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Teledyne API T703/T703U Calibrator Operation Manual Principles of Operation
215
UV
Source
ABSORPTION TUBE
UV Detector
Sample Gas OUT Sample Gas IN
Window
Window
Absorption Path Length = 42 cm
Photometer
Pre amp
PCA
O-5 VDC
analog signal
to
Motherboard
Analog current
signal is output by
Detector
Figure 9-22: O
3
Photometer Absorption Path
9.6.1.4. Interferent Rejection
It should be noted that the UV absorption method for detecting ozone is subject to
interference from a number of sources. The photometer has been successfully tested for
its ability to reject interference from sulfur dioxide, nitrogen dioxide, nitric oxide, water,
and meta-xylene.
While the photometer rejects interference from the aromatic hydrocarbon meta-xylene, it
should be noted that there are a very large number of other volatile aromatic
hydrocarbons that could potentially interfere with ozone detection. If the calibrator is
installed in an environment where high aromatic hydrocarbon concentrations are
suspected, specific tests should be conducted to reveal the amount of interference these
compounds may be causing.
07223C DCN6572