KROHNE UFM 800 EN - Manual (Page 10)

12/2000 Installation and operating instructions UFM 800 W / UFM 800 C 10
9.0 Zero-point measurement
For ultrasonic flowmeters it is important to have a good zero-point. For making a zero-point it is very important to have a situation where the flow
is absolutely zero. If that is not possible the default zero-point can be used, which is a good approximation.
● Have the fluid flow at a high flow rate for at least five minutes. Stop the flow and shut down the upstream and downstream valves (if available).
● Let the fluid stabilize until the displayed flow rate becomes stable. (At least a few minutes, but even longer for large diameters (> DN 300).
● Make a zero-point measurement (Fct. 3.1.4.) and check if the display comes to zero. Else repeat the zero-point measurement until a stable
zero-point is obtained.
Now the UFM 800W ultrasonic flowmeter should be operating in correct way.