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Piloted Ignition to Flaming in Smoldering Fire-Retarded Polyurethane FoamExperimental results are presented on the piloted transition from smoldering to flaming in the fire-retarded polyurethane foam Pyrell . The samples are small rectangular blocks with a square cross section, vertically placed in the wall of a vertical wind tunnel. Three of the vertical sample sides are insulated and the fourth side is exposed to an upward oxidizer flow of variable oxygen concentration and to a variable radiant heat flux. The gases emitted from the smoldering reaction pass upwards through a pilot, which consists of a coiled resistance heating wire. In order to compensate for the solid-phase and gas-phase effects of the fire retardants on the piloted transition from smoldering to flaming in Pyrell, it was necessary to assist the process by increasing the power supplied to the smolder igniter and the pilot (compared to that used for non-fire retarded foam). The experiments indicate that the piloted transition from smoldering to flaming occurs when the gaseous mixture at the pilot passes the lean flammability limit. It was found that increasing the oxygen concentration or the external heat flux increases the likelihood of a piloted transition from smoldering to flaming, and generally decreases the time delay to transition. The piloted transition to flaming is observed in oxygen concentrations of 23% and above in both low-density and high-density Pyrell. Comparisons with previous experiments show that the piloted transition from smoldering to flaming is possible under a wider range of external conditions (i.e. lower oxygen concentration) than the spontaneous transition from smoldering to flaming. The results show that the fire retardants in Pyrell are very effective in preventing the piloted transition to flaming in normal air, but Pyrell is susceptible to smoldering and the piloted transition to flaming in oxygen-enriched environments. Therefore, precautions should be taken in the design of applications of Pyrell in oxygen-enriched environments to reduce to the risk of a piloted transition to flaming.
Document ID
20070017904
Acquisition Source
Glenn Research Center
Document Type
Conference Paper
Authors
Putzeys, O. (California Univ. Berkeley, CA, United States)
Fernandez-Pello, A. C. (California Univ. Berkeley, CA, United States)
Urban, D. L. (NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
August 23, 2013
Publication Date
March 28, 2007
Subject Category
Nonmetallic Materials
Report/Patent Number
Paper H38
Meeting Information
Meeting: 5th U.S. Combustion Meeting
Location: San Diego, CA
Country: United States
Start Date: March 25, 2006
End Date: March 28, 2006
Sponsors: California Univ.
Funding Number(s)
WBS: WBS 732759.03.01.02.21
Distribution Limits
Public
Copyright
Public Use Permitted.

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