MQ-135 Air Quality Control Gas Sensor Module

MQ-135 Air Quality Control Gas Sensor Module — Overview

The MQ-135 air quality sensor module is a cost-effective, reliable solution for detecting harmful gases in indoor and outdoor environments. Based on proven MQ-series sensing technology, this module is especially sensitive to ammonia, benzene, smoke and other common air pollutants. It is designed for easy integration with microcontrollers, making it perfect for air quality monitoring systems, smart home projects and industrial safety applications.

Key Features of the MQ-135 Air Quality Sensor

• Wide gas detection range: Detects ammonia, benzene, smoke and multiple other volatile gases.
• High sensitivity: Accurate analog output for granular gas concentration readings.
• Dual outputs: Analog output (0-5V) plus a digital output for threshold-based alerts.
• Adjustable sensitivity: Onboard potentiometer to fine-tune the digital trigger point.
• Fast response: Rapid detection of gas level changes for near real-time monitoring.
• Stable operation: Integrated heater element ensures consistent sensor performance over time.
• Low power: Efficient operation suitable for continuous monitoring and IoT deployments.
• Compact and easy to use: Standard pin headers (VCC, GND, AO, DO) for simple connection to Arduino, ESP, Raspberry Pi and other MCUs.

Technical Specifications

• Sensor type: MQ-135 gas sensor
• Operating voltage: 5V DC
• Output:
  • Analog output AO: 0-5V proportional to gas concentration
  • Digital output DO: configurable threshold output
• Heater voltage: 5V AC or DC
• Preheat time: < 2 minutes
• Operating temperature: -10°C to 50°C
• Humidity range: < 95% RH
• Dimensions: approximately 32mm x 22mm x 20mm

Typical Applications

• Indoor air quality monitoring in homes, offices and schools
• Air purifiers and HVAC systems for pollution control
• Industrial safety systems for detecting harmful gases
• Environmental monitoring and research
• IoT and smart home projects requiring remote air quality data

Wiring and Quick Start Guide

Connect the MQ-135 module to your microcontroller using the standard headers:

• VCC: 5V power supply
• GND: Ground
• AO: Analog input pin (use analogRead() on Arduino to read gas concentration)
• DO: Digital input pin (use digitalRead() to monitor threshold-based alerts)

Adjust the onboard potentiometer to set the digital threshold. Allow a warm-up time for the sensor heater (preheat < 2 minutes) for stable readings.

Integration Tips

• Use the analog output for trend monitoring and logging of gas concentration changes over time.
• Use the digital output to trigger alarms, relays or instantaneous notifications when gas levels exceed a safe threshold.
• Calibrate in the target environment and allow the heater to stabilize for consistent results.
• For battery-powered projects, duty-cycle readings or use sleep strategies on the host MCU to conserve power.

Why Choose the MQ-135 Gas Sensor Module?

The MQ-135 module combines sensitivity, affordability and ease of use, making it an excellent choice for hobbyists, engineers and integrators building air quality monitoring systems. Its dual analog and digital outputs give you flexibility for both continuous monitoring and simple threshold alerts. With straightforward wiring and broad platform compatibility, the MQ-135 is ideal for rapid prototyping and long-term deployments.

FAQ

How do I read values from the MQ-135?

Use the AO pin with an analog input on your microcontroller. On Arduino, call analogRead(A0) to obtain a raw value, then map or convert it to a relative concentration using calibration data.

Can the MQ-135 detect specific gas concentrations?

The MQ-135 provides relative concentration values and is highly sensitive to gases like ammonia and benzene. For precise gas concentration in ppm, perform calibration with known reference gases and environmental compensation.

Is the MQ-135 suitable for continuous monitoring?

Yes, the MQ-135 is designed for continuous operation with low power consumption and a built-in heater to maintain stability. Allow for regular calibration in demanding environments.

Ordering Information

Enhance your air quality and gas detection projects with the MQ-135 Air Quality Control Gas Sensor Module. Its reliable sensing, adjustable threshold and easy MCU integration make it an essential module for smart home, industrial and environmental monitoring solutions.

Note: Images are for illustration purposes only. Actual product design and color may vary slightly.