Head–Flow Response and Short-Term Repeatability of a Low-Cost PVC Hydraulic Ram Pump

Abstract

Hydraulic ram pumps use the energy of flowing water to lift a portion of that water without external power, yet their reported performance depends strongly on how head conditions and flow boundaries are defined. This study examined the head–flow response and short-term repeatability of a low-cost hydraulic ram pump constructed from nominal 2-inch PVC components and fitted with a nominal 3-inch, 0.60-m air chamber. Three operating configurations combined supply and delivery heads of 1.50/4 m, 1.70/5 m, and 1.90/6 m. Each configuration was evaluated through fifteen volumetric tests using a fixed collection volume of 100 L. Discharge was calculated for every replicate from collection volume and filling time, then assessed using descriptive statistics, 95% confidence intervals, one-way analysis of variance, Tukey comparisons, and a Kruskal–Wallis test. Mean measured discharge increased from 10.53 ± 0.23 L s−1 in the first configuration to 11.59 ± 0.18 and 13.92 ± 0.54 L s−1 in the second and third configurations, respectively. Differences among configurations were pronounced (F2,42 = 362.58, p < 0.001, η2 = 0.945). Estimated input-side hydraulic power rose from 154.7 to 259.0 W, whereas the intermediate configuration produced the lowest coefficient of variation (1.53%). The highest-head configuration favored throughput and available hydraulic power, while the intermediate state provided the most consistent short-duration measurements. Hydraulic efficiency could not be determined because drive, waste, and delivered flows were not measured separately.