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NFPA 72F
Automatic Fire
,!
r)etectors
1990 Fdition
i/'m
mm
N F P A ~
Customer ID 45634151N O T I C E
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Policy Adopted by NFPA Board of Directors on December 3, 1982
The Board of Directors reaffirms that the National Fire Protection Association recognizes that the tox- icity of the products of combustion is an important factor in the loss of life from fire. NFPA has dealt with that subject in its technical committee documen'ts for many years.
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SC AM-90
MORGAN TECHNICAL UBRARY
NATIONAL RRE PROTECTION ASSN.
BATTERYMARCH PARK
QUINCY, MA 02269
72E- 1
Copyright © 1990 NFPA, All Rights Reserved
l
NFPA 72E
Standard on
A u t o m a t i c Fire D e t e c t o r s
1990 Edition
This edition of NFPA 72E,
Standard on Automatic Fire Detectors,
was prepared by theTechnical Committee on Detection Devices, released by the Correlating Committee on Signaling Systems, a n d acted on by the National Fire Protection Association, Inc. at its A n n u a l Meeting held May 21-24, 1990 in San Antonio, TX. It was issued by the Stan- dards Council on July 20, 1990, with an effective date of August 17, 1990, a n d super- sedes all previous editions.
T h e 1990 edition of'this d o c u m e n t has been approved by the American National Standards Institute.
Changes other than editorial are indicated by a vertical rule in the margin of the pages on which they appear. These lines are included as an aid to the user in identifying changes from the previous edition.
Origin and Development of NFPA 72E
This standard was written to assist in the p r o p e r use of automatic fire detectors. Tech- nology has produced a large n u m b e r of devices that respond to some p h e n o m e n o n of fire. T o operate effectively, these devices must be located properly within the protected space. T h e r e are various types of fires - - fast or slow, flaming or smoldering - - but each is a specific product of the type a n d form of fuel on which it feeds and the physical size a n d shape of the space in which it starts. An automatic fire detector should be selected after identification of both the type a n d size of fire to be detected a n d the response required. These detectors should be located in that space so that they are properly responsive to these fires.
T h e Committee recognizes the need for additional fire research. T h e Fire Detection Institute (FD1) is expected to perform these needed tasks. T h e c u r r e n t edition of this standard is based on the best information known to date. T h e standard will be refined as results a n d additional information are received a n d studied.
T h e first edition of this standard was submitted a n d adopted as a tentative standard in May 1972. T h e standard was adopted as an official standard in 1974. T h e 1978 edi- tion contained a complete revision of Chapter 4, "Smoke Sensing Fire Detectors," a new Chapter 6, "Gas Sensing Fire Detectors," a n d other revisions. In 1982, a new table, "Fable 3-5.1.2, addressing spacing of heat detectors on. high ceilings, was added.
In the 1984 edition, Chapter 9 was completely revised to cover the use of detectors in
air duct systems a n d to provide guidance in correlation with NFPA 90A,
Standard for the
hlstallation of Air Conditioning and Ventilating Systems,
on the use of detectors for control of smoke spread. Also, NFPA 72E-M was incorporated into NFPA 72E as new AppendiX C.72E-2 AUTOMATIC FIRE DETECTORS
T h e new material is the result of data developed by the Fire Detection Institute as a guide to spacing of heat detectors on other than 15-ft ceilings.
T h e 1987 edition was a complete rewrite of the standard. Many of the changes were for clarification. Appendix C was e x p a n d e d to include tables used to analyze an existing heat detection system.
T h e 1990 edition of NFPA 72E is a partial revision of this standard. T h e major change was a total revision a n d expansion of Chapter 5, "Flame Sensing Fire Detectors."
1990 Edition
COMM I'Iq'EE PERSONNEL 7 2 E - 3
Committee on Signaling Systems
'Correlating Committee
Patrick E. Phillips, Chairman
U.S. bept. of Energy
Richard P. Bielen, Secretary
National Fire Protection Association (Nonvoting)
Richard G. Bright, Mt. Airy, MD Irving Mande, Edwards Co. Inc. James C. Roberts, NC Dept. of Insurance
Dean K. Wilson, Industrial Risk Insurers Evan E. Stauffer, Jr., Naval Facilities Engi- neering Command
Technical Committee on Detection Devices
James c. Roberts, Chairman
NC Dept. of Insurance
Joseph A. Drouin, Secretary
Simplex Time Recorder Co. (Rep NEMA) J a c k L. Abbott, Factory Mutual Research
Corp.
Brooks H. Baker III, University of Alabama at Birmingham
Rep AHA
R i c h a r d W. B u k o w s k i , C e n t e r for Fire Research
John M. Cholin, Firetek Corp. Ralph E. Collins, R. E. Collins Assoc. Donald A. Diehl, Alison Control Inc.
Kenneth W. Dungan, Professional Loss Con- trol Inc.
C. Burton Ford, James M. Castle Inc. Rep FSSA
Robert Hall, R. A. Hall and Associates Edward Hartfik, IRM Insurance
Gregory S. Kelly, Automatic Sprinkler Corpo- ration of America
Rep NFSA
James T. King, The Protectowire Co. Robert L. Langer, Ansul Fire Protection
Rep FEMA
Dewey W. Lewis, Lewis Fire Equipment Inc. Rep NAFED
Wayne D. Moore, Mass Fire Alarms of New England
Rep AFAA
Paul E. Patty, Underwriters Laboratories Inc. Patrick E. Phillips, U.S. Dept. of Energy Edward P. Reid, E. P. Reid Inc. Martin H. Reiss, The Gamewell Corp. Walter Schuchard, Electro Signal Lab. Robert Sears, Winegardner & Hammons Inc.
Rep. AHMA
J. Brooks Scruple, Smoke/Fire Risk Mgmt. Inc. Rep T/C Air Conditioning
Timothy M. Soverino, Nantucket Fire Dept., MA
Rep. IMSA
Jeffrey L. Steplowski, U.S. Veterans Admin. Ralph E. Transue, Rolf Jensen & Associates Inc.
Frank L. Van Overmeiren, FP&C Consuhants. Inc.
Dean K. Wilson, Industrial Risk Insurers
A l t e r n a t e s
Mark E. Agar, Fire Equipment Co. Inc. (Alternate to D. W. Lewis)
Douglas S. Erickson, American Hospital Asso- ciation
(Alternate to B. H. Baker Iii)
Tate Gabbert, Sarasota Fire Department, FL Rep. AFAA
(Alternate to W. D. Moore)
Raymond A. Grill, RolfJensen & Assoc. Inc. (Alternate to R. E. Transue)
7 2 E - 4 AUTOMATIC FIRE DETECTORS M i g u e l G. Lopez, U.S. V e t e r a n s A d m i n .
( A h e r n a t e to J. L. Steplowski)
R o b e r t J. Pielow, FP&C C o n s u l t a n t s Inc. (Alternate to F. L. V a n O v e r m e i r e n ) W i l l i a m W. R o g e r s , U n d e r w r i t e r s Laborato- ries Inc.
