Stop valve structure VS gate valve structure
Time: 2021-06-10 22:15:41 Source: Yonglong Valve Reading: zero second
Stop valve structure VS gate valve structure
Stop valves and gate valves are indispensable control components in various pipeline systems, and they are different in appearance, structure and even function. However, the globe valve and gate valve have some similarities in appearance, and both have the function of cutting off in the pipeline.
Stop valve structure:
When the stop valve is opened and closed, it is of rising stem type, that is to say, when the hand wheel is turned, the hand wheel will rotate and rise along with the stem. The gate valve rotates the handwheel to make the valve stem rise and fall, and the position of the handwheel itself remains unchanged.
The movement stroke of the valve plate of the stop valve is much smaller, and the valve plate of the stop valve can stop at a certain place during the movement for flow regulation. The gate valve can only be used for cut-off and has no other functions.
There are two ways to install the stop valve. One is that the medium can enter from below the valve core. The advantage is that when the valve is closed, the packing is not under pressure, which can extend the service life of the packing, and the packing can be replaced when the pipeline in front of the valve is under pressure; The disadvantage is that the driving torque of the valve is large, about one time of the upper flow, the axial force on the valve stem is large, and the valve stem is easy to bend. Therefore, this method is generally only applicable to small diameter stop valves (below DN50). For stop valves above DN200, medium flows from above. (The electric stop valve generally uses the way of medium entering from the top.) The disadvantage of medium entering from the top is just the opposite to that from the bottom
Gate valve structure:
The gate valve can be tightly closed with the sealing surface depending on the medium pressure, so as to achieve the effect of no leakage. When opening and closing, the valve core and the sealing surface of the valve seat always contact and rub with each other, so the sealing surface is easy to wear. When the gate valve is close, the pressure difference between the front and rear of the pipeline is large, which makes the sealing surface wear more seriously.
The structure of the gate valve is higher than that of the stop valve in terms of appearance. Under the same caliber, the gate valve is higher than the stop valve and the stop valve is longer than the gate valve. In addition, there are rising stem and non rising stem for gate valves, and there are also stop valves, but the non rising stem stop valve market is less used.
The effect of gate valve flow direction is the same in both directions. The installation has no requirements for inlet and outlet directions, and the medium can flow in both directions. Because the gate valve can only be fully opened and closed, when it is fully opened, the medium flow resistance in the valve body channel is almost zero, so the opening and closing of the gate valve will be very labor-saving, but the distance between the gate plate and the sealing surface is far, and the opening and closing time is long.
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