Threaded gate valve opening and closing parts are plug shaped valve, sealing surface flat or cone, fluid along the centerline of the valve for linear motion. The movement of the stem form, there is lift rod type (the stem lift, hand wheel is not up and down), but also the lifting of the rotating bar type (hand wheel and the valve stem rotation, the nut is located in the valve body). Bellows valve is only applicable to fully open and fully closed, does not allow for adjustment and throttle.
Advantages
1.Simple structure, easy manufacture and maintenance.
2.Working schedule is small, and the opening and closing time is short.
3.Good sealing, sealing surface friction between the small, long life.
Disadvantages
1.Large fluid resistance, open and close when the required force is large.
2.Do not apply with particles, viscosity, easy to medium coke.
3.Poor regulation performance.According to the location of the valve stem threads are 4.divided into external screw type, internal screw type. According to the direction of the flow of media, there are straight, DC and angle. Closing valve according to the sealing form, there are packing bellows gate valve and bellows seal globe valve.