1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA SB 11-2011Guide for Proper Use of System Smoke Detectors Copyright 2010 by the National Electrical Manufacturers Association. NEMA SB 11-2011 Guide for Proper Use of System Smoke Detectors Published by: National Electrical M
2、anufacturers Association 1300 North 17th Street Arlington, VA 22209 www.nema.org Copyright 2011 by the National Electrical Manufacturers Association. All rights including translation into other languages, reserved under the Universal Copyright Convention, the Berne Convention for the Protection of L
3、iterary and Artistic Works, and the International and Pan American Copyright Conventions. NOTICE AND DISCLAIMER The information in this publication was considered technically sound by the consensus of persons engaged in the development and approval of the document at the time it was developed. Conse
4、nsus does not necessarily mean that there is unanimous agreement among every person participating in the development of this document. NEMA standards and guideline publications, of which the document contained herein is one, are developed through a voluntary consensus standards development process.
5、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 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 in
6、dependently test, evaluate, or verify the accuracy or completeness of any information or the soundness of any judgments contained in its standards and guideline publications. NEMA disclaims liability for any personal injury, property, or other damages of any nature whatsoever, whether special, indir
7、ect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, application, or reliance on this document. NEMA disclaims and makes no guaranty or warranty, express or implied, as to the accuracy or completeness of any information published herein, and disclaims a
8、nd makes no warranty that the information in this document will fulfill any of your particular purposes or needs. NEMA does not undertake to guarantee the performance of any individual manufacturer or sellers products or services by virtue of this standard or guide. In publishing and making this doc
9、ument available, NEMA is not undertaking to render professional or other services for or on behalf of any person or entity, nor is NEMA undertaking 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 a
10、ppropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. Information and 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
11、information not covered by this publication. NEMA has no power, nor does it undertake to police or enforce compliance with the contents of this document. NEMA does not certify, test, or inspect products, designs, or installations for safety or health purposes. Any certification or other statement of
12、 compliance with any health or safety-related information in this document shall not be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement. SB 11-2011 Page i Copyright 2011 by the National Electrical Manufacturers Association CONTENTS Foreword . iii SECT
13、ION 1 GENERAL . 1 1.1 Scope 1 1.2 Purpose . 1 1.3 Standards that Apply . 1 1.4 Manufacturers Publications 2 1.5 General Definitions 2 SECTION 2 HOW SMOKE DETECTORS WORK . 8 2.1 Smoke Detector Sensor Technologies . 8 2.2 How Ionization Smoke Detectors Work 8 2.3 How Photoelectric Smoke Detectors Work
14、 . 9 2.4 How Photoelectric Light Obscuration Smoke Detectors Work 9 2.5 How Photoelectric Light Scattering Smoke Detectors Work . 10 2.6 How Multi-Criteria Smoke Detectors Work . 11 2.7 How Video Image Detection (VID) Works . 12 2.8 Smoke Detector Design Considerations . 13 2.9 Considerations in Sel
15、ecting Detectors 13 2.10 Situations Where Other Types of Detectors May be Used . 14 2.11 Smoke Detectors Have Limitations . 14 SECTION 3 TYPICAL SYSTEM LAYOUT . 15 3.1 Electrical Supervision 15 3.2 Class B Circuits . 15 3.3 Class A Circuits . 15 3.4 Addressable Sensor Wiring . 17 3.5 Wireless Smoke
16、Detection Systems . 18 3.6 General Zoning Guidelines for Non-Addressable Smoke Detectors 18 3.7 Building Control Functions 19 3.8 Smoke Detector Installation 19 3.8.1 Wiring Installation Guidelines 19 3.8.2 Typical Wiring Techniques 19 3.8.3 Wireless Systems 23 3.9 Installation Dos and Donts . 23 3.
