Remerciez-le!

Remerciez @Admin pour avoir partagé cet document gratuitement, de la manière la plus simple, en partageant sur les réseaux sociaux.

Advanced Ideas. Advanced Solutions SYSTEM SENSOR EUROPE beam detectors applicat

Advanced Ideas. Advanced Solutions SYSTEM SENSOR EUROPE beam detectors application guide 2 Note: This document is based on the recommendations of BS5839 Part 1: 2002. It is intended only as a guide to the application of ﬁre detection systems. Reference must be made to relevant national and local standards and manufacturer’s recommendations. CONTENTS FOREWORD .............................................................................................................................3 1. GLOSSARY OF TERMS ........................................................................................................3 ANNUNCIATOR ....................................................................................................................................................................... 3 DRIFT COMPENSATION .......................................................................................................................................................... 3 BEAM SMOKE DETECTOR ...................................................................................................................................................... 3 (PROJECTED BEAM SMOKE DETECTOR) ................................................................................................................................ 3 BEAM RANGE ......................................................................................................................................................................... 3 DETECTOR COVERAGE ............................................................................................................................................................ 3 OBSCURATION ....................................................................................................................................................................... 3 RECEIVER ............................................................................................................................................................................... 3 SENSITIVITY .......................................................................................................................................................................... 3 POINT DETECTOR ................................................................................................................................................................... 3 STRATIFICATION .................................................................................................................................................................... 3 TRANSMITTER (PROJECTOR) ................................................................................................................................................ 3 2. PRINCIPLES OF OPERATION ...............................................................................................4 ACCESSORIES ........................................................................................................................................................................ 4 PROPER APPLICATION ........................................................................................................................................................... 4 3. COMPARISONS BETWEEN BEAM DETECTORS AND POINT DETECTORS ..............................5 COVERAGE ............................................................................................................................................................................. 5 CEILING HEIGHT ..................................................................................................................................................................... 6 HIGH AIR VELOCITY ................................................................................................................................................................ 6 STRATIFICATION .................................................................................................................................................................... 6 HOSTILE ENVIRONMENTS ...................................................................................................................................................... 6 4. DESIGN REQUIREMENTS ....................................................................................................7 SENSITIVITY .......................................................................................................................................................................... 7 LOCATION AND SPACING ........................................................................................................................................................ 7 PITCHED ROOFS ..................................................................................................................................................................... 7 OBSTRUCTIONS ...................................................................................................................................................................... 7 SUPPLEMENTARY DETECTION ............................................................................................................................................... 8 BUILDING MOVEMENTS ......................................................................................................................................................... 8 5. TESTING AND MAINTENANCE ............................................................................................9 MAINTENANCE ....................................................................................................................................................................... 9 FUNCTIONAL TESTING ............................................................................................................................................................ 9 6500 AND 6500S ADDRESSABLE BEAM DETECTOR .............................................................................................................11 6500RS AND 6500R CONVENTIONAL BEAM DETECTOR .......................................................................................................11 REMOTE TEST SWITCH ..........................................................................................................................................................11 3 Note: This document is based on the recommendations of BS5839 Part 1: 2002. It is intended only as a guide to the application of ﬁre detection systems. Reference must be made to relevant national and local standards and manufacturer’s recommendations. FOREWORD The purpose of this guide is to provide information on the proper utilization of beam smoke detectors in life-safety and property protection applications. This guide brieﬂy summarizes the principles of operation of projected beam smoke detectors, their design requirements, and practical applications for their use as a component of an automatic ﬁre alarm system. Beam smoke detectors can be important components of a well-designed automatic ﬁre alarm system. Their unique capabilities enable beam smoke detectors to overcome many of the problems and limitations of point detectors in some applications. This guide was developed to help the ﬁre alarm system designer gain an understanding of the beam smoke detector’s capabilities and limitations, and how they differ from point detectors. Please note that this document is intended only as a general guide to the application of beam detectors. Reference should always be made to the detector manufacturer’s installation requirements and instructions, and to local standards, for example in the UK BS5839 part 1. 