Principle Introduction:
Winsen Electronics produce semiconductor ammonia sensor, NH3 Gas sensor MQ137 for NH3 gas alarm, industrial NH3 gas leakage alarm, portable NH3 gas detector.
Sensitive material of MQ137 gas sensor is SnO2, which with 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 output signal of gas concentration through a simple circuit.
MQ137 gas sensor has high sensitivity to NH3 gas, also 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 kinds of applications.

Applications :
It is widely used in domestic NH3 gas alarm, industrial NH3 gas leakage alarm, portable NH3 gas detector.

Technical parameters :

Tips:For more parameter information, please refer to the latest manual provided by salesman.

Model			MQ137
Sensor Type			Semiconductor
Standard Encapsulation			Bakelite, Metal cap
Target Gas			Ammonia Gas(NH3)
Detection range			5～500ppm NH3
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(50ppmNH3)≥2
	Output Voltage	△Vs	≥0.5V (in 50ppm NH3)
	Concentration Slope	α	≤0.6(R200ppm/R50ppm NH3)
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

Reference Circuit :

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