17、9.1 Do: . 23 3.9.2 Dont: . 24 3.10 Wiring and System Checkout 24 SECTION 4 PROPER DETECTOR PLACEMENT AND SPACING 25 4.1 Where to Place Detectors . 25 4.2 Where Not to Place Detectors. 28 4.3 Detector Spacing . 30 4.3.1 General Spacing Guidelines . 30 4.3.2 Special Spacing Problems 32 4.4 Detectors i
18、n Air Handling and Air Conditioning Systems 34 4.5 Detectors in Ceiling Plenum Areas, Including Other Spaces Used for Environmental Air . 34 SECTION 5 TESTING AND MAINTENANCE AND SERVICE OF DETECTORS . 35 5.1 General 35 5.2 Notification of Authorities 35 SB 11-2011 Page ii Copyright 2011 by the Nati
19、onal Electrical Manufacturers Association 5.3 Typical Inspection, Test, and Maintenance Practices . 35 5.4 Maintenance 35 5.5 Testing . 35 SECTION 6 NUISANCE ALARMS . 37 6.1 Effects of Location or Environment . 37 6.1.1 Inspect Detector for Dirt and Review Maintenance . 37 6.2 Effects of Other Syste
20、ms on Alarm System Wiring . 37 6.3 Next Steps . 38 6.4 Maintain an Alarm Log 38 SECTION 7 RESPONSIBILITIES OF DETECTOR OWNERS AND INSTALLERS 40 7.1 Reasons for Nuisance Alarms . 42 7.1.1 Miscellaneous Causes of Nuisance Alarms 43 7.1.2 What to Do About Nuisance Alarms 43 7.2 Where to Get Help if the
21、 Source of Nuisance Alarms Cant be Found . 43 SB 11-2011 Page iii Copyright 2011 by the National Electrical Manufacturers Association Foreword Proper Use of Smoke Detectors Studies have shown that in the United States, an early fire warning and use of smoke detection systems has resulted in a signif
22、icant reduction in overall fire deaths. The sooner a fire is detected, the better the chances are for the survival of lives in danger, and for the reduction of property damage. A potential problem with smoke detectors, is unwanted (nuisance) alarms that can result in people being desensitized to the
23、 alarm system or, in severe cases, disconnecting the system. This is an industry-wide problem that in most cases is caused by improper application, installation, and/or maintenance of smoke detectors. It is hoped that the information in this guide will be used by those involved with the application,
24、 installation, and maintenance of automatic fire alarm systems to minimize these problems. This Guide for Proper Use of System Smoke Detectors has been published by the National Electrical Manufacturers Association (NEMA) Fire Alarm Group of the Signaling Protection and Communication Section. This i
25、s known as 3-SB for the automatic fire detection and alarm industry. This specific edition of the manual supersedes all prior versions of Guide for Proper Use of System Smoke Detectors. About National Electrical Manufacturers Association (NEMA) For more than 80 years, the National Electrical Manufac
26、turers Association has been developing standards for the electrical manufacturing industry and is one of the leading standards development organizations in the world. NEMA contributes to marketplaces and helps ensure public safety. NEMA has headquarters in Rosslyn, Virginia, just south of Washington
27、, D.C. With about 450 member companies, NEMAs members include large, medium, and small businesses. The organizations nine divisions include: Industrial Automation, Lighting Systems, Electronics, Security Imaging and Communications, Building Systems, Insulating Materials, Wire and Cable, Power Equipm
28、ent, and the Medical Imaging smoke, heat, or flame sensing device; sprinkler waterflow alarm switch; or similar device or equipment to a control unit or any similar device or equipment that, when activated, causes an alarm to be indicated or retransmitted. INITIATING DEVICE Any manually operated or
29、automatically operated equipment that, when actuated, initiates an alarm. INTELLIGENT DETECTORS Advances in electronics have improved many areas of fire detection. The inclusion of microprocessors and surface-mount electronics has made possible intelligent smoke detectors. This intelligence has allo
30、wed manufacturers to add many features to smoke detectors. While many of these features are only available in analog addressable detectors, some intelligent features are available in conventional detectors. Intelligent features include: DECENTRALIZED ALARM DECISION-MAKING An on-board microprocessor
31、can make an alarm decision without communication with the control unit. This limits unnecessary communication with the control unit and increases circuit efficiency. ENVIRONMENTAL (DRIFT) COMPENSATIONThe detectors processor ensures that the sensor adapts to changes in the environment caused by dirt,
32、 humidity, gas concentration, aging, etc. As a result, the sensitivity of the sensor is largely independent of long-term changes in its operating environment relative to the time it would take for a fire or smoke condition to develop. AUTOMATIC NOTIFICATION OF DIRTY DETECTORS When detectors reach a
33、preset level of obscuration because of the build-up of dirt, it is noted in the processors memory. The detector can then either automatically send a trouble (dirty detector) signal to the control unit, or send a signal when requested by the control unit. AUTOMATIC SENSITIVITY TESTING This feature al
