What Is an Hydraulic Water Pump?

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  • Written By: Paul Scott
  • Edited By: E. E. Hubbard
  • Last Modified Date: 05 November 2018
  • Copyright Protected:
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An hydraulic water pump is a low-flow water pumping device that works by pumping a small volume of water to a greater height by harnessing the energy in a large body of water that falls a short distance. The hydraulic water pump consists of an elevated water source delivering fluid to a arrangement of pipes fitted with a conventional waste valve, a check valve, and a pressure vessel, the two valves being the pump's only moving parts. The first part, or chamber, of the pump is fitted with the waste valve and, as water flows into this chamber, it exits the valve until pressure in the chamber closes it. The resultant rapid increase in pressure then opens the check valve to allow a small amount of water to flow out of the delivery pipe. This causes pressure in the system to drop, allowing the waste valve to open, thus repeating the cycle.


A very simple, low-cost solution for moving water at low-flow rates, the hydraulic water pump, or hydraulic ram pump, is ideally suited to domestic and small agricultural applications and is simple enough for the average do-it-yourself (DIY) enthusiast to build. The pumps function by harnessing the kinetic energy in a large water body flowing into the pump from a modest elevation to pump a smaller volume far higher than the source. Consisting of a simple arrangement of pipes, one check and one waste valve, and a small pressure chamber, the pumps are also reliable and easy to maintain. In addition, they are efficient with a 20-foot (6-meter) fall between the source and the pump being sufficient to pump the water to a height of 150 feet (45.7 meters) at rates of up to 4,000 gallons (15,140 liters) per day.

Conceptually, the pumps are very simple, with water from an elevated source entering the first pump chamber via a drive pipe. This chamber is fitted with a standard waste valve through which the water exits until the internal pressure increases enough to close it. The next section of the hydraulic water pump leads off of the first chamber and is isolated from it by the check valve. When the waste valve closes, the pressure in the chamber rises sharply, opening this check valve and allowing a small amount of water to flow out of the pump through the delivery pipe. When this happens, the pressure in the initial chamber drops, allowing the waste valve to open, repeating the pump cycle.

The pressure chamber is a vertical vessel partially filled with air positioned between the check valve and the delivery pipe. As the delivery flow surges out of the first chamber, it compresses the air in the vessel, cushioning the entire system from hydraulic shock. Although this vessel does increase the efficiency of the pump, it is not essential, and the system will work without it. Removing the pressure vessel will, however, shorten the life of the entire hydraulic water pump.



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