A check valve primarily protects against the reverse flow of liquid, safeguarding pumps, hydraulic cylinders, and some other piping systems. Choosing the right hydraulic check valve can increase the efficiency of your hydraulic system and save on maintenance and downtime.
Here we will list eight of the most popular ones, along with applications to help you to decide which one is the best for your system.
8 Common Types of Check Valves
Ball Check Valve
Inside a ball check valve, there is a steel ball. When the fluid is moving in the right direction, pressure will push the ball away from the seat, thus creating a path for the liquid to flow without interruptions. If the fluid attempts to move in the opposite direction, the ball is pushed back against the seat, blocking the flow.
The ball rotates as the fluid passes, thanks to its spherelike shape, helping small particles to flow through, and not get hung up in the valve. This means it is particularly ideal for thicker oil or small impurities. Additionally, the design is simple, cost-effective, and offers a relatively long service life.
However, under high-pressure conditions, its sealing performance will weaken, and internal leakage may occur. Therefore, it’s best used in medium and low pressure hydraulic circuits, such as lubrication lines, cooling circuits, or oil return pipelines.
Swing Check Valve
In hydraulic systems, if you want to maintain high flow while minimizing energy loss, swing check valve is often the preferred choice. This valve uses a hinged flap to control fluid passage. When fluid flows forward, the flap is pushed open, allowing liquid to pass freely. If the flow reverses, the flap swings back automatically, sealing the passage and preventing backflow.
Swing check valve relies on the influence of the operation of gravity flow to automatic shut-off, suitable for horizontal or slightly inclined to the pipeline. They have very low flow resistance and minimal pressure drop, which makes them perfect for large-diameter pipes and applications requiring high flow rates. You can use them in water management, petrochemical systems, and wastewater treatment.
Nevertheless, their response speed is slower than spring-loaded check valves. In high-frequency switching or systems needing instant closure, they may not perform well, which may accelerate wear and lead to seal failure.
Lift Check Valve
A lift check valve, sometimes called a piston check valve, works by lifting the valve disc when fluid flows forward, allowing the liquid to pass smoothly. When the fluid flows in the opposite direction, the valve disc will fall back to the valve seat under the assistance of gravity or spring, preventing backflow. These valves are typically used in vertical pipelines or hydraulic systems that rely on gravity for operation.
Its robust structure makes it well-suited for medium to high pressure environments. However, you need to ensure the fluid is clean, as excessive particles in the fluid will clog the valve and cause damage. Lift check valves are commonly used in natural gas pipelines, hydraulic pump stations, and industrial equipment that requires continuous, stable operation.
What’s more, keep in mind, the flow resistance inside the check valve is relatively high, so they are not ideal for high-flow pipelines or systems requiring frequent cycling.
If your equipment operates under high pressure and needs reliable backflow prevention, a lift check valve is an economical and durable solution.
Spring-Loaded Check Valve
A spring-loaded check valve uses a spring to help the valve core reset quickly and prevent medium backflow. Compared with a ball check valve, it responds faster and seals more tightly, working reliably even under low flow or low pressure conditions. Therefore, it is highly popular in hydraulic systems.
Compared to other types of check valves, it can be installed flexibly. You can place it horizontally, vertically, or on inclined pipelines. Moreover, it has a compact structure and can withstand high pressure. If you want to maintain stable hydraulic performance under demanding conditions, a spring-loaded check valve is an excellent choice.
Its drawbacks are also quite obvious. When you use it, the spring will generate resistance, which will increase the pressure drop in your hydraulic system. For a long time, it is easy to weaken the strength and elasticity of the spring that will shorten the service life of the check valve. Therefore, it is necessary for you to regularly inspect and maintain the check valve so that the hydraulic system works efficiently.
Diaphragm Check Valve
Diaphragm check valves often control flow by a flexible rubber. When liquid moves in the intended direction, the diaphragm lifts or bends, allowing the fluid to pass. If the flow tries to reverse, the diaphragm presses against the seat, creating a seal that prevents backflow.
This type of valve is simple, lightweight, corrosion-resistant. The diaphragm is not as easy to get stuck in as a metal check valve, so it is very suitable for handling liquids containing impurities or particles. Besides, the diaphragm material complies with safety and hygiene standards. This makes it appropriately be used for food, pharmaceutical, and corrosive fluid fields. Also lower the difficulty and cost of operation.
Nonetheless, the pressure resistance and service life of diaphragm check valves are not as good as those of other types of check valves. They are less suitable for high-pressure or fast-flow conditions. If you need a cost-effective, lightweight valve for low-pressure systems, a diaphragm check valve can be a smart choice.
Pilot-Operated Check Valve
A pilot-operated check valve works like a standard check valve under normal conditions, preventing backflow. The difference is that it can open the valve core using an external pilot oil signal, allowing controlled reverse flow. This design is especially useful in hydraulic systems where cylinder position must be maintained, such as hydraulic lifts, injection molding machines, or clamping devices.
