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INSTRUCTION MANUAL 10DX3111A&G Sizes 14 - 24 Inches
4.2.1.3 Other Liquid Variables
Other liquid variables such as viscosity, density and liquid pressure have no direct influence on
metering accuracy. Liquid density has no effect on volumetric flow rate since only the area of the
meter pipe and liquid velocity are required to determine the rate of flow. Viscosity and metering
pressure are restricted to physical limitations alone, such as the leakage pressure of the meter pipe
flange connections.
4.2.2 Metering Characteristics
The metering pipe must be completely filled at all times for accurate results. Where there is
possibility of operation with a partially filled horizontal pipeline, it is recommended that the Magnetic
Flowmeter be installed in a vertical section of that pipeline such that liquid flow moves upward. A
vertical installation also offers the advantage of an even distribution of liner wear in the event that
solid abrasives are being carried along in the liquid stream. See Figure 2-4 for recommended meter
installation orientations.
The ABB Automation Magnetic Flowmeter will measure the total amount of material passing in the
liquid stream. The meter will not, for instance, differentiate between the amount of liquid and the
amount of entrained gases. Also, in the case of a slurry, it will not differentiate the amount of liquid
from solids. If the liquid to mixant ratio is of importance to process control, then separate measure-
ments of the concentration of the desired medium must be made and appropriate correction factors
must be applied to the Magnetic Flowmeter output.
In applications involving variable quantities of uniformly dispersed, non-conductive mixing agents, it
must be determined that the higher concentrations of mixant will not drive the average conductivity of
the liquid mixture below the minimum conductivity level for the given installation.
4-5
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