Define the term 'Water Hammer'.

• A. A pressure surge in a pipeline resulting from the rapid increase or decrease in water flow
• B. A leak along a pipeline due to corrosion
• C. A device used to regulate flow
• D. A measurement of flow rate

Answer: (A)

Water hammer is a pressure surge in a pipeline that happens when water flow is changed rapidly. When a valve closes quickly or a pump stops suddenly, the moving water has inertia and continues pushing forward. Because the pipe isn’t perfectly rigid, this abrupt change generates a high-pressure wave that travels through the system. That transient pressure can spike well above normal operating pressure and may cause noise, vibration, or damage to pipes, fittings, and equipment if not controlled. To prevent it, operators slow valve closures, use surge protection devices, and ensure proper pipe sizing and support. The other options describe a leak from corrosion, a device that regulates flow, or a measurement of flow rate, none of which capture this transient pressure surge.