How is the KV value of a valve calculated?

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The last edit to this post was made by Desert Fish on 2015-7-7 at 16:33. The Kv value, which represents the flow capacity of a control valve, is an important parameter for such valves; it indicates the ability of the fluid to pass through the control valve, and in other words, it represents the capacity of the valve. The diameter of the control valve to be selected can be determined based on the calculation of its flow capacity Kv value. To correctly select the size of the control valve, it is necessary to accurately calculate its rated flow coefficient Kv value. The rated flow coefficient of a control valve is defined as the flow rate, in m3/h or t/h, that passes through the valve under specified conditions – namely when the pressure difference across the valve is 105 Pa and the density of the fluid is 1 g/cm3, at the rated stroke. 1. Calculation of the Kv value for ordinary liquids: a. Unobstructed flow – Calculation formula: b. Obstructed flow – Calculation formula: 2. Low Reynolds number correction (calculation of the Kv value for highly viscous liquids): When the viscosity of a liquid is too high, the Reynolds number decreases, which changes the flow pattern of the fluid. At Re < 2300, the fluid is in a low-speed laminar state; therefore, the Kv value calculated using the original formula yields significant errors, and a correction is necessary.