In industrial processes, where fluid flow control is critical, valves play an essential role in maintaining system efficiency and safety. Among these, the lift check valve stands out as a crucial component designed to prevent backflow and maintain smooth operation in high-pressure environments. This blog will break down what a lift check valve is, its primary function, common applications, and key benefits, all while offering practical advice for choosing and maintaining them.

 

What Is a Lift Check Valve?

A lift check valve is a type of one-way valve that allows fluid to flow in only one direction, preventing reverse flow. This is crucial in maintaining the integrity and performance of various industrial systems, where backflow can cause damage, contamination, or equipment failure. It is specifically designed for high-pressure systems where the velocity of flow is high.

The valve consists of a disc or piston that “lifts” when flow enters below the valve seat, allowing the fluid to pass. When the flow stops or reverses, gravity and backpressure push the disc or piston back to its seat, effectively blocking reverse flow. This self-activating mechanism ensures that fluid flows only in the intended direction, thereby preventing backflow issues.

 

How Does a Lift Check Valve Work?

A lift check valve is a type of valve that is used to control the direction of fluid flow within a piping system, ensuring that the flow occurs in only one direction. Its primary function is to prevent backflow, which could potentially cause contamination, damage to the system, or system inefficiencies. This is achieved by using an internal mechanism, typically a disc or ball, which is lifted from its seat when fluid flows in the desired direction, and then closes under the pressure of reverse flow to block the passage.

The operation of the lift check valve is relatively simple but highly effective. The valve typically features a disc or ball that is mounted in the valve body. In the normal flow direction, the disc or ball is lifted off the valve seat by the fluid pressure, allowing the fluid to pass through. When the flow direction reverses, the pressure from the backward flow pushes the disc or ball back onto the seat, preventing the fluid from flowing in the wrong direction.

Lift check valves are designed to function automatically without the need for external control, making them a reliable and efficient option for various applications. These valves are commonly used in piping systems where the prevention of backflow is critical, such as in water treatment plants, chemical processing, and power generation systems. The valve’s construction allows it to be installed in both horizontal and vertical piping systems, with some designs tailored for specific applications like high-pressure or upward flow systems.

In summary, a lift check valve ensures the integrity of a fluid system by automatically blocking reverse flow, thereby preventing contamination and damage. This makes it an essential component in many industries requiring controlled and directed fluid flow.

 

Types of Lift Check Valves

There are various types of lift check valves, each suited to different operational conditions and system requirements. Below are the common types of lift check valves:

Standard Lift Check Valves

These are the most basic type of lift check valve. They feature a simple design where a disc lifts off the valve seat when the flow pressure is sufficient. The disc automatically reseats when the flow stops or reverses. This type is commonly used in systems where the flow is steady and does not fluctuate greatly. They are typically used in general applications such as water and steam systems.

Spring-Loaded Lift Check Valves

source: NTGD

These valves incorporate a spring mechanism that assists in closing the valve more quickly and precisely. The spring ensures that the valve closes more securely, even when the flow rate is low or if there is a need for more rapid sealing to prevent backflow. These are commonly used in systems with lower flow rates or those that require a more rapid valve closure, such as in certain water or chemical processing systems.

Angle Pattern Lift Check Valves

source: IMPA

Angle pattern lift check valves have a design that allows them to be installed at an angle, often 45 degrees, to the pipe. This design is ideal for systems where space is constrained, and traditional straight-line installation is not feasible. The angled design facilitates easier installation and may also reduce the amount of pressure drop in certain applications. These valves are often used in industrial plants, particularly where space optimization is essential.

Tilting Disc Lift Check Valves

A specialized version of lift check valves, tilting disc lift check valves are equipped with a disc that tilts rather than lifting straight up. The tilt mechanism allows for faster closure and minimizes the possibility of backflow in high-flow applications. These valves are ideal for systems with high-pressure and high-flow conditions, such as in power stations and large-scale pumping systems.

Nozzle Check Valves

Source: Abacus Valves

Nozzle check valves are designed for rapid closing and are often used in high-pressure systems. The disc is connected to a stem that is guided along the central axis, and a spring helps to close the valve when flow ceases. These valves are typically used in applications where quick closure is critical to prevent water hammer or reverse flow, particularly in power plants and high-velocity water systems.

 

Advantages and Disadvantages of Lift Check Valves

Advantages:

• Simple Design and Easy Maintenance: Lift check valves are known for their straightforward design, making them relatively easy to manufacture and maintain. The design typically involves fewer components, reducing the chances of failure and making repairs simpler when necessary.
• Fast Response to Flow Changes: These valves respond quickly to changes in flow direction, which minimizes the risk of backflow and protects downstream equipment from potential damage caused by reverse flow.
• Low Pressure Drop: Compared to some other types of check valves, lift check valves usually have a lower pressure drop across the valve. This characteristic improves system efficiency, especially in systems requiring a stable and uninterrupted flow.
• Versatility in Applications: Lift check valves are widely used across industries, including water supply systems, pipelines, and chemical processes. They can handle a variety of fluids and are adaptable to different service conditions, including high-pressure systems.
• Reliable Shutoff: Due to their unique design, lift check valves offer an effective seal and tight shutoff, often superior to swing check valves. This ensures that no backflow occurs under typical operating conditions.

