MSA Sirius Mode D'emploi page 77

Table 7-7. CARBON MONOXIDE - Cross Reference Factors
for Sirius Calibration Using Calibration Cylinder (P/N 10045035)
NOTE: Data is presented as the indicated output in ppm, which would
result from the application of 100 ppm of the test gas.
TEST GAS (100 PPM)
Carbon Monoxide (CO)
Hydrogen Sulfide (H 2 S)
TEST GAS (100 PPM)
Sulfur Dioxide (SO 2 )
Nitrogen Dioxide (NO 2 )
Nitric Oxide (NO)
Chlorine (Cl 2 )
Ammonia (NH 3 )
Hydrogen Chloride (HCl)
Ethylene (C 2 H 4 )
Hydrogen Cyanide (HCN)
Methane (CH 4 )
Ethanol (EtOH)
Hydrogen (H 2 )
The carbon monoxide channel in the Sirius instrument is equipped with
internal and external filters. The purpose of these filters is to protect the
CO sensor from acid gases (H 2 S, SO 2 , etc.) and from the
hydrocarbons that the instrument is intended to measure, including the
calibration gas, isobutylene. In normal use, an interferent signal for
calibration or bump checking the instrument should not be observed on
the CO channel. However, exposure to large amounts of certain
hydrocarbons (either long exposure times or high concentrations) can
overwhelm the filter and appear as signals on the CO channel. In
normal operation, after the hydrocarbon exposure is ended, the filter is
designed to outgas absorbed hydrocarbons at a rate that will not cause
a signal on the CO channel. However, if the unit is exposed to high
temperature (>40°C), this desorption rate increases and spurious
signals may be observed on the CO channel due to gassing of
previously absorbed hydrocarbons. If this occurs, it may be necessary
to replace the CO sensor.
7-6
EQUIVALENT PPM
100 +9
4 +4
EQUIVALENT PPM
0 +1
2 +6
70 +10
1 +8
2 +4
3 +2
76 +9
0 +1
0 +0
0
70 +26