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5
NOTE:
If the Handi+ is used to measure the oxygen concentration with
equipment using a heated or humidified gas stream, it is recommended that
the Handi+ be placed upstream of the heater and/or humidifier. For more
information, refer to "Factors Influencing Calibration and Performance" on
page 5 of this manual.
For hospital and home care a new calibration is required when:
» The measured O
2
percentage in 100% O
2
is below 97.0% O
2
» The measured O
2
percentage in 100% O
2
is above 103.0% O
2
.
For ID testing (or optimum accuracy), a new calibration is required when:
» The measured O
2
percentage in 100% O
2
is below 99.0% O
2
.
» The measured O
2
percentage in 100% O
2
is above 101.0% O
2
.
4.0 FACTORS INFLUENCING ACCURATE READINGS
4.1 Elevation Changes
» Changes in elevation result in a reading error of approximately 1% of reading per 250 feet.
» A change in altitude greater than 500 ft will require sensor recalibration.
» This device does not automatically compensate for changes in barometric pressure
or altitude. If the device is moved to a location of a different altitude, it must be
recalibrated before use (see section 2.2).
4.2 Temperature Effects
The Handi+ will hold calibration and read correctly within ±3% when in
thermal equilibrium within the operating temperature range. The device must
be thermally stable when calibrated and allowed to thermally stabilize after
experiencing temperature changes before readings are accurate. For these
reasons, the following is recommended:
» When used in a breathing circuit, place the sensor upstream of the heater.
» For best results, perform the calibration procedure at a temperature close to the
temperature where analysis will occur.
» Allow adequate time for the sensor to equilibrate to a new ambient temperature.
4.3 Pressure Effect
Readings from the Handi+ are proportional to the partial pressure of oxygen.
The partial pressure is equal to the concentration times the absolute pressure.
Thus the readings are proportional to the concentration if the pressure is
held constant. Flow rate of sample gas can affect pressure at the sensor in
that back pressure at the sensing point may change. For these reasons, the
following is recommended:
» Calibrate the Handi+ at the same pressure as the sample gas.
» If sample gases flow through tubing, use the same apparatus and flow rates when
calibrating as when measuring.
» The Handi+ oxygen sensor has been validated at pressures up to 2 atmospheres
absolute. Calibration or operation above this pressure is beyond the intended use.