MQ-136 Hydrogen Sulfide H2S Gas Sensor Module

The MQ-136 is a semiconductor-based hydrogen sulfide (H2S) gas sensor module designed for accurate detection and monitoring of hydrogen sulfide concentrations in the surrounding environment. Utilizing a tin dioxide (SnO₂) sensing element whose electrical resistance decreases in the presence of H2S gas, the module delivers both analog and digital output signals for flexible integration into a wide range of systems.

The onboard potentiometer allows users to adjust the digital output trigger threshold, while the analog output provides continuous concentration data readable by any ADC-equipped microcontroller including Arduino, ESP32, ESP8266, and STM32 boards.

The MQ-136 is widely used in industrial safety monitoring, sewage and wastewater treatment facilities, petroleum refining environments, laboratory gas detection systems, and portable air quality monitors. It is also sensitive to sulfur dioxide (SO₂) and other sulfur-bearing gases, making it a versatile choice for multi-gas safety applications.

Its robust construction, straightforward wiring, and dual output capability make it an essential component for safety-critical and environmental monitoring projects.

Specification:

• Sensor Type : Semiconductor (SnO₂)
• Target Gas : Hydrogen Sulfide (H2S)
• Also Sensitive To : SO₂, and other sulfur-bearing gases
• Detection Range : 1 – 200 ppm
• Output Type : Analog + Digital
• Operating Voltage : 5V DC
• Heater Voltage : 5V DC
• Heater Resistance : 33Ω ± 5%
• Load Resistance : Adjustable (onboard potentiometer)
• Preheat Time : ≥ 24 hours (initial use)
• Operating Temperature : -10°C to 50°C
• Operating Humidity : ≤ 95% RH (non-condensing)
• Pins : 4 (VCC, GND, AOUT, DOUT)
• Compatible Boards : Arduino, ESP8266, ESP32, STM32