Spectrex SafEye Xenon 700S, Руководство пользователя

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Principles of Operation
TM 799200 Rev. (4), April 2017 19
2.3.2 Spectral Finger Print
Each hazardous material is detected at a specific wavelength selected
according to its specific spectral absorption or “finger print.” There are 3 IR
sensors: 2 signals and 1 reference. The detection process involves 2
separate filters, one transmitting radiation that is absorbed by a particular
gas, and one that is not sensitive to it.
2.3.3 Optical Path
The presence of hazardous airborne vapors, gases, or aerosols in a
monitored area is detected when the defined substance crosses/enters the
optical path between the radiation source unit and the detector.
Hazardous gases/vapors present in the atmosphere cause absorption of the
radiation pulse at specific wavelengths in the optical path between the
radiating source and the detector unit. This causes a change in the signal
intensity received by the detector, which is translated into an output related
to the detector’s measuring scale.
The system analyzes the defined open path at the spectral bands specific to
the materials being monitored. The Automatic Gain Control (AGC) unit
compensates for environmental disturbances such as fog and rain, through a
constant comparison with its dual spectral beam.
2.3.4 Microprocessor Based
The incoming signals are analyzed by the built-in microprocessor.
A sophisticated mathematical algorithm calculates between the various
functions of the detected signal thresholds. Statistics, ratio algorithms, data
communications, diagnostics, and other functions are performed.
2.3.5 Gas Sensitivity
The SafEye Xenon 700 Model uses wavelengths around the 3.4µ spectral
band to measure air flammability potential between the source and detector.
At this wavelength, all hydrocarbon materials have a strong absorption
peak. This peak enables the detector to achieve both regular sensitivity of
0–5 LEL.m and high sensitivity of 0–2 LEL.m, according to the function
setup. However, since the desired detection information is air flammability
and the actual measurement is radiation absorption around the 3.4μ
spectral band, the detector has different sensitivities to different gases or
gas combinations.
This difference in sensitivity is irrelevant if, in the protected area, the gas
composition is known. However, if in a protected area, the gas composition
can vary substantially, then the difference in sensitivity should be
considered in determining the detector calibration.