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LP GAS SENSORS

SCM133

Characteristics

Stability for long work periods

Long Life

Application

Gas leakage detecting equipment for home and industrial applications.

Use in the detection equipment of Methane, Propane, Isobutane and LP Gas.

Parts list

The figure 1 shows the sensor and its components.

The SCM133 has 6 pins, 4 are used to detection signals and the other 2 are used for the heater circuit.

Shows the electric measurement circuit. 

General Specifications.

Work parameters

Environmental operating and storage condition

Symbol	Description	Operating Value	Remarks
Tao	Operation temperature	-20 °C to +50 °C	Recommended ranges
Tas	Storage Temperature	-20 °C to +70 °C
RH	Relative humidity	Less than 95% Rh
O2	Oxygen concentration	21% (at standard conditions)	minimum value is above 2%

Sensibility characteristics

Symbol	Description	Operating Value	Remarks
Rs	Sensor resistance	2 KΩ - 20 KΩ (2000 ppm Isobutano)	Detection ranges: 300 – 10000 ppm of Isobutane or LP Gas
α (5000/1000) Isobutano	Concentration slope rate	≤ 0.6
Standard conditions	Temp. 20 °C ± 2 °C, Vc. 5V ± 0.1 Humedad 65% ± 5% Vh. 5V ± 0.1
Preheating time	Greater than 24 Hours

Handling characteristics

Variable	Condition	Comments
Vibration	Frecuency: 100 cpm dof vertical vibration amplitude	Should be conformed to given sensibility
Shock	100 G up to 5 times

 

Sensibility characteristic curves for the SCM133

	Relationship between VRL and the gas concentration. The curves were characterized at the following conditions: Temperature, 20 °C, Humidity, 65%, Oxygen concentration, 21%, RL= 5 KOhms.
	Relationship Relationship between surface resistance at different environment humidity. R0 is the surface resistance at 20 °C and 0% of relative humidity in 2000 ppm of LP Gas. Rs is the sensing element resistance at different temperature.

 

Sensitivity adjustment

The resistance value of the SCM133 changes with different gases and their concentrations. So, when using the sensor, it is necessary a sensitivity adjustment.

We suggest using 300-1000ppm of Isobutane or LP Gas as standard concentration to run the adjustment procedure.

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.

 

Application circuit

The application circuit shown below has a temperature compensation function.

 

 

 

MiniSuperPLC Starter Kit 8 inputs, 4 outputs, HMI Interface, cable & software $98

 

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