The MQ-8A is a Metal oxide semiconductor (MOS) sensor from the MQ gas sensor series. The module can be used to find any leaks or the presence of hydrogen gas in the air because it is sensitive to the gas. Its range of concentration is 100 to 1000 ppm.

Package Includes:

• 1x MQ8 H2 Sensor

Features:

• Good sensitivity to combustible gases in a wide range
• Fast response time
• There are four screw holes for easy positioning.
• Long life Low cost
• Simple drive circuit
• Operating Voltage: 5V DC
• Detects H2 Gas concentration in air
• Resistant to LPG, smoke, alcohol
• Heater power consumption: < 800mW
• Can detect H2 gas in the concentration range of 100 to 1000ppm
• Can be used as a Digital or analog sensor
• You can vary the Sensitivity of the Digital pin using the potentiometer

Description:

The MQ-8A is a Metal oxide semiconductor (MOS) sensor from the MQ gas sensor series . The module can be used to find any leaks or the presence of hydrogen gas in the air because it is sensitive to the gas. Its range of concentration is 100 to 1000 ppm. By altering the resistance of the detecting element in response to changes in gas concentration, the sensor creates a potential difference that can be measured as an output voltage. Its sensing component is a ceramic with an aluminum oxide base that has been coated in tin dioxide (SnO2) and is encased in a stainless steel mesh. Any H2 in the air causes a change in the sensing element's resistivity, which is then measured to determine the amount of gas present.

Principle of Work:

With MQ8, gas detection is comparatively easy. You might use the analog pin or the digital pin for this. The output LED won't turn on when the module is powered by 5V, leaving the digital output pin vacant and at 0V. These sensors must be pre-heated for a while before you can use them. After making a gas contact with the sensor, adjust the potentiometer until the output LED and digital pin go high. If your sensor is exposed to this gas at this particular concentration, the digital pin will now go high (5V), otherwise, it will remain low. The analog pin can also be utilized to achieve the same result. Using an MCU, read the analog values (0–5V), and this value will be directly proportional to the amount of gas the sensor is detecting. You can play about with these settings to see how the sensor responds to various gas concentrations and adjust your program as necessary.

Pinout of the Sensor:

Applications:

1. Detect leakages in the industry
2. Used in mines
3. Can be used in refrigerators and AC

Circuit:

The Arduino board can be used to connect the MQ8 sensor. the GND pin is linked to the GND pins of the Arduino and the VCC pin is linked to the Arduino board's +5V power source pin, the A out tied to the Arduino board's Analog pin A0. watch the readings on the Serial monitor. make the sensor near H2 source to check the abrupt changes in readings. As a result, the adjustments are visible on the serial monitor. and if the sensor Value is> 400 the Built-in LED will turn on if the value of the digital out is 1.

Library:

This Module doesn't need any Library to function.

Code:

#define MQ8pin 0
float sensorValue; //variable to store sensor value
void setup() {
 pinMode(13,1);
 Serial.begin(9600); // sets the serial port to 9600
 Serial.println(" MQ8 warming up!");
 delay(20000); // allow the MQ8 to warm up
}
void loop() {
 sensorValue = analogRead( MQ8pin); // read analog input pin 0
 Serial.print("Sensor Value: ");
 Serial.println(sensorValue);
 if(sensorValue > 400){
 digitalWrite(13,1);
 }else{
 digitalWrite(13,0);
 }
 delay(2000); // wait 2s for next reading
}

Technical Details:

• Target Gas: H2
• Detectable Concentration: 100-10000ppm CO
• Operating voltage: 5V
• Vc Circuit voltage 5V±0.1 AC OR DC<
• VH Heating voltage 5V±0.1 ACOR DC
• PL Load resistance 10KΩ
• RH Heater resistance 31±5% Room Tem
• PH Heating consumption less than800mW
• Environment condition
• Symbol Parameter name Technical condition Remarks
• Tao Using Tem -10C-50C
• Tas Storage Tem -20C-70C
• RH Related humidity less than 95%Rh
• O2 Oxygen concentration 21%(standard condition)Oxygen
• concentration can affect sensitivity
• the minimum value is over 2%

Sensitivity characteristic

• Symbol Parameter name Technical parameter Ramark 2
• Rs Sensing Resistance 10KΩ- 60KΩ (1000ppm H2)

Standard detecting condition

• Temp: 20C±2C Vc:5V±0.1
• Humidity: 65%±5% Vh: 5V±0.1
• Preheat time Over 24 hour
• Detecting concentration scope： 100-10000ppm
• Product Dimensions: 32(L)*20(W)*22(H)

Resources:

Datasheet of the MQ8

Comparisons:

The MQ series Gas sensors are the most frequently used ones when it comes to measuring or detecting a specific Gas. it is advised to purchase the sensor alone if you intend to monitor a gas' ppm levels (without a module). the MQ8  sensing range of 100-10000 PPM is suitable for H2 fast detection even in low concentrations, The MQ-2 measures gas concentration so far higher than the MQ8, so we prefer using MQ8 with H2 detection systems for its high sensitivity for co.