The manual is explicit: You need and 5 diameters downstream of straight pipe before the sensor.

: The primary guide covering safety precautions, step-by-step installation, and basic wiring. IO-Link Instruction Manual

The core of the document is the installation procedure. Unlike pressure-based flow meters, the FD-Q’s accuracy is 100% dependent on installation quality.

Thanks!

Installation can be completed in approximately with just a screwdriver.