What is Gate Valves -types , Application

A gate valve, also known as a sluice valve, is a valve which opens by lifting a round or rectangular gate/wedge out of the path of the fluid. The distinct feature of a gate valve is the sealing surfaces between the gate and seats are planar, so gate valves are often used when a straight-line flow of fluid and minimum restriction is desired. The gate faces can be parallel, but are most commonly wedge-shaped.

Types of Gate Valves

There are three ways to classify the gate valve.

1. Types of Disk
   1. Solid taper wedge
   2. Flexible wedge
   3. Split wedge or Parallel disks Valve
2. Types of Body Bonnet Joint
   1. Screwed Bonnet
   2. Bolted-Bonnet
   3. Welded-Bonnet
   4. Pressure-Seal Bonnet
3. Types of Stem movement
   1. Rising Stem or OS & Y Type (Outside Stem and Screw Type)
   2. Non-rising Stem type

Working mechanism of a gate valve
Working of gate valve is displayed here in following figure. When handle wheel will be rotated in clockwise direction, steam and gate will move in downward direction across the fluid flow line and gate will be tightly located between the two seats. Hence there will not be any leakage of fluid through the valve once valve is closed completely.

When handle wheel will be rotated in anti-clockwise direction, steam and gate will move in upward direction across the fluid flow line and valve will be opened from closed position and will permit the flow of fluid through the gate valve. Once gate valve is completely opened, it will permit no resistance or very little resistance to the flow of fluid.

We can use gate valve in semi-open condition also but there will be one issue of erosion of gate as fluid will strike the gate if valve is partially open. Therefore gate valve should be used in completely closed or completely open condition.

Gate Valve Applications

• Gate valves are used in almost all fluid services such as air, fuel gas, feedwater, steam, lube oil, hydrocarbon, and all most any services.
• Some special gate valve is used in slurry and powder product also such as knife gate valve

Advantages of Gate Valve

• Gate valve provides good
• Pressure drop during operation is very less.
• Most of the gate valve can be used as bi-directional
• They are suitable for high pressure and temperature application and required less maintenance

Disadvantage of Gate Valve

• It cannot be used to control the flow.
• A gate valve is slow in operation. Opening and closing take times which is good also as it reduces the chance of hammering.
• When partially open it creates vibration and noise.
• Repairs, such as lapping and grinding of seats are more difficult due to limited access.

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