Likelihood Of Ignition Research Articles

Fire behaviour of steel members penetrating concrete walls

In steel construction, it is often desirable for a steel member to pass through a concrete fire wall rather than being curtailed at the wall. In situations where a steel member penetrates a fire wall, the member will usually be fire protected for a certain length on each side of the wall so as to minimise the heat flow through the steel member and reduce the likelihood of ignition of combustibles on the non-fire (unexposed) side within the adjacent compartment. The testing reported in this paper suggests that it is not necessary to apply fire protection to each side of a penetrating steel member since the resulting temperature rise of the member is insufficient to cause ignition.

A study of some factors that affect the impact sensitiveness of liquids determined using the BAM Fallhammer apparatus

We report the results of a systematic investigation of the effect of two experimental parameters on the results obtained using the BAM Fallhammer test for liquids. We demonstrate that the impact sensitiveness of liquids can be highly dependent on the initial gap set between the impact sur- faces and also on the position occupied by the test material. From pressure measurements taken in the reaction chamber, a relationship is derived between the pressure generated on impact and the likelihood of ignition. The findings of our study, particularly the dependence of sensitiveness upon the initial gap, will have implications to schemes that employ the BAM Fallhammer test as part of the determination of hazardous properties (e.g. UN Test Series 3). Some recommendations are therefore made concerning changes to published impact test procedures for liquids.

The Effect of Cigarette Circumference on Ignition Propensity

The 1984 Cigarette Safety Act created a Technical Study Group (TSG) to determine the feasibility of developing cigarettes with a minimum propensity to ignite upholstered furniture. The TSG found that combinations of certain cigarette characteristics were important in reducing the ignition pro pensity. Through a statistically designed study, those characteristics were ranked as follows: tobacco packing density, paper permeability, and cir cumference. The objective of the present study was to investigate the effect of cigarette cir cumference alone on ignition propensity. Cigarettes were tested by four methods: the NBS mockup method, a controlled-fabric mockup test, a flow- through mockup method, and a liquid crystal test. Results showed that while the NBS mockup test could not discriminate among the cigarettes, the other methods could, and results call into question the TSG's conclusion that smaller circumference cigarettes reduce the likelihood of ignition.

Operational limits and confinement in JET

Operational limits on JET in terms of density, current_and piasma beta are described. The resultsfor various heating schemes are displayed in the n̂τET̂i vs T̂i plane against the contours ofconstant thermonuclear gain Q. The confinement data is compared with several scaling laws and theeventual performance of JET predicted. Finally the likelihood of ignition in the enhanced versionof NET is assessed.

Fire Risk Analysis for Nuclear Power Plants: Methodological Developments and Applications

A methodology to quantify the risk from fires in nuclear power plants is described. This methodology combines engineering judgment, statistical evidence, fire phenomenology, and plant system analysis. It can be divided into two major parts: (1) fire scenario identification and quantification, and (2) analysis of the impact on plant safety. This article primarily concentrates on the first part. Statistical analysis of fire occurrence data is used to establish the likelihood of ignition. The temporal behaviors of the two competing phenomena, fire propagation and fire detection and suppression, are studied and their characteristic times are compared. Severity measures are used to further specialize the frequency of the fire scenario. The methodology is applied to a switchgear room of a nuclear power plant.

An analysis of the ignition of slot-injected gaseous hydrogen in a supersonic air stream

The effects of an initial air-side boundary layer on the ignition of slot-injected gaseous hydrogen by a hot supersonic air stream are treated analytically. Essentially, the treatment is based on the assumption of unit turbulent Prandtl and Lewis numbers, a mass flow difference model for the eddy viscosity and a linearization of the boundary layer equations performed in the Howarth-Dorodnitzin plane. Once the flow field is determined, an isotherm and streamline pattern is constructed. These patterns can be examined to see if regions exist with both T > T ig and fuel concentration above the lean ignition limit. If not, ignition is not possible. If these conditions are met in a region, then the streamline through this area can be followed downstream to see if sufficient time for ignition is available before passing into a colder or leaner region. Previously determined ignition delay correlations are used to estimate an ignition delay time which is then compared to the residence time of a fluid particle in the ‘hot spot’ in order to assess the likelihood of ignition. The results of parametric numerical examples are presented and discussed to display the influence of the various parameters.