4.6 3410 Series gas flow meter characterizations
For Daniel 3410 Series Gas Ultrasonic Flow Meter SeniorSonic meters only, the following
flow characterizations are calculated/estimated: symmetry, cross-flow, chord turbulence,
profile factor, and swirl angle. Alarm limits are provided for the chord turbulence and swirl
angle values.
Symmetry
Symmetry is a dimensionless measure of the flow symmetry comparing the upper chords
to the lower chords and is readable via the Symmetry data point. Ideally the Symmetry
should be 1.0.
Cross-flow
Cross-flow is a dimensionless measure of the flow symmetry comparing the chords on one
side of the meter to the chords on the other side. It is readable via the CrossFlow data
point. Ideally the Cross-flow should be 1.0.
Chord turbulence
Chord Turbulence is a estimate of the turbulence (percentage) at a chord location. A value
is calculated for each active chord and is readable via the TurbulenceA, TurbulenceB,
TurbulenceC, or TurbulenceD data points. A value of 0% indicates no appreciable
turbulence.
Profile Factor
The profile factor is a dimensionless ratio of the inner chord velocities to the outer chord
velocities. It is readable via the ProfileFactor data point. Ideally the Profile Factor should be
1.17 for a 4-path transmitter head. It is not possible to calculate Profile Factor for a
reflective path transmitter head.
Swirl angle
The swirl angle is an estimate of the swirl (to the nearest degree) and is readable via the
SwirlAngle data point. It is calculated as a function of the meter body style and Profile
Factor (see above). A value of 0 degrees indicates no appreciable swirl. Swirl is only
calculated for a 4-path transmitter head.
Measurement
Operations manual 33
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