Introduction To Key Technical Performance Of Valves

Strength performance

The strength performance of Lined Valve refers to the ability of the valve to withstand medium pressure. Valves are mechanical products that withstand internal pressure, so they must have sufficient strength and rigidity 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. It is the most important technical performance indicator of the valve. There are three sealing parts of the valve: the contact between the opening and closing parts and the two sealing surfaces of the valve seat; the matching part of the packing and the valve stem and the stuffing box; the connection between the valve body and the valve cover. The leakage of the first one is called internal leakage, which is usually called loose closure, which will affect the ability of the valve to cut off the medium. For cut-off valves, internal leakage is not allowed. The leakage of the last two places is called external leakage, that is, the medium leaks from the inside of the valve to the outside of the valve. External leakage will cause material loss, pollute the environment, and cause accidents in serious cases. For flammable, explosive, toxic or radioactive media, external leakage is even more unacceptable, so the valve must have reliable sealing performance.

Flowing medium

After the medium flows through the valve, pressure loss will occur (i.e., the pressure difference before and after 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. From the perspective of energy conservation, when designing and manufacturing valves, the resistance of the valve to the flowing medium should be reduced as much as possible.

Opening and closing force and opening and closing torque

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 form a certain sealing pressure ratio between the opening and closing parts and the two sealing surfaces of the valve seat, and at the same time, it is necessary to overcome the friction between the valve stem and the packing, between the threads of the valve stem and the nut, at the end support of the valve stem and other friction parts, so a certain closing force and closing torque must be applied. During the opening and closing process of the valve, the opening and closing force and opening and closing torque required are variable, and the maximum value is at the final moment of closing or the initial moment of opening. When designing and manufacturing valves, efforts should be made to reduce their closing force and closing torque.

Action sensitivity and reliability

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

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 working conditions have special requirements for 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, etc. This should be considered when selecting the valve type.

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 ensure the sealing requirements, and can also be expressed by the use time.