Compur Ex plus Gas Detector Manual de usuario descargar pdf (Pagina 7)

Triple Plus+ and Triple Plus+ IR General description

(b) No damage caused by exposure to high gas concentrations

(d) Ability to measure at % volume levels as well as %LEL

(e) Fail safe

It must be remembered however that an infrared hydrocarbon sensor will have

no response to hydrogen and is therefore unsuitable for use where hydrogen

forms a significant part of any potential flammable risk. In order to ensure ready

identification of Triple Plus+ IR the membrane switch assembly is yellow in place

of the normal orange and carries the name designation ‘Triple Plus+ IR’.

The infrared sensor module in Triple Plus+ IR will be supplied with a calibration

for one of four hydrocarbon species i.e. methane, propane, butane or ethylene.

This calibration is factory set. Whatever the calibrated species the infrared sen-

sor will respond to any hydrocarbon present, but with differences of response

to different species. However unlike for a pellistor sensor it is not possible to

assign simple correction factors, as the basic relationship between concen-

tration and response of the detector is not linear. An infrared sensor should

therefore always be calibrated for the species to be determined or a suitable

target. If other specific hydrocarbon species need to be detected, please consult

Crowcon as to the optimum calibration.

The infrared sensor in Triple Plus+ IR can be supplied on one of two configura-

tions as follows:

• Single range %LEL

In this case the Triple Plus+ IR can have up to three other sensors from the

standard range of toxic and oxygen sensor modules available.

•

Dual range %LEL and % volume

In this case the sensor module has a second ribbon connector on a side-piece

of PCB, and therefore takes up two display positions on Triple Plus+ IR. This

allows only two other sensor modules from the toxic and oxygen range to be

used. A dual range sensor will always have both ranges calibrated for the same

species, and operates in an auto-ranging mode displaying in %LEL terms with

no numerical display for % volume until the level of gas exceeds 100%LEL,

and in volume terms with no numerical value for %LEL when the level of gas

is above 100%LEL. Note also the lower range will always display as %LEL even

if the gas is detected in an inert background gas where strictly speaking the

mixture cannot be explosive. The display indicates the equivalent %LEL level if

the gas were in an air background.

Note: It is not possible to have a pellistor or thermal conductivity sensor in a

Triple Plus+ IR.

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Compur Ex plus Gas Detector Manual de usuario Pagina 7