Design of Hydraulic Ram Pump Systems

Abstract

Automatic hydraulic ram pumps are environmentally friendly devices using a renewable energy resource to pump water for domestic or agricultural use. Since being superseded by pumps using electrical or fossil fuel energy nearly a century ago, they are now coming back into favour in many parts of the developing world. In the past, hydraulic ram pumps have been designed by rules-of-thumb having limited scientific basis. On-site adjustment has been used in the hope of rectifying the inevitable shortcomings of this process and ideal performance is rarely achieved. The present proposal for optimum design allows relevant system parameters (including the beat frequency) to be selected prior to installation. The paper shows how a ram pump system may be designed using two simple equations containing empirical factors dependent upon ram size, delivery head, material and wall thickness of the drive pipe and the configuration of the impulse valve. The design method is illustrated with reference to a number of existing tests. New experimental results for a 53 mm ram with five different impulse valve strokes are also presented.