Generic design of ram pumps

Abstract

The hydraulic ram pump was invented over 200 years ago but became obsolete with the general availability of mains water. It is used for pumping surface water and is powered by the potential energy of the supply. Ram pumps are particularly appropriate for use in remote regions of the developing world as their construction is basic and robust and they are inexpensive and easy to install and maintain. A rational design procedure applicable to any ram pump is described in this paper. The method is based on the three non-dimensional relationships that have been found to govern ram pump behaviour. The relationships express beat frequency, quantity delivered and source capacity in terms of the independent variables. By assigning upper and lower bounds to the critical velocity in the drive pipe, it is possible to derive three characteristic pump parameters from which the dependent variables may be determined directly. These parameters all take the same numerical values within a feasible design space. The design method has been confirmed using the results of existing experiments. A number of examples are given which illustrate the ease and rapidity of the procedure.