ABB COPA-XE Instruction Bulletin page 10

Electromagnetic Flowmeter
COPA-XE / MAG-XE
In a free flow outlet (drop line) the flowmeter primary should be
not be installed in the highest point or in the discharge of the
pipeline (metering spool could drain, air bubbles, Fig. 6).
Fig. 6
The measurement principle is independent of flow profile as
long as standing eddies do not extend into the measurement re-
gion (e.g. after double elbows, tangential inflows or half open
valves upstream of the flowmeter primary). In such situations
measures to condition the flow are required. Experience
indicates that in most cases a straight upstream section with a
length of 3 x D and a downstream section of 2 x D are
sufficient (D = flowmeter primary size) (Fig. 7). In calibration
stands the reference conditions of EN 29104 require straight
lengths of 10 x D upstream and 5 x D downstream.
Fig. 7
Wafer valves are to be installed in such a manner that the wafer
when open does not extend into the flowmeter. Valves or other
shut off devices should be installed downstream.
A µP-converter option offers an automatic empty pipe detector
utilizing the existing electrodes.
4
For highly contaminated fluids a bypass line (Fig. 8) is
recommended so that during a mechanical cleaning procedure
operation of the process need not be interrupted.
Fig. 8
For flowmeter primaries which are to be installed in the vicinity
of pumps or other vibration generating equipment, the utiliza-
tion of mechanical snubbers is advantageous (Fig. 9).
Fig. 9