Operating Characteristics; Liquid Variables; Liquid Conductivity - ABB K-MAG 10D1476 Instruction Manual

10D1476 K-MAG MAGNETIC FLOWMETER INSTRUCTION MANUAL
(Equation #3)
Q = γ E
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 K-MAG Magnetic Flowmeter requires a liquid conductivity of 5 µS/cm or higher for operation.
This minimum liquid conductivity requirement is not affected by the length of the signal interconnec-
tion cable when remote mounting of the Signal Converter is required, as long as the supplied
interconnection cable (with driven shields) is utilized. The nominal maximum transmission distance is
30 meters (100 feet); longer distance can be accommodated - contact the factory for details.
The conductivity of a given liquid, may be determined experimentally under a filled meter 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 polariza-
tion effects will produce completely erroneous data.
The conductivity of the process liquid (in µS/cm) may be determined from the ac electrode resistance
measurement (in megohms) by substitution of values in the following equation.
σ =
(R
where:
0.072 is the electrode barrier resistance in M ; i.e., 36 k x 2/10
s
E
r
CAUTION
1
- 0.072) x Electrode Dia. in cm
ac
6
4-3