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Chapter 1: Introduction to TZN Meters (STD & CUS)
The simple, rugged construction of TZN turbine meters provides excellent accuracy and
measurement repeatability for a wide range of industrial applications. All TZN flow meters, both
STD and CUS, are designed to provide high quality liquid volume measurement across a wide range
of viscosities (0.3 to >1,000 cSt).
The TZN CUS model was specifically developed to measure fluids containing fibers, paraffin, or
DRA (Drag Reducing Agents). The patented TZN CUS shaft and bearing system minimizes negative
impacts of these substances on measurement accuracy.
The removable measurement sub assembly (also referred to as ‘cartridge’) design allows
pressure to be equalized between the cartridge and meter body, thus eliminating sensitivity to fluid
pressure variations. Additional benefits of this design enables factory calibration of the cartridge,
independent of the meter body, which allows rotation of cartridges in challenging operational
environments (remote installations, limited access of onsite site provers, high pressure
applications, etc.), as well as selecting a different cartridge to meet changes in operational flow
rates (within calibrated flow parameters). This can significantly reduce operational downtime and
maintenance costs.
Generation of Signal
The operating principle of helical turbine flow meters is based on the electromagnetic field
generated by the rotational velocity of magnets imbedded in blades of the helical rotor passing by
a pick-up coil positioned in the flowmeter body.
Dual blade
helical rotor
Coil
Preamplifier (optional)
Embedded
magnets
Figure 1
. Mechanics of Signal Generation of Helical Turbines
Measuring the electrical signal generated allows calculation of the liquid flow rate flowing into the
pipe through the following expression:
600
,
3
Kf
F
Q
×
=
, and the transferred volume through:
Kf
N
V
=
.
With
Q Instantaneous flow rate in m
3
/h [
l/min, GPM,
BPH …
]
F
Output signal frequency in Hz
Kf Measurement cartridge Kfactor in pulses/m
3
[
p/l, p/USG,
p/bbl …
]
Kfactor is established during measurement cartridge calibration.
V
Volume in m
3
[
litres, Gallons, Bbls
]
N
Number of pulses
