Winsen MQ-3B Alcohol Gas Sensor Instruction Manual

Winsen MQ-3B Alcohol Gas Sensor

Product Information

portable alcohol detector

Product Usage Instructions

The MQ-3B Alcohol Gas Sensor is a semiconductor sensor designed to detect alcohol gas. The sensor’s conductivity increases with the concentration of alcohol gas in the air. It can be used in various applications to detect alcohol at different concentrations.

Basic Circuit:

The above figure shows the basic test circuit of the MQ-3B sensor. The sensor requires two voltage inputs: heater voltage (VH) and circuit voltage (VC). VH is used to supply standard working temperature to the sensor and can be powered by DC or AC. VRL is the voltage of the load resistance RL, which is in series with the sensor. VC supplies the detect voltage to load resistance RL and should be powered by DC.

Description of Sensor Characters:

• The above figure shows the typical sensitivity curve of the sensor. The resistance ratio of the sensor (Rs/R0) is plotted against the concentration of gases. Rs represents the resistance in target gas with different concentrations, while R0 represents the resistance of the sensor in clean air.
• The above figure shows the typical temperature/humidity characteristics of the sensor. The resistance ratio of the sensor (Rs/Rso) is plotted against temperature and humidity. Rs represents the resistance of the sensor in 125ppm alcohol (C2H5OH) under different temperature and humidity conditions, while Rso represents the resistance of the sensor in 125ppm alcohol (C2H5OH) under 20/55%RH.
• For more information or to purchase the MQ-3B Alcohol Gas Sensor, please visit www.winsen-sensor.com or contact Zhengzhou Winsen Electronics Technology Co., Ltd at the following:
• Tel : 86-371-67169097/67169670
• Fax : 86-371-60932988
• Email: sales@winsensor.com

Statement

• This manual copyright belongs to Zhengzhou Winsen Electronics Technology Co., LTD. Without the written permission, any part of this manual shall not be copied, translated, stored in database or retrieval system, also can’t spread through electronic, copying, record ways.
• Thanks for purchasing our product. In order to let customers use it better and reduce the faults caused by misuse, please read the manual carefully and operate it correctly in accordance with the instructions. If users disobey the terms or remove, disassemble, change the components inside of the sensor, we shall not be responsible for the loss.
• The specific such as color, appearance, sizes &etc, please in kind prevail.
• We are devoting ourselves to products development and technical innovation, so we reserve the right to improve the products without notice. Please confirm it is the valid version before using this manual. At the same time, users’ comments on optimized using way are welcome.
• Please keep the manual properly, in order to get help if you have questions during the usage in the future.

Profile

Sensitive material of MQ-3B gas sensor is SnO2, which with lower conductivity in clean air. When the target alcohol gas exist, the sensor’s conductivity gets higher along with the gas concentration rising. Users can convert the change of conductivity to correspond output signal of gas concentration through a simple circuit. MQ-3B gas sensor has high sensitivity to alcohol gas and can resistant to the interference of gasoline, smoke and vapor. It is with low cost and suitable for various applications of detecting alcohol at different concentration.

Features
It has good sensitivity to alcohol in wide range, and has advantages such as long lifespan, low cost and simple drive circuit &etc.

Main Applications
It is widely used in domestic alcohol gas alarm, industrial alcohol gas alarm and portable alcohol detector.

Technical Parameters

Sensor character under standard test conditions

| Heater Resistance| RH| 29Ω±3Ω (room tem.)
Heater consumption| PH| ≤900mW

Sensitivity

| ****

S

| Ro(in air)/Rs(125ppm C2H5OH)≥5

Output Voltage

| ****

Vs

| 2.5V~4.0V (in 125ppm C2H5OH)
Concentration Slope| α| ≤0.6(R300ppm/R50ppm C2H5OH)

Standard test conditions

| Tem.  Humidity| 20℃±2℃；55%±5%RH

Standard test circuit

| Vc:5.0V±0.1V VH:5.0V±0.1V
Preheat time| Over 48 hours

NOTE : Output voltage(Vs) is VRL in test environment.

Basic Circuit

Instructions: The above fig is the basic test circuit of MQ-3B.The sensor requires two voltage inputs:
heater voltage(VH) and circuit voltage(VC). VH is used to supply standard working temperature to the sensor and it can adopts DC or AC power, while VRL is the voltage of load resistance RL Figwhi1.Sche isns or Structure in series with sensor. Vc supplies the detect voltage to load resistance RL and it should adopts DC power.

