- Author
-
Brozovsky, E. L.
- Title
- Preliminary Approach to Siting Smoke Detectors Based on Design Fire Size and Detector Aerosol Entry Lag Time.
- Coporate
- Worcester Polytechnic Inst., MA
- Report
-
Thesis
August 1991
106 p.
- Keywords
-
smoke detectors
|
fire spread
|
time lag
|
aerosols
|
wind tunnels
|
velocity
- Identifiers
- empirical ceiling-jet velocity correlations; siting analysis
- Abstract
- An analog photoelectric smoke detector was tested in a wind tunnel at various low velocities, where the flow contained aerosol at a high ambient optical density, simulating smoke well above threshold optical density. The research was conducted to determine lag time to alarm associated with entry into a smoke detector when smoke density level is above alarm threshold level. A "critical velocity" was determined for the smoke detector. This velocity is defined as that below which a smoke detector will not operate reliably. A preliminary method for siting smoke detectors was developed, based upon a design fire size and the detector aerosol entry lag time. It applies only to flaming fires, producing smoke, with the detector far from a wall, and mounted on low smooth ceilings, with an r/H between 0.3 and 5.7. The effects of heating and air conditioning are not considered. The velocity--numerical fit developed and used in the method applies only to the tested smoke detector at the evaluated sensitivity setting with the optical densities used and the velocity range of 0.07 to 0.20 meters per second. Any variation in casing or design requires separate tests. This preliminary siting approach cannot be used for siting smoke detectors at the present time. It is only a research aide.