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Catalytic detectors:

Principle:

It is based on the oxidation of gases or vapour to be detected. A self regulated power source is provided on an assembly in Wheatstone bridge.A branch of the bridge is consisted the detector including / understanding two catalytic beads. The other branch contains a divider with resistance. The two catalytic beads "active" and of "reference" are rigorously identical. When a gas mixture to combustible / air diffused in the detector through the flame arrestor, a catalytic oxidation of this mixture occurs only on the active bead, the exothermic reaction which follows, modifies the resistance of this bead and involves an imbalance of tension on the bridge, proportional to the concentration of the mixture of gas, within the limits of measurement of the instrument. the signal then is amplified and converted.

Advantages:

• Direct measurements from 0 to 120% LIE.

• Simple to install

• Non specific and so well adapted out of standard to all flammable gases and vapours.

• Good resistance to the vibrations.

• Good behaviour with the occasional exposures >100% LIE.

• Resistance to the radio frequencies.

• Adapted well to all the current climatic constraints.

• Good corrosion resistance.

Principle:

The infrared detectors are in fact of the analyzers dedicated to an application, explosiveness. The principle of operation of an infrared analyzer is based on specific absorption by a gas of a radiation wavelength included / understood between 2,5 and 12 microns and passing through a volume of gas.
The measurement method of absorption to simple beam and double wavelength is used. The first is selected for its absorption by required gases and vapours. It is the wavelength of measurement. The wavelength of reference is selected to eliminate any interference which could occur following climatic variations such as moisture, snow, the fog, the vapour, the temperature. The comparison of the signals two wavelengths makes it possible to determine the concentration of required gases and vapours.

Advantages:

• Intrinsic control of correct operation.

• Possibility of measurement from 0 to 100% volume of gas.

• Simplified maintenance.

• Good corrosion resistance.

The specific detector integrates a technology into microprocessor and measurement the gases and explosive vapours from 0 to 100 % of their limit of explosiveness (LIE).
 

Principle:

The infrared barrier is schematically as an electric eye which sees passing from gas in its beam, and measures its concentration as a multitude of specific detectors, placed would do it on line. The unit consists of a transmitter and of a distant receiver of a few tens of meters the measuring unit is expressed partly per million (ppm) meter or / and in lower limit of explosiveness measures.

Advantages:

• Early detection (ppm.m).

• Intrinsic control of correct operation.

• Usable on been windy sites and to hostile environments.

• Cost of installation and wiring reduced.

• Simplified maintenance.

• Usable in the presence of corrosive agents and inhibiting.

• Adapted perfectly to the release of alarm for a slightly concentrated gas cloud.

 Principle:

The gas escaping from the break point generates ultrasounds. These ultrasounds result from the passage of gas at the speed of sound, of an environment high pressure with an environment of less pressure. The sensor used to detect the ultrasounds associated with the gas escapes is a microphone of measurement. The signal coming from the sensor is directed towards a filter, this one is especially built alisser to pass towards the circuit of time of alarm only the noise included / understood in the ultrasonic frequential spectrum. With this single technology of listening of the ultrasounds, the detector does not need more to be in contact with the escape, it hears the sound of the gas which escapes. The ultrasonic detector of gas leakage does not provide a level of concentration BINDS or ppm like the traditional detectors, but it sets off an instantaneous alarm in the event of escape.

Advantages:

• Early detection of gas.

• Insensitivity leakage to the changes of direction of the wind.

• Insensitivity to dispersion of gas between escape and sensor.

• No calibrating nor necessary maintenance.

• Detection of all the gases.

• Very short response time.

• Not saturated by highly concentrated gases.