Check valve is a kind of valve that automatically controls the unidirectional flow of fluid. It is usually used to prevent the backflow of media and ensure the normal operation of the system. In the pipeline system,
the check valve can be opened in the direction of fluid flow. When the fluid stops or reverses flow, the valve automatically closes to prevent liquid or gas backflow in the system and avoid equipment damage or abnormal operation.
Check valves are mainly divided into several types according to different structural principles. Each type has its applicable application scenarios and characteristics. Next, we can introduce different types of check valves in detail.
Common Check Valve Types:
Check valves come in various types, each designed to meet specific operational needs. Understanding these types is essential for selecting the right valve for your system,
ensuring optimal performance and preventing backflow issues.
Ball Check Valve:
Spherical check valves use a free-floating sphere as the closing element, which is pushed back against the seat by the reverse flow of fluid, automatically closing the valve. This design is simple, suitable for smaller pipe diameters and low pressure systems, and is easier to install. However, because the sphere is susceptible to dirt, special attention should be paid to cleaning when in use.
Ball check valves are not suitable for high viscosity liquids or fluids containing particles and are prone to jamming or wear.
Swing Check Valve:
Uses a swinging disc inside the valve body. As fluid flows in the forward direction, the disc opens, allowing fluid to pass through. When the fluid direction reverses, the disc swings back to the closed position, preventing reverse flow. Suitable for applications requiring minimal pressure drop, This design is simple in construction and widely used, and is especially effective in systems with large pipe diameters. For high flow applications, swing check valves are very effective, but require sufficient space for free flap swing.
such as wastewater treatment plants to prevent sewage backflow and in pump stations to prevent water flow reversal after pump shutdown.
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Lift Check Valve:
Features a vertically moving valve disc. When fluid flows in the specified direction, the disc lifts to allow fluid to pass through. In reverse flow, the disc quickly closes. Suitable for high-pressure differential systems, such as in petroleum and natural gas pipelines. Also used in boiler feedwater systems to prevent backflow.
Lift check valves have better sealing performance, but the flap may wear out faster with high frequency opening and closing, so periodic inspection is required.
Source:engineerscommunity
Diaphragm Check Valve:
Utilizes a flexible diaphragm's response to fluid pressure. When fluid flows in the predetermined direction, the diaphragm bends, allowing fluid to pass through. In reverse flow, the diaphragm returns to its original state, preventing backflow. Suitable for applications with variable flow rates, such as preventing corrosive media backflow in the chemical industry and preventing cross-contamination in food processing. Also used in water treatment systems.
Diaphragm check valves are suitable for dirty water, corrosive liquids, etc., but are ideal for applications with lower flow rates.
Source:industrialspec
Tilting Disc Check Valve:
Designed with a tilting disc that easily opens during forward flow and quickly closes during reverse flow. It has a high response speed，Suitable for high-speed fluid and high-pressure differential environments, such as in hydroelectric power stations and commonly used in the chemical and petroleum industries.
This type of check valve is very effective in high flow rate or high flow applications but also requires a high flow rate through the system to ensure proper operation.
Source:orbinox
Wafer Check Valve:
Lightweight design suitable for limited installation space. Typically installed on flange connections, it has a simple structure and lower pressure drop. The valve flap adopts a two-piece symmetrical design, which can effectively prevent backflow. It is very suitable for small and medium-sized pipelines and some applications that need to save space. Commonly used in limited installation spaces, such as air conditioning systems and some light industrial applications. Suitable for situations that require an economically compact design.
Although the design is simple and space-saving, it may not be as stable as other types of check valves for larger flows or complex conditions.
Source:povbutterflyvalve
Dual Plate Check Valve:
The double flap check valve adopts two symmetrical flaps, which will close when the fluid flows backward. It has the advantages of fast closing and small pressure loss, and is suitable for large flow and high pressure pipelines.
This type of check valve is suitable for high-pressure systems and is especially common in industries such as oil and gas. The design is compact and can withstand high flow rates.
Source:prmfiltration
Silent Check Valve:
Silent check valves usually adopt a double flap design and reduce the sound of fluid impact by special cushioning devices, which can effectively reduce the water hammer phenomenon during backflow. This type of valve is particularly suitable for environments where noise control is a requirement.
Silent check valve is very suitable for industrial facilities and civil buildings in the place of high noise requirements, but its structure is relatively complex, the installation requires special attention to the selection of the valve.
