MSA Chemgard - Caution

Section 4, Calibration
Chemgard Infrared Gas Monitor
4-2
• A SPAN gas cylinder
• Optional ZERO gas cylinder.
• A ZERO gas cylinder may not be needed.
The Calibration Kit contains a ZERO gas scrubber
which can be used in place of a ZERO gas
cylinder if the ambient air around the Chemgard
Infrared Gas Monitor contains little or no
interfering gas.
CAUTION
The zero gas scrubber must be replaced
periodically because the filter can become
saturated by ambient gas vapors. The
frequency of replacement depends on the
concentration of the ambient gas vapors.
The SPAN or ZERO cylinders (if needed) may be
included with the Calibration Kit; cylinders shown
in TABLE 4-1 are available from MSA:
Table 4-1. Calibration Gas Cylinders
DESCRIPTION
CONCENTRATION
PART NO.
Carbon Monoxide 100 ppm 806734
Pentane
.75%
804532
Pentane 1000 ppm 10014894
Iso Butylene
100 ppm
494450
R22 100 ppm 804868
Nitrous Oxide
100 ppm
806736
R11 100 ppm 803499
R134a
100 ppm
803500
Zero Air 801050
Carbon Dioxide
100 ppm
806755
R113 100 ppm 804870
R12
100 ppm
804866
R134a 30 ppm 812787
Propane
0.6%
493579
R123 30 ppm 812784
Become familiar with the Calibration Kit
components (FIGURE 4-1).
For Carbon Monoxide,
Carbon Dioxide and Nitrous
Oxide Chemgard Monitors
An affect observed on these infrared monitors is
a reduction in signal at low relative humidities.
The gas sample being drawn into the instrument
MUST contain a humidity level greater than 0.3%
by volume. At 72°F (22°C), this would represent a
relative humidity level of approximately 10%.
To ensure that the sample is humidified, MSA
recommends placing an air-tight water bubbler in
the sample line. I
f the humidity level in the
sample stream will be above 0.3% by volume at
all times, the water bubbler is not necessary.
Care MUST be used to ensure that sufficient
water is present in the bubbler such that the
humidity level is greater than 0.3% by volume at
all times, including during calibration.
WARNING
Failure to properly humidify the sample at
all times can cause erroneous monitor
readings. If the instrument is not properly
humidified, the Chemgard Monitor may fail
to perform as designed and persons who
rely on this product for their safety could
sustain severe personal injury or death.
Calibration of the infrared sensor can be achieved
by following the calibration procedure in this
manual. The sample MUST be properly humidified
during the calibration procedure.
Chemgard Infrared Gas
Monitor identification
You must identify your unit as a single-point
monito
r or a multi-point monitor for proper
calibration gas connection. Refer to FIGURE 4-2
to help identify your unit.
Calibration Procedures
Before calibrating the Chemgard Monitor,
leak-check the sample line(s) connected to
the monitor:
1. Temporarily block the sample inlet at the
end-of-line filter(s) and verify that the
monitor gives a trouble alarm.
• If the monitor is a Multipoint Sequencer,
the trouble alarm will not activate until the
blocked sampling point is selected by the
Sequencer.
2. After checking for leaks, remove the sampling
line for the Chemgard inle
t.
• On Multipoint Monitors,
use sample inlet Point 1.
3. Attach the Calibration Kit connector assembly
to the inlet.
4. Before applying gases, familiarize yourself
with the calibration screens by stepping the
monitor through the whole sequence. Press
the keys in the following order: