The commonly used stop valves are as follows:

　　1) DC stop valve: in the DC or Y-shaped stop valve, the flow channel of the valve body forms an oblique line with the main flow channel, so the damage degree of the flow state is smaller than that of the conventional stop valve, so the pressure loss through the instrument valve is correspondingly smaller.

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

　　3) Plunger stop valve: this type of stop valve is a variant of the conventional stop valve. In this instrument valve, the disc and seat are usually designed based on the plunger principle. The valve disc is polished into a column, and the plug is connected with the valve rod. 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 a variety of materials. The instrument valve is mainly used for "on" or "off", but it is equipped with a special plunger or special collar, which can also be used to adjust the flow. Guide for selection of stop valve: the stem axis of stop valve is perpendicular to the sealing surface of valve seat. The opening or closing stroke of the valve rod is relatively short, and has a very reliable cut-off action, which makes this instrument valve very suitable for medium cut-off or regulation and throttling. Once the valve disc of the stop valve is open, there will be no contact between its seat and the sealing surface of the valve disc, and it has a very reliable cut-off action. This instrument valve is very suitable for medium cut-off or regulation and throttling. Once the stop valve is in the open state, there will be no contact between its valve seat and the sealing surface of the valve disc, so the mechanical wear of its sealing surface is small. Because the valve seat and valve disc of most stop valves are easy to repair or replace the sealing elements, there is no need to remove the whole instrument valve from the pipeline, which is very suitable for the occasion where the instrument valve and pipeline are welded together. When the medium passes through such instrument valves, the flow direction changes, so the flow resistance of the stop valve is higher than that of other instrument valves.