Volumetric Flow Rate Measurement - ABB 3000 Series Instruction Manual

This may be expressed mathematically as:
(Equation #1)
where:
E = induced electrode voltage
s
B = magnetic field strength
D = meter pipe diameter
α = dimensionless constant
V = liquid velocity
The metered liquid constitutes a continuous series of conductive liquid disks moving through a
magnetic field. The more rapid the rate of liquid flow, the greater the instantaneous value of signal
voltage as monitored at the meter electrodes.

4.1.2 Volumetric Flow Rate Measurement

The meter is a volumetric flow rate measuring instrument. This can be shown by substituting the
physical equivalent of liquid velocity into equation #1 as follows:
(Equation #2)
Substituting for V in equation #1
and solving for Q:
Since B = β E
and since α, D and β are constant:
4-2
10DS3111E INSTRUCTION MANUAL
1
E s = BDV
α
Q = 4 Q
V =
2
πD
A
4 Q
E s = 1 BD
2
α πD
∴ Q = παD
• E
s
4 B
r