Irrigation Pumps

Water is heavy. Each cubic foot of water weighs almost 62.5 pounds. If an irrigation well has a casing that has an inside diameter of 12-inches extending 200 feet to the surface, the water weighs over 3,268 pounds. It takes a lot of power and suction to force that amount of water to the surface of an irrigation well.

In the 1940s, irrigators began adapting deep well turbine pumps from the oil industry to use on the farm. Basically, these pumps have a set of gears and support mechanism at the top of the well. This gearbox uses the power of an electric, gas or diesel engine to spin a long shaft supported in the middle of the well casing. Hundreds of feet below, the actual pump is submerged in the water of the underground formation.

The pump mechanism have a series of “impellers” – curved vanes shaped like a propeller on a boat or the turbine in a jet engine – that spin at high speed. The first set of impellers take in the water at the bottom of the pump, and force it up to the next set of impellers. Through a series of several stages, the water is lifted at great pressure until it rises to the surface.

According to the 1945 book Ground Water: Its Development, Uses and Conservation, published by the Johnson National Drillers’ Journal, “The outstanding features of these pumps as a class are their ease of installation and simplicity of operation. They ‘start’ and ‘stop’ easily by simply pushing a button or throwing a clutch. They do not require priming as they are submerged in the water of the well. If the water level lowers, then additional lengths of column and additional bowls [impellers in the pump] can be added to the pump. These pumps are made for all sorts of installations with either surface or underground discharges and with heads for any kind of power.”

The source of power to drive the pump was an important consideration for the irrigator as well. Very early irrigators used horse power for shallow wells. Later, they adapted steam engines. Then, as REA brought electric power to the farm, irrigators began using large electric motors. As the war ended, gas, oil and diesel motors were set up to power wells.

Then there were choices on how to get the energy transferred from the engine to the pump gearbox. Early systems used large rubber belts, like those used in threshing machines. But the belts would expand or contract depending on how hot or cold it was. That caused the belts to slip or damage the gearbox. So, by the 1940s, most irrigation systems were moving to a direct drive, mechanical linkage between the power supply and the gearbox of the pump.

For the time, this was the state of the art in pump and power technology. Today’s systems are simply refinements of the 1940s technology.

Written by Bill Ganzel, the Ganzel Group. A partial bibliography of sources is here.

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