32
Profile-effect correction
Section 4: Flow measurement
3410 Series Gas Ultrasonic Meters Operations Manual
January 2018
3-9000-777 Rev E
4.5.5
Profile-effect correction
Two path and bounce path meters (device numbers 3412 and 3411) require profile-effect
correction. All other meters do not require profile-effect correction and the profile-effect
correction factor is set to 1.
For meter types that require profile-effect correction, the correction factor can be either user-
specified or meter-calculated depending upon the value of the
SpecCorrectionFactor
data point:
if set to 0.0, then the correction factor is meter-calculated; if set within [0.90, 1.05], then the
specified value is used.
Calculating the meter factor requires that the flow-condition pressure and temperature be live
or fixed and that the AGA8 calculations are performed either internally or externally. If the
profile-effect correction factor is to be meter-calculated
but
either the flow-condition pressure
and/or temperature are/is disabled or the AGA8 calculations are not performed, then the flow-
condition correction factor is set to the default value of 0.95. Otherwise, it is calculated as
shown in
Equation 4-13
.
Equation 4-13 Profile-effect correction factor
where
=
flow-profile correction factor (
CorrectionFactor
)
=
pipe wall roughness (m) (
WallRoughness
)
=
pipe inside diameter (m) (
PipeDiam
)
=
Reynolds Number (dimensionless) (
ReynoldsNumber
) calculated
as shown in
Equation 4-14
CorrFctr
1
0.242
0.2703
WR
D
in
---------
0.835
Re
0.8
-------------
+
log
------------------------------------------------------------
+
=
CorrFctr
WR
D
in
Re
