What device may be used on the liquid line to prevent reverse flow if flow of liquid is limited to one direction (into the dispenser supply tank)?

What device may be used on the liquid line to prevent reverse flow if flow of liquid is limited to one direction (into the dispenser supply tank)?

• A. Check valve
• B. Relief valve
• C. Backflow check valve
• D. Shutoff valve

Answer: (C)

Preventing reverse flow in the liquid line is done with a one-way device that automatically blocks flow from the dispenser side back toward the source. A backflow check valve is designed to let liquid move toward the dispenser supply tank but closes if pressure on the dispenser side tries to push liquid back. This keeps the source tank safe from siphoning or contamination and is the standard protection in propane systems where one-way flow is required. A relief valve vents excess pressure, not reverse flow; a shutoff valve stops flow but doesn’t prevent backflow on pressure changes; a simple check valve may serve a similar function, but the backflow check valve specifically targets preventing backflow, making it the best fit for this scenario.

Preventing reverse flow in the liquid line is done with a one-way device that automatically blocks flow from the dispenser side back toward the source. A backflow check valve is designed to let liquid move toward the dispenser supply tank but closes if pressure on the dispenser side tries to push liquid back. This keeps the source tank safe from siphoning or contamination and is the standard protection in propane systems where one-way flow is required. A relief valve vents excess pressure, not reverse flow; a shutoff valve stops flow but doesn’t prevent backflow on pressure changes; a simple check valve may serve a similar function, but the backflow check valve specifically targets preventing backflow, making it the best fit for this scenario.