Data Sheet - Gas Analyzers
Carbon monoxide analyzer - panel mount
Gas Analysis Solutions
For safety critical applications in the workplace
Compact. Accurate. Reliable.
The 120-CO Series is a panel mounted
analyzer that accurately measures carbon
monoxide in the range of 0 to 200 ppm.
Designed for continuous operation, this
analyzer measures and displays the level of
carbon monoxide in a workplace area and
provides audible and visual alarms if the
level exceeds predetermined setpoints.
Reliable low cost sensor
The electrochemical sensor ensures reliable
performance and fast response for safety
critical measurements. The sensor is a small
fuel cell that measures carbon monoxide
directly. It is easily replaceable and
unaffected by most background gases.
Simple operation
As the sample gas from the area passes
across the CO sensor, the CO sensor
produces a small current proportional to
the amount of CO in the sample stream.
The current is amplified, filtered, and
electronically conditioned by the analyzer
circuit board. The resulting signal is then
shown on the led display and compared
with the two adjustable alarms. The alarms
are triggered if the signal reaches the
predetermined setpoints.
Two adjustable alarms
Each alarm has a dedicated relay with both
normally open and normally closed
contacts. Alarm led status indication is
provided for each alarm on the front panel.
Both alarms activate a piezoelectric horn
mounted on the left side of the front panel.
The alarms are configured at the factory as
low and high level alarms with settings of
20 ppm and 50 ppm. The “set alarms”
switch and potentiometers are used to
adjust the setpoints.
0 to 200 ppm measurement range
Electrochemical sensor is unaffected by background gases
Two adjustable alarm setpoints with relays
Alarm horn with silence switch
Large 1/2” high LED display
Alarm hysteresis
Both alarms have a 1 ppm CO hysteresis,
which is positive for the high and low
alarms. If the low alarm is set to 20 ppm,
the alarm relay will activate at 21 ppm and
deactivate at 20 ppm. This prevents
excessive wear of the mechanical devices
interfaced with the alarm relays.
Test features
The alarm circuitry, alarm relays, alarm leds,
and horn can be tested simultaneously by
pressing the “press to test” switch on the
front panel.
Horn silence
A 90 dB alarm horn is mounted on the front
panel. The “horn silence” switch will
disable the horn. The alarm horn will stay
disabled as long as it remains in the silence
Low power/switch open alarm
The low power/switch open (lpso) alarm
detects a power supply problem and the
status of an external switch or relay. The
lpso red led will illuminate if the supplied
power drops below 6.5 VDC or if an
external switch or relay wired to the main
terminal block is in the open state.
Easy to use and maintain
Ensuring safe and reliable operation of the
120-CO Series monitor requires periodic
calibration and sensor replacement. The
sensor has an expected service life of 2
years but may vary depending on the
application. The sensor will need to be
replaced when the monitor cannot be
adjusted to match the span gas during
calibration. A new filter screen and O-ring
should be installed when replacing the
The 120-CO Series monitor should be
calibrated every month. The calibration
procedure requires the use of a zero gas
and a span gas with a known level of
carbon monoxide. The zero and span
potentiometers located on the front panel
are used to adjust the display to match the
correct gas concentrations.
Loop powered current output
The 120-CO Series analyzer is available with
loop powered 4-20mA current output
calibrated to 0 to 200 ppm co.
2 | MN-A-0271 Rev A © 2015 Neutronics Gas Analysis Solutions
CO analyzer - panel mount
Operating range
Maximum overload
Sensor type
Expected sensor service life
Response time
Pressure range
Temperature range
Relative humidity
Warm up time
Low alarm factory setpoint
High alarm factory setpoint
Power supply
Analyzer warranty
Sensor warranty
Front view
Panel mount carbon monoxide analyzer
0 to 200 ppm CO
500 ppm CO
2 years in air
1 ppm
T90 < 40 seconds
Atmospheric ±10%
35 to 122° F (2 to 50° C)
0 to 90%, non-condensing
5 seconds
20 ppm
50 ppm
115/230 VAC ±20%, 50/60 Hz @ 50mA or 9 -15 VDC @ 400mA
12 months from date of shipment
6 months from date of shipment
6.75" (171mm) length x 5.00" (127mm) width x 3.81" (97mm) height
5.0 lbs. (2.3 Kg)
Specifications are subject to change without notice.
Side view
Top view
Order information
Model 120 Series CO monitor
Model 120 series CO monitor (4-20mA output)
Sensor replacement kit (sensor, filter, screen, and O-ring)
Replacement fuse
Potentiometer adjustment tool
90 dB horn
Part number
Gas Analysis Solutions
456 Creamery Way
Exton, PA 19341
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