In the field of industrial automation process control, the regulating valve receives the control signal output from the regulating control unit and uses the power operation to change the final control element of the process parameters such as medium flow, pressure, temperature, and liquid level. Generally consists of actuators and valves. According to the stroke characteristics, the regulating valve can be divided into straight stroke and angular stroke; according to the power used by the implementing agencies, it can be divided into linear characteristic, equal percentage characteristic and parabolic characteristic according to its function and characteristic. Regulating valve is suitable for air, water, steam, various corrosive media, mud, oil and other media. Common categories: pneumatic control valve, electric control valve, hydraulic control valve, self-regulating valve.
1. Cast iron valves should not be used when the ambient temperature is lower than -20°C (especially in the north).
2. The pressure rating, temperature and corrosion resistance of the body of the self-operated temperature control valve should not be lower than the requirements of the process connecting pipe, and the manufacturer's styling product should be preferred.
3. Cast iron valves should not be used for water vapor or more wet gases and flammable and explosive media.
4. For highly corrosive media, the corrosion resistant alloy must be selected according to the type, concentration, temperature, and pressure of the medium.
5. In the rectangular coordinates formed by the medium temperature and pressure difference where cavitation and erosion are severe, when the temperature is 300°C, and the pressure difference is 1.5 MPa, the pressure is 1.5 MPa. Abrasive materials such as cobalt-based alloys or surfacing alloys.
6. Vacuum valve should not use valve body lining rubber and plastic structure.
7. The selection of lining material (rubber, plastic) by the self-operated temperature control valve must meet the scope of use of the material when the temperature, pressure, and concentration of the working medium are taken into account, and the physical and mechanical damage to the valve when it is acted upon (such as Shear damage).
8. The valve body and throttling piece are treated separately. The throttling speed of the inner wall of the valve body is small and allows a certain degree of corrosion. The corrosion rate can be about 1 mm/year; the throttling piece is subject to high speed erosion and corrosion will cause the leakage to increase. Corrosion rate should be less than 0.1mm/year.
9. The two shut-off valves of the water treatment system should not use lining rubber material.
10. The most versatile corrosion resistant material is tetrafluoride, known as "Corrosion Resistant King." Therefore, all PTFE corrosion-resistant valves should be selected first, and alloys will be used only in the last resort (eg, temperature>180°C, PN>1.6).
1. Cast iron valves should not be used when the ambient temperature is lower than -20°C (especially in the north).
2. The pressure rating, temperature and corrosion resistance of the body of the self-operated temperature control valve should not be lower than the requirements of the process connecting pipe, and the manufacturer's styling product should be preferred.
3. Cast iron valves should not be used for water vapor or more wet gases and flammable and explosive media.
4. For highly corrosive media, the corrosion resistant alloy must be selected according to the type, concentration, temperature, and pressure of the medium.
5. In the rectangular coordinates formed by the medium temperature and pressure difference where cavitation and erosion are severe, when the temperature is 300°C, and the pressure difference is 1.5 MPa, the pressure is 1.5 MPa. Abrasive materials such as cobalt-based alloys or surfacing alloys.
6. Vacuum valve should not use valve body lining rubber and plastic structure.
7. The selection of lining material (rubber, plastic) by the self-operated temperature control valve must meet the scope of use of the material when the temperature, pressure, and concentration of the working medium are taken into account, and the physical and mechanical damage to the valve when it is acted upon (such as Shear damage).
8. The valve body and throttling piece are treated separately. The throttling speed of the inner wall of the valve body is small and allows a certain degree of corrosion. The corrosion rate can be about 1 mm/year; the throttling piece is subject to high speed erosion and corrosion will cause the leakage to increase. Corrosion rate should be less than 0.1mm/year.
9. The two shut-off valves of the water treatment system should not use lining rubber material.
10. The most versatile corrosion resistant material is tetrafluoride, known as "Corrosion Resistant King." Therefore, all PTFE corrosion-resistant valves should be selected first, and alloys will be used only in the last resort (eg, temperature>180°C, PN>1.6).
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