In piping contexts where steam pocket collapse occurs, which option is identified as the water hammer cause?

In piping contexts where steam pocket collapse occurs, which option is identified as the water hammer cause?

• A. Pressurized water entering a vertical steam-filled pipe (steam pocket collapse)
• B. Cause of Water Hammer
• C. Steam and water counterflow in a horizontal pipe
• D. Hot water entering a low pressure line

Answer: (A)

The key idea is that water hammer in this scenario comes from a slug of water entering a vertical pipe that is already filled with steam, causing the steam pocket to collapse and a rapid pressure surge to form. When pressurized water pours into a vertical, steam-filled section, the incoming liquid collides with the steam pocket. The steam cannot be compressed like liquid, so it rapidly condenses and the pocket collapses, converting the kinetic energy of the moving water into a sudden, high-pressure wave that propagates through the line. The vertical arrangement makes this interaction with a distinct steam pocket more likely, creating the sharp surge characteristic of water hammer. Other options don’t describe this specific mechanism as directly. A generic statement about water hammer misses the localized pocket-collapse event. Steam and water counterflow in a horizontal pipe is a two-phase flow situation that can cause instability, but it isn’t the classic steam-pocket collapse driver. Hot water entering a low-pressure line may cause flashing, but that’s not the same abrupt pressure surge from a collapsing steam pocket in a vertical steam-filled run.

The key idea is that water hammer in this scenario comes from a slug of water entering a vertical pipe that is already filled with steam, causing the steam pocket to collapse and a rapid pressure surge to form. When pressurized water pours into a vertical, steam-filled section, the incoming liquid collides with the steam pocket. The steam cannot be compressed like liquid, so it rapidly condenses and the pocket collapses, converting the kinetic energy of the moving water into a sudden, high-pressure wave that propagates through the line. The vertical arrangement makes this interaction with a distinct steam pocket more likely, creating the sharp surge characteristic of water hammer.

Other options don’t describe this specific mechanism as directly. A generic statement about water hammer misses the localized pocket-collapse event. Steam and water counterflow in a horizontal pipe is a two-phase flow situation that can cause instability, but it isn’t the classic steam-pocket collapse driver. Hot water entering a low-pressure line may cause flashing, but that’s not the same abrupt pressure surge from a collapsing steam pocket in a vertical steam-filled run.