Data: 2009-11-24 From www.supply-valve.com

According to the structure of gate valves' stem, the valves divides into two types.

1. Ring stem gate valves. When opening and closing the disc, we turn the stem nut, which is on the bonnet and yoke to move the stem up and down. This structure is good for smoothing the stem and seeing the whole movement clearly. Therefore, it is widely used in our life.

2. Non-ring stem gate valves. The stem nut, which is inside the body could contact with the flow media directly. We also need to turn the stem to open and close the disc. The advantages of this structure, control the height of valves flexibly, small room. Generally, it is applied to big size gate valves or some strictly room limited ones. Besides, this type of valves usually shows open or close by installing indicating gauge or signal lamp. The disadvantage is that the stem screw could not be smoothed well and even easy to be rusty because of directly corroding by the media. Therefore, it is used uncommon.

The non-rising stem gate valves is the one that we could not see the guide screw while the rising stem is that we could see the guide screw clearly. When opening and closing, the steering wheel and stem of non-rising stem are connected together immovably, the stem turns in a fixed point and then drive the disc to up and down. However, to the non-rising stem, when opening and closing, the disc and stem is connected together to do up and down movement and even the steering wheel is always in a fixed point. Eventually, tt is achieved by turning stem and steering wheel's screw to up and down the disc