Among the many valve products, gate valves, pneumatic butterfly valves, and stainless steel ball valves are the most commonly used valve types. However, many users do not know how to choose because they do not know the difference between them when selecting models.
Gate valve is one of the most common opening and closing valves. It uses the gate (ie, the opening and closing parts, in the gate, the opening and closing parts are called gates, and the gate seat is called the gate seat) to connect (fully open) or cut off (fully shut off) the medium in the line. It is not allowed to be used as a shut-off, and it should be avoided to slightly open the gate during use, because the erosion of the high-speed flowing medium will accelerate the damage of the sealing surface. The gate moves up and down on the side perpendicular to the center line of the gate seat channel, cutting off the medium in the pipeline like a gate, so it is called a gate valve.
Butterfly valve refers to a kind of valve whose closing member (valve disc or butterfly plate) is a disc and rotates around the valve shaft to achieve opening and closing. It mainly plays the role of cutting off and throttling on the pipeline. The butterfly valve opening and closing part is a disc-shaped butterfly plate, which rotates around its own axis in the valve body to achieve the purpose of opening and closing or adjustment. Pneumatic butterfly valve is usually less than 90° from fully open to fully closed. Butterfly valve and butterfly stem have no self-locking ability. In order to locate the butterfly plate, a worm gear reducer should be installed on the valve stem. The use of worm gear reducer can not only make the butterfly plate have self-locking ability, so that the butterfly plate can stop at any position, but also improve the operation performance of the valve.
The ball valve switch is light, small in size, can be made into a large diameter, reliable sealing, simple structure, convenient maintenance, sealing surface and spherical surface are often in a closed state, not easy to be eroded by media, and are widely used in various industries. Stainless steel ball valve and plug valve are the same type of valve, only its closing part is a sphere, and the sphere rotates around the center line of the valve body to achieve opening and closing. Ball valves are mainly used to cut off, distribute and change the flow direction of the medium in the pipeline.
The gate valve is a straight-stroke valve, that is, the valve stem drives the valve plate to move vertically up and down to complete the opening and closing of the gate valve, so the flow resistance of the gate valve is small, but because of its high opening height, the opening and closing speed is slow. Butterfly valve and ball valve are angular stroke valves, that is, the valve plate of the butterfly valve rotates 90° around the valve shaft to complete the opening and closing action of the butterfly valve. Therefore, the opening height of the butterfly valve is only one quarter of the diameter of the channel, so it opens and closes quickly. The gate valve has small flow resistance and good sealing performance. Because the valve plate of the gate valve and the flow direction of the medium are at a vertical angle, if the gate valve is not switched in place on the valve plate, the scouring of the medium on the valve plate will cause the valve plate to vibrate, which is very likely to cause damage to the gate valve seal. Therefore, it is mostly used as a cut-off for pipelines that require strict sealing and do not need frequent opening and closing, and is not suitable for adjusting the parameters of the pipeline medium.
The gate valve is not suitable for emergency cut-off due to its slow opening and closing speed. Butterfly valve not only has the function of cut-off, but also has the function of adjustment. The butterfly valve opens and closes quickly and can be opened and closed frequently, which is especially suitable for occasions requiring rapid opening or closing. Compared with the gate valve, the butterfly valve is small in size and light in weight. In some working conditions with limited installation space, the butterfly valve with wafer connection can be selected, which saves more space.
The butterfly valve can be made into a large diameter, and the price of the butterfly valve of the same diameter is much lower than that of the gate valve. The ball valve has wiping properties during the opening and closing process, so it can be used in media with suspended solid particles. The ball valve has low fluid resistance, and the full-bore ball valve basically has no flow resistance. If the diameter of the channels in a valve body is not the same, it is called diameter shrinkage. The diameter shrinkage can reduce the size of the parts, the force required for opening and closing is correspondingly reduced, and at the same time, the application range of the parts can be expanded. But after the diameter shrinks, fluid resistance loss increases. Under certain working conditions in certain departments, valves with reduced diameter are not allowed. On the one hand, it is to reduce the resistance loss of the pipeline, and on the other hand, it is to avoid obstacles to the mechanical cleaning pipeline after the diameter shrinkage. In many working conditions, pneumatic butterfly valves and ball valves gradually replace other types of valves and become the first choice of many users.