Ignitability, characteristic

The Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances (UL 94) has methods for determining whether a material will extinguish, or burn and propagate flame. The UL Standard for Polymeric Materials-ShortTerm Property Evaluations is a series of small-scale tests used as a basis for comparing the mechanical, electrical, thermal, and resistance-to-ignition characteristics of materials. 

A.P. Hardt, Ignition Characteristics of Gasless Reactions , Combustion Flame 22, 323—35... 

Experimental studies have shown that the response of propellants, and hence their ignitability characteristics, depend upon the type of propellant, the physical nature of the propellant surface, the heat flux from the igniter,... 

Price (P9) has also investigated the ignition characteristics of JPN, a double-base propellant, in an arc-imaging furnace. Price s data show agreement with the predictions of Eq. (8b) for heat fluxes below 1.5 cal/cm2-sec. Above this flux level, the data deviated from the theoretical predictions. 

Although the thermal-ignition theory was developed for double-base propellants, several investigators have attempted to correlate the ignition characteristics of composite propellants using this approach. Baer and Ryan (Bl) have correlated ignition data for a polysulfide-ammonium perchlorate... 

Anderson and Brown then suggested that the effects observed by McAlevy (M3, M4) of oxygen on the ignition characteristics of solid fuels might be the result of exothermic heterogeneous reactions, since the experimental observations of McAlevy as well as those of Shannon and Anderson (S3), can be correlated by Eq. (15). Shannon has also extended the original treatment of Anderson and Brown to include the effects of adsorption and desorption on the predicted results. 

A knowledge of the ignition characteristics of the propellant and the heat-transfer characteristics of the igniter permits the igniter designer to determine the propellant ignition-delay for a particular system. The next question is How fast does the flame spread across the propellant surface The answer to this question determines the burning area on the propellant surface as a function of time this is the function AB(t) required to solve Eq. (6) for the chamber pressure as a function of time. 

A solid waste containing lead or lead compounds may be defined as a hazardous waste if it exhibits the characteristic of toxicity. The waste is said to exhibit the toxicity characteristic if the lead concentration in the extract obtained by subjecting a sample of the waste to the TCLP exceeds 5.0 mg/L. Tetraethyl and tetraethyl lead are combustible. If they are in sufficient quantity in a waste, tetraethyl lead may show an ignitability characteristic. More details on the regulatory requirements are presented in Chapter 7. 

Both self-heating and self-ignition characteristics are commonly determined by adiabatic tests (self-heating) and hot-plate tests (self-ignition). These tests are limited in their applicability because they do not fully simulate the plant conditions. 

The quality of diesel fuel is measured using the cetane number, a measure of the tendency of a diesel fuel to knock in a diesel engine, and the scale, from which the cetane number is derived, is based on the ignition characteristics of two hydrocarbons (1) n-hexadecane (cetane) and (2) 2,3,4,5,6,7,8-heptamethylnonane. 

Ignitability characteristic of liquids whose vapors are likely to ignite in the presence of an ignition source also characteristic of nonliquids that may catch fire from friction or contact with water and that bum vigorously. 

Each identified hazard will have a range of possible scenarios it may not be reasonable to evaluate every scenario. Therefore, representative fire scenarios should be chosen to cover a range of foreseeable scenarios. The scenarios to evaluate are those where the initial release and ignition characteristics are likely to cause the most extensive damage, loss of production, and the greatest risk to personnel. The fire scenarios selected should have a sufficient inventory that will burn long enough to cause failure of equipment and/or the structure. 

In another effort, by Nickolay Smirnov s group at the M. V. Lomonosov Moscow State University, Moscow, a model for theoretical investigation of turbulent mixing and combustion of polydispersed mixtures in confined volumes was developed (Chapter 14). The numerical model and the software created make it possible to determine the combustion and ignition characteristics of polydispersed mixtures. The model has been validated with experiments. 

Segal, C., M. J. Priedauer, H. S. Udaykumar, W. Shyy, and A.P. Marchand. 1997. Ignition characteristics of a new high-energy strained fuel in high-speed flows. J. Propulsion Power 13 246-49. 

In order for a cold diesel engine to warm up effectively, fuel components must be present which have the proper autoignition characteristics to maintain smooth combustion. If a fuel contains a large proportion of components with widely different ignitability characteristics, smooth warmup will be difficult to achieve. 

Western States Sect Combust Inst, Paper, WSCI 65-23 (1965) 27) G.R. Mistier T.F. Seamans, Vacuum ignition characteristics of flox/diborane and oxygen difluoride/diborane, NASA Contract Report 1969, NASA-CR-100678. Avail CFSTI. From SciTechAerosp Rep 7 (12), 2196 (1969) 28) W.B. Powell et al, ClFj-Njli, liquid propellant evaluation and rocket motor development, TechRept 32-305, Jet Propulsion Lab, Calif Inst Tech, Pasadena, Ca, (May 1963) (NASA N63-21722) 29) H. Allen, Jr Pinna, Relative ignitability of typical solid propellants with C1F3, NASA TN-D-1533, NASA, Wash, DC, (Jan 1963) (NASA N63-11616) 30) R.F. Sawyer et al, AIAA J, 6, 11, 2111 (1968) CA 70, 13118 (1969) 31) M.C. Branch ... 

The chemical reactivity of the ingredients and their particle size have considerable influence on the ignition characteristics and burning rates of pyrotechnics. Finer particles are easier to ignite, leading to a faster reaction rate because of greater degree of contact between fuel and oxidizer particles. 

Figure 1. Effect of ethyl bromide, ethylene dibromide, and ethyl iodide on the preflame and ignition characteristics of hexane...

Figure 2. Effect of methyl iodide, ethyl iodide, and ethyl bromide on the preflame and ignition characteristics of 2-methylpentane...

Figure 3. Effect of hromoform, chloroform, and carbon tetrachloride on the preftame and ignition characteristics of 2,2-dimethylhutane...

Figure 8. Effect of methylene dichloride, chloroform, carbon tetrachloride, and bromoform on the preflame and ignition characteristics of benzene...

The location of the CO peak indicates the temperature regime for onset of fast oxidation for each hydrocarbon. At the reaction conditions of the flow reactor, the characteristic temperature regime for oxidation differs widely between fuels. Compared to methane, the C2 hydrocarbons are consumed at much lower temperatures at a given reaction time. This is consistent with the general observation that the C2 hydrocarbons have quite different ignition characteristics compared to methane [427]. As a consequence the presence of ethane (C2H6) and higher hydrocarbons in natural gas has a considerable influence on induction times. 

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