Sensitive material of the MQ137 gas sensor is SnO2, which has lower conductivity in clean air. When NH3 gas exists, the sensor’s conductivity gets higher along with the gas concentration rising. Users can convert the change of conductivity to correspond to the output signal of gas concentration through a simple circuit. The MQ137 gas sensor has high sensitivity to NH3 gas, and can monitor organic amine such as trimethylamine, cholamine well. It can detect kinds of gases including ammonia and is a kind of low-cost sensor for many kinds of applications.

Specifications:

Sensor type: Semiconductor
Encapsulation: Bakelite, Metal cap
Target gas: Ammonia (NH3)
Detection range: 5-500ppm NH3
Loop voltage: ≤24V DC
Heater voltage: 5.0V ± 0.1V AC or DC
Load resistance: Adjustable
Heater resistance (room temperature): 29Ω ± 3Ω
Heater consumption: ≤900mW
Sensitivity: Rs(in air)/Rs(50ppm NH3) ≥ 2
Output voltage: ΔVs ≥ 0.5V (in 50ppm NH3)
Concentration slope: α ≤ 0.6 (R200ppm/R50ppm NH3)
Standard test conditions: 20°C ± 2°C; 55% ± 5%RH
Standard test circuit voltage: 5.0V ± 0.1V
Preheat time: Over 48 hours