(Alternate to P. E. Patty)
R o b e r t C. Savery, Fenwal Inc. (Alternate to J. A. D r o u i n ) A n d r e a s S c h e i d w e i l e r , C e r b e r u s Ltd
(Alternate to M. H. Reiss)
T h o m a s D. Stilwell, Walter K i d d e Co. (Alternate to R. L. L a n g e r )
R i c h a r d P. Bielen, NFPA Staff Liaison
This list represents the membership at the time the Committee was balloted on the text of thi.~ edition. Since that time, changes in the membership may have occurred.
NOTE: Membership on a Conmlittee shall not in and of itself constitute an endorsement of the Associa- tion o r ;lily document developed by the Committee on which the member serves.
1990 Edition
t CONTENTS 7 2 E - 5
C o n t e n t s
Chapter 1 Introduction
. . . 7 2 E - 7 1-1 P u r p o s e . . . 7 2 E - 7 1-2 S c o p e . . . 7 2 E - 7Chapter 2 Common Requirements .
.. . . 7 2 E -7
2-1 G e n e r a l . . . 7 2 E - 7 2 - 2 C l a s s i f i c a t i o n o f F i r e D e t e c t o r s . . . 7 2 E - 8 2 - 3 S h a p e s o f C e i l i n g s . . . 7 2 E - 8 2 - 4 C e i l i n g S u r f a c e s . . . 7 2 E - 8 2 - 5 A p p r o v a l . . . 7 2 E - 9 2 - 6 A c c e p t a n c e T e s t . . . 7 2 E - 9 2 - 7 I n s t a l l a t i o n . . . 7 2 E - 9
Chapter 3 Heat Sensing Fire Detectors
. . . 7 2 E - 1 0 3-1 . . . 7 2 E - 1 0 3 - 2 O p e r a t i n g P r i n c i p l e s . . . 7 2 E - 1 0 3 - 3 T e m p e r a t u r e C l a s s i f i c a t i o n . . . 7 2 E - 1 0 3 - 4 L o c a t i o n . . . 7 2 E - 1 1 3 - 5 S p a c i n g . . . 7 2 E - 1 1Chapter 4 Smoke Sensing Fire Detectors
. . . 7 2 E - 1 2 4-1 G e n e r a l . . . 7 2 E - 1 2 4 - 2 P r i n c i p l e s o f D e t e c t i o n . . . 7 2 E - 1 2 4 - 3 C l a s s i f i c a t i o n . . . 7 2 E - 1 2 4 - 4 L o c a t i o n a n d S p a c i n g . . . 7 2 E - 1 2 4 - 5 H e a t i n g , V e n t i l a t i n g , a n d A i r C o n d i t i o n i n g ( H V A C ) . . . 7 2 E - 1 4 4 - 6 S p e c i a l C o n s i d e r a t i o n s . . . 7 2 E - 1 4Chapter 5 Flame Sensing Fire Detectors
. . . 7 2 E - 1 5 5-1 G e n e r a l . . . 7 2 E - 1 5 5 - 2 D e f i n i t i o n s a n d O p e r a t i n g P r i n c i p l e s . . . . . . 7 2 E - 1 5 5 - 3 F i r e C h a r a c t e r i s t i c s a n d D e t e c t o r S e l e c t i o n . . . 7 2 E - 1 6 5 - 4 S p a c i n g C o n s i d e r a t i o n s . . . 7 2 E - 1 6 5 - 5 F i e l d o f V i e w C o n s i d e r a t i o n s . . . 7 2 E - 1 7 5 - 6 O t h e r C o n s i d e r a t i o n s . . . 7 2 E - 1 7Chapter 6 Gas Sensing Fire Detectors
. . . 7 2 E - 1 7 6-1 . . . . . . 7 2 E - 1 7 6 - 2 O p e r a t i n g P r i n c i p l e s . . . 7 2 E - 1 8 6 - 3 L o c a t i o n a n d S p a c i n g - . . . . 7 2 E - 1 8 6 - 4 H e a t i n g , V e n t i l a t i n g , a n d A i r C o n d i t i o n i n g ( H V A C ) . . . 7 2 E - 1 8 6 - 5 S p e c i a l C o n s i d e r a t i o n s . . . 7 2 E - 1 8Chapter 7 Other Fire Detectors
. . . 7 2 E - 1 9 7-1 . . . ' . . . 7 2 E - 1 9 7 - 2 F i r e C h a r a c t e r i s t i c s . . . 7 2 E - 1 9 7 - 3 L o c a t i o n a n d S p a c i n g . . . 7 2 E - 1 9 7 - 4 S p e c i a l C o n s i d e r a t i o n s . . . 7 2 E - 19Chapter 8 Inspections, Tests, and Maintenance
. . . 7 2 E - 1 9 8-1 G e n e r a l . . . 7 2 E - 1 9 8 - 2 I n i t i a l I n s t a l l a t i o n I n s p e c t i o n a n d T e s t s . . . 7 2 E - 2 0 8 - 3 P e r i o d i c I n s p e c t i o n a n d T e s t s . . . 7 2 E - 2 0 8 - 4 D e t e c t o r M a i n t e n a n c e . . . 7 2 E - 2 1 8 - 5 T e s t s F o l l o w i n g E x p o s u r e to F i r e C o n d i t i o n s . . . 7 2 E - 2 1 8 - 6 I n s p e c t i o n F o r m s . . . 7 2 E - 2 17 2 E - 6 AUTOMATIC FIRE DETECTORS
Chapter 9 Smoke Detectors for Control of Smoke Spread . . . 7 2 E - 2 2 9-1 G e n e r a l . . . 7 2 E - 2 2 9-2 P u r p o s e s . . . 7 2 E - 2 2 9-3 A p p l i c a t i o n . . . 7 2 E - 2 2 9-4 L o c a t i o n a n d I n s t a l l a t i o n o f D e t e c t o r s in Air D u c t S y s t e m s . . . 7 2 E - 2 2 9-5 S m o k e D e t e c t o r s for D o o r Release Service . . . 7 2 E - 2 3 Chapter 10 R e f e r e n c e d P u b l i c a t i o n s . . . 7 2 E - 2 5 A p p e n d i x A . . . 7 2 E - 2 5 A p p e n d i x B S p a c i n g a n d S e n s i t i v i t y . . . 7 2 E - 4 4 A p p e n d i x C G u i d e f o r A u t o m a t i c Fire Detector S p a c i n g . . . 7 2 E - 4 4 A p p e n d i x D R e f e r e n c e d P u b l i c a t i o n s . . . 7 2 E - 1 3 2 I n d e x . . . 7 2 E - 1 3 3 1990 Edition
86E4DE1D-09B1-418B-ACA0-44A93BD8E902
INTRODUCTION/COMMON REQUIREMENTS 72E-7
NFPA 72E
Standard on
A u t o m a t i c Fire D e t e c t o r s
1990 Edition
NOTICE: An asterisk(*) following the number or letter designating a paragraph indicates explanatory material on that paragraph in Appendix A.
Information on referenced publications can be found in Chapter l0 and Appendix D.
Chapter 1 Introduction
1-1
Purpose.
1-1.1 T h e purpose of this standard is to provide basic
m i n i m u m r e q u i r e m e n t s for the performance of automatic fire detectors to e n s u r e timely w a r n i n g for the purposes of life safety a n d property protection.
