Fire Protection Engineering Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2772
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Item Strategies for Improved Fire Detection Response Times in Aircraft Cargo Compartments(2020) Wood, Jennifer Marie; Milke, James A.; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Prompt fire detection in cargo compartments on board transport aircraft is an important safety feature. Concern has been expressed for the activation time of contemporary detection technologies installed on aircraft. This project will deliver a continuation of research on the issues that have been identified relative to fire detection improvements in cargo compartments on aircraft, with a particular emphasis on freighters. Gas sensors and dual wavelength detectors were demonstrated in a previous phase to be responsive to fires in the previous experiment program. Detectors placed inside a Unit Loading Device (ULD) responded quickly to the array of fire sources. Thus, a further exploration of these observations is conducted including wireless technology along with an analysis of the effects of leakage rates on fire signatures inside ULDs. One primary goal is to assess the differences in fire detection time for detectors located within ULD versus those located on the ceiling of the cargo compartment for fires which originate in a ULD. The results indicated the detector location with the shortest activation time is inside of the ULD. Within the ULD, the wireless detector outperformed both air sampling detectors, however, the results could vary if threshold levels were more restrictive.Item OPTIMIZATION AND IMPLEMENTATION OF A THERMOACOUSTIC FLASHOVER DETECTOR(2013) Hamburger, Kenneth A; Sunderland, Peter B; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The thermoacoustic flashover detector is to be a helmet-mounted device that responds to deteriorating conditions in a compartment fire and produces an audible alarm to alert emergency personnel in time for an escape or change in tactics. An operational prototype device was designed at University of Maryland in 2011, and featured an aluminum, copper, and MACOR tube 178 mm long and 25.4 mm in diameter. The prototype was powered by an external heat band, which provided 44 watts of power at 308 deg C. Optimization of the prototype is conducted across several parameters including power consumption and temperature gradient. To that end, two scaled-down models of diameters 22 mm and 17 mm are constructed, both of which fail to produce sustained sound. Adding water to the device reduces the onset power consumption to 22 watts and the maximum temperature to 285 deg C, which represents the most efficient prototype of the device. A system of radiant heat collector panels and copper-water heat pipes is designed to replace the external heat band as a power source. A heat transfer analysis is conducted to determine the necessary size of the collector panels for proper activation, as well as the response time of the system. Total required surface area will depend on future design parameters, but reasonable estimates suggest that it will be between 0.02-0.03 sq meters. An acoustic analysis of the optimized device is conducted, revealing a fundamental frequency of 500Hz at 101 dB.Item Optimization of Carbon Monoxide Detectors in a Residential Layout and Analysis of Dispersion Characteristics(2012) Engel, Derek; Trouvé, Arnaud; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Current building and life safety standards do not specify the optimal placement of carbon monoxide (CO) detectors in residential structures. Currently, the standards advise to follow manufacturer's instructions, place one centrally on each floor and in each HVAC zone. With the use of computation fluid dynamics (CFD) software FLACS, simulations were run to observe and track CO concentrations, generated from a fire source, throughout a demonstrative box as well as a residential structure under different source and ambient conditions. A MATLAB script was developed to represent CO detector functionality. From this it was possible to evaluate detector placement throughout a structure. The time to detection criterion was analyzed as well as order of alarm in relation to other placements. Final recommendations are presented based upon the dispersion patterns observed.Item Prototype Design for Thermoacoustic Flashover Detector(2012) Buda-Ortins, Krystyna Eva; Sunderland, Peter; diMarzo, Marino; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The thermoacoustic flashover detector integrates the phenomenon of thermoacoustics into a fire fighting application. This report presents the prototype design for the thermoacoustic flashover detector to ultimately be implemented in a firefighter's gear. Upon increases in compartment fire heat flux and temperature corresponding to the onset of flashover, the device will produce a loud warning tone to alert the firefighter that flashover is impending. This is critical because post-flashover, the fire transitions to an untenable environment for a firefighter, as well as compromised structural integrity of the building. The current design produces a tone at 115 dB at about 500 Hz upon heating from an external band heater and cooling via an ice/water bath. At 38 mm from the device, this sound level is louder than the 85 dB from fire alarms and distinct from the 3000 Hz tone of smoke detectors. The minimum power input to the device for sound onset is 44 Watts, corresponding to a temperature difference of 150 degrees Celsius at a mean temperature of 225 degrees Celsius across a 2 cm long porous steel wool stack. The temperatures at the hot and cold ends of the stack are 300 and 150 degrees Celsius respectively, which is achieved with a response time of ~100 seconds. The sound is sustained as long as there is a minimum power input of 31 Watts. Although the measurement uncertainties are estimated at 10 degrees Celsius for the temperatures and 5 Watts for the power input, this design provides a foundation for future improvement and quantification of the device. The mechanisms of the thermoacoustics at work and the materials selected for the prototype are presented. Different power level inputs to the device are analyzed and temperatures for operation are determined. Suggestions for future optimization and integration of the device into firefighters' gear are presented.Item Analysis of the Effects of Temperature and Velocity on the Response Time Index of Heat Detectors(2010) Pomeroy, Andrew Tom; Milke, James A; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Recent revisions to NFPA 72, the National Fire Alarm Code, have specified the response time index (RTI) as the sensitivity listing for heat detectors. Originally derived as a sprinkler sensitivity rating, there has been little work performed to validate the use of the RTI rating for heat detectors. RTI values are determined by plunging the devices into a hot wind tunnel at 200 C (392 F) and 1.5 m/s (4.9 ft/s). These test conditions are unrealistically severe for the majority of expected ceiling jet profiles. While the RTI correlation is purported to be independent of temperature and velocity, data from previous studies indicates otherwise. This study examined the effects of low temperature and low velocity plunge test conditions on the constancy of the RTI for several common heat detectors. The RTI correlation was found to be inconsistent across temperature and velocity test conditions.