Gate valves are robust linear motion type valves used in many fluid applications because of their ability to control flow with little resistance. Their vertical motion allows for convenient operation by personnel, but they also deliver a delayed control response due to the time taken to open and close, thereby making them unsuitable for some applications. Weighing up each gate valve advantage and disadvantage can assist in determining its suitability for your application.
John Valves manufactures and supplies various valves for industrial applications, including custom-made gate valves to fit your exact system. In this article, we explain what a gate valve is and describe the key gate valve advantage and disadvantage in effectively controlling fluid flow in systems.
What is a gate valve?
A gate valve is a linear motion type valve used to start or stop the flow of liquids and gases in fluid applications. Commonly used in process plants and water systems, the ability for the gate to be located completely out of the flow path when fully open reduces flow resistance through the valve. Their lack of resistance allows for minimal pressure drop as fluid travels through the valve, making them an excellent valve for systems requiring full flow when open.
Gate valves consist of a closing component (the gate) that moves in a vertical direction perpendicular to the fluid flow. This operation enables a reliable seal when the gate is closed but lacks the ability to control the flow for throttling operations.
Advantages of gate valves
Gate valves are excellent valves for specific types of systems because of the advantages of their features listed below:
- Low fluid resistance: Because of the linear, vertical motion that the gate travels in, the flow of the medium doesn’t change direction when the valve is open or closed. This means that fluid turbulence is minimised and only results in a small pressure drop across the valve.
- Tight sealing performance: Gate valves have one direction of travel and usually incorporate a wedge-shaped gate which allows them to ‘sit’ in their seatings effectively. When set in the closed position, gate valves provide a tight seal that restricts the fluid flow and maintains the pressure on both sides of the valve. The opening and closing process of a gate valve has a low torque requirement and is convenient to operate when compared to other types of valves.
- Widely applicable: The range of applications that gate valves are suited for is broad, including steam, oil, other fluids, as well as mediums containing granular solids with high viscosity. They’re also effective as venting valves and when used in low vacuum systems.
- Dual-flow: Gate valves can allow fluid flow in both directions, making them suitable for applications where the flow of fluid changes directions. Although, this makes them unsuitable for other applications that must restrict backflow.
Disadvantages of gate valves
While gate valves have advantages for particular settings, they come with the below disadvantages, making them unsuitable to other applications:
- High friction and erosion: When used over time, the sealing faces of gates valves can erode or become damaged. During the opening and closing of the valve, there is a high level of friction between the contact sealing faces, causing erosion damage or scratches to these sealing surfaces. This has an impact on the long term sealing performance of the gate valve. Damaged sealing faces on a gate valve are hard to repair and reduce the service life of the valve.
- Delayed application: Gate valves take an extended time to open and close, which causes a functional delay in restricting the fluid flow. The gate of the valve needs to be elevated when opening the valve and lowered into place when closing, causing this delayed application.
- Large size: While the opening size of the gate valve is larger, it also has a taller overall height making them more challenging and time-consuming to install.
Summary
Like all valves that John Valves manufacture, gate valves are ideal in a particular setting due to their features but aren’t suited to all types of applications. Their linear, vertical motion makes them excellent at reducing flow resistance and pressure drop in applications, and their tight seal is appropriate for multiple types of medium. However, their speed of operation makes them unsuitable for fast flow control requirements, and their high level of friction between contact sealing faces can require regular maintenance if the valves are operated frequently.
Each gate valve’s advantages and disadvantages explained in this article should be considered when selecting an appropriate valve for your application. If you’re trying to identify the best gate valve for your system, get in touch with one of our experts to discuss your needs.
