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.

Application

It is widely used in domestic VOC gas alarm, industrial VOC gas leakage alarm and portable VOC gas detector.

Features

It has good sensitivity to organic vapour gas in wide range, and has advantages such as long lifespan, low cost and simple drive circuit &etc.

Specifications

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	5.0V±0.1V DC
	Heater Voltage	VH	5.0V±0.1V AC or DC
	Load resistance	RL	Adjustable
Sensor character under standard test conditions	Heater Resistance	RH	30Ω±3Ω（room temp.）
	Heater consumption	PH	≤950mW
	Sensitivity	S	Rs(in air)/Rs(in 50ppm toluene)≥2
	Output Voltage	△Vs	0.5V (in 50ppmtoluene)
	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

* The description and specifications might be changed without notice. Please contact us for the latest information before placing orders.

1 PC MQ138 VOC Gas Sensor