Hydraulic Ram Pumps for Irrigation in Northern Thailand

Abstract First constructed two and a half centuries ago, the hydraulic ram is one of the oldest mechanical devices for water lifting. The first application utilised the principle for the water supply of a brewery. In this set up a water valve had to be manually closed. Very soon upgrades for an automatic operation of the device were adapted. With technological progress also the ram was improved, but got superseded by electric and fuel powered pumps. Today the ram constitutes a reliable and low-maintenance, sustainable alternative to motor-driven pumps. The hydraulic ram uses the kinetic energy of water flowing in a driver pipe to pump up about 10% of it to a higher elevation. Thereby, no external energy input is needed. As a lot of studies had been carried out constructing hydraulic rams with self built valves and for high water supply, the aim of this investigation was to construct a reliable and low-cost ram, made of locally available off-the-shelf parts. Different valves were tested in the lab under varying elevations of the water column in the driver pipe. The pumping pressure and water flow in the supply pipe were recorded for determining the ram's efficiency. An off-the-shelf clap check valve proved mosrt reliable with an acceptable efficiency of over 30%. One unit of a hydraulic ram was installed at a foothill location at Ban Ha, Samoeng District, Chiang Mai Province, and connected to an automatic low pressure irrigation system to irrigate a small plot of coffee trees. Soil moisture was monitored. The hydraulic ram operated maintenance free and fully automatic over six weeks, supplying the field sufficient quantities of water during this period at a pumping efficiency of 44%.