Asphyxiant Gases

The fact that the main direct cause of death in fires has always been the toxicity of combustion products was already discussed in the National Fire Protection Association (NFPA) Quarterly in 1933 [34]. Smoke contains mainly two types of toxic gases asphyxiants and irritants, but the individual toxic gas associated with the largest fire hazard is carbon monoxide (CO). 

Release of hazardous gases (asphyxiant, toxic) from off-site and on-site storage ... 

This course covers hazardous materials including pesticides, corrosives, irritant gases, asphyxiants, hydrocarbons and halogenated hydrocarbons and chemical, biological, radiological and nuclear agents. Specific antidotes and their indications, contraindications, dosing and route are also included. 

IACUC approved protocols. These are recommended by the American Veterinary Medical Association and the protocols are regularly reviewed and revised (http //www.avma.org/issues/ animal welfare/euthanasia.pdf). Currently, a commonly used and IACUC approved euthanasia method is carbon dioxide gas asphyxiation. 

SAFETY PROFILE Mutation data reported. An asphyxiant. See also ARGON for description of inert gas asphyxiants. When heated to decomposition it emits very toxic fumes of Br", CP, and F". 

Nontoxic gas asphyxiant an exposure to 20-30% concentration for 4 h may be lethal to mice... 

Sulfur hexafluoride (CAS 2551-62-4) Considered to be essentially a nontoxic gas. Asphyxiation by the displacement of air is suggested as the greatest hazard. 1000 ppm Odorless, colorless dense gas. May be contaminated with other fluorides of sulfur, including the highly toxic sullur pentafluoride, which release HF or oxy-iluorides on contact with moisture. 

Propylene is a colorless gas under normal conditions, has anesthetic properties at high concentrations, and can cause asphyxiation. It does not irritate the eyes and its odor is characteristic of olefins. Propjiene is a flammable gas under normal atmospheric conditions. Vapor-cloud formation from Hquid or vapor leaks is the main ha2ard that can lead to explosion. The autoignition temperature is 731 K in air and 696 K in oxygen (80). Evaporation of Hquid propylene can cause skin bums. Propylene also reacts vigorously with oxidising materials. Under unusual conditions, eg, 96.8 MPa (995 atm) and 600 K, it explodes. It reacts violentiy with NO2, N2O4, and N2O (81). Explosions have been reported when Hquid propylene contacts water at 315—348 K (82). Table 8 shows the ratio TJTp where is the initial water temperature, and T is the superheat limit temperature of the hydrocarbon. 

When using inert gas, provide protection against personnel asphyxiation hazards... 

For filter boxes, provide remote and automatic filter box lid closing on trip of appropriate fire detection device. Fire detection device may also be interlocked to stop solvent feed, trip deluge internal to filter box and/or trip inert gas blanket for filter box (caution, be aware inert gas is a potential asphyxiation hazard)... 

Skin proteetion may neeessitate use of full proteetive suits. When eatalysts are dumped from reaetors at the end of a proeess they may prove to be extremely dusty as a result of reduetion in partiele size during the reaetion proeess. Again, depending upon the nature of the hazard, ventilation, personal proteetion, and use of temporary enelosures to prevent contamination of the general work area should be considered. Some catalysts are pyrophoric and some catalyst beds are inerted with the added possibility of fire, or release of inerting gas into the workplace which may cause asphyxiation. 

Carbon dioxide gas ean aet as an asphyxiant due to displaeement of air, resulting in oxygen defieieney (page 262). Sourees inelude ... 

Aeetylene is a simple asphyxiant and anaestlietie. Pure aeetylene is a eolourless, highly flammable gas with an ethereal odour. Material of eommereial purity has an odour of garlie due to the presenee of impurities sueh as phosphine. Its physieal properties are shown in Table 9.4. Aeetylene, whieh eondenses to a white solid subliming at -83°C, is soluble in its own volume of water but highly soluble in aeetone. 

Propane has a eharaeteristie natural gas odour and is basieally insoluble in water. It is a simple asphyxiant but at high eoneentrations has an anaesthetie effeet. The TLV is 2500 ppm. It is usually shipped in low-pressure eylinders as liquefied gas under its own vapour pressure of ea 109 psig at 21°C. Its pressure/temperature profile is given in Figure 9.7. 

Asphysia Asphysia is a lack of oxygen, which interferes with the oxygenation of the blood. This condition is the result of asphyxiation, which can result from a number of factors, such as (1) suffocation/strangulation or (2) inhalation of an asphyxiant, such as 100% nitrogen gas. 

Health Hazards Information - Recommended Persoruil Protective Equipment Self-contained breathing apparatus for high vapor concentrations Symptoms Following Exposure In high vapor concentrations, can act as simple asphyxiant. Liquid causes severe frostbite General Treatment for Exposure Remove from Exposure, support respiration Toxicity by Inhalation (Threshold Umit Value) Not pertinent Short-Term Exposure Limits Not pertinent Toxicity by Ingestion Not pertinent Late Toxicity None Vapor (Gas) Irritant Characteristics Vapors are nonirritating to the eyes and throat Uquid or Solid Irritant Characteristics Not pertinent appreciable hazard. Practically harmless to the skin because is very volatile and evaporates quickly Odor Threshold 899 ppm. 

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