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1、SFPE Handbook of Fire Protection Engineering Third Edition Editorial Staff Philip J. DiNenno, P.E. (Hughes Associates, Inc.), Editor-in-Chief Dougal Drysdale, PhD. (University of Edinburgh), Section 1 Craig L. Beyler, PhD. (Hughes Associates, Inc.), Section 2 W. Douglas Walton, P.E. (National Instit
2、ute of Standards and Technology), Section 3 Richard L. P. Custer (Arup Fire USA), Section 4 John R. Hall, Jr., PhD. (National Fire Protection Association), Section 5 John M. Watts, Jr., PhD. (The Fire Safety Institute), Section 5 National Fire Protection Association Quincy, Massachusetts Society of
3、Fire Protection Engineers Bethesda, Maryland FM.QXD 3/3/2003 4:26 PM Page iii Section Four Design Calculations 4-OPENER.QXD 11/16/2001 1:24 PM Page 1 Chapter 4-1Design of Detection Systems Introduction4-1 Overview of Design and Analysis4-1 Detection4-3 Heat Detection4-3 Smoke Detection4-21 Radiant E
4、nergy Detection4-30 Designing Fire Alarm Audibility4-32 Cost Analysis4-38 Summary4-38 Designing Fire Alarm Visibility4-39 Nomenclature4-41 References Cited4-41 Additional Reading4-43 Chapter 4-2Hydraulics Introduction4-44 Fluid Statics4-44 Conservation Laws in Fluid Flows4-47 Fluid Energy Losses in
5、Pipe Flows4-49 Flow Measurement and Discharge4-60 Water Hammer4-65 Pumps4-67 Nomenclature4-70 References Cited4-71 Additional Readings4-71 Chapter 4-3Automatic Sprinkler System Calculations Introduction4-72 Hydraulic Calculations4-73 Water Supply Calculations4-81 Hanging and Bracing Methods4-84 Perf
6、ormance Calculations4-85 Suppression by Sprinkler Sprays4-86 Nomenclature4-87 References Cited4-87 Chapter 4-4Foam Agents and AFFF System Design Considerations Introduction4-88 Description of Foam Agents4-88 Fire Extinguishment and Spreading Theory4-89 Assessment of Fire Extinguishing and Burnback P
7、erformance4-94 Aviation Fire Protection Considerations4-103 Foam-Water Sprinkler Systems4-112 Foam Environmental Considerations4-116 Nomenclature4-119 References Cited4-120 Additional Readings4-122 Chapter 4-5Foam System Calculations Introduction4-123 Basic Types of Foam System Protection4-125 Prote
8、ction of Incipient Spills and Related Hazards4-126 Protection for Fixed Roof Atmospheric Storage Tanks4-126 Protection of Floating Roof Storage Tanks4-127 Protection of Storage or High-Volume Hazards with High-Expansion Foam4-128 Limitations of Foam Fire Protection Systems4-129 Hydraulic Calculation
9、 for Atmospheric Storage Tanks Protected by Low-Expansion Foam Systems4-129 The Advent of Class AFoams4-144 Nomenclature4-145 References Cited4-146 Appendix4-146 Chapter 4-6Halon Design Calculations Introduction4-149 Characteristics of Halon4-149 System Configurations4-155 Design Concepts and Method
10、ology4-158 Agent Requirements: Total Flooding4-160 Flow Calculations4-163 Postdesign Considerations4-169 Environmental Considerations4-170 Nomenclature4-171 References Cited4-171 Chapter 4-7Halon Replacement Clean Agent Total Flooding Systems Introduction4-173 Characteristics of Halon Replacements4-
11、173 Clean Agent System Design4-186 Summary4-198 References Cited4-198 Additional Readings4-200 Chapter 4-8Fire Temperature-Time Relations Introduction4-201 Fire Temperatures4-201 Possible Fire Severities4-202 Characteristic Temperature Curves4-202 Standard Fire Curve4-206 Nomenclature4-207 Reference
12、s Cited4-207 Chapter 4-9Analytical Methods for Determining Fire Resistance of Steel Members Introduction4-209 Standard Test for Fire Resistance of Structural Members4-210 Methods of Protection4-212 Empirically Derived Correlations4-216 Heat Transfer Analysis4-222 Structural Analyses4-229 Nomenclatur
13、e4-236 References Cited4-237 Chapter 4-10Analytical Methods for Determining Fire Resistance of Concrete Members Introduction4-239 Material Properties of Concrete and Steel4-239 Heat Transmission4-242 Simply Supported Slabs and Beams4-245 Continuous Unrestrained Flexural Members4-246 Fire Endurance o
14、f Concrete Structural Members Restrained against Thermal Expansion4-247 Example of Continuous One-Way Span4-249 Reinforced Concrete Columns4-253 Reinforced Concrete Frames4-253 Reinforced Concrete Walls4-253 Prestressed Concrete Assemblies4-254 Composite Steel-Concrete Construction4-254 Recent Devel
15、opments4-254 References Cited4-255 Chapter 4-11Analytical Methods for Determining Fire Resistance of Timber Members Introduction4-257 Contribution of the Protective Membrane4-257 Charring of Wood4-260 Section 4 Design Calculations 4-OPENER.QXD 11/16/2001 1:24 PM Page 2 Load-Carrying Capacity of Unch
16、arred Wood4-265 One-Hour Fire-Resistive Exposed Wood Members4-268 Property Data4-269 References Cited4-271 Chapter 4-12Smoke Control Introduction4-274 Smoke Movement4-274 Smoke Management4-277 Principles of Smoke Control4-278 Purging4-281 Door Opening Forces4-281 Flow Areas4-282 Effective Flow Areas
17、4-283 Symmetry4-284 Design Parameters: AGeneral Discussion4-284 Pressurized Stairwells4-286 Stairwell Compartmentation4-287 Stairwell Analysis4-287 Elevator Smoke Control4-288 Zone Smoke Control4-289 Computer Analysis4-290 Acceptance Testing4-290 References Cited4-291 Chapter 4-13Smoke Management in
