NEMA SB 13-2012 Guide for Proper Use of Smoke Detectors in Duct Applications.pdf

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1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA SB 13-2012Guide for Proper Use of Smoke Detectors in Duct ApplicationsNEMA SB 13-2012 Guide for Proper Use of Smoke Detectors in Duct Applications Published by: National Electrical Manufacturers Association 1300 North 17th S

2、treet Rosslyn, Virginia 22209 www.nema.org Approved: October 11, 2012 Published: February 20, 2013 Copyright 2013 by the National Electrical Manufacturers Association. All rights including translation into other languages, reserved under the Universal Copyright Convention, the Berne Convention for t

3、he Protection of Literary and Artistic Works, and the International and Pan American Copyright Conventions. SB 13-2012 Page ii Copyright 2013 by National Electrical Manufacturers Association NOTICE AND DISCLAIMER The information in this publication was considered technically sound by the consensus o

4、f persons engaged in the development and approval of the document at the time it was developed. Consensus does not necessarily mean that there is unanimous agreement among every person participating in the development of this document. The National Electrical Manufacturers Association (NEMA) standar

5、ds and guideline publications, of which the document contained herein is one, are developed through a voluntary consensus standards development process. This process brings together volunteers and/or seeks out the views of persons who have an interest in the topic covered by this publication. While

6、NEMA administers the process and establishes rules to promote fairness in the development of consensus, it does not write the document and it does not independently test, evaluate, or verify the accuracy or completeness of any information or the soundness of any judgments contained in its standards

7、and guideline publications. NEMA disclaims liability for any personal injury, property, or other damages of any nature whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, application, or reliance on this document. NEMA

8、 disclaims and makes no guaranty or warranty, express or implied, as to the accuracy or completeness of any information published herein, and disclaims and makes no warranty that the information in this document will fulfill any of your particular purposes or needs. NEMA does not undertake to guaran

9、tee the performance of any individual manufacturer or sellers products or services by virtue of this standard or guide. In publishing and making this document available, NEMA is not undertaking to render professional or other services for or on behalf of any person or entity, nor is NEMA undertaking

10、 to perform any duty owed by any person or entity to someone else. Anyone using this document should rely on his or her own independent judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. Information and

11、other standards on the topic covered by this publication may be available from other sources, which the user may wish to consult for additional views or information not covered by this publication. NEMA has no power, nor does it undertake to police or enforce compliance with the contents of this doc

12、ument. NEMA does not certify, test, or inspect products, designs, or installations for safety or health purposes. Any certification or other statement of compliance with any health or safety-related information in this document shall not be attributable to NEMA and is solely the responsibility of th

13、e certifier or maker of the statement. SB 13-2012 Page iii Copyright 2013 by National Electrical Manufacturers Association TABLE OF CONTENTS Page Section 1 GENERAL 1 Section 2 APPLICATION OF DUCT SMOKE DETECTION 4 2.1 PURPOSE OF DUCT SMOKE DETECTION 4 2.2 APPLICATIONS 4 2.3 APPLICABLE DOCUMENTS .5 2

14、.4 TYPICAL SCENARIOS .5 Section 3 CHARACTERISTICS OF SMOKE IN HVAC SYSTEMS 6 3.1 GENERAL 6 3.2 SMOKE 6 3.3 CHANGE IN CONCENTRATION7 Section 4 DUCT SMOKE DETECTION EQUIPMENT8 4.1 DUCT SMOKE DETECTORS 8 Section 5 TYPICAL AIR HANDLING SYSTEMS 10 5.1 GENERAL 10 5.2 MIXED AIR SECTION 10 5.3 CONDITIONING

15、SECTION . 10 5.4 FAN SECTION 11 5.5 TERMINAL SECTION. 11 5.6 KEY PARAMETERS 11 Section 6 HOW DUCT DETECTION SYSTEMS ARE USED TO CONTROL SMOKE 13 6.1 GENERAL 13 6.2 NFPA 90A 13 6.3 TYPICAL SINGLE-ZONE HVAC SYSTEM . 13 6.4 TYPICAL FAN CONTROL CIRCUIT . 15 Section 7 PROCEDURE FOR DUCT DETECTOR APPLICAT

16、ION AND INSTALLATION. 16 7.1 APPLICATION 16 7.2 INSTALLATION IN-DUCT DETECTOR . 16 7.3 DUCT INSTRUMENTATION 20 Section 8 TESTING, MAINTENANCE AND SERVICE OF DETECTORS FOR USE IN DUCTS . 23 8.1 GENERAL 23 8.2 TYPICAL MAINTENANCE PRACTICES 23 8.3 TYPICAL TESTING PROCEDURES . 24 8.4 RECOMMENDED TESTING

