Humidity Changes; Temperature Changes; Typical Performance Specifications - MSA Sirius Mode D'emploi

sensor reading may temporarily shift, and possibly cause the detector to
go into alarm. While the percentage of oxygen may remain at or near
20.8%, the total amount of oxygen present in the atmosphere available
for respiration may become a hazard if the overall pressure is reduced
to a significant degree.

Humidity Changes

If humidity changes to any significant degree (e.g., going from a dry, air
conditioned environment to outdoor, moisture laden air), oxygen levels
can change up to 0.5%. This is due to water vapor in the air displacing
oxygen, thus reducing oxygen readings as humidity increases. The
oxygen sensor has a special filter to reduce the affects of humidity
changes on oxygen readings. This effect will not be noticed
immediately, but slowly impacts oxygen readings over several hours.

Temperature Changes

The oxygen sensor has built-in temperature compensation. However, if
temperature shifts dramatically, the oxygen sensor reading may shift.
Zero the instrument at a temperature within 30°C of the temperature-of-
use for the least effect.
Table 7-6.
CARBON MONOXIDE (appropriate models only) -

Typical Performance Specifications

RANGE 500 ppm CO
RESOLUTION 1 ppm CO, for 5 to 500 ppm CO
REPRODUCIBILITY** +5 ppm CO or 10% of reading, whichever is greater
0 to 150 ppm CO, +15% >150 ppm CO
(normal temperature range*)
+10 ppm CO or 20% of reading, whichever is greater
(extended temperature range*)
RESPONSE TIME 90% of final reading in 50 seconds with sample line and probe
(normal temperature range*)
*See TABLE 7-2 NOTE
**See TABLE 7-10 NOTE
7-5