Mass Rate And Totals - Emerson Daniel 3415 Operation Manual

Measurement
4.5.10

Mass rate and totals

The Daniel 3410 Series Gas Ultrasonic Flow Meter meter calculates the mass rate and mass
totals (forward and reverse).
These calculations requires that the flow-condition pressure and temperature are available
(either fixed or optional analog inputs,
(either fixed or optionally read from a GC,
are performed (internally by the meter or externally with the results written to the meter,
Section
The mass rate is calculated as shown in
Equation 4-18:
MassRate =
Q
Flow
ρ
Flow
Equation 4-18
The sign of the mass rate indicates the flow direction: a positive value indicates flow in the
forward direction, a negative value indicates flow in the reverse direction.
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 AGA8FlowCalcValidity where TRUE(1) indicates valid).
The mass rate is accumulated into the corresponding direction mass total regardless of the
mass 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 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:
Table 4-4:
Forward direction
Integer
PosMass
32
5.10).
Mass rate
mass rate (kg/h) (MassRate)
=
flow-condition volumetric flow rate (m
=
"in-use" flow-condition gas mass density (kg/m
Mass total data points
Fraction
PosMassFrac
Section 5.10.1), the gas composition is available
Gas property data), and the AGA8 calculations
Equation 4-18
�������� = � × �
���� ����
3
/h) (QFlow)
Reverse direction
Integer
NegMass
3410 Series Gas Ultrasonic Flow meters
3
) (RhoMixFlow)
Fraction
NegMassFrac