What is the function of a valve on a piping system?

• A. To join two pipes
• B. To control flow or shut off flow
• C. To measure flow rate
• D. To drain the system

Answer: (B)

Valves act as gates in a piping system. Their main function is to start, stop, or throttle the flow of a fluid. Opening a valve allows flow; closing it stops flow or isolates a section for maintenance. By adjusting how much a valve is open, you can regulate the flow rate or pressure downstream. Some valves are also used to prevent backflow or to drain a line, but the core purpose is control or isolation of flow. Joining pipes is done with fittings or couplings, flow rate is measured with a meter, and draining is done with a drain valve or dedicated draining device.