Description of Sensor Characters

• The ordinate is resistance ratio of the sensor (Rs/R0), the abscissa is concentration of gases. Rs means resistance in target gas with different concentration, R0 means resistance of sensor in clean air. All tests are finished under standard test conditions.
• The ordinate is resistance ratio of the sensor (Rs/Rso).Rs means resistance of sensor in 125ppm alcohol(C2H5OH) under different tem. and humidity. Rso means resistance of the sensor in 125 alcohol(C2H5OJ) under 20℃/55%RH.
• Fig5 shows the VRL in alcohol with different concentration. The resistance load RL is 4.7 KΩ and the test is finished in standard test conditions.
• Fig5 shows the changing of VRL in the process of putting the sensor into target gas and removing it out.
• Test is finished in standard test conditions, the abscissa is observing time and the ordinate is VRL.

Cautions
Following conditions must be prohibited

Exposed to organic silicon steam
Sensing material will lose sensitivity and never recover if the sensor absorbs organic silicon steam. Sensors must be avoid exposing to silicon bond, fixature, silicon latex, putty or plastic contain silicon environment.

High Corrosive gas
If the sensors are exposed to high concentration corrosive gas (such as H2S, SOX, Cl2, HCl etc.), it will not only result in corrosion of sensors structure, also it cause sincere sensitivity attenuation.

Alkali, Alkali metals salt, halogen pollution
The sensors performance will be changed badly if sensors be sprayed polluted by alkali metals salt especially brine, or be exposed to halogen such as fluorine.

Touch water
Sensitivity of the sensors will be reduced when spattered or dipped in water.

Freezing
Do avoid icing on sensor’s surface, otherwise sensing material will be broken and lost sensitivity.

Applied higher voltage
Applied voltage on sensor should not be higher than stipulated value, even if the sensor is not physically damaged or broken, it causes down-line or heater damaged, and bring on sensors’ sensitivity characteristic changed badly.

Voltage on wrong pins
For 6 pins sensor, Pin 2&5 is heating electrodes, Pin (1,3)/(4,6) are testing electrodes (Pin 1 connects with Pin 3, while Pin 4 connects with Pin 6).If apply voltage on Pin 1&3 or 4&6, it will make lead broken; and no signal putout if apply on pins 2&4.

Following conditions must be avoided

Water Condensation
Indoor conditions, slight water condensation will influence sensors’ performance lightly. However, if water condensation on sensors surface and keep a certain period, sensors’ sensitive will be decreased.

Used in high gas concentration
No matter the sensor is electrified or not, if it is placed in high gas concentration for long time, sensors characteristic will be affected. If lighter gas sprays the sensor, it will cause extremely damage.

Long time storage
The sensors resistance will drift reversibly if it’s stored for long time without electrify, this drift is related with storage conditions. Sensors should be stored in airproof bag without volatile silicon compound. For the sensors with long time storage but no electrify, they need to be long galvanized aging time for stability before using. The suggested aging time as follow

Long time exposed to adverse environment
No matter the sensors electrified or not, if exposed to adverse environment for long time, such as high humidity, high temperature, or high pollution etc., it will influence the sensors’ performance badly.

Vibration
Continual vibration will result in sensors down-lead response then break. In transportation or assembling line, pneumatic screwdriver/ultrasonic welding machine can lead this vibration.

Concussion
If sensors meet strong concussion, it may lead its lead wire disconnected.

Usage Conditions
For sensor, handmade welding is optimal way. The welding conditions as follow:

• Soldering flux: Rosin soldering flux contains least chlorine
• homothermal soldering iron
• Temperature： 250℃
• Time：less than 3 seconds

If users choose wave-soldering, the following conditions should be obey:

• Soldering flux: Rosin soldering flux contains least chlorine
• Speed: 1-2 Meter/ Minute
• Warm-up temperature：100±20℃
• Welding temperature：250±10℃
• One time pass wave crest welding machine
  If disobey the above using terms, sensors sensitivity will be reduced.

Zhengzhou Winsen Electronics Technology Co., Ltd
Add : No.299, Jinsuo Road, National Hi-Tech Zone, Zhengzhou 450001 China
Tel : +86-371-67169097/67169670
Fax : +86-371-60932988
E-mail: sales@winsensor.com
Website : www.winsen-sensor.com
Tel: 86-371-67169097/67169670 Fax: 86-371-60932988 Email: sales@winsensor.com
Leading gas sensing solutions supplier in China!

References

• Winsen Gas Sensor_CO2 Sensor_Air Quality Sensor_Dust Sensor_CO Sensor-Winsen Electronics

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