Technical Reports

Fire Behavior of Transformer Dielectric Insulating Fluids

  • 01
  • Jan
  • 1980
AUTHOR: Federal Railroad Administration
OFFICE: RPD
SUBOFFICE: RPD-30
REPORT NUMBER: DOT/FRA/ORD-80/08
KEYWORDS: Railroad Transformer; Dielectric Insulating Fluids; Askarel Contamination; Fire Behavior; Ignition; Surface Flame Spread; Heat Release Rates; Pyrolysis and Combustion; Flash; Fire; Boiling Points
ABSTRACT: This report presents results for the fire behavior of pure and askarel-contaminated Fluids which are candidates for use as railroad transformer dielectric insulating fluids. In the study a hydrocarbon and a dimethyl-siloxane fluid were examined. The fire behavior of the fluids was examined on the basis of pure and askarel-contaminated in The FM Laboratory-Scale Flammability Apparatus. The measured flash point, fire point and boiling point of the hydrocarbon fluid were lower than those of dimethylsiloxane fluid both in the presence and absence of the askarel. There was some noticeable decrease in the flash and fire points when the amount of askarel in the mixture was increased from about 5 percent to 7 percent by weight. The analyses of the results indicated that: 1) Ignition and surface flame spread for the hydrocarbon fluid are expected to be about one and a half times as fast as for the dimethylsiloxane fluid in larger-scale fires (the ignition and surfaae flame spread for red oak are expected to be about three times as fast as for the hydrocarbon fluid). Askarel contamination of hydrocarbon and dimethyl-siloxane fluids is expected to have insignificant effect on ignition and surface flame spreads of the fluids in larger-scale fires. 2) The heat release rate in the combustion of heptane, hydrocarbon and dimethyl-siloxane fluid in larger-scale fires is expected to be in the ratio of about 20:10:1 respectively. Askarel contamination of the hydrocarbon and dimethyl-siloxane fluid is expected to have insignificant effect on the heat release rate in larger-scale fires involving these fluids. The parameters from the FM Flammability Apparatus were found to be useful to predict satisfactorily the fire behavior of fluids expected in larger-scale fires.

####