1-1.2 This standard is i n t e n d e d for use by persons knowl- edgeable in the application of fire detection as part of fire protection systems.
1-2 Scope.
1-2.1 This standard covers m i n i m u m performance, loca- tion, m o u n t i n g , testing, and m a i n t e n a n c e r e q u i r e m e n t s of automatic fire detectors for protection of the occupant, building, space, structure, area, or object to be protected in accordance with the stated purpose.
1-2.2 This standard is i n t e n d e d to be used with other NFPA s t a n d a r d s that deal specifically with fire alarm, extinguishment, or control. Automatic fire detectors add to fire protection by initiating emergency action, b u t only where used in conjunction with other equipment.
1-2.3 T h e interconnection of detectors, the control con- f i g u r a t i o n s , the power supply, or the o u t p u t systems r e s p o n d i n g to a u t o m a t i c fire d e t e c t o r a c t u a t i o n a r e
J detailed in NFPA 71,
Standard for the Installation, Mainte-
nance, and Use of Signaling Systems for Central Station Service,
NFPA 72,
Standard for the Installation, Maintenance and Use of
Protective Signaling Systems,
NFPA 74,Standard for the Instal-
lation, Maintenance, and Use of Household Fire Warning
Equipment,
a n d others.1-2.4 Nothing in this standard is i n t e n d e d to p r e v e n t the use of new methods or devices provided sufficient techni- cal data are submitted to the authority having jurisdiction to demonstrate that the new method or device is equivalent in quality, effectiveness, durability, a n d safety to that pre-
Chapter 2 C o m m o n Requirements
2-1 General. Fire is a p h e n o m e n o n that occurs when a substance reaches a critical t e m p e r a t u r e a n d reacts chemi- cally with oxygen (for example) to produce heat, flame, light, smoke, water vapor, carbon monoxide, carbon diox- ide, or other products a n d effects.
An automatic fire detector is a device designed to detect the presence of fire a n d initiate action.
2-1.1
Definitions.
Approved.
Acceptable to the "authority having juris- diction."NOTE: The National Fire Protection Association does not approve, inspect or certify any installations, procedures, equipment, or materials nor does it approve or evaluate testing laboratories. In determining the acceptability of installations or procedures, equipment or materials, the authority having jurisdiction may base acceptance on com- pliance with NFPA or other appropriate standards. In the absence of such standards, said authority may require evi- dence of proper installation, procedure or use. The author- ity having jurisdiction may also refer to the listings or label- ing practices of an organization concerned with product evaluations which is in a position to determine compliance with appropriate standards for the current production of listed items.
Authority Having Jurisdiction.
T h e "authority having j u r i s d i c t i o n " is the o r g a n i z a t i o n , office or i n d i v i d u a l responsible for "approving" equipment, an installation or a procedure.NOTE: The phrase "authority having jurisdiction" is used in NFPA documents in a broad manner since jurisdictions and "approval" agencies vary as do their responsibilities. Where public safety is primary, the "authority having juris- diction" may be a federal, state, local or other regional department or individual such as a fire chief, fire marshal, chief of a fire prevention bureau, labor department, health department, building official, electrical inspector, or others having statutory authority. For insurance purposes, an insurance inspection department, rating bureau, or other insurance company representative may be the "authority having jurisdiction." In many circumstarices the property owner or his designated agent assumes the role of the "authority having jurisdiction"; at government installations, the commanding officer or departmental official may be the "authority having jurisdiction."
Ceiling. T h e u p p e r surface of a space, regardless of height. Areas with a suspended ceiling would have two ceil- ings, one visible from the floor a n d one above the sus= p e n d e d ceiling.
C e i l i n g Height. T h e height from the c o n t i n u o u s floor of the room to the continuous ceiling of a room or space.
Combination Detector.
A device that either responds to more than one of the fire p h e n o m e n a classified i n 2-2.1.1 t h r o u g h 2-2.1.5, or employs more than one operat- ing principle to sense one of these p h e n o m e n a . Typical examples are a combination of heat detector with smoke7 2 E - 8 AUTOMATIC FIRE DETECTORS
Labeled. E q u i p m e n t o r materials to which has been attached a label, symbol or o t h e r identifying m a r k of an organization acceptable to the "authority having jurisdic- tion" and c o n c e r n e d with p r o d u c t evaluation, that main- tains periodic inspection of p r o d u c t i o n o f labeled equip- m e n t o r materials and by whose labeling the m a n u f a c t u r e r indicates compliance with a p p r o p r i a t e s t a n d a r d s or perfor- mance in a specified manner.
Listed. E q u i p m e n t o r materials included in a list pub- lished by an organization acceptable to the " a u t h o r i t y hav- ing jurisdiction" and c o n c e r n e d with p r o d u c t evaluation, that maintains periodic inspection o f p r o d u c t i o n o f listed e q u i p m e n t o r materials and whose listing states either that the e q u i p m e n t o r material meets a p p r o p r i a t e s t a n d a r d s or has been tested and found suitable for use in a specified m a n n e r .
NOTE: The means for identifying listed equipment may vary for each organization concerned with product evalua- tion, some of which do not recognize equipment as listed unless it is also labeled. The "authority having jurisdiction" should utilize the system employed by the listing organiza- tion to identify a listed product.
Shall. Indicates a m a n d a t o r y r e q u i r e m e n t .
Should. Indicates a r e c o m m e n d a t i o n or that which is advised but not required.
Spacing.
A h o r i z o n t a l l y m e a s u r e d l i n e a r d i m e n s i o n relating to the allowable coverage o f fire detectors.2-2 Classification of Fire Detectors.
2-2.1 For the p u r p o s e o f this s t a n d a r d , automatic fire detectors are classified as listed below.
2-2.1.1
Heat Detector.
A device that detects a b n o r m a l l y high t e m p e r a t u r e or r a t e - o f - t e m p e r a t u r e rise.2-2.1.2
Smoke Detector.
A device that detects the visible or invisible particles o f combustion.2-2.1.3
Radiant Energy Sensing Fire Detector. A
device that detects r a d i a n t e n e r g y (ultraviolet, visible, o r infrared radiation) that is emitted as a p r o d u c t o f combustion reac- tion and obeys the laws o f optics.2-2.1.3.1 Flame Detector. See 5-2.1.4.
2-2.1.3.2
Spark/Ember Detector.
See 5-2.1.7.2-2.1.4
Fire-Gas Detector.
A device that detects gases p r o d u c e d by a fire.2-2.1.5
Other Fire Detectors.
Devices that detect a phe- n o m e n o n o t h e r than heat, smoke, flame, o r gases pro- d u c e d by a fire.2-2.2 Types of Detectors.
2-2.2.1
Line-type Detector.
A device in which detection is continuous along a path. Typical examples are rate-of- rise p n e u m a t i c tubing detectors, projected beam smoke detectors, and heat-sensitive cable.2-2.2.2
Spot-type Detector.
A device whose detecting ele- m e n t is c o n c e n t r a t e d at a p a r t i c u l a r location. T y p i c a l examples are bimetallic detectors, fusible alloy detectors, certain p n e u m a t i c rate-of-rise detectors, certain smoke detectors, and thermoelectric detectors.2-2.2.3
Air Sampling-type Detector.
