Characteristics and channel form of stainless steel stop valve

2021-09-25 澳门66yh银河 Read 44

Stainless steel stop valve is a kind of stop valve, which has high requirements for valve body materials. Generally, there are several materials such as 301.304.316, which are widely used in chemical industry, shipping, medicine, food machinery and other industries. Stainless steel stop valve is divided into manual stainless steel stop valve, pneumatic stainless steel stop valve and electric stainless steel stop valve.

The stem axis of the stainless steel stop valve is perpendicular to the sealing surface of the 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 valve very suitable for medium cut-off or regulation and throttling. Once the valve disc of the stainless steel 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 valve is very suitable for cutting off or regulating and throttling as a medium. This type of valve shall be installed horizontally in the pipeline.

Once the stop valve is in the open state, there is 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 valve from the pipeline, which is very suitable for the occasion where the valve and pipeline are welded into one. When the medium passes through such valves, the flow direction changes, so the flow resistance of the stop valve is higher than that of other valves.

Features of stainless steel stop valve:

(1) The structure is simpler than the gate valve, and the manufacturing and maintenance are more convenient.

(2) The sealing surface is not easy to wear and scratch, with good sealing performance. There is no relative sliding between the valve disc and the sealing surface of the valve body during opening and closing, so the wear and scratch are not serious, with good sealing performance and long service life.

(3) When opening and closing, the valve disc stroke is small, so the height of the stop valve is smaller than that of the gate valve, but the structural length is longer than that of the gate valve.

(4) The opening and closing torque is large, the opening and closing is laborious, and the opening and closing time is long.

(5) Large fluid resistance, due to the tortuous medium channel in the valve body, large fluid resistance and large power consumption.

(6) When the nominal pressure in the medium flow direction PN ≤ 16MPa, it is generally downstream, and the medium flows upward from the lower direction of the valve disc; When the nominal pressure PN ≥ 20MPa, countercurrent is generally adopted, and the medium flows downward from the upper direction of the valve disc to increase the sealing energy. When in use, the medium of the stop valve can only flow in one direction, and the flow direction cannot be changed.

(7) When fully opened, the valve disc is often eroded.

Channel form of stainless steel stop valve:

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

1) Straight through stop valve

2) DC stop valve: in 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 flow state is smaller than that of conventional stop valve, so the pressure loss through the valve is correspondingly smaller.

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

4) Plunger stop valve: this type of stop valve is a variant of the conventional stop valve. In this 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 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.

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