The ball valve of the thin ball valve features a clear description of the division of labor

The ball valve of the thin ball valve features a clear division of labor introduction
1, shut-off valve
The opening and closing member of the shut-off valve is a plug-shaped valve flap, the sealing surface is flat or tapered, and the valve flap moves linearly along the center line of the valve seat. The movement of the valve stem also has a lifting rotary lever type, and the shut-off valve refers to a valve in which the closing member moves along the center line of the valve seat. Due to the relatively short opening or closing stroke of the valve stem of this type of valve, and the very reliable cutting function, and because the change of the valve seat opening is proportional to the stroke of the valve flap, it is very suitable for the adjustment of the flow rate. A shut-off valve is most suitable when good throttling control is required (such as a bypass line for a control valve or a small venting port).
 
2, the ball valve
When the operating temperature is between -29oC and 200oC, most manual (open and closed) ball valves are suitable for use in hydrocarbon and utility systems. For ball valves used above 100oC, careful consideration should be given to the temperature limits of soft seal materials. Above 100oC. In the case of high temperature or severely abrasive operations, the application of metal sealed ball valves should be considered, but it should be noted that the operating torque must be increased.
    1. Ball valves are available in two designs, namely float ball and trunnion ball valves. The design of the float ball valve produces high operating torque at high pressure or large pipe diameter, but the seal is better.
    2. Ball valves are not suitable for throttling because, when the valve is partially opened, its sealing surface is exposed to the treatment fluid and is damaged.
    3. For critical operations, consider purchasing a ball valve with a ball seat and stem lubrication fitting, because lubrication can prevent slight leakage and reduce operating torque. If the valve needs to have two functions of shutting off and discharging, then A ball bleed hole that is separate from the lubrication fitting should be provided.
3, check valve
    The check valve refers to a valve that automatically opens and closes the valve flap by means of the flow of the medium itself, and is used to prevent the back flow of the medium, which is also called a check valve, a check valve, a reverse flow valve, and a back pressure valve. The check valve is an automatic valve whose main function is to prevent backflow of the medium, prevent the pump and drive motor from reversing, and discharge the container medium. The check valve can also be used to supply a line in which the pressure may rise to an auxiliary system that exceeds the system pressure. Check valves come in a variety of forms including swing, lift, ball, piston and split disc swing check valves. Among them, the fully open swing check valve is suitable for most non-fluctuation situations. The swing check valve is also applied to the vertical pipe (flow direction up). At this time, there is a stop block in the valve to prevent the valve flap from opening beyond the top dead center.
4, butterfly valve
 Ordinary butterfly valves are suitable for rough throttling and low pressure, hydrocarbon-free, non-hazardous operations. They are not suitable for use as important shut-off valves for vessels, tanks, etc. A wireless butterfly valve should be used at operating conditions above 65oC or at pressure levels above ASME150 or hazardous fluids. Since the butterfly valve can be vibrated to open with a small torque, the handle should be equipped with a locking device.
5, diaphragm valve (sheet shape)
In the design of such a valve, a diaphragm made of synthetic rubber is connected to the valve stem, and closing the valve is achieved by pressing the diaphragm against a metal boss which is part of the valve body.
6, plug valve
 Plug valves are suitable for use in hydrocarbon and utility systems. The plug valve with 90 degree rotation operation is available in both lubricated and non-lubricated designs. Lubricated plug valves must be lubricated regularly to make them sealable and easy to handle. The number of times of refueling depends on the conditions of use. Its lubrication function is a solution to prevent valve jamming.
7, needle valve
 The needle valve is basically a small shut-off valve. They are often used as shut-off valves for meters and pressure gauges for small flow throttling of instrument air, natural gas and hydraulic fluids, as well as for reducing pressure fluctuations in instrumentation piping. The needle valve has a small passage and is easily blocked, so consider this when using it.