Dalian marine valve is a device used to control the pressure, flow rate and flow direction of the fluid in the ship pipeline to meet the environmental conditions of the ship. The valve is the control device of the fluid pipeline. Its basic function is to connect or cut off the flow of the medium in the pipeline, change the flow of the medium, change the flow direction of the medium, adjust the pressure and flow of the medium, and protect the normal operation of the equipment in the pipeline.

1. According to the channel direction of the stop valve, it is divided into:

1) Straight cut-off valve

2) Direct flow stop valve: in the direct flow or Y-shaped stop valve, the flow channel of the valve body and the main flow channel form an oblique line, so the damage degree of the flow state is smaller than that of the conventional stop valve, so the pressure loss through the valve is correspondingly small.

3) Angle stop valve: in the angle stop valve, the fluid only needs to change direction once, so that the pressure drop through the valve is smaller than that of the conventional stop valve.

4) Plunger type stop valve: this type of stop valve is a variation of the conventional stop valve. In this valve, the valve disc and valve seat are designed based on the plunger principle. The valve disc is polished into a cylindrical plug and connected with the valve stem. The sealing is realized by two elastic sealing rings sleeved on the plunger. The two elastic sealing rings are separated by a collar, and the sealing ring around the plunger is firmly pressed by the load applied on the bonnet by the bonnet nut. The elastic sealing ring can be replaced and can be made of various materials. The valve is mainly used for "opening" or "closing", but it is equipped with a special plunger or special collar, which can also be used to regulate the flow.

2. According to the position of the thread on the valve stem of the stop valve, it can be divided into:

1) Upper thread stem stop valve: the thread of the stem of the stop valve is outside the valve body. Its advantage is that the valve stem is not eroded by the medium and is easy to lubricate. This structure is widely used.

2) Lower threaded stem stop valve: the thread of the stem of the stop valve is in the valve body. The thread of the valve stem with this structure is in direct contact with the medium, which is easy to be eroded and cannot be lubricated. This structure is used in places with small caliber and low temperature.