Leaks phosgene

Leaking phosgene gas can be destroyed by spraying the contaminated zone with large volumes of water. Although the reaction is slow, the excess of water helps to suppress dispersion [1318]. Water should not be sprayed directly onto phosgene cylinders, however, since this may increase the size of the leak as a result of the formation of corrosive HCI [1318,1486]. 

Spill/Leak Disposal Isolate the incident scene dress in proper personal protective equipment (see above) do not allow contact with any materials, liquid or gas stop and/or control leak or hazard if possible to do so and control water - use water spray to control vapor and any vapor cloud. Contain product and keep phosgene from entering sewers, streams, or water intakes. Dike surface flow, and depending on the temperature, try to neutralize the product for disposal using agricultural lime (slaked lime), crushed limestone, or soda ash, or sodium bicarbonate. 

Phosgene is a highly toxic gas. All safety precautions must he followed during its preparation and handling. It is stored and shipped in leak-free steel cylinders in the complete absence of any water (or moisture). 

Notes. (I) Keten is a poisonous gas having a toxicity comparable with phosgene leaks from the apparatus, which must be contained in a fume cupboard, are recognised by a pungent odour resembling acetic anhydride. For this reason it is customary to attach a second receiver flask containing a compound which readily reacts with keten, e.g. aniline, to the other arm of the three-way stopcock. In this way when the reaction in the main flask is complete the keten gas may be diverted to the second receiver flask while the apparatus is switched off and allowed to cool. Escape to the atmosphere of keten is thereby avoided. 

A major phosgene leak occurred in a chemical plant at 14.00 on December 9, 1977. Fifteen employees were exposed to the gas, but only four were detained in hospital. All those released by the hospital were symptom free and thought to have had minimal exposure to phosgene. One of these workers, a forty-seven year old male, felt well initially and went home. He was later admitted to hospital at 01.00 on... 

The prophylactic use of hmt (also known as utroprine or metheneimine) is unlikely to be commonly applied in an industrial situation, even where phosgene exposure might be anticipated, as modern gas masks, etc., afford good protection. The use of hmt may be considered where large numbers of people may be affected by a major gas leak, or in a war situation where gas bombardment is a real possibility [1432a]. 

Emissions of phosgene most commonly arise as a result of its release during manufacture and use, its formation from the decomposition of chlorinated hydrocarbons, and its formation from the photochemical oxidation of air-borne chlorinated organic materials, particularly the C, and C chloroalkanes, and chloroethenes. The location and estimation of air emissions from sources of phosgene have been described by the US Environmental Protection Agency [2088b], Catastrophic emissions and accidental spills and leaks are discussed in Section 3.6. 

Leakage rates for gaseous and liquid emissions of phosgene have been estimated for holes of different sizes [ICI60]. The gas leak from a i" (6 mm) hole at 20 C is calculated... 

Bulk phosgene is kept in underground storage tanks of double shell construction in some facilities [1488]. This provides containment in the event of a leak from the inner wall, and protection from mechanical damage to the outer wall. If the outer shell also develops a leak then the surrounding earth would prevent a large scale release of gas [1488]. 

The level of phosgene in the room exceeded the safe level by a factor of more than 100. Even if the phosgene were below the safe level, there would be an unsafe level near the floor since phosgene is denser than air, and the concentration would be much higher in the vicinity of the leak. 

In case of the accidental release of phosgene gas, such as liom a leaking cylinder or associated apparatus, evacuate the area and eliminate the source of the leak if this can be done safely. Remove cylinder to a fume hood or remote area if it cannot be shut off. In the event of a spill of a phosgene solution, soak up the solution with a spiU pillow or absorbent material, place in an appropriate container, and dispose of properly. Full respiratory protection and protective clothing wiU be necessary in the event of a spill or release in a confined area. 

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