Thermo Scientific 42i Instruction Manual page 252

Optional Equipment
Ozonator Permeation Dryer
Ozonator Permeation
Sample Permeation
Lag Volume
Principle of Operation
9-10 Model 42i Instruction Manual
3. Allow the permeation tubes in both the 42i and the Transfer Standard
to stabilize for at least 24-48 hours.
4. Carefully calibrate the 42i using the Transfer Standard. The output of
the Transfer Standard should be connected to the SAMPLE bulkhead
on the rear panel of the 42i.
5. Switch the calibrated 42i into the span mode.
6. Measure the flow rate into the ZERO bulkhead on the rear panel of the
42i. Be sure that the source of zero air is connected. Note the flow and
measured NO
7. From the flow and measured concentration, compute the permeation
tube release rate.
The permeation dryer minimizes routing maintenance procedures by
providing a continuous stream of dry air to the ozonator (using the
Dryer
selective water permeation characteristics of the dryer). With the
permeation dryer option, it is not necessary to constantly replenish the
ozonator air-drying column as in the standard instrument.
The sample permeation dryer option is used when there may be widely
varying levels of ambient water vapor present. The dryer stabilizes the
Dryer
moisture content of the sample stream providing a constant dew-point at
the outlet over a wide range of inlet ambient moisture levels.
A secondary benefit of the sample dryer option is its ability to remove
ambient levels of ammonia (NH
The Model 42i is available with the following Lag Volume option.
The Model 42i is based on the principle that nitric oxide (NO) and ozone
react to produce a characteristic luminescence with an intensity linearly
proportional to the NO concentration. Infrared light emission results when
electronically excited NO
concentration.
2
) from the sample stream.
3
molecules decay to lower energy states.
2
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