Flammability composites

For tests other than E-84, there have been some studies on the effects of fiber loading and fiber layup on composite flammability. This has primarily been work done by the U.S. Navy on the flammability of composites used in naval vessel flammability,19-20 or work by Kandola et al.10-21-22 on the effect of fiber type and content on polymer composites studied by cone calorimeter. More work is being conducted in studying the effects of fiber orientation and lay-up not on overall flammability performance, but flammability performance under structural load. This is the most important for aircraft, vehicles, and buildings where the composites are structural members. The concern here is... 

Other textile products that require composite flammability testing are protective clothing assemblies for fire fighters suits, military flight suits, etc. Flammability standards and test methods for textile components in protective clothing have been discussed by Bajaj21 and Horrocks.22... 

Flammability limits. A flammable gas will bum in air only over a limited range of composition. Below a certain concentration of the flammable gas, the lower flammability limit, the mixture is too lean to burn, i.e., lacks fuel. Above a certain concentration, the upper flammability limit, it is too rich to burn, i.e., lacks oxygen. Concentrations between these limits constitute the flammable range. 

Combustion of a flammable gas-air mixture occurs if the composition of the mixture lies in the flammable range and if there is a source of ignition. Alternatively, combustion of the mixture occurs without a source of ignition if the mixture is heated up to its autoignition temperature. 

Flammability. Plastic foams are organic ia aature and, therefore, are combustible. They vary ia their respoase to small sources of ignitioa because of composition and/or additives (255). AH plastic foams should be handled, transported, and used according to manufacturers recommendations as weU as appHcable local and national codes and regulations. 

Flammability. PhenoHcs have inherently low flammabiHty and relatively low smoke generation. For this reason they are widely used in mass transit, tiinnel-building, and mining. Fiber glass-reinforced phenoHc composites are capable of attaining the 1990 U.S. Federal Aviation Administration (FAA) regulations for total heat release and peak heat release for aircraft interior facings (1,70). 

Thermal Properties. Thermal properties include heat-deflection temperature (HDT), specific heat, continuous use temperature, thermal conductivity, coefficient of thermal expansion, and flammability ratings. Heat-deflection temperature is a measure of the minimum temperature that results in a specified deformation of a plastic beam under loads of 1.82 or 0.46 N/mm (264 or 67 psi, respectively). Eor an unreinforced plastic, this is typically ca 20°C below the glass-transition temperature, T, at which the molecular mobility is altered. Sometimes confused with HDT is the UL Thermal Index, which Underwriters Laboratories estabflshed as a safe continuous operation temperature for apparatus made of plastics (37). Typically, UL temperature indexes are significantly lower than HDTs. Specific heat and thermal conductivity relate to insulating properties. The coefficient of thermal expansion is an important component of mold shrinkage and must be considered when designing composite stmctures. 

The equilibrium vapor pressure of a flammable hquid at its closed-cup flash point about equ s its LFL in percent by volume. Thus, the vapor pressure of toluene at its closed-cup flash point (4.4°C or 40°F) of 1.2 percent (1.2 kPa) is close to its LFL of 1.1 percent. The composite LFL of a mixture may be estimated by Le Cnatelier s Rule ... 

The test gas must be of uniform and known composition. This generally requires on-line gas analysis if flammable mixtures are not supplied from a suitable reservoir. If concentration gradients are created in the surrounding air, errors can be introduced by releasing the test gas stream from a perforated probe doubling as an electrode. The maximum effective energy of a... 

In view of the above adverse effects a safety factor should be applied where flammability is assessed using flash point. For pure liquids in containers the vapor should be considered potentially flammable if the liquid temperature is upward of at least 5°C below the reported flash point. For mixtures whose composition is less certain, such as petroleum mixtures, the safety factor should be about 15°C relative to the flash point [55]. Where combinations of adverse effects are identified the safety factors should be increased accordingly. A simple but very conservative approach is to assume that all liquids having a flash point <141°F may produce a flammable atmosphere under some ambient conditions, even where no mist or froth production is involved. A more practical approach is to assume that liquids handled in air at least 5-15°C below their closed cup flash points will not present ignition risks unless... 

Of these dimethyl phthalate (DMP) is used in most compositions. It is cheap, has a high compatibility with secondary cellulose acetate and is efficient in increasing flexibility, toughness and the ease of flow at a given temperature. Its principal disadvantages are its high volatility and the fact that it increases the flammability of the compound. Similar in compatibility but rather less volatile is diethyl phthalate. This material has less of an influence on flexibility and flow properties than the methyl ester. 

The composition of the vapour in equilibrium with a miscible liquid mixture at any temperature, e.g. on heating during distillation, will be enriched by the more volatile components. The composition of the liquid phase produced on partial condensation will be enriched by the less volatile components. Such fractionation can have implications for safety in tliat tlie flammability and relative toxicity of the mixtures can change significantly. 

Gai Analyiif Gas Composition Combinations Chosan Total Ratio 1 na rt/Combuitifala Flammable Limits (Fig. 1) Lower Upper ... 

Air stripping is used to remove 90% of the toluene (molecular weight = 92) dissolved in a 10 kg/s (159 gpm) wastewater stream. The inlet composition of toluene in the wastewater is 500 ppm. Air (essentially free of toluene) is compressed to 202.6 kPa (2 atm) and bubbled through a stripper which contains sieve trays. In order to avoid fire hazards, the concentration of toluene in the air leaving the stripper is taken as 50% of the lower flammability limit (LFL) of toluene in air. The toluene-laden air exiting the stripper is fed to a condenser which recovers almost all the toluene. A schematic representation of the process is shown in Fig. 2.11. Calculate the annual operating cost and the fixed capital investment for the system. The following physical and economic data are available ... 

The target composition of the undesirable species in each MSA is assigned by the designer based on the specific circumstances of the application. The nature of such circumstances may be physical (e.g., maximum solubility of the pollutant in the MSA), technical (e.g., to avoid excessive corrosion, viscosity or fouling), environmental (e.g., to comply with environmental regulations), safety (e.g., to stay away from flammability limits), or economic (e.g., to optimize the cost of subsequent regeneration of the MSA). 

The composition of phenol in the air leaving the MEN should be below the lower flammability limit. But, the LFL for phenol in air is 5.8 w/w%. An operating composition less than 50% of the LFL is typically suggested. Hence,... 

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