1, the characteristics of the valve

Stop valve is the valve valve along the center line of the valve to move the valve, the valve in the pipeline for the main cut off.

The cut-off valve has the following advantages:

1) in the opening and closing process of sealing surface friction than the gate valve, wear.

2) Open height is small.

3) usually only a pair of sealing surface, the manufacturing process is good, easy to repair. The use of cut-off valve is more common, but because of the large opening and closing torque, structural length is longer, the general nominal diameter are limited to DN ≤ 250mm below. The loss of the fluid resistance of the shut-off valve is large, thus limiting the wider use of the shut-off valve.

2, the classification of the valve

1) According to the position of the thread on the stem can be divided into

a. Threaded stem stem valve: The cut valve stem is threaded on the outside of the valve body. The advantage is that the stem is not eroded by the medium, easy to lubricate, this structure is more common.

b. Lower thread stem stop valve: Cut valve stem thread in the valve body. This type of stem thread is in direct contact with the media, is susceptible to erosion and can not be lubricated. This structure is used for small caliber and temperature is not high place.

2) According to the direction of the cut-off valve, can be divided into:

Straight-through cut-off valve, DC cut-off valve, angle-type globe valve and three-way shut-off valve, the latter two kinds of cut-off valve usually do change the media flow and distribution media.