Flammable gas in lighters

A flammable hydrocarbon gas that is lighter than air is processed at a small facility. An office building is located 75 ft (15 m) from the processing equipment. Because of the size of the facility, no pipe racks or other significantly sized equipment are in the area that can create confinement or congestion if a release occurs. Further, the flammable gas is processed at low pressures and ambient temperatures. 

Synonym marsh gas Formula CH4 MW 16.04 CAS [74-82-8] prime constituent of natural gas formed from petroleum cracking, decay of animal and plant remains, and anaerobic fermentation of municipality landfill contents occurs in marshy pools, landfill gas, and leachate from the landfill colorless and odorless gas lighter than air gas density 0.717 g/L liquefies at-161.4°C soluble in organic solvents, slightly soluble in water (25 mg/L) flammable gas. 

The geometry of the piping layout trapped the lighter-than-air flammable gas. The coupling was 42 inches in diameter and there was a concentric reducer to 36 inches. This was... 

Aliphatic hydrocarbon compounds are found in lighter fluid and fuel gas, as well as in paint sprays, hair sprays, and air fresheners. These compounds are highly flammable and explosive. They include compounds like acetylene, butane, hexane, isobutene, and propane. Butane is often used as the propellant in aerosol sprays. 

Alpha particles, He , are released by nuclear decay of naturally occurring uranium and thorium ores. They are high-energy nuclei of helium-4, which capture two electrons apiece to become helium atoms. The low density and lack of flammability of helium make it an appropriate gas for lighter-than-air airships such as blimps. Helium is found in the atmosphere with a concentration of 5.24 ppm (parts per million by volume). 

Description and general properties. Carbon monoxide [630-08-0], with the chemical formula CO and the relative molar mass of 28.0104 is a colorless, odorless gas shghtly lighter than air (SG = 0.967) that melts at -205°C (68 K) and boils at -192°C (81 K). It is very slightly soluble in water (2.603 cmVdm at 25°C and 101.325 kPa) but it is more soluble in organic solvents such as ethanol, methanol, ethyl acetate, methyl chloride, and acetic acid. Carbon monoxide is a flammable gas that burns in air with a characteristic bright-blue flame, producing carbon dioxide. 

Vapor density The vapor density of gas is the density of the gas in comparison to air = 1. So vapor density can he defined as the weight ratio of a volume of flammable vapor compared to an equal volume of air. [Vapor density <1 (air) will rise, and vapor density >1 will fall.] This is important in the placement of detectors. Major flammable vapors are heavier than air. CH4 (0.55), CO (0.6), andNH3 (0.6) are lighter than air, whereas petroleum vapor (3.0), H2S (1.45), and propane (2.48) are heavier than air. 

Acetylene is a compound of carbon and hydrogen in proportions by weight of about 12 parts carbon to 1 part hydrogen (92.3 percent to 7.7 percent). A colorless, flammable gas, it is slightly lighter than air. Acetylene of 100 percent purity is odorless, but acetylene of ordinary commercial purity generated from calcium carbide has a distinctive, garliclike odor. 

Vapor Density (VD) — the mass per unit volume of a given vapor/gas relative to that of air. Thus, acetaldehyde with a vapor density of 1.5 is heavier than air and will accumulate in low spots, while acetylene with a vapor density of 0.9 is lighter than air and will rise and disperse. Heavy vapors present a particular hazard because of the way they accumulate if toxic they may poison workers if nontoxic they may displace air and cause suffocation by oxygen deficiency if flammable, once presented with an ignition source, they represent a fire or explosion hazard. Gases heavier than air include carbon dioxide, chlorine, hydrogen sulfide, and sulfur dioxide. 

Hydrogen cyanide (Table 15.1) is a colorless, flammable liquid or gas that boils at 25.7°C and freezes at minus 13.2°C. The gas rarely occurs in nature, is lighter than air, and diffuses rapidly. It is usually prepared commercially from ammonia and methane at elevated temperatures with a platinum catalyst. It is miscible with water and alcohol, but is only slightly soluble in ether. In water, HCN is a weak acid with the ratio of HCN to CN about 100 at pH 7.2, 10 at pH 8.2, and 1 at pH 9.2. HCN can dissociate into H+ and CN. Cyanide ion, or free cyanide ion, refers to the anion CN derived from hydrocyanic acid in solution, in equilibrium with simple or complexed cyanide molecules. Cyanide ions resemble halide ions in several ways and are sometimes referred to as pseudohalide ions. For example, silver cyanide is almost insoluble in water, as are silver halides. Cyanide ions also form stable complexes with many metals. 

Methane leaks from a tank in a 50 m3 sealed room. Its concentration is found to be 30 % by volume, as recorded by a combustible gas detector. The watchman runs to open the door of the room. The lighter mixture of the room gases flows out to the door at a steady rate of 50 g/s. The flammable limits are 5 and 15 % by volume for the methane in air. Assume a constant temperature at 25 °C and well-mixed conditions in the room. The mixture of the room gases can be approximated at a constant molecular weight and density of 25 g/mol and 1.05 kg/m3 respectively. After the door is opened, when will the mixture in the room become flammable ... 

Methane, also referred to as marsh gas, is a gas composed of carbon and hydrogen with a chemical formula of CH4. It is the first member of the paraffin or alkane series of hydrocarbons. It is lighter than air, colorless, odorless, tasteless and is flammable. It occurs in natural gas and as a by-product of petroleum refining. In atmospheric burning no smoke production normally occurs. In air methane bums with a pale, faintly luminous flame. With excess air carbon dioxide and water vapor is formed during combustion, with an air deficiency carbon monoxide and water is formed. It forms an explosive mixture with air over a moderate range. Its primary uses are as a fuel and raw feedstock for petrochemical products. 

NFPA 497A—Recommended Practice for Classification of Class I Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas contains recommendations for wiring requirements in an enclosed area where lighter-than-air flammable gases may be released [5.12]. While these recommendations are for chemical processing areas, the releases are similar in the hazard they present to what would be found for natural gas released in repair garages. These recommendations are also illustrated in Figure 5-1. 

The code s recommended distance requirements (15 ft and 18 in.) are based on the diffusion properties of lighter than air flammable gases (similar to natural gas) and the properties of conventional fuel vapors, and may need to be modified based on vehicle and building specifics. 

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