1.Clarify the purpose of the valve in the equipment or device
Determine the working conditions of the valve: the nature of the applicable medium, the working pressure, the working temperature and the control method of operation, etc.
2.Correctly choose the type of valve
The correct choice of valve type is based on the designer's full grasp of the entire production process and operating conditions as a prerequisite. When selecting the valve type, the designer should first grasp the structural characteristics and performance of each valve.
3.Determine the end connection of the valve
Among threaded connections, flange connections, and welded end connections, the first two are the most commonly used. Threaded valves are mainly valves with a nominal diameter below 50mm. If the diameter is too large, it will be very difficult to install and seal the connection. Flange-connected valves are more convenient to install and disassemble, but they are heavier and more expensive than screw-connected valves, so they are suitable for pipe connections of various diameters and pressures. Welding connection is suitable for heavy load conditions and is more reliable than flange connection. However, it is difficult to disassemble and reinstall the valve connected by welding, so its use is limited to the occasions that can usually operate reliably for a long time, or where the use conditions are heavy and the temperature is high.
4.Selection of valve material
When selecting the material of the valve's shell, internal parts and sealing surface, in addition to considering the physical properties (temperature, pressure) and chemical properties (corrosiveness) of the working medium, the cleanliness of the medium (with or without solid particles) should also be grasped. In addition, it is necessary to refer to the relevant regulations of the country and the user department. The correct and reasonable selection of the valve material can obtain the most economical service life and the best performance of the valve. The valve body material selection sequence is: cast iron-carbon steel-stainless steel, and the sealing ring material selection sequence is: rubber-copper-alloy steel-F4.
5.other
In addition, the flow rate and pressure level of the fluid flowing through the valve should also be determined, and the appropriate valve should be selected using existing information (such as valve product catalogs, valve product samples, etc.).
