Let's take a look at various types of check valves and discuss how they work, how they're applied and how to select the right type.
Systems that are designed to allow fluid media in only one direction often feature a check valve. Examples of such systems include a sewer line where the waste should only flow in one direction. Check valves are also used where backflow could cause equipment damage. Before we look at the different check valve types, applications, and selection criteria, let’s first understand how a check valve works. Wafer Type Swing Check Valve
A check valve, or a non-return valve, is a device that restricts fluid flow to only one direction. Check valves have two ports, an inlet, and an outlet port, designed to prevent fluid backflow in various industrial systems. There are different check valve types and they differ by the mechanism that causes them to open and close. However, they all rely on a pressure differential to either allow or restrict fluid flow. Unlike the other valves in the market, check valves do not need a lever, a handle, an actuator, or human intervention to work correctly. They are cheap, effective, and easy to deploy. That said, the check valve will only operate if there’s a pressure differential between the inlet and outlet ports. The minimum pressure differential that the system must exceed for the valve to open is called the ‘cracking pressure.’ The value of this cracking pressure varies from one checking valve to another based on the design and size. When there’s a back pressure or the cracking pressure is higher than the inlet pressure, the valve will close. The check valve’s closing mechanism varies based on the design, i.e., a ball check valve pushes a ball against the orifice closing it. This closing action can also be assisted either by gravity or a spring.
As stated earlier, there are multiple types of check valves, each designed for their unique applications. However, one type, called the spring loaded in-line check valve, is used in various industrial settings. The spring-loaded in-line check valve has a spring, a valve body, a disc and a guide. When the inlet pressure is high enough to overcome the cracking pressure and spring force, it pushes the disc, opening the orifice and allowing fluid to flow through the valve. If backpressure occurs, it pushes the spring and the disc against the hole/orifice, sealing the valve. The short travel distance and the fast-acting spring allow for a quick reaction time during closing. This type of valve can be installed in a horizontal or vertical orientation, in line with the system, hence must be removed entirely for inspection or servicing. Here are the other types of check valves:
Other types of check valves include the stop check valve, the butterfly/ wafer check valve, the foot valve, and the duckbill check valve.
Check valves find applications in nearly all the industries where fluids have to flow in one direction. These valves are also used in household appliances such as washing machines and dishwashers. Based on the design and mode of operation, check valves can be used for any of the following use cases:
Some of the factors you need to consider when choosing a check valve include: The compatibility of the check valve material with the fluid medium.
Check valves are popular devices in the industrial setting that are not only cheap and reliable but also relatively easy to use. When buying a check valve, make sure you understand your unique needs and the check valves’ selection criteria. Similarly, ensure you know the installation requirements to avoid flow direction issues or damaging your system due to pressure build-up.
Charles Kolstad has been working at Tameson since 2017 and is from the United States of America. He has his Mechanical Engineering degree from the University of St. Thomas in Minnesota, USA. He works remotely while traveling throughout Europe, Asia and the Americas. However, he does visit Tameson’s HQ from time to time to meet the new members of the team and to work in the office.
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