Difference between gate valve and globe valve

The opening and closing part of the gate valve is the gate. The movement direction of the gate valve is perpendicular to the fluid direction. The gate valve can only be fully opened and closed, and is not suitable for adjustment and throttling. The gate has two sealing surfaces. The two sealing surfaces of the most commonly used wedge gate valve form a wedge. The wedge angle varies with the valve parameters, usually 5O. Wedge gate valve gate can be made into a whole, called rigid gate; It can also be made into a ram that can produce a small amount of deformation, so as to improve its processability and make up for the deviation of sealing surface angle in the processing process. This kind of ram is called elastic ram. When the gate valve is closed, the sealing surface can only be sealed by the medium pressure, that is, the sealing surface of the gate valve is pressed to the valve seat on the other side by the medium pressure to ensure the sealing of the sealing surface, which is self sealing. Most gate valves are forced to seal, that is, when the valve is closed, the gate should be forced to the valve seat by external force, so as to ensure the tightness of the sealing surface.

Gate valves have the following advantages:

1. The fluid resistance is small, and the sealing surface is eroded and eroded by medium.

2. It is easy to open and close.

3. The flow direction of the medium is not restricted, the flow is not disturbed and the pressure is not reduced.

4. Simple shape, short structure length, good manufacturing technology and wide application range.

Nominal pressure or pressure class: pn1.0-16.0mpa, ANSI class 150-300lb, jis10-20k

Nominal diameter: DN 10-1000, NPs 1 / 2-36“

Connection mode: flange, butt welding, thread, etc

Applicable temperature: - 196 ℃ ~ 700 ℃

Driving mode: manual, bevel gear transmission, pneumatic, electric, hydraulic, pneumatic hydraulic, electro-hydraulic linkage

Valve body materials: WCB, zg1cr18ni9ti, zg1cr18ni12mo2ti, CF8 (304), CF3 (304L), CF8M (316), cf3m (316L), Ti. Different materials can be used for water, steam, oil, nitric acid, acetic acid, oxidizing medium, urea and other media.

Stop valve refers to the valve whose closing part (disc) moves along the center line of valve seat. According to the movement of the disc, the change of the valve seat opening is proportional to the disc stroke. Because the opening or closing stroke of the valve stem is relatively short, and it has a very reliable cut-off function, and because the change of the valve seat opening is directly proportional to the stroke of the valve disc, it is very suitable for regulating the flow. Therefore, this type of valve is very suitable for cutting off or regulating and throttling.

The selection principle is: 1, high temperature, high pressure medium pipeline or device should choose stop valve. Such as thermal power plant, nuclear power plant, petrochemical system of high temperature, high pressure pipeline.

2. On the pipeline where the resistance requirement is not strict. That is, the pressure loss is not considered.

3. Small valve can choose needle valve, instrument valve, sampling valve, pressure gauge valve, etc.

4. There are flow regulation or pressure regulation, but the regulation accuracy is not high, and the pipeline diameter is relatively small, such as the nominal diameter ≤ 50 mm pipeline, it should be selected.

5. High pressure angle stop valve or high pressure angle throttle valve with nominal pressure of pn160, nominal pressure of 16MPa or pn320, nominal pressure of 32Mpa should be selected for small and large chemical fertilizers in synthetic industry.

6. In the desiliconization workshop of alumina Bayer process and the pipeline easy to coking, it is easy to select the direct current stop valve or direct current throttle valve with separate valve body, removable valve seat and cemented carbide sealing pair.