Is it true that the higher the CV value of a control valve, the larger its valve diameter?

Logically, that’s the case: generally, KV values are provided, and the higher the corresponding KV value, the greater the flow capacity of the valve of the same type, as well as its diameter.

The last edit to this post was made by The boss is serving congee on 2019-6-13 at 08:59. Regarding the CV value, it simply quantifies the flow capacity of a valve; in other words, for valves of the same model, the larger the diameter of their valve seats, that is, the Port size (rather than just the overall diameter of the valve), the higher the CV value will be； For example, taking the single-seat control valves used in our company as an example, for a control valve with a valve port diameter of DN100, its seat diameter can be 4\", 3\", 2.5\", 2\", 1.5\", or 1.25\". For valves with a DN100 diameter, each seat diameter corresponds to a specific CV value; it cannot be said simply that the valve’s diameter determines its CV value ； Furthermore, different manufacturers use different technical processes for manufacturing valves; as a result, the CV values of valves of the same type and model produced by them can only be similar, but they basically will not be identical!

The CV value provided by the manufacturer is the rated CV value of the valve; for valves with the same diameter, the sizes of the valve core and seat can vary... Therefore, the CV value of a valve with a given diameter may differ. However, for valves from different manufacturers, even when they have the same connection specifications, their CV values can vary; this is related to the quality of the valve manufacturer. Generally speaking, it is more difficult to manufacture valves with extremely low or extremely high CV values.

　　Generally speaking, there is this trend, but not necessarily. 　　To be precise, the greater the flow coefficient, the larger the effective flow area of the valve. The effective flow area is related to various factors such as the valve’s diameter, structure, and flow channel design; among these, the effective flow area of the valve core plays a decisive role. 1. Different manufacturers, due to variations in valve structure, may use different methods for calculating the flow coefficient. The required flow coefficient obtained under the same operating conditions will also vary ； 2. The flow coefficient provided by the manufacturer is not a calculation result. It is a result selected based on calculations. 　　Theoretically, at the calculated flow coefficient, the flow rate when the valve is fully open should be the maximum flow rate under standard operating conditions ； 　　In fact, operating conditions cannot be free of fluctuations; therefore, a margin is included in the flow coefficient provided. Different manufacturers will set different amounts of margin based on the characteristics of their products. 3. Under the same conditions and with a flow coefficient that is within an appropriate range (neither too low nor excessively high), the difference in flow coefficients can be adjusted by varying the opening degree of the valve in use. 　　Therefore, unless the user has strict requirements regarding the valve opening degree under specific operating conditions, the manufacturer will create a range of flow coefficients and produce only a limited number of products with different flow coefficients. For user requirements, it is sufficient to select and provide a product from a sequence based on calculations ； 　　The serial numbers vary among different manufacturers; therefore, while meeting the user’s requirements as well as those related to the product serial number, the reported flow coefficient will also differ.

The ultimate consideration should be the opening degree of the valve, rather than its diameter. The original poster had better change their perspective when thinking about this issue!

Each one is different; for specific details, consult the manufacturer or check the user manual

Is it true that the higher the CV value of a control valve, the larger its valve diameter? It can only be said that this is the trend.