Are you curious about check valves and want to understand them better? Whether you’re a maintenance engineer or project manager, understanding check valves is essential for maintaining and troubleshooting production lines and process systems.
In this ultimate guide, we delve into different types of check valves, their functions, and the benefits they offer. We’ll discuss the importance of preventing backflow and potential risks associated with an ill-fitting valve. Lastly, we’ll explore common applications of check valves and answer frequently asked questions.
So, if you’re ready to become an expert on check valves, let’s dive in and unlock the secrets to a well-rounded understanding of these important plumbing and process components.
How do check valves work?
Check valves are mechanical devices that allow fluid to flow in one direction while preventing reverse flow. They are designed to open and close automatically, based on the pressure of the fluid passing through them. When the pressure on the inlet side is higher than the outlet side, the valve opens, allowing the fluid to flow. If the pressure on the outlet side becomes higher, the valve closes, preventing backflow.
This type of valve operates on the principle of differential pressure. This means that they rely on the pressure differential between the inlet and outlet sides to function properly. The mechanism inside traditional valves is typically a swinging or pivoting element that moves in response to the pressure changes. This simple design has become common place in both plumbing and processing.
One of the key advantages of check valves is their ability to operate without the need for any external power source. They rely on the fluid pressure to open and close, in theory, making them reliable and low-maintenance components. However, maintenance engineers will know that this isn’t the case in practice. Spring operated check valves require regular maintenance to prevent failure and resulting backflow.
Types of check valves
Swing check valves
Swing check valves are one of the most common types of check valves used in plumbing systems, such as in toilet tanks. They consist of a hinged disc or flap that swings open to allow flow in one direction and closes to prevent backflow; they are generally installed in horizontal flow. Swing check valves are suitable for applications where a full flow is required and are commonly used in sewage systems, wastewater treatment plants, power plants, oil and gas refineries and other industrial processes. This type of check valve is slower to close, prone to slamming, and isn’t suitable for pulsating flow.
Lift check valves
Lift check valves, also known as piston check valves, operate by the movement of a plug, disk or ball that lifts off the seat to allow flow in one direction. When the flow reverses, the disk, plug or ball settles back onto the seat, preventing backflow. Lift check valves are often used in water or steam systems, but they can be used in a variety of industries depending on the process. This type of check valve is very susceptible to wear and tear and may cause pressure drops.
Ball check valves
Ball check valves, as the name suggests, feature a ball inside the valve body that moves up and down to control the flow of fluid (the ball can also be spring-loaded). When the pressure on the inlet side is higher, the ball is pushed up, allowing flow. In contrast, when the pressure on the outlet side increases, the ball settles back into place, blocking the flow. Ball check valves can be installed in horizontal or vertical positions and are commonly used in fire protection, irrigation/water supply systems, as well as in the oil and gas industry.
This type of check valve is prone to slamming, may wear quickly and require higher cracking pressures. The cracking pressure of a non-return valve is the specific pressure at which the valve begins to open. When the upstream pressure exceeds the cracking pressure, the valve opens, allowing fluid to flow through. Below this pressure, the valve remains closed, and no flow occurs. For example, for a lift valve the cracking pressure is the pressure at which the ball, disk or plug begins to lift from the seat and liquid can flow. Cracking pressure is usually measured and expressed in millibars.
Spring check valves
Spring check valves feature a spring-loaded disc or piston that controls fluid flow. When the inlet pressure is higher, it overcomes the spring force, allowing flow. If pressure on the inlet side is higher, it pushes the disc/piston open against the spring to allow flow. Consequently, when pressure is higher on the outlet side, the spring forces the disc/piston closed to block backward flow. Forms of spring-loaded check valves are very common in the manufacturing, chemical and industrial sectors. This type of check valve requires higher cracking pressures, can be susceptible to vibration, and needs frequent maintenance due to spring fatigue.
Magnetic Spring Valves
Magnetic Spring valves utilise the patented YGROS magnetic technology instead of a traditional spring mechanism. When inlet pressure rises, the magnetic force is overcome, allowing flow. As the outlet pressure increases, the magnetic force automatically closes the valve to prevent backflow. Magnetic Spring valves can be used in any industry and there is a range of different valves for different applications. These types of valves are almost maintenance free, have faster closing times and longer lifespans than traditional check valves.
Installation and maintenance of check valves
Proper installation of check valves is essential to ensure their optimal performance and longevity. Install valves in the correct orientation with the flow direction clearly marked on the valve body. It is important to follow the manufacturer’s instructions and recommended guidelines for installation to avoid any potential issues. Traditional check valves require regular maintenance to check for any signs of wear, corrosion, or damage that may affect their operation. Cleaning and lubrication of moving parts will extend the lifespan of the valve and prevent malfunctions.
When installing check valves in a system, it is crucial to consider factors such as the type of fluid, pressure levels, temperature, and flow rate. Proper sizing and selection of check valves based on the system requirements will ensure efficient operation and prevent any potential issues down the line. Regularly inspect and test your check valves to identify any issues and address them promptly to avoid costly repairs or replacements.
Common applications of check valves
Check valves are used in various industries and applications to control the flow of fluids and prevent backflow. In the plumbing industry, they are found in water supply systems, sewage systems, sump pumps, and irrigation systems. Here, they maintain proper flow direction and prevent contamination. They are also used in heating and cooling systems, fire protection systems, and chemical processing plants to ensure the safety and efficiency of the operation.
Check valves play a crucial role in the oil and gas industry, controlling the flow of oil, gas, and other fluids in pipelines and storage tanks. They help to prevent the backflow of hazardous materials and ensure the integrity of the system. Applications for check valves include power generation plants, marine applications, and food and beverage processing to maintain the proper flow of fluids and protect equipment from damage. The versatility and reliability of check valves make them indispensable components in a wide range of industries.
Conclusion
In conclusion, check valves are essential components in controlling the flow of fluids and preventing backflow. Understanding the different types of check valves, how they work, and their applications is crucial for ensuring the efficient and safe operation of process systems. By choosing the right type of check valve for the specific application and following proper installation and maintenance practices, you can ensure the longevity and reliability of the valve.
Whether you are a maintenance engineer, project manager, or a professional in the industrial sector, having a solid understanding of range of available check valves is key to optimising your process. So next time you encounter a check valve failure or are carrying out maintenance (yet again!), consider how much time a magnetic check valve would save you.
Find out more about the range of valves available from Ygros here.