نقد و بررسی اجمالی

ماژول سنسور تشخیص گاز متان MQ-4

امکانات
حساسیت خوب به گازهای قابل احتراق در محدوده وسیع
حساسیت بالا به CH4، گاز طبیعی.
حساسیت کم به الکل، دود.
پاسخ سریع پایدار و عمر طولانی
مدار درایو ساده

کاربردهای سنسور گاز MQ-4
در تجهیزات تشخیص نشت گاز برای خانه ها و صنعت استفاده می شود. آنها برای تشخیص CH4 و CNG مناسب هستند.
آشکارساز گازهای قابل احتراق صنعتی
آشکارسازهای گاز قابل حمل

دیتا شیت ماژول سنسور تشخیص گاز متان MQ-4

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.

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

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 AL₂O₃ceramic 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