About pneumatic butterfly valve in the gas, liquid medium use we have discussed more, and because the pneumatic butterfly valve for solid materials (such as dust, stone powder) is not much, so in the selection and use of a lot worth Explore the place. The following combination of practical experience to talk about opinion. Butterfly valve for the control of solid materials, often at the bottom of the tank as a discharge valve to use, such as cement tanks, cans and other tank bottom, for discharging and rapid cutting. Because most dust particles contain large or small particles, the sealing surface of the valve wear is undoubted, improper selection, will greatly reduce the service life of the valve, or soon result in valve leakage, affecting the continued use. There is such a case: there is a component weighing system, the entire ingredients process with PLC to achieve full automatic control, and ingredients car discharge valve is selected pneumatic three eccentric butterfly valve, the medium is very fine particles of stone powder. After a period of time, customers reflect the valve leakage, resulting in a large pile of powder often leaks on the workbench. Valve back to factory testing is not leaked, but customers also used to reflect this valve, and the same medium, such a thing has not happened. In order to clarify the whole story, the company sent people to the scene, and finally find out the reasons: the original, this medium is very thin, and a little sticky, although the ingredients car equipped with a vibrating motor, and finally a lot of material attached to the tank wall and valve parts, When the valve is closed, the card is stuck around the sealing surface, so that the valve can not be completely closed. As a result, a leakage occurs after the material is re-installed. As time passes, the sealing surface is also worn so badly that even grooves are formed. Find out the reason, put forward the solution: In the PLC program, the motor vibration time, try to close the valve after all the shock out of the material; the zero calibration of the weighing instrument, the material will be out until all show zero , This time by the PLC issued a signal to close the valve; the three eccentric butterfly valve is replaced by double eccentric elastic hard sealing butterfly valve (also available neutral seal rubber butterfly valve, taking into account the occasional large particles in the material, the rubber seal may not be durable - if Is not fine particles of powder, you can consider the use of soft seal butterfly valve), because the valve seat of the three eccentric butterfly valve is a diagonal sealing surface, that is, the surface seal, so the material is easy to accumulate in the sealing surface, can not be quickly discharged, and Single-eccentric or double-eccentric butterfly valve does not have this drawback, even if there is a little material on the sealing surface, the valve is also closed when the valve is scraped off, thus ensuring a good seal, and the sealing surface durable. After such a transformation, such a problem never happened again. In such a system, there are other factors that need to be taken into account, such as: can not let the material directly into the valve plate from above into the car (this impact will also make the valve can not close tight), and the material Static pressure also need to exceed the design pressure of pneumatic butterfly valve, and so on. The difference between a control valve and a normal manual valve is that you can not treat it as an isolated component and must be considered as part of an overall automation system. Many of the problems with using a control valve are not a matter of choice And the configuration of the problem, but because of the user's lack of awareness of the control valve so that the control valve fails to debug with the control system, with good. As long as the key to recognize the problem, the correct selection of the valve, and commissioning of the control valve in the system debugging phase, we can greatly reduce the failure rate, the long-term stable operation of automatic control system.