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Model 4100 Series
Gas Sensor Modules
Sierra Monitor Corporation 1991 Tarob Ct. Milpitas, CA 95035 (408) 262-6611 800-727-4377 FAX: (408) 262-9042
Visit our Web site at: www.sierramonitor.com E-Mail: sierra@sierramonitor.com
The Model 4100 Series Gas Sensor Modules
monitor a variety of toxic and combustible gases
and provide a 4-20 mA DC output signal of gas
concentration
The Model 4100 Series utilizes semiconductor sensor tech-
nology to provide monitoring of gases in the parts per mil-
lion (PPM) ranges. These modules operate on 24 VDC
input and have a non-linear 4-20 mA DC current loop out-
put.
The four gas sensor modules in this series are:
4100-33 Gas Sensor Module 4-20 mA DC
4100-34 Gas Sensor Module 4-20 mA DC
4100-35 Gas Sensor Module 4-20 mA DC
4100-36 Gas Sensor Module 4-20 mA DC
These gas sensor modules can monitor a wide variety of
gases. Table A provides a partial list of gases that can be
reliably monitored. If your gas is not on this list, check
with Sierra Monitor to determine if a 4100 Series gas sen-
sor module is available to meet your requirements.
Also, these gas sensor modules can be calibrated with
the gas of interest or with methane or carbon monoxide.
Thus, the user does not have to obtain a special calibra-
tion gas.
The Model 4100 Series provides a non-linear 4-20 mA out-
put signal that can interface with the Sierra Monitor Sensys
controller or other linearizing controllers / indicators. Curves
and linearizing equations can be provided for a specific
gas and sensor to enable the operation of these sensor
modules with other brand controllers.
Specifications
Sensor
Type: Solid State Metal Oxide Semiconductor
Range: 20-500 ppm or 50-5000 ppm See Table A.
Response: 80% of concentration in less than 3 mins.
Typical Life: 1-3 years in Normal Service.
Detectable Gases And Vapors
Typical List: See Table A
Maintenance
Calibration
Adjustments:Zero Adjust, Span Adjust
Sensor LED: OFF indicates heater or film is an open circuit.
Environmental
Operating: Temperature -10
o
C to +40
o
C (14
o
F to 104
o
F)
Humidity 5% to 95% non-condensing
Storage: Temperature -55
o
C to +85
o
C (-67
o
F to 185
o
F)
Electrical Data
Wiring: 3 wire non-isolated
Input Voltage: 14 - 30 VDC
Current: 70mA @ 4mA DC loop current;
90mA @ 20mA DC loop current at 24VDC.
Power: 2.1 Watts
Output Range: 4-20mA DC Non-linear
Loop Res.: 800 ohms at 28VDC
Mechanical
Size: 6.75" x 4" x 3.5" (HxWxD)
(17.1 cm x 10.2 cm x 8.9 cm)
Material: Cast aluminum epoxy painted
Weight: 2 pounds (0.9 Kg)
Classification: Class I Division I Groups C,D
Mounting: Connects to a vertical 3/4" electrical conduit
How it Works
Semiconductor sensors have a resistance in air that is
affected by oxygen adsorbed on the surface of the sensor.
Oxygen atoms capture electrons on the semiconductor
surface, thereby increasing its resistance.
The sensors can be impregnated with dopants such that
the sensors resistance changes when specific gases dis-
place the adsorbed oxygen.
Nobel Metal Wire
Sensor
Heater Coil