Instruction manual

Model 4101-28/5100-28 IR Gas Sensor Module (7/03)
Page:
Instruction Manual
1.0 Description
The IR Gas Sensor Module utilizes Infrared technol-
ogy to monitor for combustible gases over the range
of 0-100% LEL. The IR Gas Sensor Module requires
minimal maintenance with a calibration check once a
year. Internal continuous self-diagnostics will auto-
matically indicate any fault or optics problems. The
IR Gas Sensor Module has both digital signal (5100-
28) and a 4-20 mA output signal (4101-28). The digi-
tal Sentry bus output signal interfaces directly to Si-
erra Monitor Sentry System. The 4-20 mA output sig-
nal can interface directly to the Sierra Monitor Model
4000 single controller or any standard industrial con-
troller.
Infrared technology has the benefits of:
• Reduced need for calibration and thus lower oper-
ating costs.
• Operates in high combustible gas and/or low oxy-
gen environment
• Works in environments where catalytic bead poi-
sons might exist
• Rapid recovery after exposure to high concentra-
tions of hydrocarbon gas (exceeding 100% LEL)
1.1 How It Works
Most combustible gases absorb infrared light energy
at defined wavelengths, providing an absorption sig-
nature for that gas. The principle of an infrared de-
tector is based upon the absorption of the infrared light
at a specific wavelength as it passes through the gas.
The more of the absorbing gas that is present, the more
light is absorbed. The detector measures the energy
coming from an infrared light beam at a wavelength
that is absorbed by the combustible gas and compares
it to the energy transmitted by the same. The differ-
ence in energy received by the detector indicates the
level of combustible gas in the atmosphere.
1.2 Sensors Poisons and Inhibitors
The IR Gas Sensor Module is not affected by poisons
or inhibitors that may affect Catalytic bead sensors.
Fig. 1.0 Outline Dimensions
1
3.85”
4.85”
6.75”
4.50”
3.25”
4.35”
2.60”
12.05”
CURRENT O/P CHECK
Connect cu rrent prob es
to meter jack s and
re ad mA ou tput
+ Meter Jack
- Meter Jack
Cal/Reset
Power
Statu s
Pull Here
CALIBRATION
- Ensu re clean ai r
- Hold reset 10 sec
u ntil so lid gree n
- On fish’g red apply
50% span gas
- On solid green
remove gas
Model 4101-28
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STAT US RE D
Slow- Gas
Fast- Cal or Fault
Solid- Overrange
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