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INTOXILYZER
®
S-D2 Operator’s Manual
the instrument is calibrated using a dry gas standard,
subsequent breath tests will indicate the subject’s blood
alcohol concentration (BAC).
Dry gas standards are supplied in one of three ranges,
each range based around a legal limit which is in wide use:
.045% BAC, .085% BAC and .105% BAC.
THE GAS STANDARD
The gas canister is a high-pressure, disposable cylinder
fitted with a regulator. It contains enough gas for
approximately 300 calibration checks or adjustments.
The label on each cylinder is marked with an expiration
date. The gas should not be used after that time due to
deviation of alcohol concentration of the gas mixture
outside the analytical specifications of the instrument. The
value shown on the label is within 2% of the true value of
the gas mixture.
When the cylinder is empty or time-expired, the regulator
can be safely unscrewed from the cylinder and retained for
use with a new cylinder. The old cylinder can then be
disposed or recycled.
USING A DRY GAS STANDARD AT HIGH ALTITUDE
The concentration of alcohol in the dry gas standard is
calculated and carefully controlled to give the correct vapor
concentration when the cylinder is used at sea level at
normal atmospheric pressure. At lower atmospheric
pressures, the concentration of alcohol in the vapor leaving
the cylinder will be less. The change in alcohol
concentration due to normal atmospheric pressure changes
at sea level is so small as to be negligible, but if the dry gas
standard was used at a high altitude, significant errors
would result if suitable corrections were not made.
It should be emphasized that the sensitivity of the S-D2
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