Check Valves Basics

The check valve – also at times called a clack valve, non-return valve, or one way valve – allows for fluid to flow one way only, hence the “check”. The valve have two ports, one for entry and another for exit. Check valves are used in many operation and can even be found around the house, such as in the basement sump pump. Most check valves are self-automated and do not have to be operated, although there are some valves that offer handles or stem.

Check valves can be used to move air, condensate, liquids, steam, slurry, and other types of media.

In the past, the most commonly used type of check valve was a swing valve, but check valves have now evolved to include ball, dual plate (also called double-door), piston, lift, and spring assisted (in-line, nozzle, and silent swing). There are also many types of custom check valves that are specially constructed with a certain sealing mechanism and/or materials to suit the application it is used in.