Internal UV Ozone Photometer Page 9-
Section 9 Internal UV Ozone Photometer
This section describes the setup, operation and maintenance of the
Model 2010D's optional internal UV Ozone Photometer. Unlike the
portable 2010, the rack mountable Model 2010D has an option bay
that can support an internal UV Ozone Photometer. When the
Photometer option is installed in a Model 2010D it can be used to
audit ozone calibrations, precisely control the 2010D's internal
ozone generator or it may be used independently, as a stand-alone
ozone analyzer.
Description
The Model 2010D UV Photometer option consists of a module that
is installed in the 2010D's option bay. A Power cable and two
ribbon cables carry power and electrical signals to and from the
2010D's Dilution Control Board and CPU board, resulting in a
tightly integrated photometer subsystem.
The rear panel of the Photometer module (see Figure 4-1) supports
the sample inlet, exhaust outlet and a connector (J9) that
supports analog outputs for connection to external measuring
devices such as a datalogger or strip chart recorder.
The Photometer's rear panel also supports another connector (J12)
that allows serial RS232 connection directly to the photometer
for diagnostics and internal sensor calibrations.
Theory of Operation
The Model 2010D UV Ozone Photometer is a compact, single-tube,
single-detector photometric device that measures ozone by
monitoring 254nm ultraviolet light passing through a sample tube
with an ultraviolet lamp at one end and a photo-detector at the
other. Since this wavelength of light is attenuated by ozone,
the ozone concentration can be determined by alternately
observing the detector output when clean, ozone-free air is in
the sample tube and when sample air is in the tube. An internal
pump draws sample air into the photometer, where solenoid valves
direct it either through or around a catalytic ozone scrubber
before entering the sample tube.
The ratio of the detector output when ozone-free air is directed
through the sample tube to the output when the sample air is in
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