Operating Characteristics; Liquid Variables; Liquid Conductivity - ABB COPA-XM 3000 Series Instruction Manual

Series 10DX3000 Magnetic Flowmeter Instruction Manual
Since B = β E
r
and since α, D and β are constant:
(Equation #3)
where:
Q = volumetric flow rate
A = cross-sectional area
D = pipe section diameter
E = induced signal voltage
s
E = reference voltage
r
B = magnetic flux density
α = dimensionless constant
β & γ = dimensional constant
V = liquid velocity
Therefore, volumetric flow rate is directly proportional to the induced signal voltage as measured by
the magnetic flowmeter.

4.2 Operating Characteristics

4.2.1 Liquid Variables

4.2.1.1 Liquid Conductivity

The magnetic flowmeter requires a liquid conductivity of 5 microsiemens per centimeter or higher for
operation. This minimum liquid conductivity requirement is not affected by the length of the signal
interconnection cable when remote mounting of the signal converter is required, as long as the
factory-supplied interconnection cable (with driven shields) is utilized. The nominal maximum trans-
mission distance is limited to 30 meters (100 feet), however longer distance can be accommodated
(contact factory for details).
The conductivity of a given liquid,
condition, as follows:
1) Remove the Converter housing cover. Disconnect the electrode signal interconnection leads
from terminals "1" and "2" of the signal converter. (These leads should be identified so that they will
be properly reconnected.)
2) Measure the resistance between signal leads "1" and "2" with an ac ohmmeter.
Do not use a DC ohmmeter for this measurement as polarization
Q = γ E
s
E
r
σ
, may be determined experimentally under a filled meter
CAUTION
effects will produce completely erroneous data.
4-3