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Main function parameters of valve

Main function parameters of valve

  • Categories:Industry News
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  • Time of issue:2021-10-28
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(Summary description)The valve is a control component in the pipeline fluid conveying system. It is used to change the passage section and the flow direction of the medium.

Main function parameters of valve

(Summary description)The valve is a control component in the pipeline fluid conveying system. It is used to change the passage section and the flow direction of the medium.

  • Categories:Industry News
  • Author:
  • Origin:
  • Time of issue:2021-10-28
  • Views:0
Information

The valve is a control component in the pipeline fluid conveying system. It is used to change the passage section and the flow direction of the medium. It has the functions of diversion, cutoff, adjustment, throttling, check, diversion or overflow pressure relief. Valves used for fluid control, from the simplest shut-off valve to the various valves used in extremely complex automatic control systems, have a wide variety and specifications. The nominal diameter of the valve ranges from extremely small instrument valves to large diameters up to 10m. Valves for industrial pipelines.

Valves can be used to control the flow of various types of fluids such as water, steam, oil, gas, mud, various corrosive media, liquid metals and radioactive fluids. The working pressure of the valve can be from 0.0013MPa to 1000MPa ultra-high pressure and working temperature From the ultra-low temperature of -269℃ to the high temperature of 1430℃. The valve can be controlled by a variety of transmission methods, such as manual, electric, hydraulic, pneumatic, worm gear, electromagnetic, electromagnetic-hydraulic, electric-hydraulic, pneumatic-hydraulic, spur gear, bevel gear drive, etc. Under the action of pressure, temperature or other forms of sensing signals, it can act according to predetermined requirements, or simply open or close without relying on sensing signals. The valve can be driven by * or automatic mechanism to make the opening and closing parts move up and down, Sliding, swiveling or rotating movement, thereby changing the size of the flow channel area to achieve its control function.

1. Strength performance The strength performance of the valve refers to the ability of the valve to withstand the pressure of the medium. The valve is a mechanical product that bears internal pressure, so it must have sufficient strength and rigidity to ensure long-term use without cracking or deformation.

2. Sealing performance The sealing performance of a valve refers to the ability of each sealing part of the valve to prevent the leakage of the medium. It is the most important technical performance index of the valve. The valve has three sealing positions: the contact between the opening and closing parts and the two sealing surfaces of the valve seat; the matching place between the packing and the valve stem and the stuffing box; the connection between the valve body and the valve cover. The previous leak is called internal leakage, which is commonly referred to as lax closure, 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 leakage, 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.

3. Flow performance After the medium flows through the valve, pressure loss (the pressure difference before and after the valve) will occur, that is, the valve has a certain resistance to the flow of the medium, and the medium consumes 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.

4. Action performance

1). Motion sensitivity and reliability

This refers to the sensitivity of the valve to respond to changes in media parameters. For valves with specific functions such as throttle valves, pressure reducing valves, and regulating valves, 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.

2). Hoisting force and hoisting moment

Opening and closing force and opening and closing torque 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 seal specific pressure between the opening and closing parts and the two sealing surfaces of the seat, and at the same time overcome the gap between the valve stem and the packing, the thread between the valve stem and the nut, and the support at the end of the valve stem. The frictional force of 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 opening and closing torque are changed, and the maximum value is at the final instant of closing or opening The initial instantaneous. When designing and manufacturing valves, strive to reduce their closing force and closing torque.

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