Source:landeevalve
The following is a table comparing the various types of globe valves.
| Valve Type | Applicable Fluids | Applicable Pipe Size/Flow Range | Response Speed | Pressure Range | Sealing Performance | Maintenance Requirements | Common Issues | Cost |
| Ball Check Valve | Low-viscosity fluids, no particles | Small to medium pipe sizes | Fast | Low to medium pressure | Fair | Requires regular cleaning | Ball blockage or wear | Low cost |
| Swing Check Valve | Water, gases, and general fluids | Medium to large pipe sizes | Medium | Medium to high pressure | Good | Periodic inspection of the disc | Insufficient disc swing space | Medium cost |
| Lift Check Valve | Medium to high viscosity fluids | Medium pipe sizes | Medium | Medium to high pressure | Very good | Periodic inspection of disc wear | Disc jamming or severe wear | Medium cost |
| Diaphragm Check Valve | Corrosive, dirty fluids | Small to medium pipe sizes | Medium | Low to medium pressure | Excellent | Regular inspection of diaphragm | Diaphragm damage or aging | High cost |
| Tilting Disc Check Valve | High flow fluids | Large pipe sizes | Fast | High pressure | Good | Regular inspection of disc and seat contact | Vibration or noise at high flow | High cost |
| Wafer Check Valve | Moderate pressure fluids | Small to medium pipe sizes | Medium | Medium pressure | Good | Proper maintenance, avoid blockage | Seal failure or debris jamming | Low cost |
| Dual Plate Check Valve | Water, gases, and general fluids | Medium to large pipe sizes | Fast | High pressure | Good | Periodic inspection of plates and springs | Spring fatigue or plate damage | Medium to high cost |
| Silent Check Valve | Water, gases, and general fluids | Medium to large pipe sizes | Fast | High pressure | Excellent | Regular inspection of buffer mechanism | Water hammer, excessive noise | High cost |
These types of check valves have specific characteristics in design and operation, so choosing the right one requires consideration of specific application needs, fluid properties, and pressure conditions.
What are The Key Considerations When Choosing a Check Valve for an Application?
These types of check valves have specific characteristics in terms of design and operation, etc. Therefore, the selection of a suitable check valve requires consideration of the specific application requirements, particular fluid characteristics and pressure conditions. The following are factors to consider:
Fluid compatibility:
All check valves are designed for specific fluid types. For example, solids are inevitable in raw wastewater or sewage applications, which can cause numerous operational problems. In this case, the fluid characteristics should be taken into consideration to ensure that the valve will work properly.
Fluid Characteristics：
Select the check valve that is appropriate for the fluid in your pipeline. For example, corrosive fluids, fluids containing solid particles or high viscosity fluids require different types of valves.
The valve needs to be able to withstand the operating temperature and pressure of the fluid, especially in high temperature and high pressure environments.
Whether it is a liquid, gas or gas-liquid mixture, the check valve chosen needs to be able to adapt to the different physical properties of the fluid.
Flow Characteristics：
The speed at which a check valve opens and closes can have an impact on the entire system. Rapid closing prevents upstream equipment, such as pumps, from being hit, but it also increases the likelihood of surges.
Head Loss：
Head loss is affected by fluid velocity and the internal design of the valve. Valves with narrower openings increase fluid velocities compared to piping, thereby increasing head loss. Conversely,
if the valve is designed with fewer restrictions, head loss can be minimized to ensure that it does not affect the performance of the entire system. Metrics such as zeta, Kv and Kvs values should be considered when evaluating head loss.
Total Cost of Ownership:
The cost of a check valve exceeds its purchase price. The costs of installation, maintenance and energy consumption are also important considerations. Simple valve construction usually requires less maintenance,
while high Kv values reduce energy costs. It can be seen that evaluating the total cost of a check valve over its entire service life also needs to be taken into account.
Non-Sliding Characteristics:
Check valves that slide can cause surges that put pressure on the piping and generate noise. To prevent this, the valve should close slowly and in a controlled manner as it approaches the closed position.
Auxiliary equipment such as hydraulic dampers can cushion the valve, reducing kinetic energy and pressure spikes. Swing check valves with a disc in the flow of water have better anti-slip characteristics and offer advantages in avoiding water hammer.
Maintenance and Durability：
Some check valves, such as ball check valves, may require more frequent maintenance and cleaning to prevent clogging or damage. In contrast, tilting disk check valves and double flap check valves are simpler to maintain.
In systems with long operating cycles, selecting durable and reliable valves (e.g., double flap check valves, silent check valves) can reduce breakdowns and downtime.
Installation space and structure：
Some check valves (e.g., pinch-type check valves) are compact and suitable for applications where space is limited. If there is enough space, you can choose a larger diameter swing check valve or lift check valve.
Whether the installation direction and position affect the normal operation of the valve. Some valves may have requirements for installation angle or piping configuration.
Reverse Flow Prevention Effectiveness：
If the system needs to prevent transient reverse flow, it is better to choose a check valve with fast response time (e.g., double flap check valve or silent check valve).
Water Hammer Effect Control: Certain check valves (e.g., Silent Check Valves) are designed with the reduction of the water hammer effect in mind, especially for noise-sensitive environments.
It should be noted that if the check valve is installed in reverse, the valve flap will not close properly and the seal will fail, resulting in fluid backflow, system instability, increased wear and tear and possible water hammer.
In addition, reverse installation may cause damage to the valve and shorten its service life.
It is also recommended that regular inspections and maintenance be carried out according to operating conditions, fluid characteristics and valve type, usually every 2-5 years. If performance degradation or damage exists,
it should be replaced in time to ensure safe and stable operation of the system.
By considering these factors, you can extend the life of your check valves to meet your specific application while reducing production costs!
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