HANWEI ELECTRONICS
MQ-4
www.hwsensor.com
TECHNICAL
DATA
MQ-4
GAS SENSOR
FEATURES
* High sensitivity to CH
4
，Natural
gas.
* Small sensitivity to alcohol, smoke.
* Fast response .
* Stable and long life
* Simple drive circuit
APPLICATION
They are used in gas leakage detecting equipments in family and industry, are suitable for detecting of
CH
4
,Natural gas.LNG, avoid the noise of alcohol and cooking fumes and cigarette smoke.
SPECIFICATIONS
A. Standard work condition
Symbol
Vc
V
H
P
L
R
H
P
H
Symbol
Tao
Tas
R
H
O
2
Parameter name
Circuit voltage
Heating voltage
Load resistance
Heater resistance
Heating consumption
Parameter name
Using Tem
Storage Tem
Related humidity
Oxygen concentration
Technical condition
5V±0.1
5V±0.1
20KΩ
33Ω±5%
less than 750mw
Technical condition
-10℃-50℃
-20℃-70℃
less than 95%Rh
21%(standard condition)Oxygen
concentration can affect sensitivity
Technical parameter
10KΩ- 60KΩ
(1000ppm CH
4
)
≤0.6
Vc:5V±0.1
Vh: 5V±0.1
Remarks
AC OR DC
ACOR DC
Room Tem
B. Environment condition
Remarks
minimum value is
over 2%
Ramark 2
Detecting concentration
scope：
200-10000ppm
CH
4
,
natural gas
C. Sensitivity characteristic
Symbol
Rs
Parameter name
Sensing Resistance
α
(1000ppm/
5000ppm CH
4
)
Standard
detecting
condition
Preheat time
Concentration slope rate
Temp: 20℃±2℃
Humidity: 65%±5%
Over 24 hour
D. Strucyure and configuration, basic measuring circuit
1
2
3
4
5
6
7
8
9
Parts
Gas sensing
layer
Electrode
Electrode line
Heater coil
Tubular ceramic
Anti-explosion
network
Clamp ring
Resin base
Tube Pin
Materials
SnO
2
Au
Pt
Ni-Cr alloy
Al
2
O
3
Stainless steel gauze
(SUS316 100-mesh)
Copper plating Ni
Bakelite
Copper plating Ni
Fig.2
Fig. 1
Configuration
A
Configuration
B
A向
TEL:86-371-67169080
FAX: 86-371-67169090
A向
E-mail: sales@hwsensor.com
HANWEI ELECTRONICS
MQ-4
www.hwsensor.com
Structure and configuration of MQ-4 gas sensor is shown as Fig. 1 (Configuration A or B), sensor composed by
micro AL
2
O
3
ceramic tube, Tin Dioxide (SnO
2
) 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
MQ-4
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.
10
Rs/Ro
1
LPG
CH4
H2
CO
alcohol
smoke
Air
ppm
1000
10000
0.1
100
Fig.2
sensitivity characteristics of the MQ-4
1.4
1.3
1.2
1.1
1
0.9
0.8
0.7
0.6
0.5
-10
0
10
MQ-4
33%RH
85%RH
Fig.4 is shows the typical dependence 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.
Rs/Ro
Fig.4
20
Temp
30
40
50
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.
TEL:86-371-67169080
FAX: 86-371-67169090
E-mail: sales@hwsensor.com
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