Model 4100 Series
Gas Sensor Modules
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:
How it Works
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
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.
These gas sensor modules can monitor a wide variety of
gases. Table Aprovides 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.
The sensors can be impregnated with dopants such that
the sensor’s resistance changes when specific gases dis-
place the adsorbed oxygen.
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.
Nobel Metal Wire
Sensor
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.
Heater Coil
Specifications
Sensor
Electrical Data
Wiring:
3 wire non-isolated
Type:
Range:
Response:
Typical Life:
Solid State Metal Oxide Semiconductor
20-500 ppm or 50-5000 ppm See Table A.
80% of concentration in less than 3 mins.
1-3 years in Normal Service.
Input Voltage: 14 - 30 VDC
Current:
Power:
70mA @ 4mA DC loop current;
90mA @ 20mA DC loop current at 24VDC.
2.1 Watts
Output Range: 4-20mA DC Non-linear
Detectable Gases And Vapors
Loop Res.:
800 ohms at 28VDC
Typical List:
See Table A
Mechanical
Maintenance
Size:
6.75" x 4" x 3.5" (HxWxD)
(17.1 cm x 10.2 cm x 8.9 cm)
Cast aluminum epoxy painted
2 pounds (0.9 Kg)
Calibration
Adjustments: Zero Adjust, Span Adjust
Material:
Weight:
Sensor LED:
OFF indicates heater or film is an open circuit.
Classification: Class I Division I Groups C,D
Mounting: Connects to a vertical 3/4" electrical conduit
Environmental
Operating:
Temperature -10oC to +40oC (14oF to 104oF)
Humidity 5% to 95% non-condensing
Storage:
Temperature -55oC to +85oC (-67oF to 185oF)
Sierra Monitor Corporation 1991 Tarob Ct. Milpitas, CA 95035 (408) 262-6611 800-727-4377 FAX: (408) 262-9042
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