Precautions for valve selection and valve replacement

The importance of valve selection

The selection of the regulating valve structure is based on the comprehensive consideration of factors such as the used medium, 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 the valve structure selection is directly related to the use performance, adjustment performance, adjustment stability, and service life.

Working condition information that needs to be implemented for valve selection

Process parameters:

1. The name of the medium.

2. Medium density, viscosity, temperature, clean degree of medium (with particles).

3. The physical and chemical properties of the medium: such as corrosiveness, toxicity, acidity and alkalinity.

4. Medium flow: maximum, normal, minimum.

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

6. Medium viscosity, the greater the viscosity, the more it affects the calculation of Cv value.

These parameters are mainly used to calculate dimensional parameters such as the required diameter and rated Cv value of the valve, as well as the appropriate material that the valve should use.

Functional parameters:

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

2. Valve function: adjust, cut off, adjust and cut off shared.

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

4. Action time requirements.

This part of the parameters is mainly used to determine some accessory equipment that needs to be configured for the functional requirements of the valve.

Explosion-proof protection parameters:

1. Explosion-proof grade.

2. Protection level.

Environmental and power parameters:

1. Ambient temperature.

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

Precautions for replacing the valve

If the valve is to be replaced, the following size parameters should be provided to avoid the inconsistency of the valve manufacturer, or the use of different standards, or the valve structure, which may cause the valve to be unable to be installed, or unable to install, or insufficient space occur.