Principle Introduction:
Winsen Electronics manufacture air quality sensor and VOC sensor MQ138 for IAQ monitor application.
Sensitive material of MQ138 gas sensor is SnO2, which with lower conductivity in clean air. When VOC gas exists, the sensor’s conductivity gets higher along with the gas concentration rising. Users can convert the change of conductivity to correspond output signal of gas concentration through a simple circuit.
MQ138 gas sensor has high sensitivity to toluene, acetone,alcohol,methanol,also can monitor hydrogen and other organic vapour well. It can detect kinds of organic gases and is a kind of low-cost sensor for kinds of applications.
Applications :
It is widely used in domestic VOC gas alarm, industrial VOC gas leakage alarm and portable VOC gas detector.
Technical parameters :
Tips:For more parameter information, please refer to the latest manual provided by salesman.
| Model |
MQ138 |
| Sensor Type |
Semiconductor |
| Standard Encapsulation |
Bakelite, Metal cap |
| Target Gas |
toluene, acetone, alcohol, hydrogen |
| Detection range |
5～500ppm |
| Standard Circuit Conditions |
Loop Voltage |
Vc |
≤24V DC |
| Heater Voltage |
VH |
5.0V±0.1V AC or DC |
| Load Resistance |
RL |
Adjustable |
| Sensor character under standard test conditions |
Heater Resistance |
RH |
29Ω±3Ω（ room tem.） |
| Heater consumption |
PH |
≤900mW |
| Sensitivity |
S |
Rs(in air)/Rs(in 50ppm toluene)≥2 |
| Output Voltage |
△Vs |
≥0.5V (in 50ppm toluene) |
| Concentration Slope |
α |
≤0.6(R200ppm/R50ppm toluene) |
| Standard test conditions |
Tem. Humidity |
20℃±2℃；55%±5%RH |
| Standard test circuit |
Vc:5.0V±0.1V； VH:5.0V±0.1V |
| Preheat time |
Over 48 hours |
Datasheet Download