A s a m p l i n g - t y p e detector consists of p i p i n g or tubing distribution from the detector unit to the area(s) to be protected. An air p u m p draws air from the p r o t e c t e d area back to the d e t e c t o r t h r o u g h the air sampling ports and p i p i n g o r tubing. At the detector, the air is analyzed for fire products.2-2.3 Operating Modes.
2-2.3.1
Nonrestorable Detector.
A device whose sensing e l e m e n t is d e s i g n e d to be d e s t r o y e d by the process o f detecting a fire.2-2.3.2
Restorable Detector.
A device whose sensing ele- m e n t is not ordinarily d e s t r o y e d by the process o f detect- ing a fire. Restoration may be manual o r automatic.2-3 Shapes o f Ceilings.
2-3.1 T h e shapes o f ceilings are classified as follows. 2-3.1.1 Level Ceilings. Those that are actually level o r have a slope o f I I/2 in. (40 mm) o r less p e r ft (0.3 m). 2-3.1.2
Sloping Ceilings.
T h o s e having a slope o f m o r e than 11/2 in. (40 mm) p e r ft (0.3 m). Sloping ceilings are further classified as follows:(a)
Sloping-Peaked Type.
T h o s e in which the ceiling slopes in two directions from the highest point. C u r v e d o r d o m e d ceilings may be considered p e a k e d with the slope figured as the slope o f the c h o r d from highest to lowest point.(See Figure A-3-5.4.1.)
(b)
Sloping-Shed Type.
T h o s e in which the high point is at one side with the slope e x t e n d i n g toward the opposite side.(See Figure A-3-5.4.2.)
2-4 Ceiling Surfaces.
2-4.1 Ceiling surfaces referred to in conjunction with the locations o f fire detectors are:
2-4.1.1 Beam C o n s t r u c t i o n . Ceilings having solid struc- t u r a l o r solid n o n s t r u c t u r a l m e m b e r s p r o j e c t i n g d o w n from the ceiling surface m o r e than 4 in. (100 ram) and spaced m o r e than 3 ft (0.9 m), c e n t e r to center.
2-4.1.2 G i r d e r s . G i r d e r s s u p p o r t beams o r joists and run at right angles to the beams o r joists. W h e r e girders are within 4 in. (100 ram) of the ceiling, they are a factor in d e t e r m i n i n g the n u m b e r o f detectors and are to be consid- e r e d as beams. W h e r e the top o f the g i r d e r is m o r e than 4 in. (100 mm) from the ceiling, it is not a factor in detec- tor location.
2-4.1.3
Solid Joist Construction.
Ceilings haying solid structural o r solid nonstructural m e m b e r s projecting down1990 Edition
COMMON REQUIREMENTS 7 2 E - 9
from the ceiling surface a distance o f m o r e than 4 in. (100 ram) and spaced at intervals 3 ft (0.9 m) o r less, cen- ter to center.
2-4.1.4 Smooth Ceiling. A surface u n i n t e r r u p t e d by con- tinuous projections, such as solid joists, beams, or ducts, e x t e n d i n g m o r e than 4 in. (100 mm) below the ceiling sur- face.
NOTE: Open truss constructions are not considered to impede the flow of fire products unless the upper member in continuous contact with the ceiling projects below the ceiling more than 4 in. (100 mm).
[ 2-5 Approval.
[ 2-5.1 All fire detection devices shall be listed or a p p r o v e d for the p u r p o s e for which they are i n t e n d e d and shall be installed in conformity with this s t a n d a r d .
[ 2-5.1.1" All fire detection devices that receive their power from the initiating circuit o f a fire alarm control unit shall be listed for use with the control unit. W h e r e acceptable to the authority having jurisdiction, the m a n u f a c t u r e r may provide information on the compatibility o f the detection device with the control unit to satisfy this r e q u i r e m e n t . [ 2-5.1.2 W h e r e r e q u i r e d by the a u t h o r i t y having jurisdic-
tion, complete information r e g a r d i n g the fire detectors, including specifications and floor plans showing the loca- tion o f the detectors, shall be submitted for a p p r o v a l p r i o r
to
installation o f the detectors.] 2-5.1.3 Before requesting approval of the installation by the authority having jurisdiction, the installing contractor shall furnish a written s t a t e m e n t to the effect that the detectors have been installed in accordance with a p p r o v e d plans and tested in accordance with C h a p t e r 8 o f this stan- dard. Manufacturers' installation and service manuals shall also be furnished.
[ 2 - 6
Acceptance Test.
U p o n completion o f the installa- tion, a satisfactory test of the fire detectors in accordance with C h a p t e r 8 o f this s t a n d a r d shall be m a d e in the pres- ence of a representative o f the authority having juris- diction.] 2-7 Installation.
]2-7.1 W h e r e subject to mechanical d a m a g e , d e t e c t o r s shall be protected.
[ 2-7.2 Detectors shall be s u p p o r t e d , in all cases, i n d e p e n - dently o f their a t t a c h m e n t to the circuit conductors.
J
2-7.3 Detectors shall not be recessed in any way into themounting surface unless they have been tested and listed for such recessed mounting.
] 2 - 7 . 4 D e t e c t o r s shall be i n s t a l l e d in all a r e a s w h e r e
accessible for p e r i o d i c m a i n t e n a n c e and testing. W h e r e total coverage is r e q u i r e d , this shall include all rooms, halls, storage areas, basements, attics, lofts, spaces above s u s p e n d e d ceilings, and o t h e r subdivisions and accessible spaces, and inside all closets, elevator shafts, enclosed stair- ways, d u m b w a i t e r shafts, and chutes. Inaccessible areas that contain combustible material shall be m a d e accessible and p r o t e c t e d by detector(s).
Exception No. 1: Detectors may be omitted from combustible
blind spaces where any of the following conditions prevail.
(a)
Where the ceiling is attached directly to the underside of
the supporting beams of a combustible roof or floor deck.
(b) Where the concealed space is entirely filled with a noncom-
bustible insulation. In solid joist construction, the insulation need
fill only the space from the ceiling to the bottom edge of the joist of
the roof or floor deck.
(c) Where there are small concealed spaces over rooms ~ro-
vided any space in question does not exceed 50 sq fi (4. 6m ) in
area.
(d) In spaces formed by sets of facing studs or solid joists in
walls, floors, or ceilings where the distance between the facing
studs or solid joists is less than 6 in. (150 mm).
Exception No. 2: Detectors may be omitted from below open grid
ceilings where all of the following conditions prevail.
(a) The openings of the grid are 1/4 in. (6.4 mm) or larger in
the least dimension.
(b) The thickness of the material does not exceed the least
dimension.
(c) The openings constitute at least 70 percent of the area of
the ceiling material.
2-7.5* Detectors shall also be required u n d e r n e a t h o p e n loading docks o r platforms and their covers, and for acces- sible u n d e r f l o o r spaces o f buildings without basements.
Exception:
By permission of the authority having jurisdiction,
detectors may be omitted when all of the following conditions pre-
vail.
(a) The space is not accessible for storage purposes or entrance
of unauthorized persons and is protected against accumulation of
windborne debris.
