Which of the following is NOT a concern regarding water hammer in a typical irrigation system using a well?

• A. Valve Closure
• B. Trapped Air in Long Pipe Runs
• C. Reverse Flow When Pumps Stop
• D. Uncontrolled Flow Velocity in Empty Pipes

Answer: (B)

Water hammer is a surge in pressure created when moving water is forced to stop or change direction quickly. The biggest culprits are how fast a valve closes and what happens when a pump stops, because both situations abruptly alter the momentum of the water and send a pressure wave through the system. Trapped air in long pipe runs actually helps dampen that surge—air compresses and absorbs part of the energy, acting like a cushion. That’s why it’s not a concern for causing water hammer; in practice, engineers use air chambers or pockets to reduce hammer, not to worsen it. As for flow in empty pipes, there isn’t moving water to generate a hammer, so that scenario isn’t a direct hammer risk—the surge comes from moving liquid, not an empty line.