Experimental Performance Evaluation of Low-Cost Hydraulic Ram Pump in Bhutan

Abstract

A water supplying technique where a portion of water is used to lift the water from rivers to agricultural land or any location where required and for any purpose is the hydraulic ram pump, one of the oldest mechanical devices for water lifting, invented centuries ago and still commercially available today. The first hydraulic ram was constructed by Whitehurst in 1772 (Whitehurst, 1775), and had to be operated manually. The hydraulic ram pump has not found popularity in Bhutan. According to Kubota (2020), Bhutan possesses one of the highest per capita water availabilities in the world. With an average river flow of about 2,238 cubic metres per second, the country produces approximately 70,572 million cubic metres of water annually, equivalent to around 94,500 cubic metres per person per year. Hydraulic ram pumps provide a sustainable and energy-free solution for lifting water in mountainous regions where conventional pumping systems are often impractical. This study developed and experimentally evaluated a low-cost hydraulic ram pump fabricated from locally available materials to assess its suitability for water supply applications in Bhutan. The prototype was tested under varying supply heads of 3.4 m to 4.3 m and delivery heads of 9 m and 10 m. Pump performance was evaluated in terms of discharge rate, hydraulic power and efficiency. Experimental results showed that increasing the supply head significantly improved pump performance. At a 9 m delivery head, the discharge increased from 0.225 to 0.338 m³/h, while the efficiency improved from 6.67% to 10% as the supply head increased from 3.4 m to 4.3 m. At a 10 m delivery head, the discharge ranged from 0.208 to 0.240 m³/h, with efficiencies increasing from 7.18% to 8.30%. The findings demonstrated a positive relationship between supply head and pump performance, confirming that higher available hydraulic energy enhances water delivery and system efficiency. The developed prototype operated successfully without any external energy source, showing its potential as an economical and environmentally sustainable water lifting technology suitable for Bhutan’s terrain.