(b) The space contains no equipment such as steam pipes, elec-
tric wiring, shafting, or conveyors.
(c) The floor over the space is tight.
(d) No flammable liquids are processed, handled, or stored on
the floor above.
]
2-7.6 W h e r e codes, standards, laws, o r authorities having jurisdiction require the protection o f selected areas only, the specified areas shall be protected in accordance with this standard.[ 2-7.7* Duplicate terminals or leads, o r equivalent, shall be p r o v i d e d on each automatic fire d e t e c t o r for the express p u r p o s e of connecting into tile fire alarm system to pro- vide supervision o f the connections. Such terminals o r leads are necessary to e n s u r e that the wire run is b r o k e n and that the individual connections are m a d e to the incom- ing and outgoing leads o r o t h e r terminals for signaling and power.
7 2 E - 10 AUTOMATIC FI RE DETECTORS
Chapter 3 Heat Sensing Fire Detectors
3-1 Heat is a d d e d e n e r g y that causes substances to rise in t e m p e r a t u r e as well as the e n e r g y p r o d u c e d by a b u r n i n g substance.
3-1.1 General.
3.1.1.1 T h e p u r p o s e and scope of this c h a p t e r are to p r o - vide s t a n d a r d s for location and spacing of fire detectors that sense h e a t p r o d u c e d by b u r n i n g substances. T h e detectors are usually refei'red to as heat detectors. 3-1.1.2 Heat detectors, shall be installed in all areas where required either by the a p p r o p r i a t e NFPA s t a n d a r d or the authority having jurisdiction.
3-2 Operating Principles.
3-2.1 Fixed Temperature Detector.
3-2.1.1 A fixed t e m p e r a t u r e detector is a device that will r e s p o n d when its o p e r a t i n g e l e m e n t becomes heated to a p r e d e t e r m i n e d level.
3-2.1.2 T h e r m a l Lag. When a fixed t e m p e r a t u r e device operates, the t e m p e r a t u r e o f the s u r r o u n d i n g air will always be h i g h e r than the o p e r a t i n g t e m p e r a t u r e o f the device itself. This difference between the o p e r a t i n g tem- perature of the device a n d the actual air t e m p e r a t u r e is commonly spoken o f as t h e r m a l lag, and is p r o p o r t i o n a l to the rate at which the t e m p e r a t u r e is rising.
3-2.1.3 Typical examples o f fixed t e m p e r a t u r e sensing elements are:
(a)
Bimetallic.
A sensing e l e m e n t c o m p r i s e d o f two met- als having d i f f e r e n t coefficients o f t h e r m a l e x p a n s i o n a r r a n g e d so that the effect will be deflection in one direc- tion when h e a t e d and in the o p p o s i t e d i r e c t i o n when cooled.(b)
Electrical Conductivity.
A line-type o r spot-type sens- ing element whose resistance varies as a function o f tem- perature.(c)
Fusible Alloy.
A sensing e l e m e n t of a special c o m p o - , sition (eutectic) metal, which melts rapidly at the r a t e dtemperature.
(d)
Heat-Sensitive Cable.
A line-type device whose sens- ing element comprises, in one type, two c u r r e n t - c a r r y i n g wires held separated by a heat-sensitive insulation that soft- ens at the rated t e m p e r a t u r e , thus allowing the wires to make electrical contact. In a n o t h e r type, a single wire is centered in a metallic tube and the intervening space is filled with a substance that, at a critical t e m p e r a t u r e , becomes conductive, thus establishing electrical contact between the tube and the wire.(e) Liquid Expansion.
A sensing e l e m e n t c o m p r i s i n g a liquid capable of m a r k e d expansion in volume in response to t e m p e r a t u r e increase.3-2.2 Rate Compensation Detector.
3-2.2.1 A rate c o m p e n s a t i o n d e t e c t o r is a device that will r e s p o n d when the t e m p e r a t u r e o f the air s u r r o u n d i n g the device reaches a p r e d e t e r m i n e d level, regardless o f the rate o f t e m p e r a t u r e rise.
3-2.2.2 A typical e x a m p l e is a spot-type d e t e c t o r with a t u b u l a r casing of a metal that tends to e x p a n d lengthwise as it is heated and an associated contact mechanism that will close at a certain point in the elongation. A second metallic e l e m e n t inside the tube exerts an o p p o s i n g force on the contacts, t e n d i n g to hold t h e m open. T h e forces are balanced in such a way that, on a slow rate o f t e m p e r a t u r e rise, there is m o r e time for heat to p e n e t r a t e to the inner e l e m e n t , which inhibits c o n t a c t c l o s u r e until the total device has been h e a t e d to its r a t e d t e m p e r a t u r e level. However, on a fast rate o f t e m p e r a t u r e rise, there is not as much time for heat to p e n e t r a t e to the i n n e r element, which exerts less o f an inhibiting effect so that contact clo- sure is obtained when the total device has been heated to a lower level. This, in effect, c o m p e n s a t e s for t h e r m a l lag.
3-2.3 Rate.of-Rise Detector.
3-2.3.1 A rate-of-rise d e t e c t o r is a device that will r e s p o n d when the t e m p e r a t u r e rises at a rate e x c e e d i n g a p r e d e t e r - m i n e d amount.
3-2.3.2 Typical examples are:
(a)
Pneumatic Rate-of-Rise Tubing.
A line-type detector comprising small d i a m e t e r tubing, usually c o p p e r , which is installed on the ceiling or high on the walls t h r o u g h o u t the detected area. T h e tubing is t e r m i n a t e d in a d e t e c t o r unit containing d i a p h r a g m s and associated contacts set to actu- ate at a p r e d e t e r m i n e d p r e s s u r e . T h e system is sealed except for calibrated vents that c o m p e n s a t e for n o r m a l changes in t e m p e r a t u r e .(b)
Spot-type Pneumatic Rate-of-Rise Detector.
A device consisting o f an air c h a m b e r , d i a p h r a g m , con.tacts, and c o m p e n s a t i n g vent in a single enclosure. T h e principle o f o p e r a t i o n is the same as that described in 3-2.3.2(a).(c)
Thermoelectric Effect Detector.
A device whose sensing e l e m e n t comprises a t h e r m o c o u p l e o r t h e r m o p i l e unit that p r o d u c e s an increase in electric potential in response to an increase in t e m p e r a t u r e . This potential js m o n i t o r e d by associated control e q u i p m e n t , and an alarm is initiated when the potential increases at an a b n o r m a l rate.(d)
Electrical Conductivity Rate-of-Change Detector.
A line- type sensing e l e m e n t whose resistance changes d u e to a c h a n g e in t e m p e r a t u r e . T h e rate of c h a n g e of resistance is m o n i t o r e d by associated control e q u i p m e n t , and an alarm is initiated when the rate o f increase exceeds a p r e s e t value.3-3 Temperature Classification.
3-3.1 H e a t detectors o f the f i x e d - t e m p e r a t u r e o r rate- c o m p e n s a t e d s p o t - p a t t e r n type shall be classified as to the t e m p e r a t u r e of o p e r a t i o n and m a r k e d with the a p p r o p r i - ate color code.
(See Table 3-3.1.)
