Flowmeter for very low process pressure and pressure drop

Hi every one, I need to select a flowmeter for a metal pipe, DN400 with very low process pressure (0.08 Barg) and very low pressure drop (less than 0,005). the service is off gas (pellet air) with trace of some corrosive moisture. the flow rate is about 9000kg/h. Pipe wall thickness is 7.1 mm. I already tried Coriolis, ultrasonic and vortex but the suppliers couldn't meet these requirement. could you please advice me any flowmeter type of supplier ?
thanks in advance
For low flow of a clean dry gas (I haven't a clue what pellet air is) thermal dispersion technology works well. It does not like moisture , especially condensing moisture.

Averaging pitot tube might do it, but I no longer have sizing programs. Veris/Verabar (sold through Armstrong) puts a Pitot tube in a flow tube and couples it to a smart multivariable DP for temperature and pressure compensation.