17、 AND MAINTENANCE LOG PROCEDURES 24 APPENDIX A DETECTOR TEST LOG A-1 SB 13-2012 Page iv Copyright 2013 by National Electrical Manufacturers Association FIGURES 3-1 RELATIVE SENSITIVITIES OF THREE TECHNOLOGIES AS A FUNCTION OF PARTICLE DIAMETER 6 4-1 TYPICAL INSTALLATION USING AIR SAMPLING TUBES 8 4-2

18、 TYPICAL INSTALLATION WITH SENSOR PROTRUDING INTO THE AIR STREAM 94-3 TYPICAL AIR SAMPLING DETECTOR INSTALLATION 9 5-1 TYPICAL AIR HANDLING SYSTEM 106-1 TYPICAL SINGLE ZONE SYSTEM 146-2 TYPICAL FAN CONTROL SHUT DOWN CIRCUIT 157-1 “IN-DUCT” AIR DUCT INSTALLATION 177-2 TYPICAL DUCT DETECTOR PLACEMENT

19、187-3 INLET TUBE ORIENTATION 197-4 AFTER ELECTRICAL AND RPM READINGS ARE TAKEN, THE TOTAL VOLUME OF AIR, FAN PRESSURE, AND PRESSURE DROPS ARE READ 207-5 115-AV INCLINED MANOMETER FOR VELOCITY PRESSURE READINGS IN LOW VELOCITY DUCTS, 400 TO 2000 FPM 207-6 MAGNEHELIC GAUGE FOR READING STATIC PRESSURES

20、 IN AIR SYSTEMS 217-7 THERMO-ANEMOMETER . 22 SB 13-2012 Page v Copyright 2013 by National Electrical Manufacturers Association FOREWORD Proper Use of Smoke Detectors in Duct Applications The purpose of this guide is to provide much needed information concerning the proper use of smoke detectors in d

21、uct applications. Fire protection engineers, mechanical and electrical engineers, fire alarm system designers, installers, and maintenance personnel should find the contents both educational and informative. This information is intended as a technical guide, as distinct from a listing of mandatory r

22、equirements. This Guide for Proper Use of Smoke Detectors in Duct Applications has been published by the National Electrical Manufacturers Association Fire Alarm Group of the Signaling, Protection, and Communication Section, 3-SB for the automatic fire detection and alarm industry. About the Nationa

23、l Electrical Manufacturers Association (NEMA): NEMA is the association of electrical equipment and medical imaging manufacturers headquartered in Rosslyn, Virginia, just outside of Washington, D.C. Its member companies manufacture a diverse set of products including power transmission and distributi

24、on equipment, lighting systems, factory automation and control systems, and medical diagnostic imaging systems. Worldwide annual sales of NEMA-scope products exceed $120 billion. NEMA is divided into eight divisions: Industrial Automation, Lighting Equipment, Building Equipment, Insulating Materials

25、, Wire and Cable, Power Equipment, and Diagnostic Imaging and Therapy Systems. Within these divisions are over 50 product-specific sections. The Signaling Section is one such section in the Electronics Division. Founded in 1926, the National Electrical Manufacturers Association has been developing s

26、tandards for the electrical manufacturing industry and is one of the leading standards development organizations in the world. Today NEMA contributes to the marketplace and helps ensure public safety. About the NEMA Signaling, Protection, and Communication Section (3-SB): The objective of the sectio

27、n is to be the principal source of technical, training, and educational materials essential for the specification and manufacture of reliable life safety products, their installation, performance, and inspection. The section currently represents 30 U.S., U.K., and Japanese manufacturers in support o

28、f the automatic fire detection and alarm industry and the health care communications industry. Fire detection and alarm products include life safety/fire alarm systems and devices that provide early warning of an impending or actual fire or gaseous hazard. The products detect, notify, and initiate c

29、ontrol functions in case of hazard to life or property. For more information on NEMA go to www.nema.org. For more information on the Signaling Section, go to www.nema.org/prod/elec/sig. SB 13-2012 Page vi Copyright 2013 by National Electrical Manufacturers Association SB 13-2012 Page 1 Copyright 201

30、3 by National Electrical Manufacturers Association Section 1 GENERAL 1.1 SCOPE This guide is developed by the Signaling Protection and Communication Section. It provides technical information on basic fire alarm systems with a focus on early-warning smoke detection devices installed in duct applicat

31、ions. Duct mounted smoke detectors are designed to provide a specific type of protection that cannot be duplicated by any other type of system. However, there has been a tendency to misapply these devices attempting to use them as a substitute for an early warning smoke detection system. This fact,

32、coupled with new methods of detecting smoke in ducts, has prompted the writing of this industry guide. 1.2 STANDARDS THAT APPLY There are several important documents that provide guidance concerning the performance, application, and installation of duct detectors: American Society of Heating, Refrig

