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Water Vapour Content & Dew Point:
The "Dew Point" is the temperature at which
water
vapour will start to condense
from any gas. This value depends upon the gases water vapour content & pressure.
The amount of water vapour that gets into compressed gas depends
on the compressor intake conditions and the efficiency of the purification
system.
Medical air is required to be dry enough to prevent malfunctions (i.e.
air flow blockage) due to internal condensation or "icing" of the regulators or
pipeline.
Corrosion and bacterial growth can result from high water levels. These
elevated levels can also inhibit catalysts that convert carbon monoxide
into carbon dioxide.
Standard CAN/CSA Z305.1-92 states that medical breathing air must have
a maximum water content of 1630 ppm which corresponds to a -15°C
Dew Point.
Other medical
gases must have a dew point of -45°C
The measured Dew Point is the quantity of water vapour found in the samples at
21°C and 14.7 psi pressure.
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