3-3.1.1 W h e r e the overall color o f a d e t e c t o r is the same as the color code m a r k i n g required for that detector, either one of the following a r r a n g e m e n t s , a p p l i e d in a contrasting color and visible after installation, shall be e m p l o y e d :
1990 Edition
HEAT SENSING FIRE DETECTORS 72E-11
(a) A ring on the surface of the detector.
(b) T h e t e m p e r a t u r e rating in numerals at least 3/8 in. (9.5 mm) high.
Table 3-3.1
Temperature Temp. Rating Max. Ceiling Color Classification Range °F Temp. °F Code
Low* 100 to 134 20 belowt Uncolored
Ordinary 135 to 174 100 Uncolored
Intermediate 175 to 249 150 White
High 250 to 324 225 Blue
Extra High 325 to 399 300 Red
Very Extra High 400 to 499 375 Green
Ultra High 500 to 575 475 Orange
*Intended only for installation in controlled ambient areas. Units marked to indicate maximum ambient installation temperature.
tMaximum ceiling temperature has to be 20°F or more below detector rated temperature.
NOTE: The difference between the rated temperature and the maximum ambient should be as small as possible to minimize the response time.
For SI Units: °C = 5/9 (°F-32).
3-4 Location.
3-4.1" Spot-type heat detectors shall be located on the ceiling not less than 4 in. (100 ram) from the side wall or on the side walls between 4 in. (100 ram) a n d 12 in.
(300 mm) from the ceiling.
(See Figure A-3-4.1.)
Exception No. 1 :~ In the case of solid joist construction, detectors
shall be mounted at the bottom of the joists.
Exception No. 2: In the case of beam construction where beams
are less than 12 in. (300 mm) in depth and less than 8 fi (2.4 m)
on center, detectors may be installed on the bottom of beams.
3-4.2 Line-type heat detectors shall be located on the ceil- ing or on the side walls not more than 20 in. (500 mm) from the ceiling.3-4.3 High-Temperature Areas. Detectors having fixed t e m p e r a t u r e or rate c o m p e n s a t e d e l e m e n t s shall be selected in accordance with Table 3-3.1 for the m a x i m u m ceiling t e m p e r a t u r e that can be expected.
3-5 Spacing.
3-5.1" Smooth C e i l i n g Spacing. O n e of the following rules shall apply.
(a) T h e distance between detectors shall not exceed their listed spacing, a n d there shall be detectors within a distance of one-half the listed spacing, measured at a right angle, from all walls or partitions e x t e n d i n g to within 18 in. (460 mm) of the ceiling; or
(h) All points on the ceiling shall have a detector within a distance equal to 0.7 times the listed spacing. This will be useful in calculating locations in corridors or i r r e g u l a r areas.
3-5.1.1" Irregular Areas. For irregularly shaped areas,
the spacing between detectors may be greater than the listed spacing, provided the m a x i m u m spacing from a detector to the farthest point of a side wall or c o r n e r within its zone of protection is not greater than 0.7 times the listed
3-5.1.2" High Ceilings. On ceilings 10 ft (3 m) to 30 fi
(9.1 m) high, heat detector linear spacing shall be reduced in accordance with Table 3-5.1.2.
Table 3-5.1.2
Ceiling Height fit) Percent of
Above Up To Listed Spacing
0 10 100 10 12 91 12 14 84 14 16 77 16 18 71 18 20 64 20 22 58 22 24 52 24 26 46 26 28 40 28 30 34
For Sl Units: 1 ft = 0.305 in.
Exception:
Table 3-5.1.2 does not apply to the following detec-
tors, which rely on the integration effect.
(a ) Line-type
electrical
conductivity
detectors. [See
3-2.1.3(b).1
(b) Pneumatic rate-of-rise tubing. [See 3-2.3.2(a).]
(c) Series connected thermoelectric effect detectors. [See
3-2.3.2(c).]
In these cases, the manufacturer's recommendations shall be fol-
lowed for appropriate alarvn point and spacing.
NOTE: Table 3-5.1.2 provides for spacing modifications to take into account different ceiling heights for generalized fire conditions. An alternative design method, which allows a designer to take into account ceiling height, fire size, and ambient temperature, is provided in Appendix C.
3-5.2* Solid Joist Construction. T h e spacing of heat detectors, when measured at right angles to the solid joists, shall not exceed 50 percent of the smooth ceiling spacing
allowable u n d e r 3-5.1 a n d 3-5.1.1.
(See Figure A-3-5.2.)
3-5.3* Beam Construction. It shall be t r e a t e d as a
smooth ceiling if the beams project no more than 4 in. (100 mm) below the ceiling. If the beams project more than 4 in. (100 ram) below the ceiling, the spacing of spot-type heat detectors at right angles to the direction of beam travel shall be not more than two-thirds the smooth ceiling spacing allowable u n d e r 3-5.1 a n d 3-5.1.1. If the beams project more than 18 in. (460 ram) below the ceiling, a n d are more than 8 fi (2.4 m) on centers, each bay formed by the beams shall be treated as a separate area.
3-5.4 Sloped Ceilings.
3-5.4.1" Peaked. A row of detectors shall first be spaced a n d located at or within 3 ft (0.9 m) of the peak of the ceil- ing, measured horizontally. T h e n u m b e r a n d spacing of additional detectors, if any, shall be based on the horizon- tal projection of the ceiling in accordance with the type of
ceiling construction.
(See Figure A-3-5.4.1.)
3-5.4.2" Shed. T h e shed shall have a row of detectors located on the ceiling within 3 ft (0.9 m) of the high side of
72E-12 A U T O M N I ' I C FIRE D E T E C T O R S
with the type of construction. Remaining detectors, if any, shall then be located in the remaining area on the basis of the horizontal projection of the ceiling.
(See Figure
A-3-5.4.2.)
3-5.4.3 For a roof slope of less than 30 degrees, all detec- tors will be spaced utilizing the height at the peak. For a roof slope of greater than 30 degrees, the average slope height will be used for all detectors other than those located in the peak.
C h a p t e r 4
S m o k e S e n s i n g Fire D e t e c t o r s
4-1 General.
4-1.1" T h e purpose of this chapter is to provide informa- tion to assist in the design and installation of reliable early warning smoke detection systems for protection of life and property.
4-1.2 This chapter covers general area application o f smoke detectors in ordinary indoor locations.
4-1.2.1 For information on use of smoke detectors for control of smoke spread, refer to Chapter 9 of this stan- dard.
4-1.2.2 For additional guidance in the application of smoke detectors for flaming fires of various sizes and growth rates in areas of various ceiling heights, refer to Appendix C, Section C-5.
4-1.3" Smoke detectors shall be installed in all areas where required either by the appropriate NFPA standard or by the authority having jurisdiction.
4-2 Principles o f Detection.
4-2.1
Ionization Smoke Detection.
An ionization smoke detector has a small a m o u n t of radioactive material that ionizes the air in the sensing chamber, thus rendering it conductive and permitting a current flow through the air between two charged electrodes. This gives the sensing chamber an effective electrical conductance. When smoke particles enter the ionization area, they decrease the con- ductance of the air by attaching themselves to the ions, causing a reduction in mobility. When the conductance is less than a predetermined level, the detector responds. 4-2.1.1 Ionization detection is more responsive to invisi- ble (size less than one micron) particles produced by most flaming fires. It is somewhat less responsive to the larger particles typical of most smoldering fires.4-2.1.2 Smoke detectors utilizing the ionization principal are usually of the spot type.
