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MQ-4 Methane Gas Sensor

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MQ4 Gas Sensor Pinout Configuration

For MQ-4 Sensor Module

Pin Name

Description

VCC

This pin powers the module, typically the operating voltage is +5V

GND

Used to connect the module to system ground

Digital Out (DO)

You can also use this sensor to get digital output from this pin, by setting a threshold value using the potentiometer

Analog Out (AO)

This pin outputs 0-5V analog voltage based on the intensity of the gas

For MQ-4 Sensor

Pin No.

Pin Name

Description

1

H -Pins

Out of the two H pins, one pin is connected to supply and the other to ground

2

A-Pins

The A pins and B pins are interchangeable. These pins will be tied to Supply voltage.

3

B-Pins

A pins and B pins are interchangeable. One pin will act as output while the other will be pulled to ground.

 

MQ-4 Gas Sensor Features

  • Good sensitivity to Combustible gas in wide range
  • High sensitivity to CH4, Natural gas.
  • Small sensitivity to alcohol, smoke.
  • Fast response Stable and long life
  • Simple drive circuit

 

MQ-4 Gas Sensor Specifications

  • Sensor Type Semiconductor
  • Power requirements: VCC - 5V±0.1
  • DO output: TTL digital 0 and 1 (0.1 and 5V)
  • AO output: 0.1-0 .3 V (relative to pollution), the maximum concentration of a voltage of about 4V
  • Detection Gas: Natural gas/Methane
  • Detection Concentration: 200-10000ppm (Natural gas / Methane)
  • Interface: 1 TTL compatible input (HSW), 1 TTL compatible output (ALR)
  • Heater consumption: less than 750mw
  • Operating temperature: 14 to 122 °F (-10 to 50°C)
  • RH Related humidity less than 95%Rh
  • O2 Oxygen concentration is 21% (standard condition) - Oxygen concentration can affect sensitivity
  • Load resistance: 20KΩ
  • Sensing Resistance Rs: 10KΩ- 60KΩ (1000ppm CH4)
  • Preheat time:Over 24 hour
  • Standard Encapsulation Bakelite, Metal cap

 

Alternative MQ Gas Sensors

Sensor Name

Gas to measure

MQ-2

Methane, Butane, LPG, Smoke

MQ-3

Alcohol, Ethanol, Smoke

MQ-4

Methane, CNG Gas

MQ-5

Natural gas, LPG

MQ-6

LPG, butane

MQ-7

Carbon Monoxide

MQ-8

Hydrogen Gas

MQ-9

Carbon Monoxide, flammable gasses

MQ131

Ozone

MQ135

Air Quality

MQ136

Hydrogen Sulphide gas

MQ137

Ammonia

MQ138

Benzene, Toluene, Alcohol, Propane, Formaldehyde gas, Hydrogen

MQ214

Methane, Natural Gas

MQ216

Natural gas, Coal Gas

MQ303A

Alcohol, Ethanol, smoke

MQ306A

LPG, butane

MQ307A

Carbon Monoxide

MQ309A

Carbon Monoxide, flammable gas

 

MQ-4 Equivalent Sensors

MQ-214 (Methane, Natural Gas Detection), MQ306A (LPG Detection), MQ-5 (Natural gas, LPG), MQ306A (LPG detection), MQ-2

 

MQ-4 Gas Sensor Brief Detail 

MQ-4 Sensor is highly sensitive to Methane - CH4.

MQ-4 Structure and Configuration

Structure and configuration of MQ-4 gas sensor is shown in above figure (Configuration A or B), sensor composed by micro AL2O3 ceramic tube, Tin Dioxide (SnO2) sensitive layer, measuring electrode and heater are fixed into a crust made by plastic and stainless steel net. The heater provides necessary work conditions for work of sensitive components. The enveloped MQ-4 have 6 pin ,4 of them are used to fetch signals, and other 2 are used for providing heating current.

 

How to Use MQ-4 Sensor Module?

The connections of MQ4 Gas Sensor Module are very simple. They are made as follows:

  • VCC to 5V
  • GND to GND
  • AO to AnalogO
  • DO to DigitalO

Using a MQ sensor and detecting the gas is quite easy. You can either use the digital pin or the analog pin to accomplish this. Simply power the module with 5V and you should notice the power LED on the module to glow and when no gas is detected the output LED will remain turned off meaning the digital output pin will be 0V.

Remember that these sensors have to be kept on for pre-heating time (mentioned in features above) before you can actually work with it. Now, introduce the sensor to the gas and you should see the output LED to go high along with the digital pin. Now every time your sensor gets introduced to this gas at this particular concentration the digital pin will go high (5V) else will remain low (0V).

You can also use the analog pin to detect the gas. Read the analog values (0-5V) using a microcontroller, this value will be directly proportional to the concentration of the gas to which the sensor detects. You can experiment with this values and check how the sensor reacts to different concentration of gas and develop your program accordingly.

Sensitivity Adjustment

Resistance value of MQ-4 is difference to various kinds and various concentration gases. So while using this component, sensitivity adjustment is very necessary. It is recommended to calibrate the sensor for 5000ppm of CH4 concentration in air and use value of Load resistance (RL) about 20KΩ(10KΩ to 47KΩ). When accurately measuring, the proper alarm point for the gas detector should be determined after considering the temperature and humidity influence. For more information, read the MQ-4 datasheet attached at the end of this article.

 

MQ-4 Gas Sensor Applications

  • Used in gas leakage detecting equipment for homes and industry. They are suitable for detecting of CH4 and CNG.
  • Industrial Combustible gas detector
  • Portable gas detectors

 

MQ-4 Sensor 2D Model (Configuration A and B)

MQ-4 Sensor 2D Model




Download Datasheet PDF:
MQ-4 Methane Gas Sensor Datasheet