nsitive 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.

Features:

1. Wide range of applications
2. Small appearance
3. Long service life
4. Fast response time
5. With mounting holes for easy permanent installation

Specifications:

• Detection Gas: toluene, acetone, alcohol, hydrogen
• Detection Range: 5～500ppm VOC
• Size：32mm X22mm X27mm   L x W x G
• Main chip：LM393.
• Operating voltage: DC 5V
• Heating voltage: 5 ±0.2V (AC·DC)
• Working current: 180mA.
• Circuit voltage: DC5V (Max DC 24V)
• Load resistance: 10K (adjustable)
• Test concentration range :1-100ppm.
• Clean air voltage: < 1.5V.
• Sensitivity: > 3%
• Response time: < 1S (3-5 minute warm-up, theory preheating time 48 hours)