Data Sheet

HANWEI ELECTRONICS CO ., LTD MQ –7 http://www.hwsensor.com
TEL:[phone] 67169080 FAX:[phone] Email: [e-mail]
TECHNICAL DATA MQ-7 GAS SENSOR
FEATURES
* High sensitivity to carbon monoxide
* Stable and long life
APPLICATION
They are used in gas detecting equipment for carbon monoxide(CO) in family and
industry or car.
SPECIFICATIONS
A. Standard work condition
Symbol Parameter name Technical condition Remark
Vc circuit voltage
5V±0.1
Ac or Dc
VH (H) Heating voltage (high)
5V±0.1
Ac or Dc
VH (L) Heating voltage (low)
1.4V±0.1
Ac or Dc
RL Load resistance Can adjust
RH Heating resistance
33Ω±5%
Room temperature
TH (H) Heating time (high)
60±1 seconds
TH (L) Heating time (low)
90±1 seconds
PH Heating consumption About 350mW
b. Environment conditions
Symbol Parameters Technical conditions Remark
Tao Using temperature
-20℃-50℃
Tas Storage temperature
-20℃-50℃
Advice using scope
RH Relative humidity Less than 95%RH
O2 Oxygen concentration 21%(stand condition)
the oxygen concentration can
affect the sensitivity
characteristic
Minimum value is over 2%
c. Sensitivity characteristic
symbol Parameters Technical parameters Remark
Rs Surface resistance
Of sensitive body 2-20k
In 100ppm
Carbon Monoxide
а(300/100ppm)
Concentration slope rate Less than 0.5 Rs (300ppm)/Rs(100ppm)
Temperature -20℃±2℃ relative humidity 65%±5% RL:10KΩ±5%
Standard working
condition
Vc:5V±0.1V VH:5V±0.1V VH:1.4V±0.1V
Preheat time No less than 48 hours Detecting range:
20ppm-2000ppm carbon monoxide
D. Structure and configuration, basic measuring circuit
Structure and configuration of MQ-7 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-7 have