When substituting trhe value of K into the scale shape equation:
Y = G - (G-Y
0
)(E1/E2)(D2/D1)
The two ratios E1/D1 and E2/D2, being derived each from one detector, are independent
of any detector drift. This makes the instrument output independent of any drift or change
in detector gain characteristic.
This operating routine, giving measurements first of D1 and D2 and then, with the
calibration cell in position, of E1 and E2, repeats continuously and provides an effective
continuous calibration update to enable accuracy to be maintained at all times.
A.7.3
Calculation sequence
During each operating cycle, the instrument performs the calculations given below:
•
Measure D1 & D2
•
Measure E1 & E2
•
Compute Y
•
Smooth Y
•
Linearize and correct for path length
•
Normalize the measurement
•
Smooth the result to produce a final %CO output
A.7.4
Normalization equations
Normalization of data collected by the analyzer is essential to compare emission levels of
pollutants into the atmosphere. Software in the Rosemount
™
CCO 5500 Analyzer performs
all calculations and provides results in various units, vpm, mg/m
3
, and mg/Nm
3
. The
following paragraphs describe the derivation of these results.
The Rosemount CCO 5500 Analyzer is a cross-duct type that measures the quantity
(number of molecules) of gas within its sight path. It converts this measurement into a
concentration that fully compensates for the expansion effects of temperature, while
assuming constant atmospheric pressure. The basic measurement is referred to as ppm
(parts per million). However, to achieve a true concentration vpm (ppm by volume), the
ppm
value must be normalized for pressure using the following expression.
Correction to standard pressure:
where standard pressure is taken as 101 kPa.
Conversion to mass concentration
The next stage in the process is to determine the mass concentration. The conversion at
STP uses conversion factors determined as follows:
Theory of operation
Reference Manual
107
Summary of Contents for Rosemount CCO 5500
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Page 8: ...Contents iv Rosemount CCO 5500 ...
Page 28: ...System Wiring Diagram Figure 2 7 Install 20 Rosemount CCO 5500 ...
Page 32: ...Install 24 Rosemount CCO 5500 ...
Page 88: ...Operation 80 Rosemount CCO 5500 ...
Page 98: ...Maintenance 90 Rosemount CCO 5500 ...
Page 108: ...Troubleshooting 100 Rosemount CCO 5500 ...
Page 110: ...Spare parts 102 Rosemount CCO 5500 ...
Page 122: ...Return equipment to the factory 114 Rosemount CCO 5500 ...
Page 123: ...Return equipment to the factory Reference Manual 115 ...