AES FC offers the following type of check valves:
Ball Check Valve
- The closing member, the movable part to block the flow, is a spherical ball.
- In some ball check valves, the ball is spring-loaded to help keep it shut.
- For those designs without a spring, reverse flow is required to move the ball toward the seat and create a seal
- The interior surface of the main seats of ball check valves are more or less conically-tapered to guide the ball into the seat and form a positive seal when stopping reverse flow.
Diaphragm Check Valve
- Uses a flexing rubber diaphragm positioned to create a normally-closed valve.
- Pressure on the upstream side must be greater than the pressure on the downstream side by a certain amount (pressure differential) for the check valve to open allowing flow
- Once positive pressure stops, the diaphragm automatically flexes back to its original closed position.
Swing Check Valve or Tilting Disc Check Valve
- A check valve in which the disc, the movable part to block the flow, swings on a hinge or trunnion, either onto the seat to block reverse flow or off the seat to allow forward flow.
- The seat opening cross-section may be perpendicular to the center line between the two ports or at an angle.
- Although swing check valves can come in various sizes, large check valves are often swing check valves.
Stop-Check Valve
- A check valve with override control to stop flow regardless of flow direction or pressure.
- In addition to closing in response to back-flow or insufficient forward pressure (normal check-valve behavior), it can also be deliberately shut by an external mechanism
- Thereby preventing any flow regardless of forward pressure.
Lift-Check Valve
- A check valve in which the disc, sometimes called a lift, can be lifted up off its seat by higher pressure of inlet or upstream fluid to allow flow to the outlet or downstream side
- A guide keeps motion of the disc on a vertical line, so the valve can later reseat properly
- When the pressure is no longer higher, gravity or higher downstream pressure will cause the disc to lower onto its seat, shutting the valve to stop reverse flow