Introduction to flow coefficient and characteristics of pneumatic control valve
Generally, most of the control valves used in long-distance pipelines are pneumatic control valves This is because the pneumatic control valve has the advantages of equal percentage flow characteristics, large flow capacity, short switching travel, large throttling pressure drop and low noise. Maybe some people don't know what the equal percentage traffic feature means. Let's take a look at the content of this traffic feature.
The relationship between the opening of the pneumatic control valve and the flow through it is the flow characteristic. The flow characteristic under the condition of constant pressure difference before and after the valve is also called inherent flow characteristic. The pressure difference of the control valve installed on the actual pipeline will change with the change of the opening, and the flow characteristics will change accordingly. The characteristics at this time are called the working flow characteristics. During this period, the linear inherent characteristic will become a fast opening characteristic, and the equal percentage inherent characteristic will become a linear or fast opening characteristic, and the regulation performance will decline. For the control valve of long-distance pipeline, only the rapidity or variable gain adjustment can compensate for this decline in performance, while the pneumatic control valve has an equal percentage flow characteristic, which can just meet this rapidity or gain adjustment.
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