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Difference between ball valves and gate valves

Posted by Bundor valve
What is the difference between ball valves and gate valves?
ball valve,gate valve
1. spool structure

Ball valve of the valve core to the sphere, because of its structure, fixed ball valve under the condition of high pressure, especially the closed state, the valve ball is fixed, the upper stem and lower fulcrum to decompose the part from the medium pressure, so the valve ball is not downstream migration, so the downstream seat stress in a number of relatively small, so the valve in the action to overcome the friction of the small, the seat wear is small, the valve's service life is long, especially for frequent movement of the valve and is more suitable for this kind of structure.

The valve core of a gate valve is a wedge shaped disc or parallel disc.Its lower part has no support shaft.Under high voltage application, so the valve and when closed, valve plate under the great pressure from the media, and as a result of its planar structure of valve plate, makes all the media pressure effect on the valve plate at the same time, the valve plate will now pressure downstream seat (at the same time, too much pressure on the vertical face of valve plate, makes the valve plate wedge or parallel double ram will have certain deformation), when the valve is in open to overcome a great deal of friction, is the seat of the wear print this short life of the valve.

2.The seat structure

The seat of the ball valve has a spring inside, and the sealing design of the seat makes it difficult for the dregs of the medium to enter the seat.And the valve seat under the action of the spring and valve ball contact for a long time, when the valve action, the valve seat has a certain role of scraper, can be attached to the spool residue after long-term operation, can ensure the sealing performance of the valve.Especially in high temperature and high pressure applications, because the valve seat, body, valve ball material in the selection of material with the same coefficient of thermal expansion, as well as the spring structure of the seat, when the valve is closed, the huge temperature difference and temperature drop, will not affect the valve action, the valve will not produce the phenomenon of locking.

Gate valve seats are very narrow, and in high temperature service, when the valve is closed, the temperature drops due to the non-flow of media, so the seat will tighten, resulting in a lot of pressure on the disc.When the valve is opened again, a large torque is required to overcome this compression force, resulting in significant damage to the seat, affecting the life of the seat.Thus, the service life of the valve is affected.In addition, due to the weight of the gate itself when the valve is closed, it will bring great impact force and noise to the valve.

3. travel

The ball valve travel for angular travel, therefore in the installation space is small, low height.Gate valve travel for straight travel, so large space for installation, high height.

4.Executing agency

Because the ball valve fixed ball design, its open and close of the torque value is small, so the actuator is matched accordingly small.Gate valves due to the plate on the seat of the compression force, so to overcome this great friction requires a great torque, the actuator with a large.

5.maintenance,

Ball valves generally do not require maintenance, especially the ball and seat, due to small wear, generally do not need to replace within 5 years.Gate valves require regular maintenance due to heavy seat wear.