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

V_C

Power voltage

5 V

CC or AC

V_H

Heater voltage

5 V

CC or AC

P_L

Load resistance

adjust

R_H

Heater resistance

33Ω ± 5%

at 25 °C

P_H

Heater consumption

less than 800 Mw.

Ambient conditions

Symbol

Description

Condition

Comment

T_ao

Operation temperature

20 °C to 50 °C

T_as

Storage

20 °C to 70 °C

R_H

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

R_s

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

(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%, R_L= %KΩ

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

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.

MiniSuperPLC

Starter Kit

8 inputs, 4 outputs, HMI Interface, cable & software

$98

SCM129

Characteristics

Long period stability

Widely detecting scope

Application

GAS leakage detecting equipment

Isobutene , propane, alcohol, hydrogen detection.

Work conditions

Ambient conditions

Sensibility conditions

Components.