Which component is used to isolate a section of piping for maintenance and can stop flow entirely?

• A. Backflow preventer
• B. Valve
• C. Coupling
• D. Tee

Answer: (B)

To isolate a section of piping for maintenance, you need a device that can completely shut off the flow in that run. A valve does this. When you close a valve, the passage is blocked and the fluid cannot pass, allowing safe work on the upstream or downstream side. In practice, you might place valves at both ends of a segment to fully isolate it for maintenance.

A backflow preventer, while essential for preventing contamination by stopping reverse flow, isn’t designed to provide a complete on-demand shutoff of a section by itself. It controls flow direction under certain conditions but doesn’t inherently isolate a segment when you need to work on it. A coupling merely connects two pieces of pipe and doesn’t regulate or stop flow. A tee is a branch fitting that changes the path of flow or splits it, not a shutoff device.

So the component that can isolate a section and stop flow entirely is the valve.