Why doesn't the high precision of electric butterfly valve position mean high flow accuracy?

Valve position accuracy describes position response, while flow accuracy is also affected by valve internals, pressure differentials, and measurements. Customers need to record instructions, actual valve positions, and process flow simultaneously in order to determine whether electric actuator, control, or capacity needs to be modified.

The opening and effective flow area are not the same percentage

When the butterfly plate rotates, the geometry and effective flow area of the channel change with the angle, and the percentage of opening may not correspond to the same percentage of area. The butterfly plate is still in the flow channel when fully open. Even if the angle detection is very fine, the flow changes caused by small valve movements may vary greatly depending on the working range. The evaluation should use flow data corresponding to the structure, and not consider display accuracy as hydraulic performance.

The flow rate at the same valve position will vary with the system pressure difference

When the pump operating conditions, other branches, and pipe network resistance change, the pressure difference on both sides of the valve may change. The valve position remains unchanged, but the flow rate may still change. The flow characteristics after installation therefore include the function of the pipeline network, and cannot be guaranteed to operate completely solely based on the product curve under constant pressure difference conditions. The valve position, flow rate, and pressure difference at different load points should be recorded to identify whether it is a positional deviation or a system action.

There is a difference between display resolution and actual motion performance

The display can retain many decimal places, but mechanical clearances, friction, dead zones, and actuator control capabilities still affect the actual motion. The position of valve position feedback detection also needs to be stably associated with the valve shaft. Acceptance should not only check the numbers on the screen, but should compare the changes in forward and reverse directions, stability, and response to the target operating conditions. Flow measurement also has its own errors and delays, and data analysis needs to maintain consistency between time and testing conditions.

Select the entire circuit according to the allowable deviation of the process

When maintaining flow, process sensors, control algorithms, actuators, and valve bodies participate together. Excessive pursuit of the fastest or thinnest valve position may increase the frequency of action without improving the process. The procurement should specify the normal flow range, allowable deviation, disturbance situation, pressure before and after the valve, and feedback requirements. Only when the electric actuator capability and the applicability of the valve body under this opening and pressure difference are met simultaneously, can the overall control quality be discussed.

Comparison of selection information

Corresponding products and selection entrance

Transforming the target from a beautiful valve position number to the actual flow deviation allowed by the process can more reasonably match the electric regulating butterfly valve. Accurate positioning is a necessary step, but flow control is still the result of a complete system.

Related structures can be combinedElectric regulating butterfly valve D941W-16PUnderstanding of specific product information. See more similar directionsElectric Valve Product Column。