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Operation of PMD and TOC Models
The PMD and TOC models also employ Pressure Swing Adsorption (PSA)
technology to remove water vapor and/or CO
2
from ordinary compressed air.
These models are configured differently than the PHF or PCR models, in that
they employ a shuttle valve and 4-way valve to direct the airflow through the unit.
The 4-way valve directs the incoming air into one of the two desiccant chambers,
where the water vapor and/or CO
2
are removed. Most of the purified air leaving
the desiccant chamber passes through the outlet shuttle valve to the application.
A precision orifice in the outlet shuttle disk, however, allows a portion of the
purified air to be redirected back through the off-line tower, purging it of the
accumulated moisture and CO
2
. The purge air exits the unit through the 4-way
valve and muffler. A solid state timer governs the process by controlling the 4-
way valve.
FIGURE 3: OPERATION OF PMD AND TOC MODELS
