Advantages of gate valve:
(1) Small fluid resistance Because the internal medium channel of the gate valve body is straight, the medium does not change its flow direction when flowing through the gate valve, so the fluid resistance is small.
(2) The opening and closing torque is small, and the opening and closing is more labor-saving. Because the direction of the gate movement is perpendicular to the direction of the medium flow when the gate valve is opened and closed, the opening and closing of the gate valve is more labor-saving compared with the stop valve.
(3) The flow direction of the medium is not restricted, and the medium can flow in any direction from both sides of the gate valve without disturbing the flow and without reducing the pressure, and the purpose of use can be achieved. It is more suitable for pipelines where the flow direction of the medium may change.
(4) The structural length is shorter because the gate of the gate valve is placed vertically in the valve body, and the valve disc of the stop valve is placed horizontally in the valve body, so the structural length is shorter than that of the stop valve.
(5) With good sealing performance, the sealing surface is less eroded when fully opened.
(6) When fully open, the erosion of the sealing surface by the working medium is smaller than that of the stop valve.
(7) The body shape is relatively simple, the casting process is good, and the application range is wide.
Disadvantages of gate valve:
(1) The sealing surface is easy to damage the two seals that are in contact with the valve seat during opening and closing, and there is relative friction between the two seals, which is easy to damage, affects the performance and service life of the seal, and is difficult to maintain.
(2) The opening and closing time is long, and the height is large. Because the gate valve must be fully opened or fully closed when opening and closing, the gate stroke is large, and a certain space is required for opening, and the overall size is high, and the installation space is large.
(3) Gate valves with complex structure generally have two sealing surfaces, which increase processing, grinding and maintenance. There are more difficult parts, manufacturing and maintenance are more difficult, and the cost is higher than that of globe valves.
The diameter of the gate valve shrinks:
If the diameter of the passage in a valve body is different (often the diameter at the valve seat is smaller than the diameter at the flange connection), it is called diameter shrinkage.
The shrinkage of the diameter can reduce the size of the parts, reduce the force required for opening and closing, and expand the application range of the parts. But after the diameter shrinks. The fluid resistance loss increases.
Under certain working conditions in certain departments (such as oil pipelines in the petroleum sector), valves with reduced diameters 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 of the pipeline after the shrinkage of the diameter.
The installation and maintenance of the gate valve should pay attention to the following matters:
1. Handwheels, handles and transmission mechanisms are not allowed to be used for lifting, and collisions are strictly prohibited.
2. The double gate valve should be installed vertically (that is, the valve stem is in the vertical position and the handwheel is on the top).
3. The gate valve with bypass valve should be opened before opening (to balance the pressure difference between the inlet and outlet and reduce the opening force).
4. The gate valve with transmission mechanism should be installed according to the product manual.
5. If the valve is frequently opened and closed, lubricate at least once a month.
Nortech is one of the leading industrial valve manufacturers in China with quality certification ISO9001.
Major products: Butterfly Valve, Ball Valve,Gate Valve, Check Valve, Globe Vavlve,Y-Strainers, Electric Acurator , Pneumatic Acurators .
Post time: Aug-16-2021