Disadvantages:

• Risk of Water Hammer and Noise: One notable disadvantage of lift check valves is the potential for water hammer—a sudden pressure surge caused when the valve disc slams shut. This phenomenon can lead to noise, vibration, and even damage to the valve and the surrounding piping system, especially at high velocities.
• Potential for Disc Slamming: In high flow velocity applications, lift check valves may experience “slamming,” where the disc moves too quickly to the closed position. This can result in wear on the valve components, reducing the valve’s operational lifespan.
• Limited Flow Control: While lift check valves excel at preventing backflow, they are not designed to control flow rates precisely. This can be a limitation in processes where fine adjustments to flow are required.
• Inapplicability in Low Flow Conditions: Lift check valves may not function well in low-flow scenarios. The disc or piston may not lift effectively under these conditions, leading to potential failure in maintaining the desired flow direction.
• Complex Installation Requirements: These valves often require specific installation orientations to operate effectively, especially when gravity plays a significant role in their function. Improper installation can lead to operational failures, necessitating careful planning during setup.

 

Applications of Lift Check Valves

Water Supply Systems: Lift check valves are commonly employed in water pumping stations to prevent the backflow of water when the pumps are stopped. This application is crucial in maintaining consistent water flow, protecting pumps and other system components from potential damage caused by reverse flow.

Chemical Processing: In chemical processing plants, lift check valves are used to ensure the safe, one-way flow of various chemicals. By preventing reverse flow, they protect sensitive equipment such as pumps and heat exchangers, which could be damaged by backflow or contamination.

Oil and Gas Industry: Lift check valves are vital in oil and gas pipelines, as they control the flow of petroleum products, gases, and other fluids. These valves prevent backflow, which could lead to hazardous conditions or contamination of the pipeline contents, thereby ensuring the safety and efficiency of operations.

Steam Power Generation: In power plants, lift check valves are crucial for maintaining the correct flow direction of steam within steam lines. By preventing backflow, these valves enhance the efficiency of power generation systems and ensure that the steam flows only in the intended direction, optimizing plant performance.

Wastewater Treatment: Lift check valves are used in wastewater treatment plants to prevent reverse flow of treated or untreated water. This application helps safeguard the treatment process and equipment, ensuring that water flows in a controlled and predictable manner, preventing contamination and equipment malfunction.

Food and Beverage Industry: In the food and beverage sector, maintaining sanitary conditions is paramount. Lift check valves ensure that fluid flow is unidirectional in production lines, preventing contamination of ingredients and ensuring compliance with health and safety regulations.

 

Materials Used in Lift Check Valves

Lift check valves are crafted from various materials, each chosen for specific properties to ensure the valve’s durability and functionality under varying conditions. The materials used in these valves must meet stringent performance requirements, including corrosion resistance, high-pressure tolerance, and compatibility with the fluid being transported.

Stainless Steel: Stainless steel is a prevalent choice due to its excellent corrosion resistance and ability to withstand high pressures and temperatures. This material is often used in lift check valves designed for critical industries such as petrochemical, chemical processing, and high-temperature systems. The material’s durability makes it suitable for harsh environments where the valve may be exposed to aggressive fluids or extreme conditions.

Cast Iron: Cast iron is a common material for lift check valves, particularly in larger pipeline systems or applications involving lower-pressure conditions. Its durability, combined with a relatively low cost, makes it a preferred option for many industrial settings. However, cast iron may not perform as well as stainless steel in environments where corrosion is a significant concern, such as saltwater systems.

Brass and Bronze: Brass and bronze materials are often chosen for applications requiring a combination of strength and resistance to corrosion, especially in systems handling non-corrosive fluids like water. These materials are frequently used in smaller lift check valves for HVAC systems, potable water systems, and other industrial applications where corrosion resistance is important but high pressure is not a primary concern.

PVC (Polyvinyl Chloride): In applications involving non-corrosive fluids, PVC is a cost-effective choice for lift check valves. It is lightweight, resistant to chemical attacks, and easy to install. PVC valves are commonly used in low-pressure systems, such as in agricultural irrigation or swimming pool systems, where they can withstand a variety of non-abrasive fluids.

Elastomers (Rubber or Other Soft Materials): Elastomers are frequently used for the sealing components of lift check valves. The rubber sealing ring or diaphragm helps to create a tight seal, preventing leaks and ensuring that the valve functions properly. The choice of elastomer depends on the chemical nature of the fluid and the operating temperature. Materials like nitrile rubber, EPDM (ethylene propylene diene monomer), and Viton are commonly used for their chemical resistance and flexibility.

