What is the primary function of a check valve?

The primary function of a check valve is to control flow direction. Check valves are designed to allow fluid (liquid or gas) to flow through them in one direction only, preventing backflow. This is critical in many systems, such as piping networks, where maintaining a unidirectional flow is essential for proper operation and safety. When the flow pressure from the upstream side exceeds that on the downstream side, the check valve opens, allowing flow. Conversely, if there is a reverse pressure or no flow, the valve closes, effectively stopping backflow. This ensures that the system functions correctly without the risk of contamination or damage caused by unwanted reverse flow.

While throttling flow rate, isolating system components, and regulating pressure are important functions in various system designs, they are not the primary role of a check valve. Throttling is typically accomplished with valves that can adjust the flow rate, isolation valves are used to stop flow entirely for maintenance or separation purposes, and pressure regulation is managed by specific pressure relief or control valves.