Presentation on theme: "WJH FAA Technical Center John W. Reinhardt"— Presentation transcript:
1WJH FAA Technical Center John W. Reinhardt Fire Safety Section, AAR-440 Atlantic City Int’l Airport, New Jersey 08405
2OBJECTIVESTo determine the critical parameters required to scale a water mist system combined with nitrogen, used as an aircraft cargo compartment fire suppression system that have met the MPS.
3CONSIDERATIONThe scaling consideration of the water mist/N2 fire extinguishing system is for cargo compartments of volume sizes of 719 ft3 (298 in x 125 in x 42 in) and 6252 ft3 (590 in x 164 in x 80 in).
4ADOPT NFPA 750 – STANDARD ON WATER MIST FIRE PROTECTION SYSTEMS This NFPA document was prepared by the Technical Committee on Water Mist Fire Suppression Systems and acted on by the National Fire Protection Association, Inc. on November It was issued by the Standards Council on January 2000, with an effective date of February 11, 2000In developing this standard, the committee addressed system components and hardware, system types, installation requirements, design objectives, hazard classifications, calculations, water supplies, atomizing media, plans, documentation, acceptance criteria, and maintenance considerationsNFPA 750 represents a significant advancement in water mist technology and the knowledge base associated with its application.
5SCALING APPROACHCharacterize the WMS/N2 system that passed the MPS tests using the NFPA 750 standard and other techniquesUse defined system parameters and transpose them to different scale cargo compartment, paying close attention to the vertical plane (z-axis). Adjust system as needed in scaled compartment to provide same critical parameters values.
6CHARACTERIZATION OF WATER MIST NFPA 750 Section A-5-2 (Appendix A)System Flow RateSystem Operating PressureGeneral Water RequirementsNozzle CharacteristicsNozzle Spray CharacteristicsNozzle Installation ParametersActivation DeviceGeneral Design Parameters
7CHARACTERIZATION OF WATER MIST (CONT.) NFPA 750 Section A (Appendix A)Will characterize FAA’s WMS/N2 system using the recommended method to determine the cumulative volumetric distribution of water dropletsNFPA 750 Section B-1 (Appendix B – Water Mist Droplet Size Characterization and Measurement)If the equipment is available, will characterize FAA’s WMS/N2 system using one of the following techniques: optical imaging, diffraction, or Doppler refraction (Sauter Mean Diameter, Dv0.10).
8CHARACTERIZATION OF WATER MIST (CONT.) Water collection (mass flow) on a 18” by 18” pan located on the fire zone at 36” above the cargo compartment floor in order to determine water availability.
9NITROGEN MEASUREMENTThe measurement of the nitrogen volumetric concentration, in the scaled cargo compartment, will be achieved by determining the oxygen volumetric concentration in the hypoxic condition (using gas analyzers).COMPUTER MODELINGTask group member recommended usage of computer modeling techniques to facilitate scaling analysis using critical characterized parameters. It may be used If provided by task group member.
10STATUSThe characterization of the FAA’s WMS/N2 has been initiated using the NFPA 750 standard.Test fixtures to determine water mass in the fire zone is under constructionSearching for a Phase Doppler Particle Analyzer or similar equipment to measure particle size distribution and velocity of the mist on the fire zone. Anyone who owns one and is willing to share the equipment please contact John Reinhardt at or