AUTOMATIC FIRE PROTECTION SYSTEM FOR MANNED HYPERBARIC CHAMBERS. PHASE I. SYSTEM DEVELOPMENT.
Final rept. 13 Jun 68-1 Aug 70,
SOUTHWEST RESEARCH INST SAN ANTONIO TEX
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The problems of fire detection and suppression in dense atmospheres typical of diving chamber service are analyzed, with special attention to nitrogen-oxygen up to 8 atm and helium-oxygen up to 45 atm. Spectral comparisons indicate either infrared or ultraviolet flame detectors may be used. The current IR equipment is the better choice. There is a need for a combustion products detector and an acceptable model is available. Although it is sensitive to changes in atmospheric density, automatic compensation is feasible. Dense atmospheres affect the performance of water spray nozzles. Complete data are given for a typical line of commercial nozzles for four sizes and five nozzle angles, at flow pressures of 60 psig and chamber pressures up to 500 psig. A water rate for suppression is estimated at 2-3 gpmsq ft, and supported by fire test data. The flash-off of dissolved gases can be a serious problem in system design. A closed water loop balanced to chamber pressure and pump driven when needed is preferred to any system which exposes water to gas pressures above the chamber operating level for periods long enough to permit saturation. Author
- Marine Engineering
- Safety Engineering