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Electric valve is divided into two kinds, one is Angle stroke electric valve: by the Angle stroke electric actuator with Angle stroke valve use, to achieve the valve within 90 degrees of rotation control pipeline fluid on and off; The other is straight stroke electric valve: the straight stroke electric actuator is used with the straight stroke valve to realize the upper and lower action of the valve plate to control the flow of the pipeline. Usually in the high degree of automation of equipment matching use, the valve horizontal installation adjustment accuracy is good.

The characteristics of

1, compact structure, reasonable design, good rigidity of the valve, smooth channel, small flow resistance coefficient.

2, the sealing surface adopts stainless steel and hard alloy, long service life.

3, flexible graphite packing plate, reliable sealing, light and flexible operation.

4, drive mode, motor, electric, pneumatic, gear transmission, structural form; Elastic wedge type single valve, rigid wedge type single valve plate and double gate type.

5, widely used in petroleum, chemical, thermal power plants and other oil, water, steam pipeline for connecting or cutting off the opening and closing device of the pipeline medium.

6, the valve stem after tempering and surface nitriding treatment, has good corrosion resistance, abrasion resistance.

7, wedge type elastic gate structure, large diameter set thrust bearing, small friction force, and equipped with impact manual, easy to open and close.

8, can use a variety of piping flange standards and flange sealing surface form, to meet the needs of various projects and user requirements.

Structure and classification

Gate valves are generally composed of stem, valve body, valve cover, gate, drive device and other components (fasteners, stem nuts, sealing packing), and the following structure is introduced one by one:

The valve stem

Gate valve valve stem according to the form of movement is divided into open rod (lifting shaft) and dark rod (rotating shaft), gate valve is therefore divided into open rod gate valve and dark rod gate valve two.

(1) stem gate valve. The handwheel (or other driving device) is fixed on the stem nut. When the handwheel (or other driving device) rotates the stem nut, the stem moves up and down, thus driving the gate valve to lift and close the pipeline.

When the stem gate valve is opened, the stem extends out from above the handwheel, which can directly show the opening degree of the gate valve. Stem trapezoidal threads on the upper half of the stem, no direct contact with media, media corrosion, and lubrication. Therefore, it is suitable for corrosive medium, dirty medium and high temperature steam medium on the gate valve. Valve opening and closing degree can be seen directly from the thread, easy to operate is also one of its advantages. The deficiency is that, as a result of thread leakage, easy to stick on the dust in the air, accelerate thread wear, so it should be installed indoors as far as possible. Nevertheless, the application is still relatively widespread.

(2) dark stem gate valve. The handwheel (or other drive device) is fixed on the stem, and the stem thread is fixed on the top of the gate. When the handwheel (or other drive device) turns, the stem thread drives the gate up and down. The advantage is that the stem does not rise when opened, requiring less installation space. Therefore, it is often used as a large channel gate valve, or installation space is limited occasions. Because the stem does not do the lifting movement, not like the open stem gate valve, through the length of the stem to show the degree of opening, therefore, should be installed with an opening indicator.

Dark stem gate valve due to stem thread part and stem nut are in contact with the medium inside the valve chamber, therefore, vulnerable to medium corrosion, stem threads and other difficult to lubrication.

Body and bonnet

Valve body and cover are mostly used for flange connection. The medium channel in the valve body is mostly cylindrical equal section, for the larger caliber gate valve seat shrinkage is also used, that is, the channel gradually shrink, through the hair seat, and gradually expand, its advantages are:

(1) The valve assembly size is reduced, weight is reduced, so as to save material.

(2) As the size of the gate is reduced, the acting force on the gate is reduced, and the opening and closing force of the gate valve is reduced accordingly.

Because channel shrinkage will increase water resistance. Therefore, in high pressure steam pipelines, in order to reduce resistance, often connected with a guide pipe under the closed parts, to reduce resistance and prevent particles in the medium from falling into the valve body.

ram

According to the form of the gate can be divided into cheese parallel type.

(1) Cheese gate. The sealing surface of the wedge gate dips with the vertical center line of the gate. The dips depend on the temperature of the medium and the size of the warp. Generally, the higher the temperature of the medium, the greater the pass, the greater the inclination, to prevent the gate from being stuck and unable to open when the temperature changes. Cheese - chock RAMS have better sealing performance than parallel ones. For high pressure gate valves.

Wedge - type RAMS are divided into elastic RAMS, wedge - type RAMS and wedge - line double RAMS.

A. Elastic gate. An annular groove is made on the vertical bisector surface of the gate to make it flexible. It is this elastic deformation that compensates for the deviation between the sealing surface of the gate and the sealing surface of the seat when the gate is closed to achieve a good fit.

Elastic gate valve sealing surface is reliable. Suitable for small and medium caliber gate valves of various pressures and temperatures, the medium is required to contain less solid particles, in order to prevent the jam in the annular groove of the gate, affecting the elastic sealing.

B. Wedge type single gate, it is a integral wedge type gate. In the process of opening and closing, the sealing surface is easy to bruise, and the temperature change is easy to make the gate stuck. He is used for normal temperature, medium temperature, all kinds of pressure gate.

C. Cheese double gate, it is made of two combination of RAMS, with a spherical center hinged into a cheese shaped gate. Its advantage is that the accuracy of sealing surface Angle is lower; When the sealing surface of the gate is worn, gaskets can be added at the center to compensate; Temperature change is not easy to cause the phenomenon of the main card, also should not be scraped. Because the gate is movable and has many components, it is easy to bond in the viscous medium, affecting the seal. In particular, the upper and lower baffles fall off freely after years of rust. It is usually used for water, steam and gas pipelines.

(2) Parallel gate. Parallel RAMS are the two sealing surfaces of the RAMS parallel to each other and perpendicular to the center line of the channel. Parallel RAMS are available as parallel but RAMS and parallel double RAMS.

A. Parallel single gate, simple structure, but poor sealing. Suitable for medium and low pressure; Large, medium caliber, usually used for oil or gas pipelines.

B. Parallel double RAMS, which are the opposite of parallel single RAMS. According to its structure can be divided into automatic sealing type and open type two.

Automatic sealing parallel double disc gate valve. Gate valves are composed of two disks, both of which are sheathing