The biggest advantage of a pilot-operated check valve is safety and control. It lets you release or unload fluid in a controlled way without compromising the normal anti-backflow function.
Although its cost and complexity are higher than ordinary check valves, it can hold position during power loss or shutdown, preventing equipment from dropping. If you need a check valve for hydraulic systems with high safety standards and precise control, a pilot-operated check valve is the ideal choice.
Wafer Check Valve
A wafer check valve is a type of valve that opens and closes automatically using fluid pressure. Its disc is usually single or double-leafed. When fluid flows forward, it pushes the disc open, allowing smooth passage; when the flow reverses, the disc quickly shuts, preventing backflow.
The wafer design is compact and lightweight, saving installation space and reducing the need for pipe supports. Its wafer-style connection makes installation and removal faster, lowering maintenance effort. At the same time, the valve offers low resistance when open, helping reduce energy consumption and improve pipeline efficiency. It’s widely used in water treatment, HVAC systems, power generation, and chemical fluid transport.
Wafer check valves also have some limitations. Because they rely on fluid pressure to operate, their sealing may be less reliable with high-viscosity fluids or under low-pressure conditions compared to spring-loaded valves. The valve body also has limited pressure capacity, so it’s not ideal for high-pressure, large-diameter pipelines, or fluids containing particles, as this can cause wear, jamming, and shorten service life.
Cartridge Check Valve
A cartridge check valve operates by allowing the valve core to open or close automatically under fluid pressure. The core can shut quickly, preventing any backflow.
Its compact size makes it ideal for integrating into complex hydraulic systems, enhancing overall reliability. With short internal flow paths, it experiences relatively low pressure loss and responds rapidly, making it suitable for applications that demand high efficiency and fast opening and closing. You’ll often find it used in hydraulic circuits and industrial machinery.
Additionally, cartridge check valves can handle high pressure, so they’re well-suited for demanding systems. However, since all components are built inside the unit, any malfunction requires complex maintenance. Servicing it demands skilled personnel and careful handling.
Factors You Need to Consider When Choosing Check Valves
Material of the Check Valve
Metal
Stainless steel and brass are commonly used as materials for metal check valves. Stainless steel has excellent durability and corrosion resistance, making it suitable for use in the ocean or corrosive fluids.
Compared to stainless steel, brass has average corrosion resistance and is better suited for low-pressure water or air systems. It also comes at a slightly lower cost than stainless steel, which can help you control budget without compromising basic performance.
Plastic
Common plastic check valves include PVC, PP, PVDF, etc. They are lightweight and offer decent corrosion resistance, with more affordable than metal check valves. However, its pressure and temperature resistance are lower than that of metals, and it is prone to aging or cracking. Because of that, you shouldn’t use them in high-pressure or high-temperature systems.
Rubber
Diaphragm check valves use rubber materials such as EPDM or Teflon, which helps minimize the risk of fluid contamination. Still, you need to be cautious. Certain chemicals can easily corrode EPDM and affect the sealing effect. So you had better double-check material compatibility before making a choice.
Media Characteristic
Liquid
For liquid media, you usually need a check valve with tight sealing, low flow resistance, and materials that can resist corrosion and wear. You can choose swing or lift check valves. But if the fluid contains particles, a ball check valve will be more suitable. You can also use wear-resistant valve seats or add filters to avoid blockage.
Gas
When gas flows, the pressure drop is relatively low, but it requires the check valve with higher sealing and pressure resistance. Spring-loaded and lift check valves can satisfy this point.
Slurry
Slurry generally contains solid particles or has high viscosity, which can easily clog valves. In these cases, ball check valves or valves with flap designs are reliable options.
Fluid Speed
Valves may fail to open or close in a timely manner at low flow rates, requiring a design with low opening pressure. A swing check valve is your best option because it creates minimal resistance to the fluid.
When dealing with high flow rates, spring-loaded check valves are more suitable. Due to the strong fluid impact generated by fast-moving fluid, this valve can handle it and quickly close to stop backflow.
Pressure and Temperature
High pressure: Lift check valves or cartridge check valves can be resistant to high pressure without losing reliability.
Low pressure: Diaphragm and swing check valves can better match with low-pressure systems.
High temperature: In high temperature conditions, a metal lift check valve is a good choice.
Installation Space and Direction
If your space is limited, you can use compact valves such as cartridge check valve and wafer check valve.
When you want to install a check valve horizontally, a swing check valve makes more sense since the disc can swing back with gravity.
On the other hand, if your system is vertical, a spring-loaded or lift check valve will perform better, as it can take advantage of gravity or spring tension to support flow.
Conclusion
Choosing a high-quality check valve not only helps your system run at its best but also reduces the risk of costly repairs. Picking the right one is not easy since many factors need to be considered comprehensively.
If you need some help in finding the valve that fits your specific needs, feel free to contact us for professional advice anytime.
