Questions about regulating valves
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Dear friends, what is the difference between the flow coefficient cv and kv of the control valve, and how to calculate it? Is the calculation formula of various valve manufacturers not consistent?
The calculation formulas are all unified.
The name CV value originated from the definition of valve flow coefficient in the Western industrial process control field. The flow coefficient is often expressed as Cv, and its definition conditions are different from those in China. Cv is defined as: When the regulating valve is fully open, the pressure difference ΔP across the valve is 1 pound/inch², and the medium is 60℉ clean water. The flow rate flowing through the regulating valve per minute is measured in gallons per minute. In China it is usually called: KV value, KV represents the flow capacity of the valve, its definition is: When the regulating valve is fully open, the pressure difference ΔP between the front and rear ends of the valve is 100KPa, and the fluid weight r is 1gf/cm3 (i.e. normal temperature water), the flow rate flowing through the regulating valve per hour is measured in m3/h or t/h. Since the definitions of Kv and Cv are different, the values measured in the test are different, and the conversion relationship between them is:: Cv=1.167Kv (For example, a regulating valve with Kv=50 means that when the pressure difference between the two ends of the valve is 100KPa, the water volume per hour is 50m3/h. )
The third floor is very detailed, support: victory:
Cv and Kv are both used to measure the flow coefficient. Please see the explanation above. There is a conversion relationship between the two. I am an operator. For a valve's Cv, I can qualitatively understand its flow capacity. In actual operation, estimating the flow rate corresponding to the opening of a control valve depends on different flow characteristics. The long-term use is equal percentage, for example
valve tag WA11Y8161 min flow 4500 max flow 20000 kg/h density 947.9 kg/m3 max flow 21.09927208 m3/h Valve adjustment ratio t 50 Valve opening H 34% x 1.3301 Volume flow V 1.595685393 m3/h Mass flow mass flow 1512.550184 kg/h
valve tag WA11Y8161 min flow 4500 max flow 20000 kg/h density 947.9 kg/m3 max flow =H11/H12 m3/h Valve adjustment ratio t 50 Valve opening H 0.34 x =LN(H14)* H15 volume flow rate V =EXP(H16) * H13/H14 m3/h mass flow =H17 * H12 kg/h
All are unified. The same goes for imported control valves.
As a reminder, the flow characteristics of the regulating valve will be modified by the characteristics of the entire system after the valve is connected to the pipeline system. In other words, the valve itself, for example, has a characteristic curve of equal percentage, and the curve will change to a certain extent when it is connected to the actual process system.
3L explained very professionally! It would be nice to post the formula for LS calculation 1