MQ sensors are physicochemical sensors for detecting a wide variety of gases, pollutants and fumes in the atmosphere . This table lists the main technical information and refers to the technical documentation as well as the calibration instructions found on the internet.

Note. Before operating and delivering a correct measurement, some sensors must be preheated. This is the case for example of MQ-131, MQ-135, MQ-137 which require 24 hours of preheating. The MQ-137 even takes 48 hours.

Warning, do not use this detector for applications that may endanger the safety of people (medical, industrial applications, etc.)

Warning. The sensor heats up after a few minutes of use. This is normal, it is the very principle of operation of all physicochemical sensors. Take this into account when designing your project.

Sensor	Sensitive to	Preheating *	Technical documentation	Calibration	Example
MQ-2	Methane, Butane, LPG and fumes	48h	Read		Read
MQ-3	Alcohol, Ethanol and fumes	24h	Read	Read the article of nootropicdesign (English)
MQ-4	Methane (CH4). From 300 to 10,000 ppm	48h	Read
MQ-5	Natural gas, LPG. From 300 to 50,000 ppm. Response time less than 10s	24h	Read
MQ-6	LPG, butane. From 200 to 10,000 ppm	48	Read
MQ-7	Carbon monoxide (CO). From 20 to 2000 ppm	48h	Read
MQ-8	Hydrogen. From 100 to 10,000 ppm	24h	Read
MQ-9	Carbon monoxide, methane (CH4)		Read	Read the seeedstudio article
MQ131	Ozone		Read
MQ135	Air quality	24h	Read		Read
MQ136	Gaseous hydrogen sulfide (H2S). From 1 to 1000 ppm	24h	Read
MQ137	Ammonia. From 5 to 500ppm		Read
MQ138	Benzene, Toluene, Alcohol, Acetone, Propane, Formaldehyde, Hydrogen. From 10 to 1000ppm except for NH3, from 10 to 3000 ppm	24h	Read
MQ214	Methane (from 3000ppm to 20000ppm), LPG and propane (500ppm to 10000ppm, butane (500ppm to 10000ppm)	24h	Read
MQ216	Natural gas, coal gas, Propane, CH4	24h	Read
MQ303A	Alcohol, Ethanol, fumes	+ 48h	Read		Read
MQ306A	LPG, butane Same as MQ-6 but with lower heating voltage (0.9V)	+ 48h	Read
MQ307A	Carbon monoxide (CO) Identical to MQ-7 but with a voltage varying from 0.2 to 0.9V	+ 48h	Read
MQ309A	Carbon monoxide, flammable gases Identical to MQ-9 but with a voltage varying from 0.2 to 0.9V	+ 48h	Read