Infrared point sensor: Difference between revisions

Revision as of 16:33, 22 January 2008

Revision as of 20:33, 22 January 2008

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==Principle==

Dual source and [[Passive infrared sensor|dual receivers]] are used for self compensation of changes in [[alignment]], light source intensity and component efficiency. The transmitted beams from two [[infrared]] sources are superimposed onto an internal [[beam splitter]]. 50% of the overlapping sample and reference signal is passed through the gas measuring path and reflected back onto the measuring detector. The presence of combustible [[gas]] will reduce the intensity of the sample beam and not the [[reference beam]], with the difference between these two signals being proportional to the concentration of gas present in the measuring path. The other 50% of the overlapped signal passes through the beam splitter and onto the [[compensation detector]]. The compensation detector monitors the intensity of the two infrared sources and automatically compensates for any long term drift.

[[Mean time between failures]] may go up to 15 years.