 

Comparing Lift Check Valves to Other Check Valve Types

Feature	Lift Check Valve	Swing Check Valve	Tilting Disc Check Valve	Ball Check Valve
Design	Disc lifted off its seat by fluid flow, gravity or reverse flow forces it back.	Hinged disc swings open with fluid flow, closes with reverse flow.	Disc tilted in the direction of flow, combining swing and lift design.	Ball that moves within the valve body to block reverse flow.
Flow Characteristics	Suitable for low to moderate flow, works well in steady flow systems.	Ideal for high flow rates and steady flow conditions.	Best for high-velocity flow and dynamic systems.	Suitable for low-flow, smaller pipelines.
Pressure Drop	Low pressure drop in moderate flow conditions.	Higher pressure drop due to swinging disc design.	Higher pressure drop compared to lift check valves.	Minimal pressure drop due to simple design.
Response to Flow Reversal	Effective for moderate flow reversals.	Less effective for rapid flow reversal, prone to water hammer.	Provides smooth and controlled closure, better for quick reversals.	Effective for low flow reversals, but not suitable for high-pressure systems.
Applications	Best for systems where moderate flow and reliable backflow prevention are needed.	Used in large pipelines with steady flow conditions, like water supply.	Ideal for high-velocity fluid flows and dynamic systems.	Ideal for smaller applications with limited space and low flow rates.
Size & Space Requirements	Compact, suited for moderate-sized pipelines.	Larger design, requires more space due to hinged mechanism.	Moderate size; requires space for the tilting disc.	Compact design, suitable for smaller pipelines.
Maintenance	Low maintenance; less prone to wear.	Requires more maintenance due to moving parts.	Moderate maintenance; susceptible to wear at higher pressures.	Low maintenance but can be less reliable in large systems.
Water Hammer Resistance	Moderate; susceptible in very dynamic systems.	High susceptibility to water hammer.	High resistance to water hammer, better for rapid flow changes.	Low resistance to water hammer; not ideal for high-pressure systems.

 

Factors to Consider When Selecting a Lift Check Valve

When selecting a lift check valve for a specific application, there are several critical factors that influence its performance, efficiency, and longevity. These factors ensure that the valve meets the specific requirements of the fluid handling system it will be installed in. Below are the primary considerations:

1. Flow Conditions and Media Type

The type of media (liquid, gas, slurry, etc.) flowing through the system significantly affects the choice of a lift check valve. For instance, lift check valves are well-suited for clean fluids but may struggle with highly viscous or particulate-laden fluids unless designed with specific features to accommodate such conditions. The viscosity and density of the media will affect how easily the valve disc lifts and seals.

Additionally, the corrosiveness and chemical properties of the media must be considered to ensure the valve’s materials are compatible. For aggressive fluids, materials like stainless steel or bronze may be necessary to avoid corrosion and ensure long-term durability.

2. Pressure Rating

The valve’s pressure rating is another crucial factor in selection. It must be able to withstand the operating pressures of the system, including pressure surges and transient pressure changes. Lift check valves are often preferred in high-pressure systems, where they provide tight sealing and reliable backflow prevention. The cracking pressure (the pressure required to open the valve) should also align with the system’s requirements, balancing the need for tight sealing with the ability to open under normal operating pressures.

3. Installation Orientation

Lift check valves must be installed horizontally to ensure proper operation. This is because gravity assists in closing the valve disc. Incorrect orientation may lead to valve failure, poor sealing, or inefficient flow control. Therefore, confirming the installation orientation is key when choosing the appropriate valve for the system.

4. Material Compatibility

Materials for lift check valves should be selected based on the operating conditions, including the fluid type, temperature, and potential for abrasive wear. Materials like gunmetal or stainless steel are commonly used due to their resistance to corrosion and wear. Compatibility with the fluid’s chemical properties is essential to prevent degradation over time, especially in applications involving harsh chemicals or extreme temperatures.

5. Sealing and Performance Reliability

Lift check valves are designed to prevent backflow by sealing tightly under low or reversed flow conditions. The sealing mechanism is a key feature of the valve’s performance, ensuring no fluid leakage occurs when the valve is closed. The material and design of the disc and seat are crucial in achieving a reliable seal, especially under varying pressure conditions. The valve must also be able to close quickly and completely to avoid contamination or damage to the system.

6. Maintenance and Durability

While lift check valves are relatively low-maintenance, factors such as the valve’s construction material, flow conditions, and frequency of operation will affect its longevity. Frequent flow reversals, for instance, can cause wear on the internal components, reducing the valve’s performance over time. Therefore, valves should be chosen based on expected service life and ease of maintenance, such as the availability of spare parts and the ease of cleaning or servicing the valve if necessary.

 

Conclusion

Lift check valves are indispensable components in industrial systems where backflow prevention is crucial. Whether you’re working in water supply systems, oil pipelines, or chemical processing, understanding how these valves operate and their importance in maintaining safe, efficient operations is key. By selecting the right lift check valve, installing it correctly, and maintaining it well, you can ensure the long-term success of your fluid control systems.

Tanggong Valve Group offers reliable Lift Check Valves for your systems. Contact us today to ensure optimal performance and backflow prevention.