700 CLD / O2
5-04-2017
6
Operating Principle
The California Analytical Instruments CLD Analyzer utilizes the principle of
chemiluminescence for analyzing the NO, NO
x
or NO
2
concentration within a gaseous
sample. It uses paramagnetic technology for measurement of oxygen.
In the NO mode, the measurement is based upon the chemiluminescent reaction between
ozone and nitric oxide (NO) yielding nitrogen dioxide (NO
2
) and oxygen. This reaction
produces light which has intensity proportional to the mass flow rate of NO
2
into the
reaction chamber. The light is measured by means of a photodiode and associated
amplification electronics.
In the NO
x
mode, NO plus NO
2
is determined as above; however, the sample is first
routed through the internal NO
2
to NO converter which converts the NO
2
in the sample to
NO. The resultant reaction is directly proportional to the total concentration of NO
x
.
Sample enters the analyzer directly into a heated chamber and is maintained at an
elevated temperature. The moisture will remain in the vapor state, ensuring no loss of the
NO
2
.
Reaction Chamber
The sample and ozone are delivered to the reaction chamber via the unique regulated
flow system described below, and mixed together at the center of the chamber where the
reaction takes place. The sample is vented from the chamber through a ¼-inch tube. The
chamber contains a long-pass filter that is sealed with an integral O ring. The chamber
assembly is mounted to the photodiode.