Check valves are ubiquitous throughout fluid processing operations. These simple devices permit fluid flow in one direction only. While there are numerous design variants available in the marketplace, the operation is very similar in all check valves. Fluid pressure and movement in the desired direction move a plate, plug, ball, or other obstruction to a position that allows the flow to pass. The plate or other obstruction has a design countervailing force applied to it by a spring, gravity, or some other means that will move the trim to the closed position. When pressure drop across the valve decreases below the design level, the trim will close. Fluid pressure exerted on the outlet side of the valve will maintain a closed position in the valve. In this manner, a check valve allows fluid to pass in one direction, but not in the reverse.
Beneficial features of a check valve would include some or all of the following:
- Lightweight and compact design
- Tight shutoff that meets any applicable standards
- Low-pressure drop when open
- The operation that minimizes seal wear
- Installation simplicity and flexibility
- Easy to insulate
- Low maintenance requirements
- No slamming to the closed position
- No valve chatter
- Available in numerous configurations to meet a wide range of applications