The Main Technical Performance Specification Of The Valve

A valve is a device in a fluid system that controls the direction, pressure, and flow of the fluid. A valve is a device that allows the flow or stopping of a medium (liquid, gas, powder) in piping and equipment and controls its flow. After years of learning and understanding of valves, the main technical performance specifications of valves are summarized as follows:



Strength properties

Valve strength performance refers to the ability of the valve to withstand the pressure of the medium. Valves are mechanical products under internal pressure and must have sufficient strength and stiffness to ensure long-term use without cracking or deformation.



The sealing performance

The sealing performance of the valve refers to the ability of the valve to prevent the leakage of the media in the sealing position, which is the most important technical performance index of the valve. The sealing position of the valve has three places: the contact between the opening and closing parts and the sealing surface of the seat; Fitting of packing with stem and stuffing box; Joint between valve body and bonnet. The previous leak is called an internal leak, which is often referred to as a loose shut and affects the valve's ability to cut through the medium. For cut-off valves, internal leakage is not allowed. The latter two leakage is called leakage, that is, the medium leakage from the valve to the valve. Leakage will cause material loss, pollution of the environment, serious will also cause accidents. For flammable, explosive, toxic or radioactive media, leakage is not allowed, so the valve must have reliable sealing performance.



The flow of medium

After the medium flows through the valve will produce pressure loss (both before and after the valve pressure difference), that is, the valve has a certain resistance to the flow of the medium, the medium to overcome the resistance of the valve will consume a certain amount of energy. When designing and manufacturing valves for energy conservation, minimize the resistance of the valve to the flow medium.



Opening and closing forces and opening and closing moments

Opening and closing force and opening and closing moment refers to the valve to open or close the force or torque must be applied. Close the valve, the need to make the open-close part and send a form a seal between the two sealing surface pressure, but also overcome between stem and packing, the valve stem and between threads of the nut, valve rod end bearing friction and other parts of the friction force, and therefore must exert closing force and close moment, in the process of opening and closing, the valve is required for opening and closing force and the open-close torque changes, its maximum is in the closed end transient or open the initial transient. Valves should be designed and manufactured to reduce the closing force and closing torque.



Opening and closing speed

The opening and closing speed is expressed by the time it takes the valve to complete a single opening or closing action. Generally, there is no strict requirement 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 requirements for quick opening or closing, in case of accidents, some requirements for slow closing, in case of water hammer, etc., this should be considered in the selection of valve type.



Action sensitivity and reliability

This refers to the valve to the medium parameter changes, make the corresponding response to the sensitivity. For throttle valve, pressure reducing valve, regulating valve and other valves used to regulate medium parameters and valves with specific functions such as relief valve and steam trap, its functional sensitivity and reliability are very important technical performance indicators.



The service life of the

It indicates the durability of the valve, is an important performance index of the valve, and has great economic significance. It is usually expressed in terms of the number of times the seal is opened and closed, or in terms of the time it is used.