Check Valve allows flow in which direction?

• A. Check Valve
• B. Lavatory
• C. Wet Pipe Sprinkler System
• D. System Arrangement

Answer: (B)

A check valve is designed to let fluid move in one direction only and to stop any flow going the other way. In a residential water distribution context, water is intended to flow from the supply toward the fixtures (like a lavatory). The check valve allows that forward flow toward the lavatory, but it prevents water from flowing backward toward the main supply. This unidirectional behavior is essential for preventing backflow and maintaining proper pressure in the system, which is why the lavatory (as the downstream fixture example) is the direction the flow is allowed to go. The other terms listed are fixture types or system concepts, not directions of flow.