Technical data

3.5.1 Raw volumetric flow rates
Raw Volumetric Flow Rate Equation 3-9:
Q
Flow
= V
CustomerCal
×
πD
m
2
4
× 3600s
/
hr
Q
Raw
=
“raw” volumetric flow rate (m3/h) (QMeter)
V
CustomerCal
=
customer-calibrated average flow velocity (m/s) (AvgFlow)
π =
geometric constant, pi (dimensionless) (3.14159...)
D
in
=
pipe inside diameter (m) (PipeDiam)
3.5.2 Flow-condition volumetric flow rate
The flow-condition volumetric flow rate is the result of applying expansion correction to
the raw volumetric flow rate as shown in the following equation, subject to the low-flow
cut-off.
If the resulting value is below the low-flow cut-off value, it is set to zero. The low-flow cut-
off volumetric flow rate (CutRate) is the specified low-flow velocity threshold (ZeroCut)
converted to a volumetric flow rate.
Flow condition volumetric flow rate Equation 3-10:
Q
F
low
=
(
Q
R
aw
)(
ExpCorr
P
)(
ExpCor
T
)
Q
Flow
=
flow-condition volumetric flow rate (m3/h) (QFlow)
Q
Raw
=
“raw” volumetric flow rate (m3/h) (QMeter)
ExpCorr
P
=
expansion correction factor due to pressure (dimensionless) (ExpCorrPressure)
ExpCorr
T
=
expansion correction factor due to temperature (dimensionless)
(ExpCorrTemperature)
3.5.3 Pressure Expansion Correction
The meter is capable of correcting the raw volumetric flow rate for the effect of pipe
expansion due to pressure changes. Note that for the pressure-effect expansion correction
factor to be calculated, the correction must be enabled (via the EnableExpCorrPress data
point) and the flow-condition pressure must be available (i.e., the EnablePressureInput
data point must be set to “Live”(1) or “Fixed”(2).
Flow measurement
22 Daniel 3810 Series Operations Manual