MSA ALTAIR 5 Manuel D'utilisation page 30

If the gas concentration reaches or exceeds the alarm setpoint,
the instrument:
• alarm message displays and flashes in combination with the
corresponding gas concentration:
• backlight turns ON
• alarm sounds (if active)
• alarm LEDs flash (if active)
• vibrating alarm triggers (if active).
When gas reading exceeds 100% of the Lower Explosive Limit (LEL),
the instrument enters a Lockalarm
the actual reading.
A combustible gas reading of "XXX" indicates the
atmosphere may be above 100 % COMB or 5.00 %vol CH 4
and an explosion hazard exists. Leave the contaminated
area immediately.
Certain IR sensors use a calibration gas >100% LEL. When the
calibration sequence shown in section 3.8.2 is followed, the combustible
LEL sensor will display the "XXX" reading. This state can only be reset
by turning the instrument OFF and then ON again.
state and displays "XXX" in place of
TM
! WARNING
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