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This post was last edited by 鎴戠編鎴戜换鎬р樅 on 2020-11-9 at 14:13. Hi, your little industrial control assistant has arrived right on time! Today, I’ll introduce to you the professional terms related to pneumatic control valves. By understanding these basic terms, I believe we’ll be able to use these valves more easily in the future. Strength performance: The strength performance of a pneumatic control valve refers to its ability to withstand the pressure of the medium. Valves are mechanical components that are subjected to internal pressure; therefore, they must possess sufficient strength and stiffness to ensure they do not crack or deform over long-term use. Sealing performance: The sealing performance of a pneumatically controlled valve refers to the ability of its various sealing elements to prevent the leakage of the medium, and it is the most important technical parameter of such valves. There are three sealing areas in a valve: the contact point between the moving part and the two sealing surfaces of the valve seat ； The fit between the packing and the valve stem as well as the packing box ； The connection between the valve body and the valve cover. The leakage in the former case is known as internal leakage, which is what is commonly referred to as poor sealing; it affects the valve’s ability to block the flow of the medium. For cut-off valves, internal leakage is not allowed. The leaks in the latter two locations are called external leaks, that is, the medium leaks from inside the valve to outside it. Leaks can lead to material loss, environmental pollution, and in severe cases, accidents. For flammable, explosive, toxic, or radioactive media, leaks are absolutely unacceptable; therefore, valves must have reliable sealing properties. When a fluid flows through a valve, pressure loss occurs (that is, a pressure difference before and after the valve), meaning that the valve presents a certain resistance to the flow of the fluid. The fluid must expend energy in order to overcome this resistance. From the perspective of energy conservation, when designing and manufacturing valves, it is necessary to minimize the resistance exerted by the valves on the flowing medium as much as possible. Opening force and opening torque: The opening force and opening torque refer to the force or torque that must be applied to open or close a valve. When closing the valve, it is necessary to create a certain sealing pressure between the sealing surfaces of the moving part and the seat. At the same time, it is also required to overcome the friction forces between the valve stem and the packing, between the threads of the valve stem and the nut, at the support points at the end of the valve stem, and in other friction-prone areas. Therefore, a certain closing force and closing torque must be applied. During the opening and closing process of the valve, the required opening and closing forces and torques change, with their maximum values occurring at the final moment of closure or the initial moment of opening. When designing and manufacturing valves, efforts should be made to reduce their closing force and closing torque. Response sensitivity and reliability refer to the degree to which a valve is sensitive to changes in medium parameters and can respond accordingly. For valves such as throttle valves, pressure reducing valves, and control valves that are used to adjust the parameters of a medium, as well as valves with specific functions like safety valves and steam traps, their functional sensitivity and reliability are very important technical performance indicators.