Commercial transport aircraft cargo compartments require both fire detection and suppression capabilities in order to meet regulatory requirements. System reliability is very important since in many cases the cargo compartment is inaccessible during flight. Historically, while there have been few fires reported in cargo compartments, false alarms are a more frequent event. A recent study places the false alarm to smoke detection at 200:1 over the last five years. A significant fraction of false alarms is thought to be due to nuisance sources such as condensed water vapor, and other aerosol sources. The Federal Aviation Administration requires that each new cargo compartment design must pass a system test on the ground and in flight using smoke which may be produced from aerosol generators, tobacco smoke or other non-fire sources. The FAA is developing standard flaming fire and smoldering fire sources that will be more repeatable than the range of aerosol sources currently in use and will allow other types of detectors besides smoke detectors to be qualified. NIST has performed tests in the fire emulator/detector evaluator (FE/DE) with the same smoldering and flaming fire source developed by the FAA in addition to performing other smoldering, flaming and nuisance source tests. The additional flaming source tests include a propene smoke and heat addition to emulate a hydrocarbon or plastics pool fire, and flaming ethanol-soaked cottton/polyester blend fabric circles. Additional smoldering sources include cotton smolder smoke generated by the staged-wick-ignition device, and wood blocks placed on an electrical hotplate. Nuisance sources reproduced in the FE/DE include dust exposure, nebulized oil mist aerosol, and high humidity, condensed water vapor exposures. Laser light extinction, air temperature, CO, CO2, and water concentrations were recorded for each test. The outputs from an analog output photoelectric, ionization, thermal multi-sensor detector were recorded. The alarm conditions for a spot-type and a draw-through photoelectric aircraft smoke detectors also were monitored during the tests.
Citation: Special Publication (NIST SP) - 965
NIST Pub Series: Special Publication (NIST SP)
Pub Type: NIST PubsReport Number:
fire detection, fire detection systems, aircraft compartments, cargo space, commercial aircraft, transport aircraft, fire suppression, false alarms, test fires, combustion gases, temperature rise, particulates