There is no denying that check valves are the most misunderstood valves ever used. Given that these are found almost everywhere, especially in industries and even in homes, the role of check valves cannot be neglected. Needless to say, they are quite effective in enabling flow in one direction and preventing reverse flow (backflow), but still, they are the least popular valves in use today.

What is a Check Valve?

A check valve (also known as reflux valve, clack valve, a one-way valve or retention valve) is a valve that permits the flow of liquid or gas through it in one direction and also ensures that backflow of fluid is prevented. There are only a few self-automated valves and check valve proudly sits among them – this means that it does not need any support to open or close.

What makes these check valves so effective is that they continue to work unlike other valves even if there is an interruption in the facility’s electricity or air pressure. All in all, check valves are used just like other valves and they are generally inexpensive, easy and simple.

How They Operate

The operating process of these valves is quite simple. Given that they are flow sensitive, their opening and closing are entirely dependent on the line fluid, that’s why they do not need to be controlled by manually. The valve is opened once the internal disc permits the flow of fluid in one direction. As soon as the forward flow decreases or is reversed, the disc starts to close the valve.

Types of Check Valves

Here are some of the types of these valves which are used for various applications:

  • A ball check valve
  • A diaphragm check valve
  • A Stop-check valve
  • A swing-check valve (also called as tilting disc check valve)
  • A lift-check valve
  • A duckbill valve
  • An in-line check valve

It is worth mentioning here that multiple check valves can be used for additional purposes by simply connecting them in series. For instance, contaminated water is prevented from going back into municipal water supply lines by using a double check valve as a device that prevents backflow of fluid. You have to comprehend that not all these types are good for all applications and that is why it is imperative to contact the manufacturer or provider before selecting any of them.


Here are some of the most common applications of check valves:

Industrial Processes

These valves are used in fluid systems in many industrial processes such as chemical and power plants. They are used in nuclear industry as well for various applications such as dump lines, feed water control systems, N2 systems, and monitoring various systems.


These are generally used with few types of pumps, especially diaphragm and piston-driven pumps. Check valves are fitted with injectors or feed pumps that are used to for supplying water to the steam boilers for the purpose of preventing back-flow. Overall, these valves play an important role in the functioning of


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