Shutoff valve is closed parts (valve) moves along the centerline of the valve seat.

The main shut-off valve in the pipeline for cutting purposes. Valve has the following advantages:

1. The opening and closing process of the sealing surface of the valve is small compared friction, wear.

2. Small opening height.

3. Usually only one sealing surface, manufacturing processes, and ease of maintenance. Valves are more commonly used, but due to the larger opening and closing moments, the structure length is longer, generally nominal diameter are limited to DN ≤ 200mm or less. Valve fluid resistance losses. Thus limiting valve is more widely used.

Many different types of valves, according to the position of the valve stem threads can be divided into:

1.The valve stem threads on the threaded valve stem out of the valve body. The advantage is that erosion of the stem from the media, to facilitate lubrication, such a structure using more common.

2.The following valve stem thread

Threaded valve stem in the valve body. This structure stem threads in direct contact with the media, vulnerable to erosion, and can not be lubricated. This structure for small diameter and the temperature is not high place.

According to the passage direction valve can be divided into; straight-through valves, angle type valve and three-way valve, the latter two valves normally do change the media flow and distribution of media use.

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