Detectors for gases

Dankner Y, Jacobson E, Goldenberg E, et al. 1995. Optical based UV-IR gas detector for monitoring hydrocarbons and toxic gases. Proceedings of SPIE-The International Society for Optical Engineering 2426 144-147. 

Miles, J.C.H. and J. Dew, A Passive Radon Gas Detector for use in Homes, in Proceedings 11th International Conference on Solid State Nuclear Track Detectors (P.H. Fowler and V.M. Clapham, eds.) pp 569-579, Pergamon Press (1982). 

Since detectors are by definition exposed to combustible gases they should be rated for electrically classified areas, such as Class I, Division I or 2, the specific gas groups (normally groups C and D), and temperature ratings. It should be noted the UL presently does not specifically test combustible gas detector sensor heads for use in classified areas, although they do tests enclosures for control and data acquisition circuits. Several other international standards do evaluate combustible gas detectors for use in classified areas (e.g., BS 6020). 

Gas detectors for toxic and inflammable gases (please also refer to chapter on Instrumentation) shall be installed near reactors, process vessels, flanged joints in pipes, and chemical storages. 

Regular testing and maintenance of aU pressure vessels and pipelines, fuel storages and gas pipes, electrical overhead travelling (EOT) cranes, hoists and chain pulley blocks, fire fighting equipments, provision of gas detectors for inflammable, and toxic gases are to be carried out as per instructions issued by statutory authorities and inspection personnel deputed by insurance companies. 

Air pollution control (APC) alkali absorber Induced draught fans for areas of chlorine handling area, near electrolytic cells This is required for the absorption of free chlorine/HCl and for removal of any CI2 leak HCl gas will be released in the atmosphere working area becomes suffocating and dangerous if CI2 is not removed Keep gas detectors for CI2, HCl 200 % spares for absorber and ID fans... 

Escape of CI2 or HCl from tail gas scrubber Can be dangerous Provide alkali scrubbers, exit gas analysers, and gas detectors in working areas Provide installed spare circulation pumps for scmbber install gas detectors for CI2 and HCl and alarms... 

Confirmation that safety equipment for personal use, eyewash fountains, first-aid boxes, breathing apparatus, gas detectors for dangerous gases (toxic, inflammable), and gas masks are in working order. 

Gas Titration with Soiid Eiectroiytes, Fig. 7 Utilization of a noncontrolled SE pumping cell as a multi-gas detector for gas chromatography... 

Quantity for fire detectors and flammable and toxic gas detectors for the facility... 

There are currently no standards for use of gas detectors for fuel storage installations and no fuel storage installations within the UK where gas detectors are installed. Gas detectors are available but the dispersion of gasoline vapour is complicated and hence effective detection by gas detectors is subject to many uncertainties. Open path detection devices are available and could provide boundary detection at bund walls or around tanks. Liquid hydrocarbon detectors, however, may offer effective detection because it is easier to predict where escaping liquid will collect and travel. There are a number of installations where liquid hydrocarbon detectors are installed. Typical locations would be in a bund drain, gutter or sump where sensors can detect oil on water using conductivity measurement. The detection system may be subject to failures or spurious trips... 

Combustible gas detectors for the air intakes should be considered with the enclosures that are in close proximity to processes containing combustible... 

MSA s ALTAIR 5X multi-gas detector for detection of up to six gases simultaneously is now available in Canada... 

Schematic diagram of a thermai conductivity detector for gas chromatography.

In addition, the appHcation of the mass spectrometer (ms) as a detector for gas—Hquid chromatography has made the positive identification of peaks possible. High performance Hquid chromatography (hplc), which involves various detectors, can be used to measure hydrophilic and hydrophobic organic compounds in water. 

Infrared (in) spectrometers are gaining popularity as detectors for gas chromatographic systems, particularly because the Fourier transform iafrared (ftir) spectrometer allows spectra of the eluting stream to be gathered quickly. Gc/k data are valuable alone and as an adjunct to gc/ms experiments. Gc/k is a definitive tool for identification of isomers (see Infrared and raman spectroscopy). 

Gas Chromatography. Gas chromatography is a well recognised method for the analysis of H—D—T mixtures. The substrate is alumina, AI2O2, coated with ferric oxide, Fe202. Neon is used as the carrier gas. Detectors are usually both thermal conductivity (caratherometer) and ion chamber detectors when tritium is involved (see Chromatography). 

We put a lot of effort into improving safety by adding protective equipment onto our plants, new and old gas detectors, emergency isolation valves, interlocks, steam curtains, fire insulation, catchment pits for LPG storage tanks, and so on. We also introduced new procedures, such as hazard and operability studies and modification control, or persuaded people to follow old ones, such as permits-to-work and audits. 

Required locations of gas detectors (sensors) are often specified by the authority having jurisdiction. For example, API RP 14C recommends certain locations for combustible detectors. These recommendations have been legislated into requirements in U.S. Federal waters by the Minerals Management Service. RP 14C should be referred to for specific details, but, basically, combustible gas detectors are required offshore in all inadequately ventilated, classified, enclosed areas. The installation of sensors in nonenclosed areas is seldom either required or necessary. Ignitible or high toxic levels of gas seldom accumulate and remain for significant periods of time in such locations. 

Most combustible gas detector sensors are installed in the upper portions of buildings for the detection of natural gas. However, in many cases the vapor which flashes off oil in storage tanks can be heavier than air. Below grade areas should be considered for sensor installations where heavier-than-air vapors might collect. 

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