LamaPLC: MQ Winsen Gas-sensors

Winsen's MQ series gas sensors are low-cost, semiconductor-type (chemiresistive) sensors designed to detect a wide range of gases, including flammable gases, alcohol, and smoke. Each model is tailored to detect specific gases or a range of gases.

• Operating Principle: The sensors use a sensitive material (typically SnO2 semiconductor) and a heating element. The sensor's conductivity varies with air-gas concentration, enabling measurement using a simple voltage divider.
• Voltage: They operate on a standard 5-volt DC power supply.
• Low Cost: A major advantage is their affordability, making them popular for a wide variety of civil and industrial applications, including smart homes and IoT projects.
• “Burn-in” Time: A “burn-in” period of 12 to 24 hours is often recommended to improve measurement accuracy.

smoke LPG (liquefied petroleum gas) propane hydrogen	Winsen MQ-2	Flammable gas concentracion: 300 .. 10'000ppm Heater Resistance; RH: 29Ω ±3Ω（room tem.） Heater consumption; PH: ≤950mW Sensitivity;S: Ro(in air) / Rs (2000 ppm C3H8) ≥ 5 Output Voltage;Vs: 2.5V～4.0V（in 2000 ppm C3H8） Concentration Slope;α: ≤0.6 (R3000 ppm / R1000 ppm C₃H₈)
alcohol (C₂H₅OH) Small sensitivy: Benzine gas	Winsen MQ-3	Detecting concentration scope：0.05 mg / 10 mg/L Alcohol Sensing Resistance: 1 MΩ - 8 MΩ (0.4 mg/L alcohol)
Methane CH₄ Natural gas LNG Small sensitivy: Alcohol Smoke	Winsen MQ-4	Detecting concentration scope：200-10'000ppm CH₄, natural gas Sensing Resistance: 10KΩ- 60KΩ (1000ppm CH4)
LPG Iso-butane Propane Small sensitivy: Alcohol Smoke	Winsen MQ-5	Detecting concentration scope: 200-10,000ppm LPG, LNG, Natural gas, Iso-butane, Propane, Town gas Sensing Resistance: 10KΩ- 60KΩ (5000 ppm methane)
Town gas Natural gas LPG LNG Iso-butane Propane Small sensitivy: Alcohol Smoke	Winsen MQ-6	Detecting concentration scope：200-10'000ppm LPG ,iso-butane, propane, LNG Sensing Resistance: 10KΩ- 60KΩ (10'00ppm LPG)
CO	Winsen MQ-7	Detecting concentration scope： over 300 ppm CO (Carbon Monoxide) Sensing Resistance: 2KΩ- 20KΩ (100 ppm CO)
H2 Small sensitivy: Alcohol LPG cooking fumes	Winsen MQ-8	Detecting concentration scope：100-10000ppm Hydrogen (H₂) Sensing Resistance: 10KΩ- 60KΩ (1000 ppm H2)
CO Methane CH₄ LPG	Winsen MQ-9	Detecting range： 20 ppm .. 2000 ppm carbon monoxide 500 ppm .. 10'000 ppm methane CH₄ 500 ppm .. 10'000 ppm LPG Sensing Resistance: 2KΩ- 20KΩ (100 ppm CH4)
ozone	Winsen MQ-131	-
NOx Ammonia NH₃ alcohol Benzene smoke CO₂	Winsen MQ-135	Detecting range： 10 ppm .. 300 ppm Ammonia NH₃ 10 ppm .. 1000 ppm Benzene 10 ppm .. 300 ppm Alcohol Sensing Resistance: 30KΩ- 200KΩ (100 ppm Ammonia NH₃)
Ammonia NH₃	Winsen MQ-137	Detecting range： 5 ppm .. 500 ppm Ammonia NH₃

Interfacing the MQ-135 air quality sensor with an Arduino can be done either by reading raw analog signals or by using a dedicated library to obtain calibrated PPM (parts per million) readings.

This code provides a raw reading from 0 to 1023, which is useful for basic threshold detection (e.g., triggering a fan or an alarm).

int sensorPin = A0; // Select the input pin for MQ-135
 
void setup() {
  Serial.begin(9600); // Initialize serial communication
}
 
void loop() {
  int sensorValue = analogRead(sensorPin); // Read analog value (0-1023)
  Serial.print("Raw Air Quality Value: ");
  Serial.println(sensorValue);
  delay(1000); // Wait 1 second for next reading
}

This page has been accessed for: Today: 1, Until now: 23