check valve (non-return or one-way valve) is a mechanical device that automatically prevents backflow in piping systems, allowing fluid or gas to flow in only one direction. They operate based on pressure differentials, opening with forward flow and closing when pressure drops or reverses, which protects pumps and reduces water hammer. Common types include swing, ball, diaphragm, and wafer styles.

• Function: Ensures unidirectional flow, preventing media from returning upstream.
• Operation: Automatic, relying on system pressure (no manual actuation).
• Common Applications: Water supply, HVAC systems, industrial pumping, and process lines.
• Benefits: Prevents damage from backflow, minimizes water hammer, and facilitates system maintenance.
• Types:
  • Swing Type: Uses a hinged disc that lifts to allow flow and seals when flow stops.
  • Ball Check Valve: A ball moves on a seat to open/close based on pressure.
  • Diaphragm: Flexible seal, ideal for low-pressure, clean environments.
  • Dual Disc (Wafer): Compact, lightweight, uses two semicircular doors for quick sealing.
• Materials: Often constructed from brass, bronze, or stainless steel to withstand specific pressures and corrosion.