The Differences Between 4 Common Check Valves | Lift, Swing, Dual Plate & Butterfly, Key Benefits & Industrial Selection Guide

A check valve is a one-way fluid control valve whose main function is to prevent backflow of the medium and ensure the safety and stability of the pipeline system. Check valves can be divided into four categories according to their structure and opening method:
1. Lift check valve
2. Swing check valve
3. Dual-plate check valve
4. Butterfly check valve

In practical applications, lift check valves, swing check valves, dual-plate check valves, and butterfly check valves are the four most common types. Although all four types of check valves have the function of preventing backflow of the medium, they differ significantly in structural design, working principle, applicable scenarios, and installation and maintenance methods.

This article will provide an in-depth comparative analysis of the characteristics, advantages, disadvantages, and applications of these four types of check valves to help users better select the appropriate valve type.

I. Structure and Characteristics of Swing Check Valves

(1) Structure and Working Principle
A swing check valve is a disc that rotates around a pivot pin, similar in structure to a freely swinging door. The working principle of the valve is as follows:
Forward flow: When the medium flows in the set direction, the fluid pressure pushes the valve disc open, allowing the medium to pass through smoothly.
Backflow: When the medium attempts to flow back, gravity or reverse pressure automatically closes the valve disc, thus preventing backflow.

(2) Main Characteristics
Low fluid resistance:
Due to the relatively wide passage of the swing check valve, the medium can flow through the valve relatively freely in the open state, so its pressure loss is small.
General sealing performance:
Because the valve disc of the swing check valve closes by its own weight or reverse fluid pressure, the sealing surface may be impacted by the medium, causing wear.
Flexible installation:
It can be installed on horizontal, vertical, or inclined pipes.
If installed on a vertical pipe, there are requirements for the installation direction; the medium must flow from bottom to top to ensure the normal operation of the valve disc.
Suitable for large-diameter pipes:
Swing check valves are usually used in large-diameter pipes because their design allows for high flow rates and can accommodate large pressure fluctuations.

(3) Applicable Scenarios
Water treatment systems: Widely used in water supply, sewage treatment plants, pumping stations, etc.
Oil and gas industry: Suitable for conveying high-temperature, high-pressure media.
Power industry: Used in boiler feedwater systems to prevent water hammer.
Chemical industry: Suitable for corrosive or high-viscosity fluids.

II. Structure and Characteristics of Lift Check Valves

(1) Structure and Working Principle
The main components of a lift check valve are the valve disc and valve seat. Its working principle is similar to that of a globe valve:
Forward flow: When the medium pressure is high enough, the valve disc is pushed upwards by the fluid, allowing the medium to pass through.
Backflow: When the fluid stops or flows in the opposite direction, the valve disc falls back onto the valve seat under its own weight and backflow pressure, preventing backflow.

(2) Main Characteristics
Good sealing performance:
Because the valve disc moves vertically and can make close contact with the valve seat, the sealing performance is usually better than that of swing check valves.
High fluid resistance:
Because the fluid needs to change direction within the valve cavity, the fluid resistance of a lift check valve is greater than that of a swing check valve, resulting in higher pressure loss.
Limited installation methods:
Horizontal lift check valves must be installed on horizontal pipes.
Vertical lift check valves must be installed on vertical pipes, ensuring that the medium flows from bottom to top.
Suitable for small-diameter pipes:
Because the lifting movement of the valve disc requires considerable pressure, lift check valves are usually used in small-diameter, high-pressure applications.

(3) Applicable Scenarios
Steam pipelines: Suitable for high-temperature and high-pressure steam systems to ensure safe operation.
Hydraulic systems: Used to prevent liquid backflow and improve system stability.
Chemical and pharmaceutical industries: Suitable for high-purity or corrosive fluids.

III. Structure and Characteristics of Dual-Plate Check Valves

(1) Structure and Working Principle
A dual-plate check valve consists of two symmetrical semi-circular discs, usually installed between pipe flanges. Its working principle is as follows:
Forward flow: When the medium flows forward, the valve discs open to the sides under the pressure of the fluid, allowing the medium to pass through. Reverse Flow: When the medium flows in reverse, the spring force and the reverse pressure of the medium cause the valve disc to close quickly, preventing backflow.

