MQ-3 Semiconductor Sensor for Alcohol
Sensitive material of MQ-3 gas nsor is SnO 2, which with lower conductivity in clean air. When the target alcohol gas exist, The nsor’s conductivity is more higher along with the gas concentration rising. Plea u simple electrocircuit, Convert change of conductivity to correspond output signal of gas concentration.
MQ-3 gas nsor has high nsitity to Alcohol, and has good resistance to disturb of gasoline, smoke and vapor. The nsor could be ud to detect alcohol with different concentration, it is with low cost and suitable for different application.
Character Configuration
* Good nsitivity to alcohol gas * Long life and low cost * Simple drive circuit
Application
* Vehicel alcohol detector * Portable alcohol detectorsortable
Technical Data Basic test loop
The above is basic test circuit of the nsor.
The nsor need to be put 2 voltage, heater voltage （VH ） and test voltage （VC ）. VH ud to supply certified working temperature to the nsor, while VC ud
to detect voltage (VRL) on load resistance （RL ）whom is in ries with nsor. The nsor has light polarity, Vc need DC power. VC and VH could u same power circuit with precondition to assure performance of nsor. In order to make the nsor with better performance, suitable RL value is needed: Power of Sensitivity body(Ps):
Ps=Vc 2×Rs/(Rs+RL)2
Model No. MQ-3 Sensor Type Semiconductor Standard Encapsulation
腐蚀英文Bakelite (Black Bakelite)
Detection Gas
qxp
Alcohol gas
Concentration 0.04-4mg/l alcohol Loop Voltage
V c
2014世界杯赛程表≤24V DC Heater Voltage V H
5.0V±0.2V AC or DC
Circuit
Load Resistance R L Adjustable
Heater Resistance R H 31Ω±3Ω（Room Tem.）
Heater consumption
P H
≤900mW
Sensing Resistance
R s 2K Ω-20K Ω(in 0.4mg/l alcohol )
Sensitivity S Rs(in air)/Rs(0.4mg/L
Alcohol)≥5
Character
Slope
α
≤0.6(R 300ppm /R 100ppm Alcohol)Tem. Humidity
20℃±2℃；65%±5%RH
Standard test circuit
Vc:5.0V±0.1V ； V H : 5.0V±0.1V
Condition
Preheat time
Over 48 hours
Vc
V H GND
R L
V RL
Resistance of nsor(Rs): Rs=(Vc/VRL-1)×RL
Sensitivity Characteristics Influence of Temperature/Humidity
Fig.1 shows the typical nsitivity characteristics of Fig.2 shows the typical temperature and humidity the MQ-3, ordinate means resistance ratio of the nsor characteristics. Ordinate means resistance ratio (Rs/Ro), abscissa is concentration of gas. Rs means of the nsor (Rs/Ro), Rs means resistance of nsor resistance in different gas, Ro means resistance of in 0.4mg/l alcohol under different tem. and humidity. nsor in 0. 4mg/l alcohol. All test are under standard Ro means resistance of the nsor in environment of test conditions. 0.4mg/l alcohol, 20℃/65%RH
重庆外语培训P.S.: Sensitivity to smoke is ignite 10pcs cigarettes in 8m3
room, and the output equals to 0.1mg/l alcohol行尸走肉漫画结局
Structure and configuration
Structure and configuration of MQ-3 gas nsor is shown as Fig. 3, nsor compod by micro AL2O3 ceramic tube, Tin Dioxide (SnO2) nsitive 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 nsitive components. The enveloped MQ-4 have 6 pin, 4 of them are ud to fetch signals, and other 2 are ud for providing heating current.
Notification
1 Following conditions must be prohibited 1.1 Expod to organic silicon steam
Organic silicon steam cau nsors invalid, nsors must be avoid exposing to silicon bond, fixature, silicon latex, putty or plastic contain silicon environment 1.2 High Corrosive gas
If the nsors expod to high concentration corrosive gas (such as H 2Sz, SO X ，Cl 2，HCl etc), it will not only result in corrosion of nsors structure, also it cau sincere nsitivity attenuation. 1.3 Alkali, Alkali metals salt, halogen pollution
The nsors performance will be changed badly if nsors be sprayed polluted by alkali metals salt especially brine, or be expod to halogen such as fluorin.
1.4 Touch water Sensitivity of the nsors will be reduced when spattered or dipped in water. 1.5 Freezing
Do avoid icing on nsor’surface, otherwi nsor would lo nsitivity. 1.6 Applied voltage higher
Applied voltage on nsor should not be higher than stipulated value, otherwi it cau down-line or heater damaged, and bring on nsors’ nsitivity characteristic changed badly.
1.7 Voltage on wrong pins For 6 pins nsor, if apply voltage on 1、3 pins or 4、6 pins, it will make lead broken, and without signal when apply on 2、4 pins
2 Following conditions must be avoided 2.1 Water Condensation
Indoor conditions, slight water condensation will effect nsors performance lightly. However, if water condensation on nsors surface and keep a certain period, nsor’ nsitivity will be decread.
2.2 Ud in high gas concentrationa开头的单词
No matter the nsor is electrified or not, if long time placed in high gas concentration, if will affect nsors characteristic.
2.3 Long time storage
The nsors resistance produce reversible drift if it’s stored for long time without electrify, this drift is related with storage conditions. Sensors should be stored in airproof without silicon gel bag with clea
n air. For the nsors with long time storage but no electrify, they need long aging time for stbility before using.
2.4 Long time expod to adver environment
No matter the nsors electrified or not, if expod to adver environment for long time, such as high humidity, high temperature, or high pollution etc, it will effect the nsors performance badly.
2.5 Vibration
Continual vibration will result in nsors down-lead respon then repture. In transportation or asmbling line, pneumatic screwdriver/ultrasonic welding machine can lead this vibration.
2.6 Concussion
If nsors meet strong concussion, it may lead its lead wire disconnected.
2.7 Usage
cpmpFor nsor, handmade welding is optimal way. If u wave crest welding should meet the following conditions:
关于新年的英语作文2.7.1 Soldering flux: Rosin soldering flux contains least chlorine 2.7.2 Speed: 1-2 Meter/ Minute 2.7.3 Warm-up temperature ：100±20℃ 2.7.4 Welding temperature ：250±10℃
2.7.5 1 time pass wave crest welding machineadmirable
If disobey the above using terms, nsors nsitivity will be reduced.
