- Author
-
Lee, T. G.
|
Mulholland, G. W.
- Title
- Physical Properties of Smokes Pertinent to Smoke Detector Technology. Final Report.
- Coporate
- National Bureau of Standards, Gaithersburg, MD
- Report
-
NBSIR 77-1312,
November 1977,
45 p.
- Distribution
- Available from National Technical Information Service
- Keywords
-
aerosols
|
size distribution
|
smoke
|
smoke detections
|
test methods
- Abstract
- Several commercially available aerosol instruments including the electrical aerosol analyzer, nuclei condensation monitor, quartz mass monitor, and optical particle counter were used to measure particle size distribution of smokes from burning heptane and cellulosic materials. Some limitations of these instruments are discussed. Parameters such as mode of exposure (flaming versus smoldering), pyrolysis temperature, air velocity at smoke emitting site, and aging were found to have a large effect on the smoke particle size distribution. Mass and number concentration of smokes from cotton lamp wick as a function of smoke obscuration in the standard UL 217 detector test chamber were determined. The maximum alarm threshold obscuration of 0.06 OD/m (4% per ft), required for detector approval, was found to correspond to lamp wick aerosol mass concentration of 40 mg/m(3) and particle concentration of about 4 x 10(6) cm(-3) with the peak size in the number distribution of about 0.15 mu m. The present UL 217 test method was shown to be affected by smoke coagulation and did not provide a complete measure of sensitivity in smoke detectors. An algebraic model size distribution, with number and mass concentration the only free parameters, was shown to provide a good estimate for all the smoke size distributions measured.