Select the valve diameter based on the KV value
Thread Content
According to the process conditions shown in the figure, the calculated KV values are 55, 50, 25 (is that correct?) ), based on the valve specifications provided by a certain manufacturer and considering equal percentage characteristics, should a DN65 valve (with a KV value of 63) be chosen? Is this choice correct?
The KV values calculated based on the process conditions you provided are 55, 50, and 25 respectively. If you choose the valve according to the equal percentage characteristics provided by a certain manufacturer, it is recommended that you opt for a DN65 valve, whose corresponding KV value is 63. This choice is correct, as the diameter of the valve to be selected needs to be determined based on parameters such as flow rate, pressure, and the medium. The principle for selecting the valve diameter based on the KV value is that the valve diameter for which the calculated KV value is closest to the corresponding KV value on the valve’s characteristic curve is the most suitable diameter. Furthermore, the equal percentage characteristic means that, as the valve opening changes from 0% to 100%, the change in flow rate follows the same proportional relationship as the change in valve opening. Valves with this feature enable higher precision in regulation, which is why they are commonly used in practical applications. .
“Based on the process conditions shown in the diagram, the calculated KV value is 55, 50, 25”. From the first diagram you provided, it seems to be a table of process conditions, not a calculation sheet, right? So “55 50 25” should be traffic data, not KV values.
I don’t understand where the values “55, 50, 25” for KV come from.
Since all the process parameters are given, isn’t it possible to calculate the KV value?
Since all the process parameters are given, isn’t it possible to calculate the KV value?
From your diagram, it appears that the numbers 55, 50, and 25 represent flow rates, not Kv values.
With flow rate, pressure difference, and density given, isn’t the KV value then calculable? It just happens to be the same as the flow rate value
This post was last edited by feng*aosa on 2023-5-8 at 16:53. The three numbers provided for the process parameters are flow rate values. After estimating, the value of KV is the same as the traffic value.
Bro, we have the flow rate, the pressures before and after the valve, as well as the density; just calculate the KV value and it’s done. It happens to be the same as the flow rate, which is 55, 50, 25
1. First, use Baidu to look up the values of Cv and Kv. 2. Then download a software or formulas for calculating control valves. 3. Calculate Cv/Kv (where Cv = 1.167 × Kv); the resulting values are 64.35/58.50/29.25, corresponding to Kv values of 55/50/25 respectively. 4. Based on the relationship between the rated Cv values specified in HGT20507/SHT3005 and the calculated Cv values, or depending on the valve opening degree, it is customary to take the rated Cv value as 2–4 times the calculated Cv value. 5. Choose a valve size of DN80 or DN100 according to the manufacturer’s table of rated Cv values. PS: Is a pressure difference of 0.1 too high? In such cases, it is sufficient to use a calculated pressure difference of 30 kPa/50 kPa for the control valve.