Safety flammability

Water has an unusually high (374°C) critical temperature owing to its polarity. At supercritical conditions water can dissolve gases such as 02 and nonpolar organic compounds as well as salts. This phenomenon is of interest for oxidation of toxic wastewater (see Waste treatments, hazardous waste). Many of the other more commonly used supercritical fluids are listed in Table 1, which is useful as an initial screening for a potential supercritical solvent. The ultimate choice for a specific application, however, is likely to depend on additional factors such as safety, flammability, phase behavior, solubility, and expense. 

HAZARD RISK Potential release of toxic vapors and solutions pose a threat to public safety flammable NFPA Code H 2 F 3 R 0. 

Supercritical water and CO2 are substances that are compatible with various applications and processed materials. However, several other supercritical fluids can be equally used such as methanol or ethanol. The final choice of the fluid depends on the specific application and additional factors such as safety, flammability, phase behavior and solubility at the operating conditions, the price of the fluid, and the related storage and processing costs. Due to this unique property, supercritical water is essentially used to treat toxic wastewater and/ or process forestry and agricultural wastes/residues. Therefore, this chapter will focus only on supercritical CO2. 

The best way to deal with a hazard in a flowsheet is to remove it completely. The provision of safety systems to control the hazard is much less satisfactory. One of the principal approaches to making a process inherently safe is to limit the inventory of hazardous material, called intensification of hazardous material. The inventories we wish to avoid most of all are flashing flammable liquids or flashing toxic liquids. 

If the material in two process alternatives is both flammable and highly toxic, then they can be compared on both bases separately. If the assessments of the relative flammability and toxicity are in conflict, then we can only resort to a safety index. 

It should be noted finally that adding gasoline to diesel fuel which was sometimes recommended in the past to improve cold behavior conflicts with the flash point specifications and presents a serious safety problem owing to the presence of a flammable mixture in the fuel tank airspace. Adding a kerosene that begins to boil at 150°C does not have the Scune disadvantage from this point of view. 

Potential health and safety problems of acryflc polymers occur in their manufacture (159). During manufacture, considerable care is exercised to reduce the potential for violent polymerizations and to reduce exposure to flammable and potentially toxic monomers and solvents. Recent environmental legislation governing air quality has resulted in completely closed ketde processes for most acryflc polymerizations. Acryflc solution polymers are treated as flammable mixtures. Dispersion polymers are nonflammable. 

UE 94 Standardfor Safety, Tests for Flammability of Plastic Materials for Parts in Devices and Appliances, Underwriters Laboratories, Inc., Northbrook, lU.,... 

In vinyls, the aryl phosphates are frequently used in combinations with phthalate plastici2ers. The proportion of the more expensive phosphate is usually chosen so as to permit the product to reflably pass the flammability specifications. In plastici2ed vinyls used in automotive interiors, these phosphates are used to pass the Federal Motor Vehicle Safety Standard 302. 

Health and Safety Factors. VDE is a flammable gas its combustion products are toxic. Liquid VDE on contact with the skin can cause frostbite. Acute inhalation toxicity of VDE is low median lethal concentrations (LC q) for rats were 128,000 ppm after a single 4-h exposure (52) and 800,000 ppm after a 30-min exposure (53). Cumulative toxicity is low exposure of rats and mice at levels of up to 50,000 ppm for 90 days did not cause any... 

The various fumigants often exhibit considerable specificity toward insect pests, as shown in Table 8. The proper choice for any control operation is determined not only by the effectiveness of the gas but by cost safety to humans, animals, and plants flammabdity penetratabdity effect on seed germination and reactivity with furnishings. The fumigants may be used individually or in combination. Carbon tetrachloride has been incorporated with carbon disulfide, ethylene dichloride, or ethylene dibromide to decrease flammability, and carbon dioxide is used with ethylene oxide for the same purpose. 

Health and Safety Factors. MEK is slightly more toxic than acetone, but is not considered highly toxic, and nor does it exhibit cumulative toxicological properties. The OSHA time weighted average iu air is 200 ppm other measured toxicity values are shown iu Table 3. Methyl ethyl ketone is highly flammable. 

Eactory Mutual Engineering Corp. 1151 Boston-Providence Turnpike Norwood, Mass. 02062 Standards for safety equipment, safeguards for flammable Hquids, gases, dusts, industrial ovens, dryers, and for protection of buddings from wind and other natural ha2ards. 

Health and Safety. Petroleum and oxygenate formulas are either flammable or combustible. Flammables must be used in facUities that meet requirements for ha2ardous locations. Soak tanks and other equipment used in the removing process must meet Occupational Safety and Health Administration (OSHA) standards for use with flammable Hquids. Adequate ventilation that meets the exposure level for the major ingredient must be attained. The work environment can be monitored by active air sampling and analysis of charcoal tubes. 

Health and Safety. Both N-methylpyrrohdinone and dibasic esters have very low vapor pressure which limits worker exposure to vapors. Manufacturers recommend that the same safety precautions be taken as with other organic solvents. Ha2ardous location requirements must be considered if the formula is flammable. Ventilation that reduces vapors to manufacturer s recommended exposure levels should be used. 

Safety is a critical aspect in the design of phenol plants. Oxidation of cumene to CHP occurs at conditions close to the flammable limits. Furthermore, the CHP is a potentially unstable material which can violendy decompose under certain conditions. Thus, phenol plants must be carefully designed and provided with weU-designed control and safety systems. 

Health and Safety Factors, Toxicology. Because low molecular weight phosphines generally are spontaneously flammable, they must be stored and handled in an inert atmosphere. The upper explosion limit is 1.6% and the upper limit is near 100% (93). The higher and less volatile homologues are more slowly oxidized by air and present less of a problem. 

Health and Safety Factors. Ttimesic acid is an irritant to the skin, eyes, and respiratory system (140). It is mildly toxic when iagested. The oral LD q ia tats has been reported as 8.4 g/kg (141). Ttimesic acid is flammable, and precautions similar to those noted for tetephthaUc acid and isophthahc acid as regards dust clouds and fire extinguishing agents should be followed. 

Flammable Hquids used in indoor workplaces and laboratories should be contained in approved safety cans having self-closing spouts and flash... 

Health and Safety Factors. Animal-feeding studies of DMPPO itself have shown it to be nontoxic on ingestion. The solvents, catalyst, and monomers that are used to prepare the polymers, however, should be handled with caution. Eor example, for the preparation of DMPPO, the amines used as part of the catalyst are flammable toxic on ingestion, absorption, and inhalation and are also severe skin and respiratory irritants (see Amines). Toluene, a solvent for DMPPO, is not a highly toxic material in inhalation testing the TLV (71) is set at 375 mg/m, and the lowest toxic concentration is reported to be 100—200 ppm (72). Toxicity of 2,6-dimethylphenol is typical of alkylphenols (qv), eg, for mice, the acute dermal toxicity is LD q, 4000 mg/kg, whereas the acute oral toxicity is LD q, 980 mg/kg (73). The Noryl blends of DMPPO and polystyrene have PDA approval for reuse food apphcations. 

Great care must be exercised ia the preparation and use of Ziegler-Natta catalysts. They are easily poisoned by moisture, among other things. They are pyrophoric and are used ia conjunction with large amounts of flammable monomer and solvent, and so can present a significant safety hazard. 

Lower flammability limits (LFL) are expressed as vol % in dry ambient air. No entry means ASHRAE Safety Classification (2) (see Fig. 3). NR = not rated. 

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