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- Infrared_open-path_detector abstract "Infrared open-path gas detectors send out a beam of infrared light, detecting gas anywhere along the path of the beam. This linear 'sensor' is typically a few metres up to a few hundred metres in length. Open-path detectors can be contrasted with Infrared point sensors.They are widely used in the petroleum and petrochemical industries, mostly to achieve very rapid gas leak detection for flammable gases at concentrations comparable to the lower flammable limit (typically a few percent by volume). They are also used, but so far to a lesser extent, in other industries where flammable concentrations can occur, such as in coal mining and water treatment. In principle the technique can also be used to detect toxic gases, for instance hydrogen sulfide, at the necessary parts-per-million concentrations, but the technical difficulties involved have so far prevented widespread adoption for toxic gases.Usually, there are separate transmitter and receiver units at either end of a straight beam path. Alternatively, the source and receiver are combined, and the beam bounced off a retroreflector at the far end of the measurement path. For portable use, detectors have also been made which use the natural albedo of surrounding objects in place of the retroreflector. The presence of a chosen gas (or class of gases) is detected from its absorption of a suitable infrared wavelength in the beam. Rain, fog etc. in the measurement path can also reduce the strength of the received signal, so it is usual to make a simultaneous measurement at one or more reference wavelengths. The quantity of gas intercepted by the beam is then inferred from the ratio of the signal losses at the measurement and reference wavelengths. The calculation is typically carried out by a microprocessor which also carries out various checks to validate the measurement and prevent false alarms.The measured quantity is the sum of all the gas along the path of the beam, sometimes termed the path-integral concentration of the gas. Thus the measurement has a natural bias (desirable in many applications) towards the total size of an unintentional gas release, rather than the concentration of the gas that has reached any particular point. Whereas the natural units of measurement for an Infrared point sensor are parts-per-million (ppm) or the percentage of the lower flammable limit (%LFL), the natural units of measurement for an open path detector are ppm.metres (ppmm) or LFL.metres (LFLm). For instance, the fire and gas safety system on an offshore platform in the North Sea typically has detectors set to a full-scale reading of 5LFLm, with low and high alarms triggered at 1LFLm and 3LFLm respectively.".
- Infrared_open-path_detector wikiPageExternalLink fgdetect.htm.
- Infrared_open-path_detector wikiPageID "28500068".
- Infrared_open-path_detector wikiPageRevisionID "560617862".
- Infrared_open-path_detector hasPhotoCollection Infrared_open-path_detector.
- Infrared_open-path_detector subject Category:Chemical_engineering.
- Infrared_open-path_detector subject Category:Detectors.
- Infrared_open-path_detector subject Category:Fire_prevention.
- Infrared_open-path_detector subject Category:Gas_sensors.
- Infrared_open-path_detector subject Category:Offshore_engineering.
- Infrared_open-path_detector subject Category:Oil_platforms.
- Infrared_open-path_detector subject Category:Oil_refineries.
- Infrared_open-path_detector subject Category:Optics.
- Infrared_open-path_detector subject Category:Optoelectronics.
- Infrared_open-path_detector subject Category:Petroleum_production.
- Infrared_open-path_detector subject Category:Petroleum_technology.
- Infrared_open-path_detector subject Category:Safety_equipment.
- Infrared_open-path_detector type Artifact100021939.
- Infrared_open-path_detector type Detector103180969.
- Infrared_open-path_detector type Detectors.
- Infrared_open-path_detector type Device103183080.
- Infrared_open-path_detector type GasSensors.
- Infrared_open-path_detector type HorizontalSurface103536348.
- Infrared_open-path_detector type Instrumentality103575240.
- Infrared_open-path_detector type Object100002684.
- Infrared_open-path_detector type OilPlatforms.
- Infrared_open-path_detector type PhysicalEntity100001930.
- Infrared_open-path_detector type Platform103961939.
- Infrared_open-path_detector type Surface104362025.
- Infrared_open-path_detector type Whole100003553.
- Infrared_open-path_detector comment "Infrared open-path gas detectors send out a beam of infrared light, detecting gas anywhere along the path of the beam. This linear 'sensor' is typically a few metres up to a few hundred metres in length.".
- Infrared_open-path_detector label "Infrared open-path detector".
- Infrared_open-path_detector sameAs m.0crhmxq.
- Infrared_open-path_detector sameAs Q17056402.
- Infrared_open-path_detector sameAs Q17056402.
- Infrared_open-path_detector sameAs Infrared_open-path_detector.
- Infrared_open-path_detector wasDerivedFrom Infrared_open-path_detector?oldid=560617862.
- Infrared_open-path_detector isPrimaryTopicOf Infrared_open-path_detector.