Emerson Daniel 3410 Series, Руководство по эксплуатации

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30 Pressure-effect expansion correction
Section 4: Flow measurement 3410 Series Gas Ultrasonic Meters Operations Manual
January 2018 3-9000-777 Rev E
4.5.3 Pressure-effect 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), see Section 5.10.3 ). The pressure-effect calculation is shown in Equation
4-10 . If the pressure-effect expansion correction factor is not calculated, it is set to 1.0.
Equation 4-10 Pressure-effect expansion correction
where
Equation 4-11 Pressure-effect strain per unit stress
where
= expansion correction factor due to pressure (dimensionless)
(ExpCorrPressure)
= pipe strain per unit stress (MPaa-1) (StrainPerUnitStress) calculated
as shown in
Equation 4-8
= flow-condition absolute pressure (MPaa) (AbsFlowPressure)
calculated as shown in
Equation 4-15
= reference absolute pressure (MPaa) (0.101325 MPaa)
= pipe strain per unit stress (MPaa-1) (StrainPerUnitStress)
= outside diameter of the meter or pipe (m) (PipeOutsideDiameter)
= inside diameter of the meter or pipe (m) (PipeDiam)
= Poisson’s Ratio (dimensionless) (PoissonsRatio)
= Young’s Modulus of elasticity (MPaa) (YoungsModulus)
ExpCorrP 1 3 β ¥ Pabs f
,
Pref
–
( ) ¥ [ ] + =
ExpCorrP
β
Pabs f,
Pref
β
Dout
2
1 υ + ( ) Din
2
1 2 υ
–
( ) +
E Dout
2
Din
2
–
 
 
Þ
----------------------------------------------------------------------------------- =
β
Dout
Din
υ
E