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DESCRIPTION MSA
24 ALTAIR 5 - Operating Manual
2.7. Monitoring the Oxygen Concentration
The instrument monitors the oxygen concentration in ambient air. The alarm
setpoints can be set to activate on two different conditions:
• Enriched - oxygen concentration > 20.8 % or
• Deficient - oxygen concentration < 19.5 %.
While the instrument can detect up to 25% oxygen in the ambient air, it is
approved for use only up to 21% oxygen-content.
When the alarm setpoint is reached for either of the above conditions:
• the alarm message displays and flashes in combination with the
corresponding gas concentration
• backlight turns on
• alarm sounds
• alarm LEDs flash
• vibrating alarm triggers
The LOW alarm (oxygen deficient) is latching and will not reset when the
O
2
concentration rises above the LOW setpoint. To reset the alarm press the
button. If the alarm is latching, the
button silences the alarm for five seconds.
False oxygen alarms can occur due to changes in barometric pressure (altitude)
or extreme changes in ambient temperature.
It is recommended that an oxygen calibration be performed at the temperature
and pressure of use. Be sure that the instrument is in known fresh air before
performing a calibration.
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