we have one ultrasonic flowmeter type Krohne ufm 3030K Installed in 24.0" line, with flow through it , problem is instrument only shows 0 bbls/day (04 ma)
Yes you are right - did not read the meter type properly.
You could have a problem though if you are using a doppler type instead of transient time measurement. You might also have problems with the process medium itself.