To obtain good flow measurement accuracy and repeatability in large line sizes, a single point flow sensor will most likely not provide an effective solution. This is because, in most cases, large line sizes do not have a sufficient straight run available and may have elbows, blockages, dampers, valves, etc. close to the desired flow sensor location. This results in the desired sensor location being susceptible to swirl and inconsistent, skewed or otherwise distorted flow profiles. Flow rates can be significantly different in different locations across the pipe or duct.
So, what is the solution? One best-practices solution is the use of thermal flow meters in multipoint configuration.