumping Glossary

Short Water Pumping Terms By Windy Dankoff Courtesy of Dankoff Solar Products, Inc.

Pump Mechanisms
Centrifugal Pump - A pumping mechanism that spins water to push it out by centrifugal force.

Diaphragm Pump - A type of pump in which water is drawn in and forced out of one or more chambers, by a flexible diaphragm.

Positive Displacement Pump - Any mechanism that seals water in a chamber, then forces it out by reducing the volume of the chamber. Examples: piston & diaphragm pumps. Used for low volume and high lift. Contrast with "centrifugal". Synonyms: volumetric pump, force pump.

Jet Pump - A surface-mounted centrifugal pump that uses an "ejector" (venture) device to augment its suction capacity. The ejector may be down in the well, to assist the pump in overcoming the limitations of suction. (Some water is diverted back down the well, causing an increase in energy use.)

Multistage Centrifugal - A centrifugal pump with more than one impeller and chamber used to produce higher pressure. Conventional AC deep well submersible pumps and higher power solar submersibles work this way.

Pump Jack - A deep well piston pump. The piston and cylinder is submerged in the well water and actuated by a rod inside the drop pipe, powered by a motor at the surface. This is an old-fashioned system still used for extremely deep wells, including solar pumps as deep as 300m.

Submersible Pump - A motor/pump assembly designed to be placed entirely below the water surface.

Surface Pump - A pump that is not submersible. It must be placed no more than about 7m above the surface of the water in the well.

Solar Pump Components
DC Motor, Brush-Type - The traditional DC motor, in which small carbon blocks called "brushes" conduct current into the spinning portion of the motor. Used in DC surface pumps and in some DC submersible pumps. Brushes wear after years of use, and may be easily replaced. It is a variable-speed motor, well suited to direct solar power.

DC Motor, Brushless - High-technology motor used in some DC submersibles. An electronic system eliminates the need for brushes.

Induction Motor (AC) - The type of electric motor used in conventional AC water pumps. It requires a high surge of current to start and a stable AC voltage supply, making it relatively expensive to run from by solar power.

Pump Controller - An electronic device which varies the voltage and current of a PV array to match the needs of an array-direct pump. It allows the pump to start and to run under low sun conditions without stalling. Electrical analogy: variable transformer. Mechanical analogy: automatic transmission. Sometimes called Curent Booster.

Water Well Components
Borehole - Synonym for water well, especially outside of North America.

Casing - Plastic or steel tube that is permanently inserted in the well after drilling. Its size is specified according to its inside diameter.

Drop Pipe - The pipe that carries water from a pump in a well, up to the surface.

Perforations - Slits cut into the well casing to allow groundwater to enter. May be located at more than one level, to coincide with water-bearing strata in the earth.

Safety Rope - Plastic rope used to suspend the pump, primarily in case of pipe breakage.

Submersible Cable - Electrical cable designed for in-well submersion. In U.S.A., size is specified by American Wire Gauge (AWG), in which a higher number indicates smaller wire. Elsewhere it is specified in millimeters.

Water Well Characteristics
Drawdown - Lowering of the level of water in a well due to pumping.

Recovery Rate - Rate at which groundwater refills the casing after the level is drawn down. This is the term used to specify the production rate of the well. Static Water Level - Depth to the water surface in a well under static conditions (not being pumped).

Pump System Engineering
Friction Loss - The loss of pressure due to flow of water in pipe. This is determined by 3 factors: pipe size (inside diameter), flow rate, and length of pipe. It is determined by consulting a friction loss chart. See total dynamic head.

Head - See synonym: vertical lift.

Suction Lift - Applied to surface pumps: Vertical distance from the surface of water in the source, to a pump located above surface pump located above. This distance is limited by physics to around 7m at sea level (subtract 1m. per 1000m altitude) and should be minimized.

Submergence - Distance beneath the static water level, at which a submersible pump is set. Synonym: immersion level. Total Dynamic Head - vertical lift + friction loss in piping (see friction loss).

Vertical Lift - The vertical distance that water is pumped. Total vertical lift = vertical lift from surface of water in the source, up to the discharge in the tank. Synonym: static head. Note: Horizontal distance does NOT add to the vertical lift, except in terms of pipe friction loss. NOR does the volume (weight) of water contained in pipe or tank. Submergence of the pump does NOT add to the vertical lift in the case of a centrifugal type pump. In the case of a positive displacement pump, it may add to the lift somewhat.

Copyright 1996 by Dankoff Solar Products, Inc. Used with permission to The Sustainable Village.