1. GLOSSARY OF TERMS ANNUNCIATOR A device, which gives a visible or audible indication of the condition or status of a detector or module, Usually Normal (Standby), Fault, or Fire Alarm. DRIFT COMPENSATION Compensation made by a detector for signal degradation due to a build up of dust and dirt over time. Rate of compensation is limited to ensure that the detector is still sensitive to slow, smouldering ﬁres. BEAM SMOKE DETECTOR (PROJECTED BEAM SMOKE DETECTOR) A ﬁre detector, which uses a beam of light (usually invisible) projected across an area to monitor for smoke emitted by an incipient ﬁre. There are two basic types of beam detector: • End to End: Transmitter and receiver are mounted at either end of the protected area. • Reﬂective: Transmitter and receiver are mounted in the same housing, and the beam is directed at a specially designed reﬂector, mounted at the opposite end of the protected area. BEAM RANGE The beam range is the total distance between the beam transmitter and receiver for end-to-end type detectors, and transmitter / receiver to reﬂector for reﬂective type detectors. DETECTOR COVERAGE Detector coverage is the area in which a ﬁre detector is considered to effectively sense an incipient ﬁre. This area is deﬁned by local and national codes. OBSCURATION Obscuration is the amount by which a beam of light is reduced by the presence of particles in the beam path, normally expressed as a percentage or as dB attenuation. RECEIVER The device, in a projected beam smoke detector system, which monitors the signal level of the light received after it has passed through the protected area. SENSITIVITY The ability of a smoke detector to respond to a given level of smoke. POINT DETECTOR A device, which senses an incipient ﬁre at a single location, most commonly using optical or ionisation smoke detection or heat detection. The area of coverage of a point detector is deﬁned in local or national standards. STRATIFICATION The effect which occurs when smoke, which is hotter than the surrounding air, rises until equal to the temperature of the surrounding air, causing the smoke to stop rising. TRANSMITTER (PROJECTOR) The transmitter, or projector is the section of a Projected Beam Smoke Detector that emits the light beam. 4 Note: This document is based on the recommendations of BS5839 Part 1: 2002. It is intended only as a guide to the application of ﬁre detection systems. Reference must be made to relevant national and local standards and manufacturer’s recommendations. 2. PRINCIPLES OF OPERATION There are two basic types of projected light beam detectors, both of which operate on the principle of light obscuration: a light beam is projected across the area to be protected, and is monitored for obscuration due to smoke (See ﬁgure 1). There are two basic types: An End-to-End type detector has separate transmitter and receiver units, mounted at either end of the area to be protected. A beam of infrared light is projected from the transmitter towards the receiver, and the signal strength received is monitored. End-to End type detectors require power to be supplied both to the transmitter and the receiver ends of the detector. This leads to longer wiring runs, and thus greater installation costs than the reﬂective type device. Reﬂective or Single-Ended type detectors have all the electronics, including the transmitter and receiver mounted in the same housing. The beam is transmitted towards a specially designed reﬂector mounted at the far end of the area to be protected, and the receiver monitors the attenuation of the returned signal. Figure 1: Operation of Reﬂective Type Optical Beam Smoke Detector The detector is typically calibrated to a number of preset sensitivity levels based on the attenuation of the beam seen by the receiver. The sensitivity setting is selected based on the beam range and site environment. Unlike point type optical smoke detectors, the response of beam smoke detectors is generally less sensitive to the type and colour of smoke. Therefore, a beam smoke detector may be well suited to applications unsuitable for point optical smoke detectors, such as applications where the anticipated ﬁre would produce black smoke. Beam smoke detectors do however require visible smoke and therefore may not be as sensitive as ion detectors in some applications. Since the sudden and total obscuration of the light beam is not a typical smoke signature, the detector will normally see this as a fault condition, rather than an alarm. This minimizes the possibility of an unwanted alarm due to the blockage of the beam by a solid object, such as a sign or ladder, being inadvertently placed in the beam path. This “beam blocked” fault threshold will typically be set by the manufacturer at a sensitivity level exceeding 7 to 10dB. Very small, slow changes in the quality of the light source also are not typical of a smoke signature. These changes may occur because of environmental conditions such as dust and dirt accumulation on the transmitter and / or receiver’s optical assemblies. These changes are typically compensated for by automatic drift compensation. When the detector is ﬁrst turned on and put through its setup program, it assumes the light signal level at that time as a reference point for a normal condition. As the quality of the light signal degrades over time, due to dust build up, the detector will compensate for this change. The rate of compensation is limited to insure that the detector will still be sensitive to slow or smouldering ﬁres. When the detector can no longer compensate for the loss of signal (as with an excessive accumulation of dirt) the detector will signal a trouble condition. ACCESSORIES Accessories to the beam smoke detector may include remote annunciators, remote test stations which allow for the periodic electronic testing of the detector, and ﬁlters used as a “go / no go” test of the detector’s proper calibration. Intelligent ﬁre alarm systems can give the beam smoke detector a discrete address to provide better indication of the ﬁre location. Conventional systems may also indicate alarms and faults through the use of relays. PROPER APPLICATION Like point smoke detectors, beam smoke detectors are inappropriate for outdoor applications. Environmental conditions such as temperature extremes, rain, snow, sleet, fog, and dew can interfere with the proper operation of the detector and cause nuisance alarms. In addition, outdoor conditions make smoke behaviour impossible to predict and thus will affect the detector’s response to a ﬁre. Up to 100M Up to 25m height Combined Emitter / Receiver Unit Reflector Beam attenuated by smoke plume 5 Note: This uploads/Industriel/ beam-detectors-application-guide-system-sensor-europe.pdf