Water Hammer In Irrigation Systems: CIR828/AE066, 2/2022

Abstract

Irrigation system design includes pump sizing and selection, valve sizing and selection, and pipe sizing as well as the proper selection and placement of many other components. Good design involves selecting and sizing components to perform their intended tasks within the constraints of the system, to ensure an efficient, cost effective, and durable irrigation system. Cost effectiveness will result when oversizing is avoided. Undersizing of components will cut initial costs but often results in poor irrigation distribution uniformity or the complete or partial failure of the system through ruptured pipes, damaged valves, or pump damage.

Like any other moving fluid, flowing water has momentum. When subjected to a sudden change in flow, shock waves propagate through the system. This occurrence is referred to as "water hammer." Flow changes can occur due to operation of valves, starting and stopping of pumps, or directional changes caused by pipe fittings. The intensity of water hammer effects will depend upon the rate of change in the velocity or momentum. This publication discusses the causes of water hammer and the importance of proper system design and management to ensure a cost effective, long-lasting irrigation system.