What causes water hammer in water lines?

• A. High pressure in the water system
• B. Velocity of air and water
• C. Faulty plumbing materials
• D. Improper installation of fixtures

Answer: (B)

Water hammer is primarily caused by the sudden change in velocity of water in the pipes, leading to a pressure surge. When water flowing at high speed is abruptly stopped due to a valve closing or a fixture being shut off, the momentum of the water creates a shock wave that propagates through the water lines. This phenomenon results in the characteristic bang or thump heard in pipes, often referred to as a water hammer.

The factor of velocity is critical because it relates directly to the kinetic energy gained by the moving water, which, when stopped suddenly, converts into an intense pressure spike. This increase in pressure can cause stress on the piping system, potentially leading to damage over time. Understanding this principle is essential for diagnosing and remedying water hammer issues, emphasizing the importance of considering flow dynamics in plumbing systems.

The other options focus on different aspects like overall pressure, materials, or installation practices, which, while they may contribute to plumbing issues, do not explain the specific mechanism behind water hammer as effectively as the velocity of water does.