MSA altair 5 - Page 9

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MSA INSTRUMENT SAFETY
ALTAIR 5 - Operating Manual 9
Check calibration more frequently if the unit is subjected to physical shock or high
levels of contaminants. Also, check calibration more frequently if the tested
atmosphere contains the following materials, which may desensitise the
combustible gas sensor and reduce its readings:
• Organic silicones
• Silicates
• Lead-containing compounds
• Hydrogen sulphide exposures over 200 ppm or exposures over 50 ppm
for one minute.
• The minimum concentration of a combustible gas in air that can ignite is
defined as the Lower Explosive Limit (LEL).
A combustible gas reading of "100” or "5.00” indicates the atmosphere is
above 100 % LEL or 5.00 %vol CH
4
, and an explosion hazard exists.
Move away from hazardous area immediately.
• Do not use the ALTAIR 5 Multigas Detector to test for combustible or toxic
gases in the following atmospheres as this may result in erroneous readings:
• Oxygen-deficient or oxygen-rich atmospheres
• Reducing atmospheres
• Furnace stacks
• Inert environments
• Atmospheres containing combustible airborne mists/dusts.
Measurement in the above atmospheres (except oxygen-rich
atmospheres) can be done with the infrared sensor in the ALTAIR 5 IR.
• Do not use the ALTAIR 5 and ALTAIR 5 IR Multigas Detectors to test for
combustible gases in atmospheres containing vapours from liquids with a high
flash point (above 38 °C, 100°F) as this may result in erroneously low
readings.
• Do not block sensor openings as this may cause inaccurate readings. Do not
press on the face of the sensors, as this may damage them and cause
erroneous readings. Do not use compressed air to clean the sensor holes, as
the pressure may damage the sensors.
• Allow sufficient time for unit to display accurate reading. Response times vary
based on the type of sensor being utilised (see chapter 5.5, "Performance
Specifications"). Additionally, when using a sample pump, allow a minimum of
1 second per foot (3 seconds per metre) of sample line to allow the sample to
be drawn through the sensors.
• Sampling lines made from 1.57 mm (0.062 inch) inner diameter tubing provide
fast transport times to the instrument; however, they must be limited to 15 m
(50 feet) in length.