Venturi gas flowrate measurement pipe

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I used this Venturi pipe for my Master's thesis project to measure the gas flow rate of a Biogas burner. It can be connected to 10mm-13mm inner diameter flexible hoses. Two small outlets for 4mm inner diameter hose were linked to an MPX5010DP pressure sensor (https://www.nxp.com/files-static/sensors/doc/data_sheet/MPX5010.pdf). As I had relatively low flow rates, this Sensor was at the very bottom of its measuring range, but it was the only one I found that met both affordability and suitability for this purpose. The small outlets could also be connected directly to a U-shaped tube filled with water mounted next to a ruler to indicate pressure difference with a sensitivity of 9.8Pa/mm: https://en.wikipedia.org/wiki/Pressure_measurement#Liquid_column_(manometer). For this specific pipe, I measured a relation of about 5.04 (l/min)/mBar * (pressure difference in mBar) + 2.24 l/min in a 3 to 8 l/min range. Standard deviation for my measurements was 5.6%. I included the Fusion 360 file, allowing you to adjust the narrow Venturi pipe section, which is recommended for higher flow rates. Then, the tube would also be more accurate as it now can switch from laminar to turbulent flow in the narrow section. However, you will need to calibrate it. The Part was printed standing with brim and supports for the small outlets.