SEN-10916

Zhengzhou Winsen Electronics Technology Co., Ltd www.winsensor.com
Tel: 86-371-67169097/67169670 Fax: 86-371-60932988 Email: sales@winsensor.com
Basic Circuit
Fig2. MQ-8 Test Circuit
Instructions: The above fig is the basic test circuit of MQ-8.The sensor requires two voltage inputs: heater
voltage (V
H
) and circuit voltage (V
C
). V
H
is used to supply standard working temperature to the sensor and
it can adopt DC or AC power, while V
RL
is the voltage of load resistance R
L
which is in series with sensor. Vc
supplies the detect voltage to load resistance R
L
and it should adopts DC power.
Description of Sensor Characters
Fig3.Typical Sensitivity Curve
The ordinate is resistance ratio of the sensor (Rs/R
0
), the abscissa
is concentration of gases. Rs means resistance in ta rget gas with
different concentration, R
0
means resistance of sensor in clean air.
All tests are finished under standard test conditions.
Fig4.Typical temperature/humidity characteristics
The ordinate is resistance ra tio of the sensor (Rs /Rso).Rs
means resistance of sensor i n 1000ppm H
2
gas under different
tem. a nd humidity. Rso means resistance of the sensor in
1000ppm H
2
ga s under 20/55%RH.
H
2
Air
Alcohol
CO
CH
4
Zhengzhou Winsen Electronics Technology Co., Ltd www.winsensor.com
Tel: 86-371-67169097/67169670 Fax: 86-371-60932988 Email: sales@winsensor.com
Cautions
1 .Following conditions must be prohibited
1.1 Exposed to organic silicon steam
Sensing material will lose sensitivity and never recover if the sensor absorbs organic silicon steam.
Sensors must avoid exposing to silicon bond, fixature, silicon latex, putty or plastic contain silicon
environment.
1.2 High Corrosive gas
If the sensors are exposed to high concentration corrosive gas (such as H
2
S, SO
X
, Cl
2
, HCl etc.), it will
not only result in corrosion of sensors structure, also it cause sincere sensitivity attenuation.
1.3 Alkali, Alkali metals salt, halogen pollution
Fig7.long-term Stability
Tes t is finished in standard test conditions, the a bscissa is observing time and the ordinate is V
RL
.
Fig5.Sensitity Curve
Fig5 shows the V
RL
in hydrogen with different concentration.
The resistance load R
L
is 4.7 and the test is finished in
sta ndard test conditions.
Fig6.Responce and Resume
Fig5 shows the changing of V
RL
in the process of putting
the sensor i nto target gas and removing i t out.
400ppm H
2
(RL=4.7k)
Zhengzhou Winsen Electronics Technology Co., Ltd www.winsensor.com
Tel: 86-371-67169097/67169670 Fax: 86-371-60932988 Email: sales@winsensor.com
The sensors performance will be changed badly if sensors be sprayed polluted by alkali metals salt
especially brine, or be exposed to halogen such as fluorine.
1.4 Touch water
Sensitivity of the sensors will be reduced when spattered or dipped in water.
1.5 Freezing
Do avoid icing on sensors surface, otherwise sensing material will be broken and lost sensitivity.
1.6 Applied higher voltage
Applied voltage on sensor should not be higher than stipulated value, even if the sensor is not
physically damaged or broken, it causes down-line or heater damaged, and bring on sensors
sensitivity characteristic changed badly.
1.7 Voltage on wrong pins
For 6 pins sensor, Pin 2&5 is heating electrodes, Pin (1,3)/(4,6) are testing
electrodes (Pin 1 connects with Pin 3, while Pin 4 connects with Pin 6).If
apply voltage on Pin 1&3 or 4&6, it will make lead broken; and no signal
putout if apply on pins 2&4.
Fig8. Lead sketch
2 .Following conditions must be avoided
2.1 Water Condensation
Indoor conditions, slight water condensation will influence sensors performance lightly. However, if
water condensation on sensors surface and keep a certain period, sensors sensitive will be decreased.
2.2 Used in high gas concentration
No matter the sensor is electrified or not, if it is placed in high gas concentration for long time, sensors
characteristic will be affected. If lighter gas sprays the sensor, it will cause extremely damage.
2.3 Long time storage
The sensors resistance will drift reversibly if it’s stored for long time without electrify, this drift is
related with storage conditions. Sensors should be stored in airproof bag without volatile silicon
compound. For the sensors with long time storage but no electrify, they need long galvanical aging
time for stability before using. The suggested aging time as follow:
Stable2.
Storage Time
Suggested aging time
Less than one month
No less than 48 hours
1 ~ 6 months
No less than 72 hours
More than six months
No less than 168 hours
2.4 Long time exposed to adverse environment
No matter the sensors electrified or not, if exposed to adverse environment for long time, such as high
humidity, high temperature, or high pollution etc., it will influence the sensors performance badly.
2.5 Vibration
Continual vibration will result in sensors down-lead response then break. In transportation or
assembling line, pneumatic screwdriver/ultrasonic welding machine can lead this vibration.
2.6 Concussion
If sensors meet strong concussion, it may lead its lead wire disconnected.
2.7 Usage Conditions

SEN-10916

Mfr. #:
Manufacturer:
SparkFun
Description:
Air Quality Sensors Hydrogen Gas Sensor - MQ-8
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
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