Check Valves

Pipelines are installed with check valves to help prevent backflow of fluids. They are a useful device for keeping water flowing in the desired direction and they are found in a range of applications, including commercial and industrial settings.

At RS, you will find a full range of flow-controlling check valves designed to suit the job you’re working on, such as swing and double check valves. We have a full selection in stock from brands that specialize in these fluid control tools, including AVENTICS, Norgen, SMC Corporation, and our own brand RS PRO so you can be assured that you are buying the highest quality products.

Read on to find out more about check valves.

What are check valves?

Check valves are installed in pipelines to make sure that fluid flows through in one direction. The reason why you might need to add one to your pipeline is to protect piping, other valves in the system, or any pumps.

They feature two ports (or openings). The first of these is there to allow the fluid to flow in through the body of the valve – known as the input port – and the second is to let the fluid flow out, which is known as the outlet. It’s a one-way check valve system. So, if the fluid were to change course, the valve closes, meaning it doesn’t allow it to reverse its path.

For this system to work, check valves need higher pressure coming through the input side. This is because this pressure pushes through and opens the valve, allowing the fluid through. When the pressure is higher on the outlet side, or if there’s not enough pressure through the input side, the valve closes.

What the valve is made of will depend on what it’s used for. If you’re working on a hydraulic application and need a check valve, the valve will have a steel body as this is durable. Pneumatic applications have a lower pressure rating than hydraulic ones, so the valves can be made of a variety of materials. You may want a plastic check valve or there may be a brass version that’s suited to the pneumatic system you’re working on.

What are the different types of check valve?

While the purpose of these valves is the same, no matter what type of check valve you opt for, the way the different valves operate differs slightly.

Inline check valves are smaller, spring-loaded valves that tend to be used for vertical installation, however they’re versatile enough to be used in any direction. They have a spring-loaded ball fitted inside that is forced to move to an open setting if enough pressure is applied at the input port. When pressure reduces, the spring presses the check valve closed.

Unlike spring-operated inline check valves, swing check valves feature a disc that swings on a hinge. When there’s enough pressure through the input, the disc swings off the seat to allow the fluid through and when the flow stops and the pressure drops, the disc swings back into the seat into a closed position. This closing motion blocks any reverse flow. How heavy the disc is impacts on how the valve shuts off.

A double check valve, meanwhile, features two check valves assembled together. This means one of the valves will always work, even if the other is stuck. Also, if one of the valves is closed, the pressure is reduced, meaning the valve is more likely to provide a good seal and prevent backflow.

Why are check valves needed?

Without a check valve, water hammer can occur. Also known as hydraulic shock, water hammer is where a surge of fluid changes direction and causes a wave. This wave can cause major damage to your piping, such as ruptures, or the pipes might even collapse altogether.

Therefore, these valves are added to keep the fluids flowing in the right direction.

Where are check valves used?

There are different applications for check valves, and they’re found in almost every industry. They’re used on the outlet side of pumps, such as centrifugal pumps. These valves are also found in commercial and industrial settings in heating, ventilating, and air conditioning (HVAC) systems. For instance, they will be used in large office buildings where coolants are used.

In industrial applications, they’re used on boilers, gas systems, and furnaces, as well as vacuum systems. They’re also used in domestic settings. Dishwashers and washing machines depend on these check valves for controlling flow direction.

Why choose RS for check valves?

We stock a full range of check valves that are designed to efficiently and effectively control the flow of fluids. We are a leading authorized distributor of check valves in North America and stock leading names, so you’re assured of the highest quality products. Additionally, each of our check valves meet the highest industry and safety standards.

Should you have any questions, our team is on hand to help. Contact us today for advice. You can also find tips in our expert content hub.