Precautions for valve selection and replacement

The importance of valve selection

The structure selection of the regulating valve is determined by comprehensive consideration of the medium used, temperature, pressure before and after the valve, flow, physical and chemical properties of the medium, and cleanliness of the medium. The correctness and rationality of valve structure selection is directly related to service performance, regulation performance, regulation stability and service life

Working condition information to be implemented for valve selection
I. Process parameters:

1. Media name

2. Medium density, viscosity, temperature, medium cleanliness (with particles)

3. Physical and chemical properties of media: such as corrosivity, toxicity, acidity and alkalinity

4. Medium flow: maximum, normal and minimum

5. Pressure before and after the medium valve: maximum, normal and minimum

6. The higher the viscosity of the medium, the more it will affect the calculation of Cv value

These parameters are mainly used to calculate the required diameter, rated Cv value and other dimensional parameters of the valve, as well as the appropriate materials for the valve

Second, functional parameters:

1. Action mode: electric, pneumatic, electro-hydraulic and hydraulic

2. Valve function: common for regulation, cut-off, regulation and cut-off

3. Control mode: positioner, solenoid valve and pressure reducing valve

4. Action time requirements

This part of parameters is mainly used to determine some accessory equipment required for the functional requirements of the valve

III. Explosion-proof protection parameters:

1. Explosion-proof grade

2. Degree of protection

IV. Environment and power parameters:

1. Ambient temperature

2. Power parameters: air supply pressure, power supply pressure

Precautions for valve replacement

If the valve is to be replaced, the following dimension parameters shall also be provided to avoid that the valve cannot be installed, or cannot be installed, or the space is insufficient due to the inconsistency of the valve manufacturer, or the different standards adopted, or the different valve structure