The opening and closing part of the fluorine-lined globe valve is a plug valve, the sealing surface is a flat or cone surface, and the valve moves linearly along the fluid center line. The movement form of the valve stem includes the lifting rod type (the valve stem is raised and lowered, the hand wheel does not rise), and the lifting rotating rod type (the hand wheel and the valve stem rotate and rise together, and the nut is set on the valve body). The stop valve is only suitable for fully open and fully closed, adjustment and throttling are not allowed.
Basic overview
The fluorine-lined globe valve is a forced sealing valve, so when the valve is closed, pressure must be applied to the valve to avoid leakage of the sealing surface. When the medium enters the valve from under the valve, the resistance that the operating force must overcome is the thrust generated by the friction between the valve stem and the filling material and the pressure of the medium. The force to close the valve is greater than the force to open the valve, so the diameter of the valve is large. If the top of the valve is bent, it will malfunction. After the appearance of the self-sealing valve, when the medium flow of the shut-off valve enters the valve cavity from above the valve, under the medium pressure, the force to close the valve is small, and the force to open the valve is large, and the diameter of the valve is correspondingly reduced. At the same time, under the action of the medium, this type of valve is also very tight. According to the regulations of my country's three-phase valve, the flow of the stop valve is adopted from top to bottom.
When the fluorine-lined stop valve is opened, when the opening height of the valve is 25%~30% of the nominal diameter, the flow reaches the maximum, which means that the valve has reached the fully open position. Therefore, the fully open position of the shut-off valve should be determined by the valve stroke.
Fluorinated globe valve has the following advantages
1. Simple structure, convenient manufacturing and maintenance.
2. The working stroke is small and the switching time is short.
3. Good sealing, low friction between the sealing surfaces, and long service life.
4. The disadvantages of fluorine-lined stop valve are as follows
5. The fluid resistance is large, and the force required for opening and closing is large.
6. It is not suitable for media with particles, high viscosity and easy to coke.
The types of high-pressure shut-off valves are divided into external thread type and internal thread type according to the position of the valve stem thread. According to the flow direction of the medium, there are straight-through type, direct-flow type and angle type. According to the sealing form, the globe valve is divided into packing seal globe valve and bellows seal globe valve.
The fluorine-lined globe valve has compact structure, flexible opening and closing, and strong corrosion resistance. It is widely used in petroleum, chemical and other pipeline systems to cut off the medium. However, it should be emphasized that the fluorine-lined globe valve must not be adjusted in flow to avoid throttling. The resulting high-speed medium flow erodes and destroys the sealing surface. The valve and the valve stem are designed as an integrated structure to prevent the possibility of internal parts rushing out of the valve body due to pipeline pressure fluctuations. The structure is compact and safe to use. The surface is evenly covered with FEP. The inner surface of the valve body channel is smooth, with low fluid resistance, high CV value, strong flow capacity, and moderate torque. It adopts a four-stage sealing structure and matches the temperature and aging SI rubber elastic sealing valve seat outside the sealing surface to completely achieve zero leakage of the medium.
|
Address
Mailbox
Contact