33、eration, and Air-Conditioning Engineers (ASHRAE) 1791 Tullie Circle, N.E. Atlanta, GA 30329 ASHRAE Handbook and Product Directory, 2009, Chapter 38, “Fire and Smoke Management” National Fire Protection Association (NFPA) 1 Batterymarch Park Quincy, MA 02269 NFPA 101 Life Safety Code NFPA 72 National

34、 Fire Alarm and Signaling Code (2010) NFPA 90A Standard for the Installation of Air-Conditioning and Ventilating Systems NFPA 92A Standard for Smoke-Control Systems Utilizing Barriers and Pressure Differences National Institute of Science and Technology 100 Bureau Drive Gaithersburg, MD 20899 IR 78-

35、1502, Smoke Measurements in Large and Small Scale Fire Testing Underwriters Laboratories Inc. (UL) 333 Pfingsten Road Northbrook, IL 60062 UL 268A Smoke Detectors for Duct Application SB 13-2012 Page 2 Copyright 2013 by National Electrical Manufacturers Association 1.3 TERMS AND DEFINITIONS air samp

36、ling detector: an extremely sensitive smoke detection device that can sample, test, and evaluate the amount of particle concentration within an air sample. area smoke detector: a device that will detect visible or invisible particles of combustion, also called a spot type detector. coil: a cooling o

37、r heating element made of pipe or tubing. coil, direct expansion: coil using the direct refrigeration method. CFM: unit volume of flowcubic feet per minute. damper: a valve or plate regulating the flow of air or other fluid. damper, multiple louver: a damper having a number of adjustable blades used

38、 to vary the volume of air passing through a confined section by varying the cross sectional area. duct: a passageway made of sheet metal or other suitable material not necessarily leak-tight, used for conveying air or other gas at low pressures. duct smoke detector: a type of smoke detector located

39、 within the duct, protruding into the duct, or located outside the duct that will detect visible or invisible particles of combustion flowing within the duct. Actuation of the device may allow operation of certain control functions. exhaust tube: usually a round tube that provides a path for sampled

40、 air to return from the detection device to the duct. fan: an air moving device comprising a wheel or blade and a housing or orifice plate. humidifier: a device to add moisture to the air. inch of water: a unit of pressure equal to the pressure exerted by a column of water at a temperature of 4.0 g1

41、13C (39.2 g113F). ionization smoke detector: a type of smoke detector has a small amount of radioactive material that ionizes the air in the sensing chamber, thus rendering it conductive and permitting a current to flow between two charged electrodes. This gives the sensing chamber an effective elec

42、trical c onductance. When smoke particles enter the ionization area they decrease the conductance of the air attaching themselves to the ions causing a reduction in mobility. When the conductance is less than a predetermined level, the detector responds. light beam amok detector: a smoke detection d

43、evice that operates on a smoke obscuration principle. photoelectric smoke detector: a type of smoke detector in which a light source and a photosensitive sensor are so arranged that the rays from the light source do not normally fall on the photosensitive sensor. When smoke particles enter the light

44、 path some of the light is scattered by reflection and refraction onto the sensor causing the detector to respond. pitot tube: a device used to measure the total pressure of a fluid stream. It is essentially a tube attached to a manometer at one end and pointed upstream at the other. SB 13-2012 Page

45、 3 Copyright 2013 by National Electrical Manufacturers Association pre ssure : the normal force exerted by a homogenous liquid or gas per unit of area on the wall of a container. pressure differential: a pressure difference (usually specified in inches of water) between two points in a duct. return

46、exhaust: the duct used to return the air to the HVAC processing center for conditioning. sampling tube: usually a round tube with holes that collects air form the duct and brings it to a detection device mounted outside the duct. smoke detector: a device that detects the visible and/or invisible par

47、ticles of combustion. stratification: a phenomenon where smoke or other gases travel in layers at different levels within the duct, rather than being evenly distributed throughout the duct. supply duct: the duct that distributes conditioned air, i.e. cooled, heated, cleaned, humidified, etc. SB 13-2

48、012 Page 4 Copyright 2013 by National Electrical Manufacturers Association Section 2 APPLICATION OF DUCT SMOKE DETECTION 2.1 PURPOSE OF DUCT SMOKE DETECTION 2.1.1 National and local safety standards and codes recognize the ability of air duct systems to transfer smoke, toxic gases, and flame from ar

49、ea to area. Often smoke can be of sufficient magnitude to be a serious hazard to life safety unless blowers are shut down and dampers actuated. The primary purpose of duct smoke detection is to prevent injury, panic, and property damage by reducing the spread (recirculation) of smoke. Duct smoke detection can also serve to protect the air conditioning system itself from fire and smoke damage and can be used to assist in equipment protection applications, for example, in the ventilation/exhaust duct work of mainframe computers and tape drives. 2.2 APPLICATIONS 2.2.1 NFPA 9