Check valves are a useful type of valve that can be used in a fluid or gas control application to prevent the flow of fluids from moving in more than one direction. Due to their size and versatility, check valves are a helpful addition to a wide array of fluid and process control applications.
So, if you’ve ever found yourself wondering what are check valves or how does a check valve function, read our handy guide below. Find out more about check valve functions, the types of check valves available and the high-quality Parker and Burkert check valves that are available from Fluid Controls.
Here, we will answer the question, ‘what is a check valve?’. Put simply, a check valve, also referred to as a non-return valve or one-way valve, is a valve that allows fluids such as liquids or gases to flow through it in only one direction. A check valve works to prevent any form of backward flow.
Check valves are two-port valves. This means that they have two openings in one body; one for fluid to enter and the other for fluid to exit.
Although they are available in a wide range of sizes and costs, check valves are generally small, simple and inexpensive – therein lies their appeal. They work automatically and, therefore, most do not have any valve handle or stem. The bodies (external shells) of most check valves are made of plastic or metal.
Often, a pressure differential is required for a check valve to function. This means that they require a higher pressure on the input side of the valve than on the output side of the valve to open the valve.
When the pressure is higher on the outlet side, the valve will close. However, thanks to the extensive range of check valves available, the closure mechanism is different for each valve type. As such, check valves do not need a handle, level, actuator, or human to correctly work.
Check valves come in several different types. A ball check valve is a check valve in which the closing member, the movable part to block the flow, is a spherical ball. Whereas a diaphragm check valve uses a flexing rubber diaphragm positioned to create a normally closed valve. A swing check valve, or tilting disc check valve, is a check valve in which the disc, the movable part that blocks the flow, swings on a hinge or trunnion, either onto the seat to block reverse flow or off the seat to allow forward flow.
Meanwhile, a stop-check valve is a check valve with override control to stop flow regardless of flow direction or pressure. A lift-check valve is a check valve in which the disc, sometimes called a lift, can be lifted up off its seat by higher pressure of inlet or upstream fluid to allow flow to the outlet or downstream side. Finally, an in-line check valve is a check valve similar to the lift check valve. However, this valve generally has a spring that will compress when there is pressure on the upstream side of the valve and allow the valve to open.
Here at Fluid Controls, we are experts in the use of check valves across a range of applications, including Parker high-purity check valves. Learn more about our range of check valves by browsing our range.
If you are wondering what are check valves, it’s likely you’ve also found yourself wondering how does a check valve function and in which applications they are used. Check valves are often used when multiple gases are mixed into one gas stream. A check valve is installed on each of the individual gas streams to prevent the mixing of the gases in the original source. For example, if a fuel and an oxidiser need to be mixed, then check valves will normally be used on both the fuel and oxidiser sources to ensure that the original gas cylinders remain pure and non-flammable.
Check valves are used with some types of pumps. Piston-driven and diaphragm pumps, such as metering pumps and pumps for chromatography, commonly use inlet and outlet ball check valves. These valves often look like small cylinders attached to the pump head on the inlet and outlet lines. Many similar pump-like mechanisms for moving volumes of fluids around use check valves, such as ball check valves.
Check valves are also used in many fluid systems, such as those in chemical and power plants. Some examples of applications in the nuclear industry include feedwater control systems; dump lines and monitoring and sampling systems. In aircraft and aerospace, check valves are used where high vibration, large temperature extremes and corrosive fluids are present.
Parker C Series Check Valves are designed for unidirectional flow control of fluids and gases in industries such as chemical processing, oil and gas production and transmission, pharmaceutical, pulp and paper, power and utilities. They feature resilient, custom-moulded, blow-out resistant seat design and a backstopped poppet that minimises spring stress
These check valves are 100% factory tested for both crack and reseat, with cracking pressures ranging from 1/3 through to 100 psi. Port connections include male and female NPT, CPI, A-LOK and Seal-Lok. Plus, heat code traceability ensures complete material accountability.
The Bürkert Type BBS-10 Sterile Check Valve and Strainer is for fluids and steam. The design is such that the flow direction is selectable, making installation simple and very cost-effective. These check valves feature fully traceable wetted materials (traceable seal also available) and are suitable for CIP and SIP applications.
The construction provides continuous flushing and the unique feature of the eccentric check valve is that it can be mounted in the horizontal position and will self-drain until empty providing the correct angle is achieved according to standard installation techniques.
We hope we have helped you to get some insight into what is a check valve and what a check valve’s function is. If you would like to find out more about how different pressure control products work and plenty of other handy articles, take a look at our news page.
Speak to a Fluid Controls adviser today if you would like to discuss your check valve requirements or talk to us about our wide range of other products by calling +44 (0) 118 970 2060 or email fluid@fluidcontrols.co.uk.