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The valve that is most common used for this is the gate valve.
The design of most types of gate valves makes them unsuitable for throttling applications.
This is due to the erosion of the seat and disc that occurs from the vibrations of the disk created in throttling.
This is known as disk chattering. With some fluids a globe valve may be recommended for on/off service instead, because a globe valve will provide a tighter closure.
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Solid Wedge Gate Valve has either a flexible or a solid wedge disc.
This type of gate may be used for throttling normally in 6" and larger.
To prevent chattering the disc must be fully guided through out the entire travel length.
This type is suitable for most services including air, gas, oil and steam.
The flexible wedge type was designed to overcome the sticking caused by the cooling of a high temperature service.
It is also designed to reduce the torque required to operate the valve.
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Double-disk parallel-seat gate valve has two discs parallel to each other.
When the valve is in the closed position the discs are pressed against parallel seats by a spreader.
This type is unsuitable for throttling service.
They are commonly used in liquid and gas services at normal temperatures.
This type should be installed horizontally with the hand wheel up to prevent jamming of the valve.
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Double-disk (split-wedge) wedge gate valve. This type has two disks that are parallel.
When closed the disks are pressed against inclined seats with or without the aid of a spreader.
They are commonly used in liquid and gas services at normal temperatures. Smaller valves are used for steam services.
Most valves of this type are built with rotating disks which will distribute the wear evenly.
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Single-disk parallel-seat gate valve.
Unlike the single-seat valve, this design will close with flow on either side of the seat.
This design also reduces the stresses on the stem and on the bonnet.
This type is primarily used for gases and liquid hydrocarbons.
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Plug gate valve. This type has a round tapered disk that moves up or down.
This type may be used for either throttling or full-flow use.
It is only available in the smaller sizes.
Plug gate valves are most often used for slurries, oils, gases and water.
One of it’s advantages is the compactness of size.
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