Main technical specifications of valves

Valve strength performance is the ability to withstand the media pressure. Valve is a mechanical product under internal pressure, so it must have sufficient strength and rigidity to ensure long-term use without cracking or deformation. 

Valve sealing performance is to prevent the leakage of the valve sealing parts of the capacity of the media, it is the most important technical indicators of the valve. Sealing parts of the valve there are three: opening and closing parts and valve seat sealing surface between the two contact points; packing and valve stem and stuffing box with the office; valve body and valve cover connection. Among them, the former is called internal leakage, which is often said to be off, it will affect the ability of the valve to cut off the medium. For the cut-off valve type, the internal leakage is not allowed. After the two leakage is called external leakage, that is, the media from the valve leakage to the outside of the valve. External leakage will result in material loss, pollute the environment, will cause serious accidents. For flammable, explosive, toxic or radioactive medium, the leakage is not allowed, so the valve must have a reliable sealing performance. 

 Media flow through the valve will produce pressure loss (both before and after the valve pressure difference), that is, the flow of the valve on the media have a certain resistance, medium to overcome the resistance of the valve will consume a certain amount of energy. From the energy conservation considerations, design and manufacture of valves, to reduce the resistance of the valve on the flow media as much as possible. 

The opening and closing torque is the force or moment that must be applied to open or close the valve. When the valve is closed, to make sure the sealing pressure formed hoist pieces of the two seat sealing surface, but also to overcome the stem and packing, between the stem and stem nut thread between end bearing, friction and other parts of friction, it should exert certain closing force and closing torque, the valve in the open in the process of closing, opening and closing force and closing torque change is needed, the maximum value is in the initial instantaneous instantaneous closing or opening end. Design and manufacture of valves should be sought to reduce the closing force and closing torque. 

 The speed of opening and closing is the time required to complete an opening or closing action of the valve. The general speed of opening and closing the valve without strict requirements, but some conditions have special requirements on the opening and closing speed, if the requirements of rapidly turned on or off, to prevent accidents, and some asked slowly shut down to prevent water hammer, etc., which should be considered in the selection of valve type. 

This refers to the valve for the medium parameters change, to respond to the sensitivity of the corresponding. With a specific function for the throttle valve, reducing valve, regulating valve used to adjust the parameters of the valve and safety valve, drain valve of the valve, the sensitivity and reliability of its functions are very important indicators of technical performance. 

 It means that the durability of the valve, the valve is an important performance indicators, and has great economic significance. Usually to ensure that the sealing requirements of the opening and closing times to say, you can also use the time to express.