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6.6
When operating any pure air generator which has a "B" reactor, mixer-receivers
must be incorporated in the system. These units, Figures 5 and 8 (10), are located
after the purification reactor, and before the output pressure regulator (see Figure
10). They mount within the generator cabinets. Their purpose is to homogenize the
oxygen/nitrogen effluent developed by the "B" reactor. It is imperative that no other
chamber be used for this purpose and that this chamber remain empty.
6.7
The "B" purification reactor should not be used to produce air which is to serve as
diluent in the production of air blends, standards, etc., for air monitoring equipment.
Nor should it be used for instrumentation where air is used as the carrier gas or
support air, as with total hydrocarbon analyzers. The hyper oxygenation will cause
difficulties with calibration and the increased response will appear as hydrocarbon
response even though the air is hydrocarbon-free. The "A" or "C" purification
reactors should be utilized for these applications.
6.8
The "C" PURIFICATION REACTOR is identical with the "A" unit except that the
carbon dioxide concentration will be less than 0.3-ppm. This reactor is mandatory
in those situations where carbon dioxide is actually being measured; e.g.,
non dispersive infrared where the hydrocarbons and carbon monoxide are oxidized
to carbon dioxide before measurement, the moving wire liquid chromatograph
whereby all carbon dioxide is converted to methane and measured with flame
ionization detection, and those TOC systems employing the technique. For those
situations where the carbon dioxide serves as an interferant for the analysis of other
components, such as carbon monoxide, the "C" purification reactor must be used.
This is the preferred reactor for FTIR applications.
6.9
The "D" PURIFICATION REACTOR is for those applications requiring high purity
and extremely low moisture. It has the same performance specifications as the
other three reactors but has a moisture content of less than 1-ppm. lonmobility
analyzers and plasma chromatographs require this purification reactor. Other
applications include air supplies for automatic samplers, valves, and pneumatic
systems. The low moisture content eliminates maintenance problems with these
systems.
6.10
For those instances were pure air with high humidity is required, AADCO
Instruments, Inc. will supply a humidifier to be located after the pure air generator.
This device will operate under pressure and produce air with 50-90+% RH. This
addition alleviates the drying problem associated with the premapure dryer used in
some air monitoring instrumentation.
13
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