Model 202 Ozone Monitor Manual Rev. J-4
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6.5.4. Intercomparison Test
Comparison of the calibration setup with other ozone standards is a good check of the
overall accuracy of the setup. If measurements from another ozone standard are
found to deviate from the calibration setup greater than the instrument specifications,
one of the calibration setups is not accurate.
6.6.
Calibration Procedure
A multipoint calibration should be performed at least every 12 months or within the
calibration frequency, any time major disassembly of components is performed, or any
time the zero or span checks give results outside of the acceptable limits.
6.6.1. Instrument Preparation
1. Turn on the Model 202 Ozone Monitor and allow it to stabilize for a
minimum of one hour.
2. Enter the calibration menu (
Main Menu / Cfg / Cal / O3
) and set the zero
(Z) value to 0 and the slope (S) value to 1.00.
3. Connect the ozone monitor to the manifold on the ozone calibration setup.
If a particle filter will be used in normal operation, the calibration must be
performed through the filter. The manifold must be vented to atmosphere
so that pressure does not build up in the calibration setup. Connection of
the Model 202 directly to a pressurized output of any device can damage
the ozone monitor.
4. Verify that the flow rate into the manifold is greater than the total flow
required by the ozone monitor plus any other flow demand drawing from
the manifold such as a UV photometer or ozone transfer standard.
6.6.2. Measurement of Zero Air
1. Verify that the zero air supply is on and the ozone generator is off. The
same zero air supply used in the ozone generator must be used in the
ozone generator.
2. Allow the Model 202 to sample zero air until the response is stable.
3. Record the average zero air response.
6.6.3. Measurement of Ozone Standards
1. Generate an ozone concentration slightly less than the concentration range
of interest and allow the ozone generator to warm up for at least 5 minutes.
The same zero air supply used for making zero air measurements must be
used in the ozone generator.
2. Allow the Model 202 Ozone Monitor to sample the ozone concentration
standard until a stable response is measured.
3. Record the average response of the ozone monitor as well as either the
average response of the UV photometer or the transfer standard.
4. Generate several other ozone concentration standards. At least 5 ozone
concentration standards are recommended over the range of interest.
