Emerson Process Management 3422 用户手册
Reference, Installation, and Operations Manual
Section 6: Meter operation
3-9000-743 Rev S
June 2013
Seniorsonic flow characterizations
205
The mass rate validity is indicated by the
MassRateValidity data point (TRUE(1) indicates valid).
The mass rate is valid if the flow-condition volumetric flow rate is valid (indicated by
QFlowValidity where TRUE(1) indicates valid) and if the AGA8 flow-condition calculation is
valid (indicated by
valid (indicated by
AGA8FlowCalcValidity where TRUE(1) indicates valid).
The mass rate is accumulated into the corresponding direction mass total regardless of the mass
rate validity.
rate validity.
The forward and reverse direction mass totals are each stored in non-volatile memory as a data
pair: a 64-bit unsigned integer portion and a 32-bit floating point fractional portion. For
example, a mass total of 12345.750 kg is stored as 12345 kg for the integer portion and
0.750 kg as the fractional portion. Note that while the mass rate can be positive (indicating
forward flow) or negative (indicating reverse flow), the mass totals are always positive values.
pair: a 64-bit unsigned integer portion and a 32-bit floating point fractional portion. For
example, a mass total of 12345.750 kg is stored as 12345 kg for the integer portion and
0.750 kg as the fractional portion. Note that while the mass rate can be positive (indicating
forward flow) or negative (indicating reverse flow), the mass totals are always positive values.
The non-volatile mass total data points are as listed in the table below:
6.1.14
Seniorsonic flow characterizations
For Daniel Mark III Ultrasonic Gas Flow Meter SeniorSonic meters only, the following flow charac-
terizations 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.
terizations 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
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
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
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.
Table 6-5 Mass Total Data Points
Forward direction
Reverse direction
Integer
Fraction
Integer
Fraction
PosMass
PosMassFrac
NegMass
NegMassFrac