Emerson Daniel 3415

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, Section 5.10.1), the gas composition is available
(either fixed or optionally read from a GC, Gas property data), and the AGA8 calculations
are performed (internally by the meter or externally with the results written to the meter,
Section 5.10).
The mass rate is calculated as shown in Equation 4-18
Mass rate Equation 4-18:
 = 

× 

MassRate =
mass rate (kg/h) (MassRate)
Q
Flow
=
flow-condition volumetric flow rate (m
3
/h) (QFlow)
ρ
Flow
=
"in-use" flow-condition gas mass density (kg/m
3
) (RhoMixFlow)
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:
Mass total data pointsTable 4-4:
Forward direction Reverse direction
Integer Fraction Integer Fraction
PosMass PosMassFrac NegMass NegMassFrac
Measurement
32 3410 Series Gas Ultrasonic Flow meters