Gate valves (also known as knife valves or slide valves) are linear motion valves in which a flat closure element slides into the flow stream to provide shut-off. They are one of the most common valves used. Gate valves are advantageous in applications involving slurries, as their “gates” can cut right through the slurry, is pointed out by a Gate Valves Supplier. They are designed to minimize pressure drop across the valve in the fully opened position and stop the flow of fluid completely. The direction of fluid flo w does not change, and the diameter through which the process fluid passes is essentially equal to that of the pipe. Hence, they tend to have minimal pressure drop when opened fully.
Gate valves are designed for fully open or fully closed service. They are installed in pipelines as isolating valves, and should not be used as control or regulating valves.
Gate valves are usually divided into the following types:
The parallel gate valves: These valves use a flat disc gate between two parallel seats, upstream and downstream. Shut-off is obtained by the free-floating seat or disk gate allow the upstream pressure to seal the seat and disk against any unwanted seat leakage. This is why most of the valve manufacturers prefer a design of the parallel gate valves that allows the seat to be spring-energized by an elastomer that applies constant pressure to the disk gate seating surface.
• Knife valves are a specific type of parallel gate valve. They have a sharp edge on the bottom of the gate to shear entrained solids or separate slurries.
• The through-conduit gate valves have a rectangular closure element. The closure has a circular opening equal to the full-area flow passageway of the gate valve; as the element is lowered the opening is exposed to the flow. Raising the element shuts off the flow. In this design the seating surface of the gate is in contact with the gate at all times.
Wedge-shaped gate valves: use two inclined seats and a slightly mismatched inclined gate, allowing for tight shut-off.
Disk flexibility is inherent to the split wedge design. This flexibility allows the split wedge to seal more easily and it reduces stickiness between the sealing surfaces in cases where the valve seats are angularly misaligned. The mismatched angle is also designed with some free movement to allow the seating surfaces to match with each other as the actuator forces them closed. It is also best used for handling non-condescending gases and liquids at normal temperatures, particularly corrosive liquids.
• Solid wedges are the most common because of their simplicity and strength. They can be installed in any position, are suitable for almost all fluids, and are practical for turbulent flow.
• Flexible wedge gate valves are commonly used in steam systems. The disk is one piece with a cut around the perimeter to improve the ability to match error or change the angle between the seats. Different sizes, shapes, and depths are available.
Gate valves are used in many industrial applications including the oil and gas industry, pharmaceuticals, manufacturing, automotive, and marine wherein standardized valves are widely preferred.
• Gate valves are widely used for all types of applications and are suitable for both above ground and underground installation.
• Gate valves most commonly the Valves Made in Europe are designed for fully open or fully closed service and are preferably installed in pipelines as isolating valves, and should not be used as a control or regulating valves.
• Gate valves can be used in demanding environments such as high temperature and high pressure environments. They are often seen in power plants, water treatments, mining, and offshore applications.
• The body of a gate valve holds all of the operational parts of the valve. It is connected to the system with one of the mounting options below. The mounting option should be selected based on the current system mounting features and the type and size of the media.
• The bonnet of a gate valve contains the moving parts and is attached to the valve body. The bonnet can be removed from the body in order to allow for maintenance and replacing parts.
• The trim of a gate valve contains the functioning pieces of the valve: the stem, the gate, the disc or wedge, and the seat rings.
It is important to consider the size of the valve and system when selecting a gate valve. This is especially true if the valve uses a rising stem. Most of the time gate valves should be installed horizontally with the manual actuator in the top position. This allows for easy access for maintenance and replacing parts.
For industrial applications, the gate valve is one of the most versatile valves with a simple working mechanism. There are many gate valve supplier around the world and we Fevisa, one of the leading valve stockist in UAE, we export different types of valves to various industries.
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