Data Sheet

HANWEI ELECTRONICS MQ-4 www.hwsensor.com
TEL:[phone] FAX: [phone] E-mail: [e-mail]
Structure and configuration of MQ-4 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-4 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-4
SENSITVITY ADJUSTMENT
Resistance value of MQ-4 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
5000ppm of CH
4
concentration in air and use value of Load resistance ( R
L
) 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.
Fig.3 is shows the typical
sensitivity characteristics of
the MQ-4 for several gases.
in their: Temp: 20℃、
Humidity: 65%、
O
2
concentration 21%
RL=20kΩ
Ro: sensor resistance at 1000ppm of
CH
4
in the clean air.
Rs:sensor resistance at various
concentrations of gases.
Fig.4 is shows the typical depe
ndence of
the MQ-4 on temperature and humidity.
Ro: sensor resistance at 1000ppm of CH
4
in air
at 33%RH and 20 degree.
Rs: sensor resistance at 1000ppm of CH
4
in air
at different temperatures and humidities.
Fig.4
MQ-4
0.1
1
10
100 1000 10000
ppm
Rs/Ro
LPG
CH4
H2
CO
alcohol
smoke
Air
MQ-4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
-10 0 10 20 30 40 50
Temp
Rs/Ro
33%RH
85%RH