What is the purpose of a check valve?

• A. To measure flow rate
• B. To regulate pressure
• C. To indicate pipe blockages
• D. To control direction of flow

Answer: (D)

A check valve is a one-way valve that allows fluid to flow in the forward direction while automatically closing to stop flow if the direction reverses. This directly achieves the purpose of controlling the direction of flow, preventing backflow that could contaminate the supply, damage equipment, or cause loss of prime in pumps. It isn’t used to measure flow rate (that’s a flow meter), nor to regulate pressure (that’s a pressure regulator or relief valve), nor to indicate blockages (that’s done by indicators or alarms). The essential function is to ensure flow goes only where intended.