Extinction Studies of Propane/Air Counterflow Diffusion Flames: The Effectiveness of Aerosols
Abstract
The fire suppression effectiveness of solid aerosols as suitable halon replacements has examined. Experiments were performed in a counterflow diffusion burner, consisting of two 1 cm i.d. tubes separated by 1 cm. Aerosols were delivered to propane/air flames in the air flow. Both sodium bicarbonate (NaHCO3) and potassium bicarbonate (KHCO3) powders were examined. The NaHCo3 and KHCO3 powders were separated into various size groupings (<38 , 38-45 , 45-53 , 53-63 , and 63-75 ) using a commercial sieving system. The agent delivery system incorporated a variable orifice for gross adjustment of the delivery rate, and a variable frequency vibration unit for fine adjustments and to maintain powder flow. Light scattering using a modulated HeNe laser beam and a lock-in amplifier was used to monitor the amount of powder exiting the air tube and entering the flame. Extinction concentrations were determined for each agent sample as a function of the strain rate of the uninhibited flame. In general, suppression effectiveness increased with decreasing particle size or increasing strain rate for the size range studied. Potassium powders were 2.5 times by weight more effective than sodium powders. The suppression effectiveness of these powders as a function of particle size can be interpreted using a simplified model of the behavior of particle in counterflow steams.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1998
- Accession Number
- ADA379908
Entities
People
- Bradley A. Williams
- Eric J. Zegers
- James W. Fleming
- Mark D. Reed
- Ronald S. Sheinson
Organizations
- United States Naval Research Laboratory