Most of the media in chemical production equipment are characterized by high toxicity, flammability, explosiveness and corrosiveness. The working conditions are complex and harsh, and the operating temperature and pressure are high. If the valve fails, the light will cause the medium to leak, and the heavy one will cause the device to stop working. Suspension of production, and even caused a serious accident. Therefore, the scientific and rational selection of the valve can not only reduce the construction cost of the device, but also ensure the safe operation of the production.
The DIN valve supplier takes you to understand the key points of valve selection:
- Identify the use of the valve in equipment or equipment
Determine the working conditions of the valve: the nature of the medium, working pressure, operating temperature and control method.
- Correct choice of valve type
The correct choice of valve type is pre-requisite for the designer to fully grasp the entire production process and operating conditions. When selecting the valve type, the designer should first grasp the structural characteristics and performance of each valve.
- Determine the end connection of the valve
The first two are most commonly used in threaded, flanged, and welded end connections. The threaded valve is mainly a valve with a nominal diameter of 50mm or less. If the diameter of the thread is too large, the connection and sealing of the joint are very difficult. Flange-connected valves are easy to install and disassemble, but they are more cumbersome and more expensive than thread ball valves, making them suitable for pipe connections of various diameters and pressures. Welded connections are more reliable than flanged connections in harsher conditions. However, the removal and reinstallation of the welded joint valve is difficult, so its use is limited to applications that are usually reliable for long periods of time, or where the conditions are harsh and the temperature is high.
- Valve material selection
Select the material of the valve housing, inner part and sealing surface. In addition to considering the physical properties (temperature, pressure) and chemical properties (corrosiveness) of the working medium, you should also know the cleanliness of the medium (with or without solid particles). In addition, it is also necessary to refer to the relevant provisions of the state and the use of the department. Proper and reasonable selection of the material of the valve can achieve the most economical life and optimum performance of the valve. The order of valve body material selection is: cast iron-carbon steel-stainless steel, but stainless steel socket weld ball valve is good, and the order of sealing material is: rubber-copper-alloy steel-F4.
In addition, the flow rate and pressure level of the fluid flowing through the valve should be determined, and the appropriate data should be selected using existing data (such as valve catalogues, valve product samples, etc.).
Other than this, single-sealed regulator valves such as single-seat valves, high-pressure valves, and single-sealed sleeve valves without balance holes require flow direction selection. There are advantages and disadvantages to opening and closing. The flow-opening valve works stably, but the self-cleaning performance and the sealing performance are poor, and the service life is short; the flow-closed valve has a long service life, self-cleaning performance and good sealing performance, but the stability is poor when the valve stem diameter is smaller than the spool diameter. Single-seat valves, small-flow valves, and single-seal sleeve valves are usually selected for flow-opening. When flushing is strong or self-cleaning is required, flow closure is optional. The two-position quick-opening characteristic regulating valve is selected for flow closing type.