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This output change is linear, for most gases, up to and beyond 100% LEL, response time is a few seconds to detect alarm levels (around 20% LEL), [1] at least 12% oxygen by volume is needed for the oxidation.
Oldham EX2000 portable explosimeter. An explosimeter is a gas detector which is used to measure the amount of combustible gases present in a sample. When a percentage of the lower explosive limit (LEL) of an atmosphere is exceeded, an alarm signal on the instrument is activated.
The E-T secondary electron detector can be used in the SEM's back-scattered electron mode by either turning off the Faraday cage or by applying a negative voltage to the Faraday cage. However, better back-scattered electron images come from dedicated BSE detectors rather than from using the E–T detector as a BSE detector.
An open path detector usually costs more than a single point detector, so there is little incentive for applications that play to a point detector's strengths: where the point detector can be placed at the known location of the highest gas concentration, and a relatively slow response is acceptable. The open path detector excels in outdoor ...
In a photoionization detector, high-energy photons, typically in the vacuum ultraviolet (VUV) range, break molecules into positively charged ions. [2] As compounds enter the detector they are bombarded by high-energy UV photons and are ionized when they absorb the UV light, resulting in ejection of electrons and the formation of positively charged ions.
Flame ionization detectors cannot detect inorganic substances and some highly oxygenated or functionalized species like infrared and laser technology can. In some systems, CO and CO 2 can be detected in the FID using a methanizer, which is a bed of Ni catalyst that reduces CO and CO 2 to methane, which can be in turn detected by the FID.
Dusts also have upper and lower explosion limits, though the upper limits are hard to measure and of little practical importance. Lower flammability limits for many organic materials are in the range of 10–50 g/m 3, which is much higher than the limits set for health reasons, as is the case for the LEL of many gases and vapours. Dust clouds ...
"Lel", a form of "lol", meaning "laughing even louder" Topics referred to by the same term This disambiguation page lists articles associated with the title LEL .