What is Waterhammer?
Waterhammer (also known as surge) occurs when fluid velocity is changed by actions such as valve position changes and planned or unplanned pump trips.
Little guidance exists in codes and standards, and accidents are more frequent than we would like to admit. It is the purpose here to summarize existing knowledge and practice on waterhammer, discuss the abilities and limitations of commonly used calculation methods, provide warnings on what may happen when systems experience phenomena such as transient cavitation and liquid column separation, and give some high-level guidance on how to solve surge issues in pumping systems.
Waterhammer is fundamentally the same phenomenon across all industries which need to transfer fluids. However, depending on the nature of the fluid (benign, toxic, flammable, biologically active, etc.) and nature of the application (high pressure, proximity to people, remotely located such as in Space) different concerns and strategies are involved.
It is essential that engineers take proper precautions in their design and operations to ensure safe operation of pumping systems.