The valve strength performance
The valve strength refers to the valve 's ability to bear the pressure medium. Valve is under internal pressure of mechanical products, which must have sufficient strength and stiffness,to ensure the long-term use without cracking or deformation occurred.
Sealing performance of the valve means of the sealed parts of the valve to prevent leakage of medium capacity, it is the most important valves technical performance indicators. Sealing valve has three parts: opening and closing piece and the valve seat sealing surface between the two contact points; fill with the stem and fill with the letter and the Department; valve connection with the valve cover. The first one is called the leak within the leak, which is commonly referred to as Guan lax, it will affect the media's ability to cut-off valve. The cut-off valve type, the internal leakage is not allowed. After two called the leakage of leakage, theleakage of media from the valve to the valve. Leakage would cause material loss, pollution of the environment, it will result in serious accidents. For flammable and explosive, toxic or radioactive medium, is allowed to leak, so the valve must have a reliable sealing performance.
Medium flow through the valve will produce pressure loss ( both before and after the valvepressure difference ), which is the flow valve on the media have a certain resistance, mediumto overcome the resistance of the valve will consume energy. From the conservation of energy considerations, the design and manufacture of valves, the valves to minimize theresistance to the flow of media.
Opening and closing and opening and closing moment
Opening and closing force and hoisting moment is to open or close the valve that must be imposed by force or torque. When the valve is closed, need to make the hoist pieces withthe two sealing cover form a sealing pressure ratio, but also overcome the stem and packing, between the stem and the threads of the nut, the end of the valve rod betweensupport and other parts of friction friction, thus must exert a closing force and closing moments, valves in the Rev. Closing process, the opening and closing force and hoisting moment is changing, the maximum value is at the closed end or open the initialinstantaneous instantaneous. Design and manufacture of valves should be closed to reduce its force and closing moments.
The speed of the valve gate is open or closed to complete a move to indicate the time required. Valves open and close speeds generally no strict requirements, but some conditions the speed of opening and closing with special requirements, such as the prompt to open or closed, to prevent an accident, and some require closed slowly, to prevent water hammer and other produce, which in the selection of valve type should be taken into account.
Sensitivity and reliability of action
This refers to the valve for the medium parameters change, corresponding to the sensitivity of the reaction. The throttle valve, relief valve, regulating valve is used to regulate theparameters of the valve and safety valve, drain valve has a specific function of the valve, the sensitivity and reliability of its functions are very important indicators of technical performance.
It is said that the durability of the valve, the valve is an important performance index, and has great economic significance. Usually sealed to ensure that the requirements of theopening and closing times said, also can use time to express.