Title of Document: Analyzing Photo-electric Smoke Detector Response Based on Aspirated Smoke Detector Obscuration Analyzing Photo-electric Smoke Detector Response Based on Asprirated Smoke Detector Obscuration
Accurate obscuration levels at the response time of photo-electric smoke detectors are needed for proper detection modeling and analysis. In recent works, obscuration meters were used to measure the obscuration level at photo-electric detector response. In this study, aspirated smoke detectors (VESDA) were used to measure this same obscuration level. These detailed measurements were used to reduce the ambient light and the technology difference error associated with the obscuration meters. The use of aspirated smoke detection (VESDA) instead of light obscuration meters displayed increased accuracy for a majority of the experiments conducted in the 2008 report titled " Validation of a Smoke Detection Performance Prediction Methodology " involving flaming and non-flaming incipient fire sources at 3 different ventilation conditions.
Design of Detection Systems
Fire detection and alarm systems are recognized as key features of a building’s fire prevention and protection strategy. This chapter presents a systematic technique to be used by fire protection engineers in the design and analysis of detection and alarm systems. The majority of discussion is directed toward systems used in buildings. However, many of the techniques and procedures also apply to systems used to protect planes, ships, outside storage yards, and other nonbuilding environments.
The interaction of an isolated sprinkler spray and a two-layer compartment fire environment. phenomena and model simulations
Abstract A general description of the interaction of sprinklers and compartment-fire-generated smoke layers is presented. Various possible aspects of the interaction phenomena (upper-layer smoke entrainment into the sprinkler spray, momentum and mass exchange between droplets and entrained gas, gas cooling by evaporation, buoyancy effects, and others) are discussed in the context of a two-layer-type description of the fire environment. The inputs and outputs for a mathematical submodel which simulates the phenomena are discussed. The submodel is suitable for general use in any two-layer, zone-type compartment fire model. Results from exercising the submodel are presented. These example calculations simulate the interaction between the spray of a real sprinkler device and a range of two-layer fire environments. The calculations reveal an important generic interaction phenomenon, namely, an abrupt and large change in the growth rate of the upper layer that would accompany an increase in upper-layer thickness beyond a critical thickness (for a given upper-layer temperature) or an increase in upper-layer temperature beyond a critical temperature (for a given upper-layer thickness). Exceeding these critical values would lead to a very large rate of growth of upper layer thickness, a growth that could lead to rapid and complete smoke filling of even the largest compartments of fire origin.