34、lows detectors to meet or exceed the scheduled sensitivity testing requirements of NFPA 72. This testing can be automatically performed as often as every few minutes or on demand. ADJUSTABLE SENSITIVITY LEVELS Detectors with adjustable sensitivity can be adjusted to the upper, middle, or lower of th
35、e listed sensitivity range. Detectors are usually available with three to five settings. Additionally, some detectors can be programmed to use multiple sensitivity ranges during a 24-hour period. INTERNAL HISTORY LOGOn -board memory in the sensor/detector stores the information about the sensor/dete
36、ctor. The log may include the sensors original and current sensitivity, ambient environment, the number of alarms and troubles, hours of operation, time and date, and sensor/detector readings at the time of the last alarm or trouble. This log can be stored in non-volatile memory. SELF-DIAGNOSTICS De
37、tectors can run diagnostic checks and signal when the detector is unable to operate within its normal operating parameters. IONIZATION SMOKE DETECTORAn ionization smoke detector has a small amount of radioactive material that ionizes the air in the sensing chamber, thus rendering it conductive, and
38、permitting a current to flow between two charged electrodes. This gives the sensing chamber an effective electrical conductance. When smoke particles enter the ionization area, they decrease the conductance of the air by attaching themselves to the ions, causing a reduction in mobility. When the con
39、ductance is less than a predetermined level, the detector responds. LIGHT SCATTERINGThe action of changing the path of a beam of light by reflection and/or refraction. In smoke detectors that use this principle, the light is reflected or refracted by particles of combustion. SB 11-2011 Page 5 Copyri
40、ght 2011 by the National Electrical Manufacturers Association LIGHT SCATTERING PHOTOELECTRIC SMOKE DETECTORA smoke detector that uses the reflection and/or refraction of a light beam caused by smoke particles to cause light to impinge on the photosensitive sensing element initiating the detector res
41、ponse. LISTEDEquipment or materials included in a list published by an organization acceptable to the “Authority Having Jurisdiction,” and concerned with product evaluation that maintains periodic inspection of production of listed equipment or materials; and, whose listing states either that the eq
42、uipment or material meets appropriate standards or has been tested and found suitable for use in a specified manner. MONITORING INTEGRITYA feature where digital electronic two-way communication through system field wiring ensures system readiness. This is a technique commonly employed in an addressa
43、ble system to provide an equal means to conventional wiring supervision. MULTI-CRITERIA SMOKE DETECTOR A detector comprised of a smoke sensor plus one or more additional sensors such as heat, radiant energy, fire gases or smoke that operates on different principles. Each sensor in the set is separat
44、ely monitored for the presence or absence of physical stimuli. The individual signal from each sensor is mathematically evaluated together with the signals from the other sensor(s), to determine when a smoke alarm signal is warranted. Aside from this smoke detector alarm signal the detector may gene
45、rate other independent alarm signals such as but not limited to a CO alarm, Heat alarm, or a Flame alarm for which each alarm type complies with the applicable UL standard. NATIONAL FIRE PROTECTION ASSOCIATION (NFPA)NFPA administers the development of and publishes codes, standards, and other materi
46、als concerning all phases of fire safety. NATIONALLY RECOGNIZED TESTING LABORATORIES (NRTLs)Nationally Recognized Testing Laboratories are accredited by the Occupational Safety and Health Administration (OSHA) to test and certify products to published national standards (such as American National St
47、andards). Testing laboratories test smoke detectors, control units, and other components of fire alarm systems to verify conformance with NFPA requirements and their own standards. Equipment that passes their tests is identified by label. NRTLs are accredited to test products based on product catego
48、ries. The following NRTLs are accredited in the fire and/or gas detection categories. For a complete list of NRTLs, visit the OSHA website: www.osha.gov/dts/otpca/nrtl. Canadian Standards Association (CSA) FM GLOBAL (FM) Intertek Testing Services NA, Inc. (ITSNA) (formerly ETL) Underwriters Laborato
49、ries Inc. NRTLs accredit to test and certify the standards for smoke detectors, smoke alarms, and fire alarm control equipment. NUISANCE (UNWANTED) ALARMAn alarm caused by everyday events such as cooking, cigarette smoke, dust, insects, etc. OBSCURATIONA measure of the reduction in the atmospheric transparency caused by smoke, usually expressed in percent per foot. PARTICLES OF COMBUSTIONSubstances resulting from the chemical process of a fire, which either remain at the site of burning, such as ash, or scatter as volatile products. SB 11-2011 P
