A Hycheck Valve is held shut by what?

A Hycheck Valve is held shut by what?

• A. Firemain
• B. Water pressure
• C. Air
• D. Steam

Answer: (A)

Hycheck valves are hydraulic check valves used to prevent backflow into the ship’s firemain. They are held closed by the firemain pressure. When the AFFF pump is not delivering, the firemain pressure keeps the valve shut, blocking any reverse flow. When the AFFF pump is running and its pressure exceeds the firemain pressure, the valve opens to allow flow. Air or steam wouldn’t provide the appropriate hydrostatic backpressure, and while water pressure is involved, the specific source that holds it closed on a ship is the firemain.

Hycheck valves are hydraulic check valves used to prevent backflow into the ship’s firemain. They are held closed by the firemain pressure. When the AFFF pump is not delivering, the firemain pressure keeps the valve shut, blocking any reverse flow. When the AFFF pump is running and its pressure exceeds the firemain pressure, the valve opens to allow flow. Air or steam wouldn’t provide the appropriate hydrostatic backpressure, and while water pressure is involved, the specific source that holds it closed on a ship is the firemain.