SEEED GRV GAS SENS MQ3 Datasheet

HANWEI ELETRONICS CO.,LTD MQ-3 http://www.hwsensor.com

7

TECHNICAL DATA

MQ-3 GAS SENSOR

FEATURES

* High sensitivity to alcohol and small sensitivity to Benzine .

* Fast response and High sensitivity
* Stable and long life
* Simple drive circuit

APPLICATION

They are suitable for alcohol checker, Breathalyser.

SPECIFICATIONS

A. Standard work condition

Symbol Parameter name Technical condition Remarks
Vc Circuit voltage 5V±0.1 AC OR DC
V

H

R

L

R

H

P

H

B. Environment condition

Symbol Parameter name Technical condition Remarks
Tao Using Tem

Tas Storage Tem
R

H

O

2

C. Sensitivity characteristic

Symbol Parameter name Technical parameter Remarks
Rs Sensing Resistance

α

(0.4/1 mg/L)
Standard

detecting
condition
Preheat time Over 24 hour

D. Structure and configuration, basic measuring circuit

Heating voltage 5V±0.1 ACOR DC
Load resistance
Heater resistance
Heating consumption less than 750mw

Related humidity less than 95%Rh
Oxygen concentration 21%(standard condition)Oxygen

Concentration slope rate
Temp: 20℃±2℃ Vc:5V±0.1

Humidity: 65%±5% Vh: 5V±0.1

200KΩ
33Ω±5%

-10℃-50℃

-20℃-70℃

concentration can affect sensitivity

1MΩ- 8 MΩ
(0.4mg/L alcohol )

≤0.6

Room Tem

minimum value is
over 2%

Detecting concentration
scope：

0.05mg/L—10mg/L
Alcohol

Parts Materials
1 Gas sensing

layer
2 Electrode Au
3 Electrode line Pt
4 Heater coil Ni-Cr alloy
5 Tubular ceramic Al2O
6 Anti-explosion

network

Clamp ring Copper plating Ni
8 Resin base Bakelite
9 Tube Pin Copper plating Ni

Configuration A

SnO

2

3

Stainless steel gauze
(SUS316 100-mesh)

A向

Fig.2

Fig. 1

Configuration B

A向

TEL: [phone] 67169080 FAX: [phone] E-mail: [e-mail]

HANWEI ELETRONICS CO.,LTD MQ-3 http://www.hwsensor.com

Fig.3 is shows the typical

Fig.4 is shows the typical

Structure and configuration of MQ-3 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-3 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

10

MQ-3

Alcohol
Benzine
CH4
Hexane
LPG
CO
Air

Rs/Ro

1

0.1

0.1 1 10

Fig.2 sensitivity characteristics of the MQ-3

mg/L

sensitivity characteristics of
the MQ-3 for several gases.

in their: Temp: 20℃、
Humidity: 65%、
O2 concentration 21%
RL=200kΩ
Ro: sensor resistance at 0.4mg/L of

Alcohol in the clean air.
Rs:sensor resistance at various
concentrations of gases.

1.70

1.60

1.50

1.40

1.30

1.20

1.10

Rs/Ro

1.00

0.90

0.80

0.70

0.60

0.50

-10 0 10 20 30 40 50 60

Rs/Ro--Temp

Fig.4

33%RH
85%RH

Temp

dependence of the MQ-3 on
temperature and humidity.

Ro: sensor resistance at 0.4mg/L of
Alcohol in air at 33%RH and 20 ℃
Rs: sensor resistance at 0.4mg/L of
Alcohol at different temperatures
and humidities.

SENSITVITY ADJUSTMENT

Resistance value of MQ-3 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

0.4mg/L ( approximately 200ppm ) of Alcohol concentration in air and use value of Load resistancethat( R

200 KΩ(100KΩ to 470 KΩ).

) about

L

When accurately measuring, the proper alarm point for the gas detector should be determined after

considering the temperature and humidity influence.

TEL: [phone] 67169080 FAX: [phone] E-mail: [e-mail]