Ignited zone

The data reported in Table VI for Halon 1301 concentration required for flame extinguishment vary in the range of 3 to %, which is comparable to the range found for ordinary combustibles. Thus maintenance of Halon 1301 concentrations in excess of is expected to extinguish fires in the ignition zone for the FRC materials this concentration limit satisfies the current Halon 1301 requirements for fire suppression systems for tracked vehicles. 

The flame extinguishment data for Halon 1301 measured in this study suggest that for extended ignition zone covering large surface areas, maintenance of a concentration in excess of A by volume would be sufficient for the control of fire growth and extinguishment for the MTL samples. 

Zone 2 is the preignition reaction zone where the NaNOs and binder react producing gases which drive the Mg particles from the lance surface into zone 3, the ignition zone. 

There have been proposed two hypotheses concerning the nature of detonation spin 1) The effect is elicited by the fact that in a spin detonation the reaction takes place periodically 2) The effect is elicited by the motion of ignition zone ... 

Since a rapid flow of gas occurs from the ignition zone at the spin head, rather than slow heat transfer, the critical value of r2/i>2 at the head is smaller than the critical value of Ti/d. for a normal wave in a tube. 

Reaction zone—flan. Ignition zone—flam -for ... 

The fluid entrained consists of combustion products that are recirculated back along the walls. The walls also serve to prevent the jet from spreading out too rapidly. If the walls are hot, this ERZ (external recirculation zone) serves to recycle hot combustion products back into the ignition zone, which is good for flame stability. 

The spontaneous combustion three-zone is divided in goaf using O2 index. The oxidation zone is defined by the area of the oxygen concentration which is from 18% to 8% (Wang 2008). It would be possible to obtain the range of spontaneous combustion three zone that non-ignition zone is 0 15 m, the spontaneous combustion zone is 15 45 m and the suffocative zone is over 45 m. 

The model, as posed in eqs. (135-138), is spatially unbiased. To break symmetry, gaussian noise is added at each timestep to the discrete solution of eqn. (136). The noise is biased toward the outlet end (y = 1) of the cell, with the mean varying from 0.0075 at the outlet to —0.0075 at the inlet. These perturbations, on the order of 1 part in 1000, are designed to mimic the variation of humidity level within the gas plenum due to the convection, and force the ignited zone to be toward the outlet end of the cell. 

The polymer surface location for ignition and establishment of a sustained flame is defined as the ignition zone. The sustained combustion extends beyond the ignition zone if the heat flux from the flame of the burning polymer is of sufficient magnitude to ignite the polymer surface ahead of the flame front. The... 

Nonpropagating There is no fire propagation beyond the ignition zone. 

Decelerating Fire propagation rate beyond the ignition zone decreases and propagation stops before covering the entire polymer surface. 

Propagating Fire propagates beyond the ignition zone until the entire polymer surface is involved on fire. 

For FPI < 6 flames are close to extinction conditions and fire propagation is limited to the ignition zone. 

For 10 < FPI < 20 there is fire propagation beyond the ignition zone, the rate increasing with the FPI value. 

Large-Scale Test Polymer fpF Propagation Mode Propagation Beyond the Ignition Zone % of total height) ... 

Determined from the measurements for the ignition zone fire propagation length (thin pyrolyzed surface layer), and... 

The interruption of pyrolysis by passive and/or active fire protection techniques would prevent fires to propagate beyond the ignition zone resulting in reduced fire hazards. The passive fire protection technique involves changes in the polymer to increase the values of the surface re-radiation loss and heat of gasification. 

The CHF and TRP values depend on the physical and chemical characteristics of the polymers. Increasing the CHF and TRP values of the polymers by various passive protectiOTi techniques would delay initiation of combustion and flame would propagate at lower rate or there would be no fire propagation beyond the ignition zone. 

Decrease in the flame heat flux and increase in the heat of gasification and surface re-radiation loss through various passive fire protection techniques would prevent the fire to grow and propagate beyond the ignition zone and the thermal and nonthermal hazards would be reduced and/or ehminated. 

Flame propagation is a process where the pyrolysis front moves beyond the ignition zone over the polymer surface. 

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