Fire Detection in MicrogravityPrepared by: Lt Paul Konyha & Lt Jennifer SchutzenhoferFires: Microgravity vs. Earth• Non-convecting purely diffusive environment• No bouyant flow-- heated gases don’t rise– Example: Candle Experiment•O2supply dependent on STS/ISS ventilation fans• CO orders of magnitude higher-- more toxic • Flammable material still present after fire is extinguished• Hemispherical flamesSTS/ISS Detection Designs• CURRENT (STS)– Ionization detection, Freon-1301 bottles, and hand-held Halon-1301 extinguishers – NASA requirements: Each payload must monitor SOH-- multiple sensors• FUTURE (STS/ISS)– SECOND GENERATION HALON REPLACEMENTS: Flame-Ex & Halon 1211– FIRESCAPE: Images invisible flames of alcohol & hydrogen fires-- sees through smoke– SOLID-SOLID HYBRID GAS GENERATORConcluding Remarks• Need more data on microgravity combustion• Ground-based scientists will have to adopt new approaches to space combustion phenomena• Each component will continuously need to be monitored for overheat conditions• Combination of new technologies utilized– Portable extinguishers will continue to be used in manned area so 2nd generation Halon replacements are a given– Solid-solid hybrid gas generators likely since the pros far outweighed the cons– FIRESCAPE will possibly be an asset on the launch pad but not relevant to STS or ISSReferences• http://liftoff.msfc.nasa.gov/shuttle/usmp4/science/combust.html• http://microgravity.grc.nasa.gov/fcarchive/combustion/edmps/scmedmp.html• http://quest.arc.nasa.gov/shuttle/ask/living• http://science.msfc.nasa.gov/newhome/headlines/msad12jul97_1.htm• http://science.msfc.nasa.gov/newhome/headlines/msad08jul97_1.htm• http://www.floridatoday.com/space/explore/releases/1996b/n96200.htm• http://www.ksc.nasa.gov/shuttle/technology/sts-newsref/sts-caws.html#sts-fire• http://www.lerc.nasa.gov/WWW/RT1996/6000/6711u.htm• http://www.mainstream-engr.com/chemical.html• http://www.microgravity.com/combustion.html•
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