First, the strength properties Strength properties of the valve is the valve the ability to withstand the media pressure. Valve is subjected to inner pressure of mechanical products, and therefore must have sufficient strength and rigidity to ensure the long-term use without breakage or deformation. Second, the sealing performance Valve sealing performance is part of the sealing valve to prevent the ability of media leaks, it is the valve of the most important technical performance indicators. Valve seal has three parts: opening and closing pieces and valve seat sealing surface between the contact points; filler stem and the stuffing of the distribution and office; body and bonnet connection. Which is called before a leak within the leak, which is usually as loose, it will affect the ability of the media cut off valve. For the cut valve, internal leakage is not allowed. Leakage after the two called the leak, that media leaks from the valve to the valve outside. Leakage will result in material losses, environmental pollution, can also cause serious accidents. The explosive, toxic or radioactive medium, leakage is not allowed, therefore, the valve must have a reliable sealing performance. Third, the mobile media Medium flow through the valve will generate pressure loss (both before and after the valve pressure difference), that is, the flow valve on the media have a certain resistance, medium to overcome the resistance of the valve, it takes some energy. From energy conservation considerations, the design and manufacture of valves, to minimize the resistance of the valve on the flow media.
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