4-2.2* Photoelectric Light Scattering Smoke Detection.
In a photoelectric light scattering smoke detector, a light source and a photosensitive sensor are so arranged that the rays from the light source do not normally fall on the pho-
tosensitive sensor. When smoke particles enter the light path, some of the light is scattered by reflection and refrac- tion onto the sensor, causing the detector to respond. 4-2.2.1 Photoelectric light scattering detection is more responsive to visible (size more-than one micron) particles produced by most smoldering fires. It is somewhat less responsive to the smaller particles typical of most flaming fires. It is also less responsive to black smoke.
4-2.2.2 Smoke detectors utilizing the light scattering principle are usually of the spot type.
4-2.3* Photoelectric Light Obscuration Smoke Detection.
In a photoelectric light obscuration smoke detector, the loss of light transmission between a light source and a pho- tosensitive sensor is monitored. When smoke particles are introduced in the light path, some of the light is scattered and some absorbed, thereby reducing the light reaching the receiver, causing the detector to respond.
4.2.3.1 T h e response of photoelectric light obscuration smoke detectors is usually not affected by the color of smoke.
4-2.3.2 Smoke detectors utilizing the light obscuration principle are usually of the line type. These detectors are commonly called projected beam smoke detectors.
4-2.4
Cloud Chamber Smoke Detection.
A smoke detec- tor utilizing the cloud chamber principle is usually of the sampling type. An air p u m p draws a sample of air from the protected areas into a high humidity chamber within the detector. After the humidity of the sample has been raised, the pressure is lowered slightly. If smoke particles are present, the moisture in the air condenses on them, form- ing a cloud in the chamber. T h e density o f this cloud is then measured by a photoelectric principle. When the den- sity is greater than a predetermined level, the detector responds.4-3 Classification.
4-3.1
Spot-type S m o k e Detectors.
S p o t - t y p e s m o k e detectors shall be marked with their normal production sensitivity (percent per foot obscuration), measured as required by the listing. T h e production tolerance a r o u n d the normal sensitivity shall also be indicated.4-3.1.1 Smoke detectors that have provision for field adjustment of sensitivity shall have an adjustment range of not less than 0.6 percent/ft obscuration, and the adjusting means shall be marked to indicate its nominal factory cali- bration position.
4-4 Location and Spacing.
4-4.1" G e n e r a l . T h e location and spacing o f smoke detectors shall result from an evaluation based on engi- neering j u d g m e n t supplemented by the guidelines detailed in this standard. Ceiling shape and surfaces, ceiling height, configuration of contents, burning characteristics of com- bustible material present, and ventilation are some of the conditions that shall be considered.
1990 Edition
SMOKE SENSING FIRE D E T E C T O R S 7 2 E - 13
4-4.1.1 W h e r e the intent is to protect against a specific hazard, the detector(s) may be installed closer to the haz- ard in a position where the detector will readily intercept the smoke.
4-4.1.2" Stratification. T h e possible effect o f smoke strat- ification at levels below the ceiling shall also be considered. 4-4.2*
Spot-type Smoke Detectors.
S p o t - t y p e s m o k e detectors shall be located on the ceiling not less than 4 in. (100 mm) from a sidewall to the near e d g e or, if on a side- wail, between 4 in. and 12 in. (100 m m and 300 mm) down from the ceiling to the top of the detector.(See Figure
A-3-4.1.)
Exception No. 1: See 4-4.1.2.
Exception No. 2: See 4-4.6.
Exception No. 3: See 4-4.7.
4-4.2.1" To minimize dust contamination o f smoke detec- tors where installed u n d e r raised r o o m floors and similar spaces, they shall only be m o u n t e d in an orientation for which they have been listed
(see Figure A-4:4.2.1).
4-4.3 Projected Beam-type Smoke Detectors.
Projected beam-type smoke detectors(see 4-2.3.1)
shall normally be located with their projected beams parallel to the ceiling and in accordance with the m a n u f a c t u r e r ' s instructions.Exception No. 1: See 4-4.1.2.
Exception No. 2: Beams may be installed vertically or at any
angle needed to afford protection of the hazard involved. (Exam-
pie: vertical beams through the open shaft area of a stairwell
where there is a clear vertical space inside the handrails.)
4 - 4 . 3 . 1 T h e beam length shall not exceed the m a x i m u m p e r m i t t e d by the e q u i p m e n t listing.
4-4.3.1.1" W h e r e m i r r o r s are used with projected beams, they shall be installed in accordance with the nmnufactur- er's r e c o m m e n d a t i o n s .
4-4.3.1.2 T h e detector installation shall comply with the requirements contained in the listing.
4-4.4
Sampling-type Smoke Dectector.
Each s a m p l i n g p o r t o f a sampling-type smoke detector shall be treated as a s p o H y p e detector for the p u r p o s e of location a n d spacing.4-4.5 Smooth Ceiling Spacing.
4-4.5.1
Spot-type Detectors.
On smooth ceilings, spacing of 30 ft (9.1 m) may be used as a guide. In all cases, the manufacturer's r e c o m m e n d a t i o n s shall be followed. O t h e r spacing may be used d e p e n d i n g on ceiling height, dift~rent conditions, o r response requirements.(See Appendix C for
detection of flaming fires. )
4-4.5.1.1 W h e r e a specific s p a c i n g is selected by the
points on the ceiling shall have a detector within a distance equal to 0.7 times the selected spacing. This will be useful in calculating locations in c o r r i d o r s o r i r r e g u l a r areas.
(See
A-3-5. I and Figure A-3-5.1.1.)
For irregt, larly s h a p e d areas, the spacing between detectors may be g r e a t e r than the selected spacing, p r o v i d e d the m a x i m u m spacing from a detector to the furthest point of a sidewall o r c o r n e r within its zone of protection is not g r e a t e r than 0.7 times the selected spacing (0.7S).(See Figure A-3-5.1.1.)
4-4.5.2* Projected Beam-type Detectors.
F o r location and spacing o f projected b e a m - t y p e detectors, the manu- facturer's installation instructions shall be followed.(See
Figure A-4-4.5.2.)
4-4.6* Solid Joist Construction.
4-4.6.1 Ceiling construction where joists are 8 in. (200 mm) or less in d e p t h shall be considered equivalenl to a smooth ceiling. Spot-type detectors shall be m o u n t e d on the b o t t o m o f the joists.
(Also see 4-4.1.2.)
4-4.6.2 If joists exceed 8 in. (200 ram) in d e p t h , the spac- ing o f spot-type detectors in the direction p e r p e n d i c u l a r to the joists shall be r e d u c e d by onc-third. If the projected light beams of line-type detectors run p e r p e n d i c u l a r to the joists, no spacing reduction is necessary; however, if the projected light beanas are parallel to the.joists, thc spacing between light beams shall be reduced. Spot-type dctcctors shall be m o u n t e d on the bottom o f the joists.
(Also see
4-4.1.2.)
4-4.7 Beam Construction.
