Water Hammer in the Pump Discharge Line Equipped with Semi-open End Valve

Abstract

This study aims at obtaining data on the pressure rise due to water hammer caused by the impact to the semi-open valve at the end of a discharge pipe by the water flow that starts flowing in the distribution pipe at the time when the pump starts. Experiments were conducted to measure the pressure variation by oscillograph in the following two cases, namely the first case was in the end valve opening with the velocity of impact kept constant and the second case was in the velocity of impact with the end valve opening kept constant. (1) The pressure rise becomes greater, when the end valve opening is smaller and the impact velocity is larger. (2) Velocity measured at the impact coincides well with the calculated velocity which is obtained from the cross point of the heat capacity curve and pipe resistance curve. (3) We could get the relationship between the experimental value and the calculated value by a graphical method.