3410 Series Gas Ultrasonic Meters Operations Manual
Section 4: Flow measurement
3-9000-777 Rev E
January 2018
Energy rate and totals
35
The non-volatile volume accumulator data points are as listed in the table below:
4.5.9
Energy rate and totals
The Daniel 3410 Series Gas Ultrasonic Flow Meter meter calculates the energy rate and energy
totals (forward and reverse). These calculations require that the flow-condition pressure and
temperature are available (either fixed or optional analog inputs,
see Section 5.10.1
), the gas
property data (composition and heating value) are available (either fixed or optionally read from
a GC,
see Section 5.10.1
), and the AGA8 calculations are performed (internally by the meter or
externally with the results written to the meter,
see Section 5.10.1
).
The energy rate is calculated as shown in
Equation 4-16
.
Equation 4-16 Energy rate
where
The sign of the energy rate indicates the flow direction: a positive value indicates flow in the
forward direction, a negative value indicates flow in the reverse direction.
The energy rate validity is indicated by the
EnergyRateValidity
data point TRUE(1) indicates
valid). The energy rate is valid if the base-condition volumetric flow rate is valid (indicated by
QBaseValidity
where TRUE(1) indicates valid) and if the in-use gas properties are valid (indicated
by
AreGasPropertiesInvalidInUse
where FALSE(0) indicates valid).
The energy rate is accumulated into the corresponding direction energy total regardless of the
energy rate validity.
The forward and reverse direction energy 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, an energy total of 12345.750 MJ is stored as 12345 MJ for the integer portion and
0.750 MJ as the fractional portion. Note that while the energy rate can be positive (indicating
forward flow) or negative (indicating reverse flow), the energy totals are always positive values.
Table 4-3 Volume accumulation data points
Volumetric flow
rate type
Forward direction
Reverse direction
Integer
Fraction
Integer
Fraction
Raw
PosVolUncorr
PosVolUncorrFrac
NegVolUncorr
NegVolUncorrFrac
Flow-condition
PosVolFlow
PosVolFlowFrac
NegVolFlow
NegVolFlowUncorr
Base-condition
PosVolBase
PosVolBaseFrac
NegVolBase
NegVolBaseUncorr
=
energy rate (MJ/h) (
EnergyRate
)
=
base-condition volumetric flow rate (m
3
/h) (
QBase
)
=
“in-use” heating value (kJ/dm
3
) (
HeatingValueInUse
)
Q
E
Q
Base
HV
×
1
MJ
1000
kJ
-----------------
1000
dm
3
1
m
3
-----------------------
×
×
=
Q
E
Q
Base
HV
