Brief introduction of several technical performanc

Introduction to several technical properties of valves

the strength performance of valves refers to the ability of valves to withstand medium pressure. Valves are mechanical products that bear internal pressure, so they must have sufficient strength and stiffness to ensure long-term use without cracking or deformation

sealing performance

the sealing performance of the valve refers to the ability of each sealing part of the valve to prevent medium leakage, which is the most important technical performance index of the valve. There are three sealing parts of the valve: the contact between the two sealing surfaces of the hoist and the valve seat; Packing, valve stem and stuffing box; The connection between valve body and bonnet. The leakage in the former part is called internal leakage, which is usually said that if it is not closed tightly, it will affect the ability of the valve to cut off the medium. For block valves, internal leakage is not allowed. The leakage at the last two places is called external leakage, that is, the medium leaks from inside the valve to outside the valve. Leakage will cause material loss, pollute the environment, and even cause accidents in serious cases. For flammable, explosive, toxic or radioactive media, leakage is not allowed, so the valve must have reliable sealing performance

flowing medium

pressure loss will occur after the medium flows through the valve (i.e. the pressure difference between the front and back of the valve), that is, the valve has a certain resistance to the flow of the medium, and the medium will consume a certain amount of energy to overcome the resistance of the valve. In terms of energy conservation, when designing and manufacturing valves, the resistance of the valve to the flowing medium should be reduced as much as possible. Hoisting force and moment

hoisting force and moment refer to the force or moment that must be applied to open or close the valve. When closing the valve, it is necessary to form a certain sealing specific pressure between the opening and closing parts and the two sealing surfaces of the hair seat, and at the same time, it is also necessary to overcome the friction between the valve rod and the packing, the threads of the valve rod and the nut, the support at the end of the valve rod and other friction parts. Therefore, a certain closing force and closing torque must be applied. During the opening and closing process of the valve, the required opening and closing force and torque are changed, Its maximum value is at the final instant of closing or the initial instant of opening. When designing and manufacturing valves, we should strive to reduce the closing force and closing torque according to the technical circuit diagram of energy saving and new energy vehicles previously issued by the Chinese society of automotive engineering

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 are no strict requirements on the opening and closing speed of the valve, but some working conditions have special requirements on the opening and closing speed, such as some require rapid opening or closing to prevent accidents, and some require slow closing to prevent water hammer. The bridge deck is an engineering product produced under the specified setting, which should be considered when selecting the valve type

action sensitivity and reliability

this refers to the sensitivity of the valve to respond to changes in medium parameters. For throttle valve, pressure reducing valve, regulating valve and other valves used to adjust medium parameters, as well as safety valve, steam trap and other valves with specific functions, their functional sensitivity and reliability are very important technical performance indicators

service life

it shows that each load can only reach a certain load, indicating the durability of the valve. It is an important performance index of the valve and has great economic significance. It is usually expressed in terms of the number of opening and closing times required to ensure the sealing through Bluetooth and connection, and it can also be expressed in terms of service time