Data Sheet

HANWEI ELETRONICS CO.,LTD MQ-3 http://www.hwsensor.com
TEL: [phone] 67169080 FAX: [phone] E-mail: [e-mail]
Structure and configuration of MQ-3 gas sensor is shown as Fig. 1 (Configuration A or B), sensor composed by
micro AL2O3 ceramic 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-3 have 6 pin ,4 of them are used to fetch signals, and other 2 are used
for providing heating current.
Electric parameter measurement circuit is shown as Fig.2
E. Sensitivity characteristic curve
Fig.2 sensitivity characteristics of the MQ-3
SENSITVITY ADJUSTMENT
Resistance value of MQ-3 is difference to various kinds and various concentration gases. So,When using
this components, sensitivity adjustment is very necessary. we recommend that you calibrate the detector for
0.4mg/L ( approximately 200ppm ) of Alcohol concentration in air and use value of Load resistancethat( R
L
) about
200 KΩ(100KΩ to 470 KΩ).
When accurately measuring, the proper alarm point for the gas detector should be determined after
considering the temperature and humidity influence.
Rs/Ro--Temp
0.50
0.60
0.70
0.80
0.90
1.00
1.10
1.20
1.30
1.40
1.50
1.60
1.70
-10 0 10 20 30 40 50 60
Temp
Rs/Ro
33%RH
85%RH
Fig.3 is shows the typical
sensitivity characteristics of
the MQ-3 for several gases.
in their: Temp: 20℃、
Humidity: 65%、
O
2
concentration 21%
RL=200kΩ
Ro: sensor resistance at 0.4mg/L of
Alcohol in the clean air.
Rs:sensor resistance at various
concentrations of gases.
Fig.4 is shows the typical
dependence of the MQ-3 on
temperature and humidity.
Ro: sensor resistance at 0.4mg/L of
Alcohol in air at 33%RH and 20 ℃
Rs: sensor resistance at 0.4mg/L of
Alcohol at different temperatures
and humidities.
Fig.4
MQ-3
0.1
1
10
100
0.1 1 10
mg/L
Rs/Ro
Alcohol
Benzine
CH4
Hexane
LPG
CO
Air