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GAS SENSORS
 

SCM129

Characteristics

Long period stability

Widely detecting scope

Application

GAS leakage detecting equipment

Isobutene , propane, alcohol, hydrogen detection.

Work conditions

Symbol

Description

Technical condition

Comment

VC

Power voltage

5 V

CC or AC

VH

Heater voltage

5 V

CC or AC

PL

Load resistance

adjust

Ps

RH

Heater resistance

33Ω ± 5%

at 25 °C

PH

Heater consumption

less than 800 Mw.

 

Ambient conditions

Symbol

Description

Condition

Comment

Tao

Operation temperature

 20 °C to 50 °C

 

Tas

Storage

20 °C to 70 °C

 

RH

Relative humidity

less than 95% Rh

 

O2

Oxygen concentration

21% ( at standard condition) The oxygen concentration may affect sensibility

The minimum value is over 2%

Sensibility conditions

Symbol

Description

Parameter

Comment

Comment

Rs

Sensor resistance

1 KΩ - 10 KΩ

(1000 ppm isobutene)

suitable for 3000 ppm of LPG and propane

Detection range:

300 – 5000 ppm liquid petroleum gas , propane and isobutene

 

5000 – 20000 ppm of methane

α

(3000/1000)

Isobutene

 

Concentration slope rate

≤ 0.6

Standard detecting conditions

Temp. 20 °C ± 2 °C, Vc. 5V ± 0.1

Humidity 65% ± 5% Vh. 5V ± 0.1

Pre heat time

More than 24 hours

Characteristics

Variable

Conditions

Vibration

May support up to 100 cps for 1 hour

Punch

Aceleration 100G - 5 times

 

Tipical curves of the SCM129 sensor

Temperature 20 °C, Humidity 65%,  Oxigen concentration 21%, RL= %KΩ

Fig 1: relation VRL and gas concentration.     Fig 2: relation superficial humidity and relative humidity.

Components.

Part

Description

Material

1

Gas sensing layer

SnO2

2

Measurement electrode

Au

3

Measurement electrode 

Pt

4

Heating line electrode

Ni-Cr Alloy

5

Heater 

Al2O3

6

Ceramic tube 

100 stainless steel double layer (SUS316)

7

Explosion proof net 

Plating Ni

8

Base

Bakelite

9

Pin

Plating Ni

 

Electric parameters of the measurement circuit

 

Figure 4.-The mentioned are block diagram of standard test of SCM129.

As environment temperature and humidity have certain effect to sensitivity.

So, must consider environment factor when accurately measuring.

Figure 5.-Shows the reference circuit (temperature compensation included)

 

Sensitivity adjustment.

Resistance value changing of SCM129 will be cause by different pieces and gas concentration. So, when using the component, sensitivity adjustment is necessary.

We suggest that use 300-3000ppm LPG gas, or 300ppm-1000ppm <i-C4H10> as sensitivity adjustment gas concentration.

Adjustment steps:

1. Input gas to application circuits.

2. After storage please pre-heating sensor over 24 hours in order to guarantee sensor can reach stability completely.

3. In the detecting gas concentration, adjust load resistance RL until suitable output signal coming out.

 

 
     

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SCM International, Inc.

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SCM International, Inc.
2648 E. Workman Ave. suite 527
West Covina, CA 91791 
USA

Fax: +1 (530)3256895

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POBOX 9793
Reno, NV . 89507
USA

SCMStore.com, license and Conditions of use

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(c) 2008, SCM International, Inc. All right reserved.

 

 

 

 

 

 

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