Canisters, vapor trapping

Analytes are introduced into GC colmtms with several techniques. An ahquot of a relatively concentrated vapor or air sample— for example, from a plastic bag or a canister—can be introduced into a short section of tubing of known volume, called a sample loop, and subsequently pinged with carrier gas into the GC colurmt Volatile analytes in ambient air samples in a canister or trapped on a solid phase adsorbent are usually concentrated and focused in a cryogenic trap or a secondary adsorbent trap, then thermally vaporized into the GC carrier gas stream. However, in some analytical methods, volatiles trapped on an absorbent are thermally desorbed directly into the GC colunm. Aliquots of organic solvent extracts from various aqueous and solid samples are usually injected with a syringe into the carrier gas stream in a heated injection port. Both manual and antomated syringe injection systems (autoinjectors) are used and the latter are generally very reliable, precise, and have the capacity to process many samples unattended. 

Evaporative emissions from the fuel tank and carburetor have been controlled on all 1971 and later model automobiles sold in the United States. This has been accomplished by either a vapor recovery system which uses the crankcase of the engine for the storage of the hydrocarbon vapors or an adsorption and regeneration system using a canister of activated carbon to trap the vapors and hold them until such time as a fresh air purge through the canister carries the vapors to the induction system for burning in the combustion chamber. 

The first bombs developed by the US Navy, CBU-55, were used in Vietnam, and tests to perfect an advanced version of the weapons system have continued. The CBU-55B air-to-surface free-fall cluster bombs were developed for helicopter.and siow-speed fixed-wing aircraft delivery to clear helicopter landing zones of mines booby traps. This FAE bomb was designed to disperse a mixt of vaporized fuel (ethylene oxide, propylene oxide, m e thy lacetylene/propa diene/pro pane and others) in a cloud 50 ft in dram and approx 8 ft thick. It has three 100-lb individual canisters 13.6 inches in diam by 21 inches long, each containing ca 72 lbs of fuel. The canisters separate from the dispenser after... 

Fuel vapor canisters represent a relatively new automotive use of molded impact-modified nylon 6,6, and it is experiencing rapid growth (Fig. 9.5). It s an excellent choice for the application, given its inherent toughness and resistance to the combined effects of temperature and gasoline vapor. The Clean Air Act of 1990 mandated that aU cars, beginning with the 1998 model year, must make provisions to trap hydrocarbon fumes emitted from the fuel tank and related to the refuehng process. 

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