Sealing performance

       The sealing performance of a valve refers to the ability of each sealing part of the valve to prevent medium leakage. It is a relatively important technical performance index of the valve. There are three sealing positions of the valve: the contact between the opening and closing member and the two sealing surfaces of the valve seat; the combination of the packing with the valve stem and the stuffing box; The previous leak is called internal leakage, which is commonly known as improper closing, which will affect the valve's ability to intercept the medium. For shut-off valves, internal leakage is not allowed. The latter two leaks are called external leaks, that is, the medium leaks from the inside of the valve to the outside of the valve. Leakage can cause material loss, pollute the environment, and cause accidents in severe cases. For flammable, explosive, toxic or radioactive media, leakage is not allowed, so the valve must have reliable sealing performance.

       Flowing medium

       After the medium flows through the valve, there will be a pressure loss (the pressure difference between the front and rear of the valve), that is, the valve has a certain resistance to the flow of the medium, and the medium needs to consume a certain amount of energy to overcome the resistance of the valve. From the perspective of energy conservation, when designing and manufacturing the valve, it is necessary to reduce the resistance of the valve to the flowing medium as much as possible.

       Opening and closing force and opening and closing moment

       Opening and closing force and opening and closing torque refer to the force or torque that must be applied to open or close the valve. When closing the valve, it is necessary to make a certain sealing specific pressure between the opening and closing member and the two sealing surfaces of the hair seat. At the same time, it is necessary to overcome the valve stem and the packing, the valve stem and the nut thread, the valve end support and The frictional force of other friction parts must apply a certain closing force and closing torque. During the opening and closing process of the valve, the required opening and closing force and opening and closing torque change, and its peak value is at the moment of closing or the moment of opening. . Valves should be designed and manufactured to reduce their closing force and closing torque.

       Opening and closing speed

       The opening and closing speed is expressed by the time required for the valve to complete an opening or closing action. Generally, there is no strict requirement for the opening and closing speed of the valve, but some conditions have special requirements for the opening and closing speed. If required, it should be opened or closed quickly to prevent accidents, and some require to be closed slowly to prevent water hammer. This should be considered when selecting the valve type.

Motion sensitivity and reliability

       This refers to the sensitivity of the valve to the corresponding changes in media parameters. Functional sensitivity and reliability are very important technical performance indicators for valves that have specific functions, such as throttle valves, pressure reducing valves, regulating valves, and other valves that are used to adjust media parameters.

Service life

       It indicates the durability of the valve, is an important performance indicator of the valve, and has great economic significance. It is usually expressed by the number of openings and closings that can guarantee the sealing requirements, and it can also be expressed by the use time.