
Manual CWD 2005
Appendices
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Manual CWD2005.doc
107
11.9.2. Air Consumption with CO measurement
CO contents in the process gas not allow only a calculation of the air consumption.
Variable content of CO needs an additional measurement of CO. this is the only way
to reach exact values of air consumption.
It is possible to install a CO-module in the CWD 2005. The module is delivered
separately and has to be installed before the instrument is started. The CO
measuring cuvette is sensitive and could possibly be damaged if it was installed
during transportation. The direction of the installation is indicated.
Parallel to the density measurement the CO part in the process gas is detected with
an infrared measurement in the CO-module. From the caloric value, the density and
the CO part of the process gas the air requirement is correlatively calculated.
The air requirement is presented as a 4-20 mA signal. The CO proportion is
displayed in the upper right window of the screen. Both values may also be bus
interrogated by a bus, if a bus interface (profibus-DP) is activated.
The CO-Module is tested with a separate calibration gas (combustible 0-Gas with the
same Wobbe Index as the second calibration gas but without CO) and adjusted to
zero. The second calibration gas contains a CO proportion to calibrate the span of
the CO-Module as well as the complete instrument in the described configuration.
The calibration procedure is full automatically.
At delivery the two calibration gases are defined by the factory and the customer will
be informed. The CO-module needs no more adjustments and is completely
maintenance-free. The central processor of the CWD 2005 takes care of the
calculation of the value. It also detects if a module is installed or not. The CO
indication is only active when a module is installed.
The calibration procedure cycle consists of 3 steps
.
After the start the calibration 0
–
gas is connected to the inlet and the zero cal. point for the CO measurement is
defined. After that the calibration gas with known CO part is connected to the inlet
and the span of the CO module is adjusted. Following the normal calibration
procedure of the CWD 2005 is started.
In menu point 7.1.1.2. at position 7 und 8 the values for IR Zero Cal and IR FS Cal
are entered. In case these values are deleted, the CO-module will not be calibrated.
Important : Only the calibration gases subscribed by the factory may be used.
Other gas compositions will result in an incorrect calibration of the instrument.