(Equation #3)
Q =
γ
E
s
E
r
where:
Q = volumetric flow rate
A = cross-sectional area
D = pipe section diameter
E
s
= induced signal voltage
E
r
= reference voltage
B = magnetic flux density
α
= dimensionless constant
β
&
γ
= dimensional constant
V = liquid velocity
Therefore, volumetric flow rate is directly proportional to the ratio of the induced signal voltage to the
reference voltage as measured by the meter.
4.2 Operating Characteristics
4.2.1 Liquid Variables
4.2.1.1 Liquid Conductivity
The meter requires a liquid conductivity of 20 microsiemens per centimeter or higher for operation.
This minimum liquid conductivity requirement is not affected by the length of the signal interconnec-
tion cable as long as the factory-supplied or factory-approved interconnection cable (with driven
shields) is used. The nominal maximum transmission distance is limited to 100 feet (30 m) which is
the standard length of cable supplied unless specified otherwise.
The conductivity of a given liquid,
σ
, may be determined experimentally under a filled meter
condition, as follows:
1) Turn off power to the signal converter. Remove the converter housing cover. Disconnect
and identify the electrode signal interconnection leads from terminals "1" and "2" of the sig-
nal converter.
2) Measure the resistance between signal leads "1" and "2" with an ac ohmmeter.
CAUTION
Do not use a dc ohmmeter for this measurement as polarization
effects will produce completely erroneous data.
10DS3111E INSTRUCTION MANUAL
4-3