(2) Main Features
Compact structure, lightweight
Low fluid resistance, low pressure loss
Spring-assisted closing to reduce water hammer effect
Flexible installation, can be installed horizontally or vertically
Suitable for large diameter and high flow applications

(3) Applicable Scenarios
Municipal water supply systems
Seawater desalination equipment
Oil and gas pipelines
Boiler water supply systems
Chemical and metallurgical industries

IV. Structure and Characteristics of Butterfly Check Valves

(1) Structure and Working Principle
Butterfly check valves generally refer to low-resistance slow-closing butterfly check valves. They adopt a butterfly structure, and the valve disc's closing speed is controlled by a spring and a damping mechanism.  Its working principle is as follows:
Forward Flow: When the medium flows forward, the valve disc opens under the action of fluid pressure, allowing the medium to pass through smoothly.
Reverse Flow: When the fluid stops or flows in the reverse direction, the spring and damping device work together to slowly close the valve disc, thereby reducing the water hammer effect.

(2) Main Features
Slow-closing design, effectively reducing water hammer impact
Reduces fluid resistance and improves pipeline transportation efficiency
Compact structure, small footprint
Suitable for high-frequency opening and closing situations

(3) Applicable Scenarios
Water supply networks
Fire protection systems
Industrial circulating water systems
Urban sewage treatment

V. Comparative Analysis of Swing Check Valves and Lift Check Valves

VI. Key points for maintenance and upkeep

Before shutting down for maintenance, ensure that the pipeline pressure has been fully released and adhere to safety operating procedures.

When disassembling valves, take care to protect the sealing surfaces to avoid damage.

When replacing parts, please use parts recommended by the original manufacturer to ensure compatibility and durability.

After resuming operation, gradually increase the flow rate and observe whether the valve is functioning correctly.

(1) Maintenance of Swing Check Valves
Regularly inspect the sealing surfaces of the valve disc and seat for wear or accumulation of debris.
Replace aging sealing materials such as rubber or synthetic gaskets promptly.
Ensure the flexibility of the pivot pin to prevent jamming that could hinder the normal swinging of the valve disc.

(2) Maintenance of Lift Check Valves
Regularly clean deposits between the valve disc and seat to prevent sealing failure.
Check that the lifting movement of the valve disc is smooth, avoiding jamming caused by dirt.
Ensure that the spring (if present) is in good condition to maintain the normal movement of the valve disc.

(3) Maintenance of Dual Plate Check Valves
Regularly check that the valve discs open and close flexibly, and that there is no jamming, deformation, or damage.
Observe whether the contact surfaces of the valve discs and seats are worn, corroded, or scaled.
Ensure that the spring mechanism has not suffered fatigue failure; replace the spring if necessary.
Regularly clean dirt, deposits, or impurities inside the valve to prevent valve disc blockage and affect operation.
Lubricate the shaft and hinge components with appropriate lubricant to reduce wear and maintain flexibility.
Ensure that the fastening bolts of the mounting flange are not loose to prevent leakage or vibration from affecting valve performance.

(4) Maintenance of Butterfly Check Valves
Regularly check the sealing performance of the valve to ensure that the valve disc closes completely to prevent backflow of the medium.
Check that the opening and closing of the valve disc are smooth, without jamming or slow movement.
Check if the spring is fatigued or damaged, and replace it promptly.
Ensure that there are no leaks at the connection between the valve and the pipeline, and that the bolts are not loose.

Swing check valves and lift check valves each have their own advantages and disadvantages in terms of structure, performance, and application scenarios. Generally, swing check valves are suitable for large-diameter, low-resistance applications, while lift check valves are more suitable for piping systems requiring high sealing performance and high pressure with small diameters. Double-plate check valves have low flow resistance, low pressure loss, and flexible installation, making them suitable for large-diameter, high-flow applications. Butterfly check valves are suitable for large-diameter systems with high flow rates and low pressure.

In practical applications, the most suitable type of check valve should be selected based on pipe conditions, media characteristics, pressure, and installation conditions to ensure the safety and efficiency of the system.