Ideal Gas Flow - ABB SM2000 User Manual Supplement

Videographic Recorders
SM1000 and SM2000
Mass Flow – Derived density correction
This method uses a preset table of temperature and density
values to define the correction, which is calculated as follows:
Qmd = Qc x density correction
× ×
a1 a3 scaling factor
m3
= -----------------------------------------------------------
m2
Note. Input a3 is the actual product temperature input (as
a2 in previous examples) but with the density correction
applied using a custom linearizer – see Section 4.9.1 of the
User Guide (IM/SM1000 or IM/SM2000).
Mass Flow – Measured Density Correction
Qmm = Qc x input from density meter.
× ⁄
a1 a3 m2
m3 = ------------------------------ -
m2
Where a3 is the input from an external density meter.
Note. With all of the above calculations the engineering
range should allow for the extremes of all the input variables.
IM/SM2000ADV Issue 7

2.10.2 Ideal Gas Flow

Gas flow is usually measured using a differential pressure device
across orifice plates and wedges.
Corrections can be applied to compensate for variations in
temperature and pressure – see Fig. 2.13.
Fig. 2.13 Temperature and Pressure Compensation
Where Q = K h , the square root extraction and scaling can be
achieved on the DP device or on the input set up of the recorder.
Let m1 = constant 1 x a3
Qc = m2 = a1 x constant2 x a2/m1
Note. The engineering range should allow for the extremes
of all the input variables.
2 Math Configuration
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