M&C CG-2 - Cross Sensitivities and Influence of Interfering;Carrier Gas

www.mc-techgroup.com CG-2 | 1.04.00 13
NOTE!
High NO
2
-concentrations, especially in connection with high flow ratios
need higher operating temperatutres of the converter, in particular the
start up process of the maximum values.
NOTE!
High operating temperatures of the converter, especially the start up
process of the maximum values leads to an increased abrasion of con-
verter components, in particular sealing- and oven-components!
DANGER!
The maximum allowable operating temperature for catalyst type C is
380 °C [716 °F). Temperatures above 400 °C [752 °F] lead to a combus-
tion of the converter material. Urgent fire danger !
DANGER!
The maximum allowable operating temperature for catalyst type SS is
680 °C [1256 °F]. Temperatures above 680 °C [1256 °F]. can lead to a
destruction of the catalyst resp. converter!
8.3 CROSS SENSITIVITIES AND INFLUENCE OF INTERFERING/CARRIER GAS
From operating experiences in different applications as well as laboratory measurements with differrent
CG-converter- and catalyst types we got a lot of experiences about influencing factors on the NO
2
-NO
conversion process. The following hints make no claim to be complete, but can help choosing the ade-
quate catalyst type as well as give an indication for the integration of the CG-converter into a certain
system environment.
In practice, often several influencing factors have any effect at the same time. With their effect on the
NO
2
- conversion they are possibly interacting and therefore can complicate an explicit interpretation of
a certain device performance.
NOTE!
Carbon monoxide (CO)
In the conversion process from NO
2
to NO carbon monoxide is generated or
destroyed (oxydised). The hereby resulting CO-concentration downstream the
converter depends on: catalyst type, NO
2
-concentration, O
2
-concentration in
the sample gas and can be some 10 ppm.
Therefore, a CO-measurement should not be installed downstream the con-
verter but with a separate sample gas way to avoid faulty measurements.
NOTE!
Oxygen (O
2
)
In the conversion process, oxygen is generated proportional to the NO
2
con-
centration. This fact can lead to a faulty measurement in a downstream oxygen
trace measurement (ppm)!