Gate valves and ball valves are two kinds of valves which is used for cutting off, what is the difference between them? This article analyse for you from the gate valve and ball valve structure, operation, use and other aspects.
On/Off Parts Shape Difference
The ball valve switching part is a ball, ball is driven by the valve stem, and around the ball valve axis to do the rotary motion, is angle travel, when the handle direction parallel to the pipeline, the flow hole in the ball is parallel to the pipeline , the valve is open. When the handle is perpendicular to the pipeline, the flow hole in the ball is perpendicular to the pipeline ,the valve is closed. Ball valves are generally used to fully open or fully closed, cut off the flow. It can also be used part open or part close, so as to regulate the flow.
Gate valve disc is wedge type or parallel type. The valve disc is driven by the valve stem to do up and down straight line movement, is a straight line travel, when the valve disc lift, the valve is open. When the valve disc falls, the valve is closed, the direction of movement of the valve disc is perpendicular to the direction of the substance, the direction of movement of the valve disc determines the gate valve can only be used as a fully open or fully closed, can not be opened or closed partly, can not be used to regulate the flow. The valve disc and valve stem can be easily damaged by the fluid pressure in the pipeline when partially open or close, thus losing the sealing function.
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NRS Resilient Seated Gate Valve
OS&Y Metal Seated Gate Valve
Knife Gate Valve
Operation Difference
The valve seat of ball valve has a spring inside, so the valve seat has little wear and tear, wear-resistant, usually do not need maintenance, good sealing performance, because the seal of the hard seal ball valve is manually ground until the valve ball and the seal ring are completely matched before it can be used, so its sealing performance is reliable and the switch is light.
Gate valves have high wear and tear on the valve seat and require regular maintenance.
The ball valve switches on and off exceptionally fast and is simple to operate. Mainly used in the branch of the water pipe and other pipelines that require frequent on/off, Users can judge whether the valve is open or closed by the position of the handle.
Gate valve can be only fully open or fully closed, need to continue to rotate to achieve fully open or fully closed, the switch is more time-consuming and labour-intensive, for the commonly used non rising stem gate valve, the user can not know the gate valve is open or close from the position of the hand wheel or stem nut. Rising stem gate valves need much more space, and can only be used above the ground, the use is very restricted. Therefore, rising stem gate valve is only used for some specific situation like fire fight system which need to easily know the valve open/close status ,not very popular.
Use Difference
Ball valve is compact structure, good sealing performance, suitable for high pressure, high temperature and high viscosity pipeline, easy to operate and maintain. Ball valves are widely used, floating type ball valve is suitable for low pressure pipeline , fixed ball valve is used for high pressure pipeline, it is better not to use the ball valve for partially open or close , unless it is a special regulating type or V-type ball valve.
Gate valve is suitable for large diameter, low pressure fluid control, with good sealing performance, relatively slow operation. Requires a large opening torque, is not suitable for frequent open/close occasions. Generally used in the main pipeline and other pipelines which do not require frequent open/close operations.
Conclusion
For industrial production, chemical, petroleum etc pipeline, due to the substance is high pressure and high temperature, high viscosity factors, will generally use the ball valve to control; and in the water, industrial drainage etc, due to the substance is usually a low-pressure liquids, gate valves are more suitable. When you know the difference between ball valves and gate valves very well, it can help you to choose the right valve, thus improving the operational efficiency of the piping system.
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