In the valve industry, gate valves are widely used fluid control devices. Depending on different designs and connection methods, gate valves can be categorized into various types, including threaded bonnet gate valves and regular gate valves. Understanding the differences between them is crucial for selecting the appropriate valve type and ensuring efficient system operation.

1. Valve cover connection method

In a threaded bonnet gate valve, the bonnet is connected to the valve body via threads. This threaded connection makes the bonnet-body connection more compact and reliable, facilitating easier installation and removal.

A regular gate valve's bonnet is typically connected using methods such as flanged connections, bolted connections, or welding. Flanged connections are more common and offer good sealing and strength, but they have a more complex structure, making installation and maintenance relatively cumbersome.

2. Structural Features

The structure of a threaded bonnet gate valve is relatively simple, consisting mainly of the valve body, bonnet, stem, and gate. The stem is fixed to the bonnet through a threaded connection, and the rotation of the handwheel drives the stem to move up and down, achieving the opening and closing of the valve.

Applicable Size: Generally suitable for small diameter pipeline systems, usually below DN50.

The structure of a regular gate valve is somewhat more complex, typically including components such as the valve body, bonnet, stem, gate, and seals. The stem can be connected to the bonnet in various ways, and the handwheel drives the stem and gate to move up and down through a nut or other mechanical device.

Applicable Size: Suitable for small, medium, and large diameter pipeline systems, with a wide range of applications from DN15 to above DN1200.

3. Sealing performance

The sealing performance of a threaded bonnet gate valve depends on the precision of the threaded connection and the selection of sealing materials. It typically employs a soft seal or hard seal structure, suitable for low and medium pressure conditions.

Regular gate valves usually adopt soft seal, hard seal, or metal seal structures, providing reliable sealing performance and the ability to adapt to different pressure and temperature conditions.

4. Installation and Maintenance

The installation of a threaded bonnet gate valve is relatively simple, requiring no complex tools or equipment, making it suitable for the quick installation and replacement in small diameter pipeline systems. Additionally, due to its simple structure, the maintenance of a threaded bonnet gate valve is relatively easy. Particularly, when replacing the bonnet and stem, there is no need to disassemble the entire valve.

The installation of a regular gate valve typically requires specialized installation tools and equipment, especially for large diameter valves, which need lifting and flange alignment. Due to its more complex structure, maintaining a regular gate valve requires more time and effort. Particularly for high-pressure or special condition valves, professional personnel are needed for operation.

5. Application field

Threaded Bonnet Gate Valve: Suitable for low pressure, medium pressure, and normal temperature conditions, such as water supply and drainage systems, HVAC systems, and small industrial pipeline systems.

Regular Gate Valve: Widely used in complex conditions such as high pressure, high temperature, and corrosive media, including large and medium-sized pipeline systems in industries such as petroleum, chemical, power, and metallurgy.

6. Summary

As a special type of valve, diaphragm valves offer significant advantages in industrial applications. Compared to conventional valves, diaphragm valves have many unique features in terms of structure, working principle, performance, and application scenarios.

The Special Features of Diaphragm Valves

Diaphragm Design

1. Flexible Diaphragm: The most notable feature of diaphragm valves is the use of a flexible diaphragm to isolate the fluid from the internal moving parts of the valve body. This design effectively prevents fluid corrosion and contamination of the stem, seat, and other components.

2. Multiple Materials: The diaphragm can be made from various materials such as rubber or fluoroplastic to accommodate the characteristics and requirements of different media.

Excellent Sealing

Due to the tight contact between the diaphragm and the valve seat, diaphragm valves have excellent sealing performance, effectively preventing fluid leakage. They are especially suitable for applications requiring high sealing integrity.

Fluid Isolation

The design of diaphragm valves ensures that the fluid only comes into contact with the diaphragm and the inner walls of the valve body, not with the stem or other components. This isolation design is particularly suitable for industries with high purity requirements for the medium, such as pharmaceuticals, food, and electronics.

Easy to Operate

Simple Operation: The operating mechanism of diaphragm valves is straightforward. The valve can be opened and closed by rotating the handwheel or using an actuator. The operation is smooth, making diaphragm valves suitable for automated control systems.

The Differences Between Diaphragm Valves and Regular Valves

Structure Design

Diaphragm Valve: Utilizes a flexible diaphragm to isolate the fluid from internal components, featuring a simple structure that is easy to clean and maintain.

Common Valves: Such as gate valves, ball valves, butterfly valves, etc., typically employ metal or soft seals, with the fluid coming into direct contact with internal components such as the valve stem and seat, which may be subject to corrosion or contamination from the medium.

Sealing Method

Diaphragm Valve: Achieves sealing through the contact between the diaphragm and the valve seat, eliminating the need for packing seals and avoiding issues such as packing aging and leakage.

Common Valves: Rely on packing glands or other sealing structures for sealing, which may experience leakage after long-term use, requiring regular maintenance and replacement of sealing components.

Applicable Medium

Diaphragm Valve: Suitable for corrosive media, high-purity media, and fluids containing particulate matter, especially strong acids, strong alkalis, pure water, food, and pharmaceuticals.

Common Valves: Have a wide range of applications, but their adaptability to corrosive media and high-purity media is poor, requiring valves with special materials and structures to meet the requirements.

Maintenance and Cleaning

Diaphragm Valve: Due to its simple structure and the fact that the fluid only comes into contact with the diaphragm and the inner wall of the valve body, cleaning and maintenance are very convenient. Diaphragm replacement is also relatively simple and does not require disassembly of the entire valve.

Common Valves: The internal structure is complex, and cleaning and maintenance are cumbersome, requiring professional personnel for operation. Additionally, the replacement of some components is difficult.

Operation Life

Diaphragm Valve: Due to the minimal impact and friction generated during the opening and closing process of diaphragm valves, the diaphragm and valve seat have a longer service life.

Common Valves: Significant friction and impact may occur during the opening and closing process, leading to wear on the sealing surface and affecting the service life.