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Huczek J.P.,Southwest Research Institute | Stephenson R.R.,Friedman Research Corporation FRC
Fire and Materials 2015 - 14th International Conference and Exhibition, Proceedings | Year: 2015

The National Highway Traffic Safety Administration (NHTSA) contracted with SwRI to develop test apparatuses and test procedures to evaluate candidate fire detection and suppression systems for motorcoach engine compartments, and hot wheel warning systems to prevent tire fires in the wheel well. This paper focuses on the work performed in support of fire protection of motorcoach engine compartments. The project team has conducted inspections of the three largest-selling motorcoaches in the U.S. and used this information to design a typical engine compartment and completed fabrication of this engine compartment mock-up in March of 2014. Several fire scenarios will be replicated in the engine compartment apparatus. Fire scenarios include a hot surface re-ignition test, diesel and power steering fluid spray fires, overheated cable fires and plastic (Class A) fires. The same apparatus can be used for both detection and for suppression. Suppliers of fire detection and suppression systems were invited to bring their hardware to SwRI for evaluation to these procedures in the Summer of 2014. Results of this testing and recommendations on final evaluation procedures will be discussed. This research could be used by NHTSA to create draft safety standards for such active fire protection systems. © 2015 Interscience Communications Limited. Source


Stephenson R.R.,Friedman Research Corporation FRC | Huczek J.P.,South west Research Institute SwRI
Fire and Materials 2015 - 14th International Conference and Exhibition, Proceedings | Year: 2015

In 2005 there was a motorcoach fire near Wilmer, Texas (USA) which killed 23 people. The National Transportation Safety Board (NTSB) determined that the fire was caused by an improperly lubricated wheel bearing, which caused a hot wheel, which in turn ignited the tag axle tire. The fire spread vertically along the side of the motorcoach, penetrated the window, and quickly spread throughout the passenger compartment. Tire fires are difficult to extinguish and the wheel well is an extremely hostile environment for any fire detection sensor. However it is possible to detect a hot wheel prior to the ignition of the tire. Based on research conducted by The National Institute of Standards and Technology (NIST)1 a temperature of approximately 400°C is required to ignite a tire. This is a much higher temperature than the wheel develops during braking operations. So there is a wide temperature (and time) window to measure the temperature and alert the driver before the tire ignites. The National Highway Traffic Safety Administration (NHTSA) has contracted SwRI to develop test fixtures and test procedures to evaluate countermeasures for both engine compartment and wheel well fires. This paper focuses on the wheel well test procedure. SwRI designed and built a 200 HP wheel dynamometer which uses a dragging air disk brake to provide a heat source that can represent either a dragging brake or a wheel bearing failure. This paper describes the results of testing of both rotating and stationary sensors, which can be used to detect a hot wheel. © 2015 Interscience Communications Limited. Source

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