MQ-9 Gas Sensor Module For Carbon Monoxide, Methane, and LPG Detector Module
π₯ MQ-9 Gas Sensor Module β CO, Methane & LPG Detector
π Overview
The MQ-9 Gas Sensor Module is a versatile gas sensor designed to detect:
β οΈ Carbon Monoxide (CO)
π₯ Methane (CHβ)
π’ LPG (Liquefied Petroleum Gas)
π Ideal for multi-gas detection in safety and IoT systems.
π§ Working Principle
Uses SnOβ (Tin Dioxide) sensing material
Clean air β low conductivity
Gas present β conductivity increases
π Output changes as voltage depending on gas concentration
β οΈ Special Feature:
Dual heating cycle (similar to MQ-7):
π₯ High temperature β detects methane & LPG
π‘ Low temperature β improves CO detection
π Infographic Summary
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β π₯ MQ-9 GAS SENSOR β
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β π― Detects: CO, CHβ, LPG β
β β‘ Voltage: 5V β
β π Range: 10β10,000 ppm β
β π Output: Analog + Digital β
β π Dual heating cycle β
β π₯ Multi-gas detection β
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π Pin Configuration
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β MQ-9 Module β
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β VCC β 5V
β GND β Ground
β AO β Analog
β DO β Digital
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βοΈ Key Specifications
β‘ Operating Voltage: 5V DC
π Detection Range: 10 β 10,000 ppm
π Output:
Analog (gas concentration)
Digital (threshold detection)
π₯ Heater Consumption: ~150 mA
π‘ Operating Temperature: -10Β°C to 50Β°C
π Key Features
π₯ Detects multiple gases
β‘ Fast response time
π§ Easy to interface
π Adjustable sensitivity
π° Low cost
π§ͺ Applications
π Gas leakage alarm systems
π Vehicle exhaust monitoring
π Industrial safety
π€ IoT gas monitoring
π Multi-gas alarm systems
π Interfacing
Compatible with:
π΅ Arduino
π‘ ESP32 / ESP8266
π Raspberry Pi
π Use:
AO β measure gas level
DO β trigger alarm
π Working Example
π Gas Leak Alarm:
Gas leaks detected
Sensor output rises
Microcontroller reads value
Buzzer/LED activates π¨
β οΈ Important Notes
β³ Requires 24β48 hours preheating
β οΈ Not highly selective (multiple gases trigger response)
β οΈ Needs heater voltage cycling for accuracy
β οΈ High power consumption
π¬ Practical insight:
MQ-9 is great for detection, not precise measurement
π MQ-9 vs MQ-7 vs MQ-4
| Sensor | Best For |
|---|---|
| MQ-4 | Methane (CNG) |
| MQ-7 | Carbon Monoxide |
| MQ-9 | Multi-gas (CO + LPG + CHβ) |
π‘ Pro Tip
Combine with buzzer + relay for automatic shutdown systems
Use in ventilation control systems
π Best choice when you need multi-gas detection in one module
