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Reference, Installation, and Operations Manual Section 6: Meter operation
3-9000-743 Rev S June 2013
Volume 201
Equation 6-19 Base-condition volumetric flow rate
where
6.1.10 Volume
The Daniel Mark III Ultrasonic Gas Flow Meter meter provides forward and reverse volume
accumulators for each of the three volumetric flow rate values: raw, flow-condition (raw with
expansion and/or profile correction), and base-condition. Each volume accumulator is actually
stored as a data pair: (64-bit unsigned integer portion, 32-bit floating point fractional portion).
For example, a volume of 12345.750 m
3
is stored as 12345 m
3
for the integer portion and
0.750 m
3
as the fractional portion. Note that while a volumetric flow rate can be positive
(indicating forward flow) or negative (indicating reverse flow), the volume accumulators are
always positive values.
The non-volatile volume accumulator data points are as listed in the table below:
=
“raw” volumetric flow rate (m
3
/h) (QMeter)
=
flow-condition volumetric flow rate (m
3
/h) (QFlow)
=
base-condition absolute pressure (MPaa) (PBase)
=
flow-condition absolute pressure (MPaa)
(AbsFlowPressure) calculated as shown in Equation 6-23
=
base-condition temperature (K) (TBase)
=
flow-condition temperature (K) (FlowTemperature)
=
base-condition compressibility factor (ZBase)
=
flow-condition compressibility factor (ZFlow)
Table 6-3 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
Q
Base
Q
Flow
P
abs f,
P
abs b,
---------------
T
b
T
f
-----
Z
b
Z
f
-----
=
Q
Base
Q
Flow
P
abs b,
P
abs f,
T
b
T
f
Z
b
Z
f