The hydraulic ram pump was invented over 200 years ago but became obsolete with the availability of mains water. Ram pumps make use of a renewable energy resource and are environmentally friendly. They are particularly appropriate for use in the developing world ns their construction is basic and robust and they are inexpensive and easy to install and maintain. Unfortunately, simple rational design procedures applicable to any size of pump are nor available. The paper analyses the behavior of ram pumps under zero recoil conditions from which three nondimensional design relationships, applicable at any delivery head are derived for beat frequency, quantity delivered, and source capacity in terms of the independent variables. These relationships incorporate constants consistent with existing experimental results. Recommendations are given for the maximum length of drive pipe which supersede traditional rules-of-thumb for the ratios L/D and L/H. The procedure allows selection of all system parameters, including the drive pipe length, for a set of homologous ram pumps.
