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Full-Scale Flammability Measures for Electronic Equipment.


pdf icon Full-Scale Flammability Measures for Electronic Equipment. (1780 K)
Bundy, M.; Ohlemiller, T. J.

NIST Technical Note 1461; NIST TN 1461; 52 p. August 2004.

Keywords:

electronic equipment; flammability; fire hazard; thermoplastics; enclosures; resins; ignition; ignition source; cone calorimeters

Abstract:

This report describes an experimental investigation by NIST to study the fire hazard of electronic equipment having thermoplastic enclosures. This work was part of the project titled "Flammability Measures for Electronic Equipment" which was supported under the NIST "Reduced Risk of Flashover" program. It was one of several related projects aimed at studying fire growth and spread on real materials. Consumer electronics are ubiquitous in today's society. The fact that fires originating from consumer electronic equipment represent less than one percent of all residential fires in the United States is largely credited to the use of flame retardant plastics. Although fires originating within these items are rare, the hazard presented when exposed to a small external ignition source (such as a candle) is not well known. Even when the equipment is not the first item involved in a fire its contribution to the total fire load and impact on flashover of a room can be significant. Both of these issues are important due to an increasing number of both candles and electronics in the home. It should also be noted that in recent years the number of electronic fires has increased in many European countries following a reduction in the use of some flame retardant compounds due to environmental concerns. It is anticipated that this trend could follow in the United States. The objective of this work is to relate the full-scale flammability and fire hazard of consumer electronics assemblies having enclosures made from different resin formulations to bench-scale fire performance of these resins. A research consortium was established between NIST, UL, Dow, Polyone, Albemarle and Samsung Cheil to conduct this research. Eighteen commercial resins were evaluated using three different standard bench-scale flammability tests. Based on the bench-scale test results, five of these resins were molded into 19" computer monitor housings and examined in full-scale fire tests that measured the overall heat release rate (HRR) and the heat flux threat to the surroundings. The selection of these materials was based on HRR, UL94 performance and physical burning behavior such as melting and charring. The results are compared and contrasted to bench-scale results from a previous study to infer useful guidelines. There is a current international effort (IEC TC108) to develop a hazard based standard for electronic equipment. This report aims to provide useful data to help determine standard requirements.