The sudden surge in pressure or liquid velocity within a piping system caused by rapid start/stop of flow, valve action, or steam condensation is known as?

The sudden surge in pressure or liquid velocity within a piping system caused by rapid start/stop of flow, valve action, or steam condensation is known as?

• A. Cavitation
• B. Water Hammer
• C. Thermal Expansion
• D. Pressure Surge

Answer: (B)

When a liquid within a piping system experiences a rapid change in flow, its inertia resists the sudden shift, generating a pressure wave that travels through the pipe. This transient surge in pressure or velocity is known as water hammer. The rapid start, sudden valve action, or steam condensation creates an abrupt deceleration or acceleration of the moving liquid, producing high-pressure spikes that can propagate along the line and reflect at boundaries. The effect can be described by the basic relation that the pressure rise is tied to the fluid density, the speed of the pressure wave, and the change in velocity (ΔP ≈ ρ c ΔV). Water hammer is the classic term for this phenomenon, which explains the banging noises and potential damage in piping systems after sudden valve closures or start-ups. Cavitation involves vapor bubble formation due to low pressure, not this general transient surge; thermal expansion is about temperature-driven volume change, and the more generic term “pressure surge” lacks the specific mechanism of momentum change that defines water hammer.

When a liquid within a piping system experiences a rapid change in flow, its inertia resists the sudden shift, generating a pressure wave that travels through the pipe. This transient surge in pressure or velocity is known as water hammer. The rapid start, sudden valve action, or steam condensation creates an abrupt deceleration or acceleration of the moving liquid, producing high-pressure spikes that can propagate along the line and reflect at boundaries. The effect can be described by the basic relation that the pressure rise is tied to the fluid density, the speed of the pressure wave, and the change in velocity (ΔP ≈ ρ c ΔV). Water hammer is the classic term for this phenomenon, which explains the banging noises and potential damage in piping systems after sudden valve closures or start-ups. Cavitation involves vapor bubble formation due to low pressure, not this general transient surge; thermal expansion is about temperature-driven volume change, and the more generic term “pressure surge” lacks the specific mechanism of momentum change that defines water hammer.