Toxic vapors

Flammability Acrolein is very flammable its flash point is <0° C, but a toxic vapor cloud will develop before a flammable one. The flammable limits in air are 2.8% and 31.0% lower and upper explosive limits, respectively by volume. Acrolein is only partly soluble in water and will cause a floating fire, so alcohol type foam should be used in firefighting. The vapors are heavier than air and can travel along the ground and flash back from an ignition source. 

Enclosed agitated filters are useful when volatile solvents are in use or when the solvent gives off toxic vapor or fume. Another significant advantage is that their operation does not require any manual labor. Control can be manual or automatic, usually by timers or by specific measurements of the product. Most filters are made of mild steel, with the exposed surfaces protected by lead, tile, mbber lining, or by coating or spraying with other substances as necessary. Filtration areas up to 10 m are available and the maximum cake thickness is 1 m. Apphcations are mainly in the chemical industry for the recovery of solvents. 

Some compounds, such as mbidium chromate and mbidium iodide, emit toxic vapors when heated. Other compounds, such as mbidium perchlorate, are irritants. 

In the laboratory, excess reagent in a product should be destroyed before workup. Addition of diluted aqueous ammonia is the most effective practice, if ammonia is otherwise acceptable. Combustibility is a minor problem. The open-cup flash point of 116°C for dimethyl sulfate is well above normal handling temperatures. Elammable, toxic vapors are given off at elevated temperatures. 

Some vent streams, such as light hydrocarbons, can be discharged directly to the atmosphere even though they are flammable and explosive. This can be done because the high-velocity discharge entrains sufficient air to lower the hydrocarbon concentration below the lower explosive limit (API RP 521, 1997). Toxic vapors must be sent to a flare or scrubber to render them harmless. Multiphase streams, such as those discharged as a result of a runaway reaction, for example, must first be routed to separation or containment equipment before final discharge to a flare or scrubber. 

Loss of sealing fluid for vessel agitator seal. Possible seal failure and emission of flammable or toxic vapors. 

Install flammable and/or toxic vapor sensors where needed... 

Operator exposure to toxic vapors during opening and cleaning. 

Health Hazards Information - Recommended Personal Protective Equipment Goggles or face shield protective gloves dust mask Symptoms Following Exposure Contact with yes causes mild eye irritation and can cause skin rashes General Treatment for Exposure EYES flush with water Toxicity by Inhalation ( Threshold Limit Value) Data not available Short-Term Exposure Limits Data not available Toxicity by Ingestion Grade 0 LDjq >21.5 g/kg (rat) Late Toxicity Vapor (Gas) Irritant Characteristics Data not available Liquid or Solid Irritant Characteristics Data not available Odor Threshold Data not available. 

Fire Hazards - Flash Point (deg. F) 175 - 185 OC 178 CC Flammable Umits in Air (%) LEL 1.4 (ortho) 1.1 (meta or para) Fire Extinguishing Agents Water, dry chemical, carbon dioxide, and foam Fire Extinguishing Agents Not To Be Used Not pertinent Special Hazards of Combustion Products Flammable toxic vapors given off in a fire Behavior in Fire Sealed closed containers can build up pressure if exposed to heat (fire) Ignition Temperature (deg. f) 1110 (o-cresol) 1038 (m-or p-cresol) Electrical Hazard Data not available Burning Rate Data not available,... 

PR valves in toxic vapor services where discharge to the atmosphere would result in the calculated concentration at the property line or at any working area (either at grade or an elevated platform) exceeding the Threshold Limit Value (TLV). 

Secure the scene get medical attention to tlie injured. Move bystanders aw ay to a safe distance. Inform print and electronic media. Protect people and property as necessary. Be aware tliat explosive materials and toxic vapors can do damage at a great distance... 

Bums and Hazzan demonstrated tlie use of event tree and fault tree analysis in tlie study of a potential accident sequence leading to a toxic vapor release at an industrial chemical process plant. The initiator of tlie accident sequence studied is event P, the failure of a plant programmable automatic controller. Tliis event, in conjunction willi the success or failure of a process water system (a glycol cooling system) mid an operator-manual shutdown of tlie distillation system produced minor, moderate, or major release of toxic material as indicated in Fig. 21.4.1. The symbols W, G, O represent tlie events listed ... 

Figure 21.4.1. Event tree for toxic vapor release.

The seven single failures causing moderate release of toxic vapor... 

The second case study (Section 21.3), focusing on tlie healtli impact of the release of toxic vapors during transportation of a hazardous chemical, illustrated tlie derivation of a risk curve showing tlie relation between number of people affected and average aimual frequency of exposure to a potential letlial concentration of toxic vapors. 

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