The main technical performance of the valve:
1. Sealing performance refers to the ability of each sealing part of the valve to prevent medium leakage. It is the most important technical performance index of the valve. There are three sealing parts of the valve: the contact between the sealing surface of the opening and closing parts and the valve seat; the joint of the packing with the valve stem and the stuffing box; the connection between the valve body and the valve cover. The leak in the former place is called endoleak, which is commonly referred to as the lack of tightness, which will affect the ability of the valve to cut off the medium. For shut-off valves, internal leakage is not allowed. The latter two leaks are called external leaks, ie the medium leaks from the valve to the outside of the valve. External leakage can cause material loss, pollute the environment, and cause accidents in severe cases. For flammable, explosive, toxic or radioactive media, external leakage is not allowed, so the valve must have a reliable sealing performance.
2. Flow medium refers to the pressure loss (the pressure difference between the front and the back of the valve) when the medium flows through the valve, that is, the valve has a certain resistance to the flow of the medium. The medium consumes a certain amount of energy to overcome the resistance of the valve. In terms of energy conservation, when designing and manufacturing valves, it is necessary to reduce the resistance of the valve to the flowing medium as much as possible. Third, the opening and closing force and opening and closing torque refers to the force or torque that must be applied when the valve is opened or closed. When closing the valve, it is necessary to form a certain sealing specific pressure between the opening and closing parts and the sealing surface of the bearing seat, and at the same time overcome the between the valve stem and the packing, between the thread of the valve stem and the nut, and at the end of the valve stem and The friction of other friction parts must be applied with a certain closing force and closing torque. During the opening and closing process, the required opening and closing force and opening and closing torque are changed. The maximum value is the final moment or opening of the closing. The initial moment. When designing and manufacturing valves, it is desirable to reduce their closing force and closing torque.
3. The opening and closing speed is expressed by the time required to complete an opening or closing action with a valve. Generally, there is no strict requirement for the opening and closing speed of the valve, but some working conditions have special requirements for the opening and closing speed. If some requirements are quickly opened or closed, in case of accidents, some requirements are required to be slowly closed to prevent water hammer, etc. This should be considered when selecting the valve type.
4. Action sensitivity and reliability refers to the sensitivity of the valve to the corresponding changes in the media parameters. For valves with regulating functions such as throttle valves, pressure reducing valves, regulating valves, etc., as well as valves with special functions such as safety valves and traps, the functional sensitivity and reliability are important technical performance indicators.
5. Service life refers to the durability of the valve, is an important performance indicator of the valve, and has great economic significance. Usually indicated by the number of opening and closing times that can guarantee the sealing requirements, it can also be expressed by the use time.
