HANWEI ELETRONICS CO.,LTD
MQ-8
http://www.hwsensor.com
TECHNICAL DATA
MQ-8
GAS SENSOR
FEATURES
* High sensitivity to Hydrogen (H
2
)
* Small sensitivity to alcohol, LPG,cooking fumes
* Stable and long life
APPLICATION
They are used in gas leakage detecting equipments in family and industry, are suitable for
detecting of Hydrogen (H
2
), avoid the noise of alcohol and cooking fumes, LPG,CO.
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
Technical condition
5V±0.1
5V±0.1
10KΩ
31±5%
less than800mW
Technical condition
-10℃-50℃
-20℃-70℃
less than 95%Rh
21%(standard condition)Oxygen
concentration can affect sensitivity
Technical parameter
10KΩ- 60KΩ
(1000ppm H
2
)
≤0.6
Vc:5V±0.1
Vh: 5V±0.1
Remarks
AC OR DC
ACOR DC
Room Tem
B. Environment
condition
Remarks
Parameter name
Using Tem
Storage Tem
Related humidity
Oxygen concentration
minimum value is
over 2%
Ramark 2
Detecting concentration
scope：
100-10000ppm
C. Sensitivity characteristic
Symbol
Rs
Parameter name
Sensing Resistance
α
(1000ppm/
500ppmH
2
)
Standard
detecting
condition
Preheat time
Hydrogen (H
2
)
Concentration slope
rate
Temp: 20℃±2℃
Humidity: 65%±5%
Over 24 hour
D. Structure 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- 67169070
67169080
FAX: 86-371-67169090
A向
E-mail:
sales@hwsensor.com
HANWEI ELETRONICS CO.,LTD
MQ-8
http://www.hwsensor.com
Structure and configuration of MQ-8 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-8 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
100
MQ-8
Fig.3 is shows the typical
sensitivity characteristics of
the MQ-8 for several gases.
10
1
H2
LPG
CH4
in their: Temp: 20℃、
Humidity: 65%、
O
2
concentration 21%
RL=10kΩ
Ro: sensor resistance at 1000ppm
H
2
in the clean air.
Rs:sensor resistance at various
concentrations of gases.
Rs/Ro
0.1
CO
alcohol
air
ppm
100
1000
10000
0.01
Fig.2
sensitivity characteristics of the MQ-8
1.3
1.2
1.1
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-10
0
10
MQ-8
Fig.4 is shows the typical dependence of
the MQ-8 on temperature and humidity.
Rs/Ro
33%RH
85%RH
Fig.4
20
30
40
50
Ro: sensor resistance at 1000ppm of H
2
in air at
33%RH and 20 degree.
Rs: sensor resistance at 1000ppm of H
2
in air
at different temperatures and humidities.
Temp
SENSITVITY ADJUSTMENT
Resistance value of MQ-8 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
1000ppm H
2
concentration in air and use value of Load resistance ( R
L
) about 10 KΩ(5KΩ to 33 KΩ).
When accurately measuring, the proper alarm point for the gas detector should be determined after
considering the temperature and humidity influence.
TEL: 86-371- 67169070
67169080
FAX: 86-371-67169090
E-mail:
sales@hwsensor.com
Power technology
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