Sfpe handbook of fire protection engineering 2008 pdf

Optical beam smoke detectors are often installed in warehouses as a cost effective means of protecting large open spaces. Once a certain percentage of the transmitted light has been sfpe handbook of fire protection engineering 2008 pdf by the smoke, a fire is signalled.

The photosensitive receiver monitors light produced by the transmitter under normal conditions. In the absence of smoke, light passes from the light transmitter to the receiver in a straight line. In a fire, when smoke falls within the path of the beam detector, some of the light is absorbed or scattered by the smoke particles. This creates a decrease in the received signal, leading to an increase in optical obscuration i. An end-to-end optical beam smoke detector is a system that has a separate light transmitter and receiver.

The small size of the detector is also an advantage for aesthetic installations, where fire protection is required without introducing unsightly or overtly modern devices. End-to-end detectors include open-area smoke imaging detection, in which two wavelengths of light are used to detect smoke. UV and IR wavelengths of light react to smoke differently, and the comparative difference helps to verify real smoke by comparing the reflections and seeing a difference in the profile. A reflective optical beam smoke detector incorporates a light transmitter and the detector on the same unit. Motorised reflective optical beam smoke detector. A motorised optical beam smoke detector automatically aligns itself during installation and can compensate for alignment ‘drift’ i. Both end-to-end systems and reflective systems can be motorised.

Most commonly, the build-up of dust, dirt and other debris would lower the detection threshold for the detector, causing the system to enter alarm when no fire was present. Building movement is another common problem, where movement of the building causes the optical beam smoke detector to lose alignment. Motorised beam detectors have partially addressed this issue, but it can still be problematic in certain installations. The SFPE handbook of Fire Protection Engineering 4th Ed. This page was last edited on 7 September 2017, at 14:19. This article is about the collection of airborne particulates. Unsourced material may be challenged and removed.

An internationally recognizable “No Smoking” sign. Smoke is used in rituals where incense, sage, or resin is burned to produce a smell for spiritual purposes. Smoke is sometimes used as a flavoring agent, and preservative for various foodstuffs. The composition of smoke depends on the nature of the burning fuel and the conditions of combustion.