4-4.7.1 Ceiling construction where beams are 8 in. (200 ram) or less in d e p t h shall be considered equivalent to a smooth ceiling.
(Also see 4-4.1.2.)
4-4.7.2 If beams are over 8 in. (200 ram) in d e p t h , the spacing of spot-type detectors in the direction p e r p e n d i c u - lar to the beams shall be rcduced. T h e spacing o f projected light b e a m detectors run p e r p e n d i c u l a r l y to the ceiling beams need not be reduced; however, if the projected light beams are run parallel to the ceiling beams, the spacing shall be reduced.
(Also see 4-4.1.2.)
4-4.7.3 If beams are less than 12 in. (304 nun) in d e p t h and less than 8 ft (2.4 m) on center, spot-type detectors shall be p e r m i t t e d to be installed on the bottom o f beams. 4-4.7.4* I f the beams exceed 18 in. (460 ram) in d e p t h and are m o r e than 8 ft (2.4 in) on centers, each bay shall be treated as a separate area r e q u i r i n g at least one spot- type o r projected b e a m - t y p e detector.
4-4.8 Sloped Ceilings.
4-4.8.1 P e a k e d . D e t e c t o r s shall first be s p a c e d a n d located within 3 ft (0.9 m) o f the peak, m e a s u r e d horizon- tally. T h e n u m b e r and spacing o f additional detectors, if
7 2 E - 14 AUTOMATIC FI RE DETECTORS
4-4.8.2 Shed. Detectors shall first be spaced and located within 3 ft (0.9 m) o f the high side o f the ceiling, m e a s u r e d horizontally. T h e n u m b e r and spacing o f additional detec- tors, if any, shall be based on the horizontal projection of the ceiling.
(See Figure A-3-5.4.2.)
4-4.9 R a i s e d
Floors and Suspended
Ceilings. In u n d e r - floor spaces and above ceiling spaces that are not HVAC plenums, detector spacing shall be in accordance with See- uon 4-4.4-4.10 P a r t i t i o n s . W h e r e partitions e x t e n d u p w a r d to within 18 in. (460 ram) o f the ceiling, they will not influ- ence the spacing. W h e r e the partition extends to within less than 18 in. (460 ram) of the ceiling, the effect o f smoke travel shall be considered in reduction o f spacing.
4-5 Heating, Ventilating,
and Air Conditioning
(HVAC). 4-5.1" In spaces served by air handling systems, detectors shall not be located where air from supply diffusers could dilute smoke before it reaches the detectors. Detectors shall be located to intercept the air flow toward the r e t u r n air opening(s). This may require additional detectors, since placing detectors only near r e t u r n air openings may leave the balance of the area with i n a d e q u a t e protection when the air handling system is shut down. T h e detector manu- facturer shall be consulted before installation o f detectors. 4-5.2 In spaces u n d e r floors and above ceiling spaces that are used as HVAC plenums, detectors shall be listed to be compatible with air velocities present. Detector spacings and locations shall be selected based u p o n anticipated air- flow patterns and fire type.4-5.2.1 Detectors placed in e n v i r o n m e n t a l air ducts or plenums shall not be used as a substitute for open area I detectors.
(See Chapter 9 and "Fable A-4-6.1.4.)
Smoke may not be d r a w n into the d u c t o r p l e n u m s when the ventilating system is shut down. F u r t h e r , when the ventilating system is o p e r a t i n g , the detector(s) may be less responsive to a fire condition in the r o o m of fire origin due to dilution by clean air.
4-6 Special Considerations.
4-6.1 General. T h e selection and installation o f smoke detectors shall take into c o n s i d e r a t i o n both the design characteristics of the detector and the areas into which the detectors will be installed so as to p r e v e n t false o p e r a t i o n or n o n o p e r a t i o n after installation. Some o f the consider- ations are as follows.
[4-6.1.1" T h e installation o f smoke detectors shall take into c o n s i d e r a t i o n the e n v i r o n m e n t a l c o n d i t i o n o f the area(s). Smoke detectors are i n t e n d e d for installation in areas where the normal a m b i e n t conditions are not likely to:
(a) Exceed 100°F (38°C) o r fall below 32°F (0°C); or (b) Exceed 93 percent relative humidity; or (c) Exceed air velocity of 300 fpm (1.5 mps).
Exception: Detectors .specifically designed for use in ambients
exceeding the above limits and listed for the temperature, humid-
ity, and air velocity conditions expected.
14-6.1.2" T o a v o i d u n w a n t e d a l a r m s , t h e l o c a t i o n o f s m o k e d e t e c t o r s shall take into c o n s i d e r a t i o n n o r m a l sources of smoke, moisture, dust o r fumes, and electrical o r mechanical influences.
4-6.1.3 Detectors shall not be installed until after the con- struction cleanup o f all trades is complete and final.
Exception: Where required by the authority having jurisdiction
for protection during construction.
Detectors that have been installed p r i o r to final cleanup by all trades shall be cleaned o r replaced p e r Section 8-4.
4-6.2 Spot-type Detectors.
4-6.2.1 Smoke detectors having a fixed t e m p e r a t u r e ele- m e n t as p a r t o f the unit shall be selected in a c c o r d a n c e with Table 3-3.1 for the m a x i m u m ceiling t e m p e r a t u r e that can be expected in service.
4-6.2.2* Air holes in the back of a detector shall be cov- e r e d by a gasket, sealant, o r equivalent, a n d the detector shall be m o u n t e d so that air-flow from inside the housing o r from the p e r i p h e r y of the housing will not p r e v e n t the entry o f smoke d u r i n g a fire o r test condition.
4-6.3 Projected Beam-type Detectors.
4-6.3.1 Projected b e a m - t y p e detectors and m i r r o r s shall be firmly m o u n t e d on stable surfaces, so as to p r e v e n t false o r erratic o p e r a t i o n d u e to movement. T h e b e a m shall be so d e s i g n e d that small a n g u l a r m o v e m e n t s o f the light source o r receiver do not p r e v e n t o p e r a t i o n d u e to smoke and do not cause false alarms. Ordinarily, m o v e m e n t o f I/4 d e g r e e shall be tolerated (1/2 d e g r e e circular included angle).
4-6.3.2 Since the projected b e a m - t y p e unit will not o p e r - ate for alarm but will give a trouble signal
(see A-4-2.3)
when the light-path to the receiver is a b r u p t l y i n t e r r u p t e d or obscured, the light-path shall be kept clear o f o p a q u e obstacles at all times.
4-6.4* H i g h Rack Storage.
(See Figures A-4-6.4(a) and
A-4-6.4(b).)
Detection systems are often installed in addi- tion to suppression systems. W h e r e smoke detectors are installed for early warning in high rack storage areas, it shall be necessary to consider installing detectors at several levels in the racks to ensure quicker response to smoke. W h e r e detectors are installed to actuate a suppression sys- tem, see NFPA 231C,Standard for Rack Storage of Materials.
4-6.5 High Air Movement Areas.
4-6.5.1 General. T h e p u r p o s e a n d scope o f this section are to provide location and spacing guidance for smoke detectors in high air m o v e m e n t areas for early w a r n i n g o f fire.
1990 Edition
