Teledyne T200, Operation Manual, Page: 301 / 425

Teledyne API
– T200 NO/NO
2
/NO
X
Analyzer Operation Manual Principles of Operation
299
13.2.3.3. OZONE SUPPLY AIR FILTER
The T200 uses ambient air as the supply gas for the O
3
generator and may produce a
variety of byproducts. Small amounts of water, ammonia and various sulfur oxides can
combine to create ammonium sulfate, ammonium nitrate, nitric acid and other
compounds. Whereas sulfates and nitrates can create powdery residues inside the
reaction cell causing sensitivity drift, nitric acid is a very aggressive compound, which
can deteriorate the analyzer‟s components. In order to remove these chemical
byproducts from the O
3
gas stream, the output of the O
3
generator flows through a
special filter between the generator and the reaction cell.
The small amount of NO
X
produced in the generator (from the reaction of O
2
or O
3
and
N
2
in the air) will not affect the T200‟s ability to measure NO
x
, NO and NO
2
as it is
accounted for and removed from the concentration calculations by the analyzer‟s Auto
Zero feature (see Section 13.1.4).
13.2.3.4. OZONE DESTRUCT
Even though ozone is unstable and typically reacts to form O
2
, the break-down is not
quite fast enough to ensure that it is completely removed from the exhaust gas stream of
the T200 by the time the gas exits the analyzer. Due to the high toxicity and reactivity
of O
3
, a highly efficient catalytic converter scrubs or converts all of the O
3
from the gas
exiting the reaction cell. The conversion process is very safe. It only converts ozone to
oxygen and does not produce any toxic or hazardous gases.
The O
3
destruct is located just inside the NO
2
converter. As this is a true catalytic
converter, there are no maintenance requirements as would be required for charcoal-
based ozone destructs.
A certain amount of fine, black dust may exit the catalyst, particularly if the analyzer is
subjected to sudden pressure drops (for example, when disconnecting the running pump
without letting the analyzer properly and slowly equilibrate to ambient pressure). To
prevent the dust from entering the reaction cell or the pump, the ozone destruct is
equipped with a quartz wool filter material.
06858E DCN7057