Select the valve gate valve according to the on-off

by:AIRWOLF     2020-06-18
Gate valves are used as cut-off media for the entire flow through at full opening, where the pressure loss of medium operation is minimal. Gate valves are usually designed for operating conditions where frequent opening and closing is not required and where the gate is fully open or fully closed. Not suitable for regulating or throttling use. For high speed flow media, the gate vibration can be caused by partial opening of the gate, which may damage the sealing surface of the gate and seat, while the throttling will cause the gate to be eroded by the medium. From the form of structure, the main difference is the use of the form of sealing elements. Gate valves are often divided into several types according to the form of sealing elements, such as: wedge gate valve, parallel gate valve, parallel double gate valve, wedge double gate gate, etc. The most common form is wedge and parallel gate valves. Globe valve The stem axis of the globe valve is perpendicular to the sealing surface of the seat. The relatively short stem opening or closing stroke and very reliable shutoff make the valve ideal for medium shutoff or regulating and throttling. Once the disc is in an open condition, there is no longer contact between the seat and disc sealing surface and a very reliable shutoff action, making the valve ideal for medium shutoff or regulating and throttling. Once stop valve is fully open, it will no longer have a contact between the seat and clapper sealing surfaces, and thus its sealing surface mechanical wear and tear is small, because most of the cut-off valve seat and valve disc is easy to repair or replace the whole valve sealing components without removed from the pipeline, for the valve and pipeline welding into one occasion is very applicable. The flow direction of the medium through such valves has changed, so the flow resistance of globe valves is higher than other valves. The commonly used globe valves are as follows :1) Angle globe valves; In angular globe valves, the fluid needs to change direction only once so that the pressure drop through the valve is smaller than in conventional globe valves. 2) Direct flow globe valve; In a straight flow or Y-shaped globe valve, the flow path of the body is diagonally aligned with the main flow so that the flow state is less destructive than conventional globe valves and the pressure loss through the valve is correspondingly less. 3) Plunger globe valve: This form of globe valve is a variant of the conventional globe valve. In this valve, disc and seat are usually designed based on plunger principles. Disc polished plunger is connected to the stem and the seal is achieved by two elastic sealing rings mounted on the plunger. The two elastic sealing rings are separated by a sleeve ring and are secured around the plunger by a load applied to the cover by the cover nut. Resilient seals are replaceable in a variety of materials. The valve is primarily used for 'on' or 'off' but is provided with a special form of plunger or special sleeve for flow regulation.
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