Is the adjustable ratio R value used in the calculation of the control valve opening always 30?
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This post was last edited by kylestone on 2017-4-1 at 14:36. Some small software programs found online indicate that the R value is 29.5527. I wonder whether, when manufacturers calculate the opening degrees of control valves under maximum, minimum, and normal flow conditions, the R value is also 30? May I ask how the manufacturer selects this adjustable ratio R when making calculations? Does the value of R determine the hardware structure of the valve core? When the calculated opening degree is not ideal, should we then switch to calculating with another R value? Why is the R value used for calculating the opening degree never shown in the calculation sheets provided by control valve manufacturers?
I would like to ask you how the adjustable ratio R is defined.
This post was last edited by hfrs on 2017-3-31 at 13:41. Valves of general design are usually 50, 30, and 100 models are also available.
May I ask how the manufacturer selects this adjustable ratio R when making calculations? Does the value of R determine the hardware structure of the valve core? When the calculated opening degree is not ideal, should we then switch to calculating with another R value? Why is the R value used for calculating the opening degree never shown in the calculation sheets provided by control valve manufacturers?
This post was last edited by dhwfz on 2020-2-23 at 11:13. Regarding the selection of the adjustable ratio R for control valves, there is a parameter table for such valves; different types of control valves (with varying valve stem and seat configurations) have different values for R. The value is usually 30, but it can also be 100 for eccentric rotary valves, 200 for ball valves, 10 for diaphragm valves, and 15 for butterfly valves. If the calculation results are not appropriate, it is also possible to consider using two control valves and employing split-control for regulation, or to use valves of another diameter and check the process data.
The last edit to this post was made by cqdfwy on 2020-2-26 at 17:49. The selection process for control valves involves first determining the type, and then calculating the appropriate specifications. Different types of control valves have different R values; most are 30, but there are also values of 100 (eccentric rotary valves), 200 (ball valves), 10 (diaphragm valves), and 15 (butterfly valves). If the opening check does not meet the requirements, it is necessary to select a different type and then recalculate to determine the specifications.