18、 Covered Malls and Atria Introduction4-292 Hazard Parameters4-293 Smoke Management Approaches4-293 Analytical Approach4-294 Smoke Filling Period4-295 Vented Period4-298 Special Conditions4-304 Limited Fuel4-306 Opposed Airflow4-307 Nomenclature4-308 References Cited4-309 Chapter 4-14Water Mist Fire
19、Suppression Systems Introduction4-311 Fundamentals of Water Mist Systems4-313 Fire Suppression Modeling4-320 The Importance of Fire Testing4-325 Engineering Details of Water Mist Systems4-327 Conclusions4-334 References Cited4-335 4-OPENER.QXD 11/16/2001 1:24 PM Page 3 41 Introduction Fire detection
20、 and alarm systems are recognized as key features of a buildings fire prevention and protection strategy. This chapter presents a systematic technique to be used by fire protection engineers in the design and analysis of detection and alarm systems. The majority of discussion is directed toward syst
21、ems used in buildings. However, many of the techniques and procedures also apply to systems used to protect planes, ships, outside storage yards, and other nonbuilding environments. Scientific research on fire growth and the movement of smoke and heat within buildings provides fire protec- tion engi
22、neers with information and tools that are useful in the design of fire detection systems. Also, studies of sound production and transmission allow communication systems to be engineered, thus eliminating the uncertainty in locating fire alarm sounders. All of this information al- lows engineers and
23、designers to design systems that meet specific, identifiable goals. Sections 1, 2, and 3 of this handbook introduced and discussed a series of concepts and tools for use by fire protection engineers. This chapter shows how some of these tools can be used collectively to design and evaluate detection
24、 and alarm systems. A Note about Precision When solving multiple equations with numerous variables from many sources, it is often easy to overlook the importance of precision and confidence in the final answer. This acknowledgment is particularly true since engineers have progressed from slide ruler
25、s to calculators to computers in a relatively short span of time. Most cal- culations in this chapter have been done using a com- putermost often with a simple spreadsheet. The generally accepted practice for these types of tools is to round off only the final answer to the correct number of signifi
26、cant digits. The standard and most widely taught rule for round- ing is to round off using the same number of significant digits as the least precisely known number used in the calculation. An alternate rule suggests using one more significant figure than suggested by the standard rule. It has been
27、shown that the alternate rule is more accurate and does not lead to loss of data as does the standard rule.1,2The alternate rule for rounding has been used in this chapter. For more information or to refresh your knowledge of precision, rounding, and significant fig- ures, consult the references or
28、a standard text on engi- neering and scientific measurements. Overview of Design and Analysis To design a fire detection and alarm system, it is first necessary to establish the systems goals. These goals are established by model codes, the property owner, risk manager, insurance carriers, and/or th
29、e authority having jurisdiction. Ultimately, the goals of the system can be put in four basic categories: 1. Life safety 2. Property protection 3. Business protection 4. Environmental concerns SECTION FOUR CHAPTER 1 Design of Detection Systems Robert P. Schifiliti, Brian J. Meacham, and Richard L. P
30、. Custer Robert P. Schifiliti, P.E., is a fire protection consultant based in Read- ing, Massachusetts, and an adjunct associate professor of fire protec- tion engineering at Worcester Polytechnic Institute. He specializes in fire detection and fire alarm system design and analysis. Brian J. Meacham
31、, Ph.D., P.E., is Principal Risk Consultant and Principal Fire Protection Consult for Arup Fire, located in Massa- chusetts. Dr. Meacham is a fellow of the Society of Fire Protection Engineers. Richard Custer, M.Sc., is Technical Director and Principal Fire Ana- lyst for Arup Fire. Mr. Custer is a f
32、ellow of the Society of Fire Protec- tion Engineers. 04-01.QXD 11/16/2001 11:52 AM Page 1 Some designers include heritage conservation in the list of goals. However, the protection of historic property is really another form of property and mission protection, although the methodology and extent for
33、 protection may vary. When designing for life safety, it is necessary to pro- vide early warning of a fire condition. The fire detection and alarm system must provide a warning early enough to allow complete evacuation of the danger zone before conditions become untenable. The fire detectors or fire
34、 alarm system may be used to activate other fire protec- tion systems, such as special extinguishing systems and smoke control systems, that are used to help maintain a safe environment during a fire. In some situations, the life safety mission of a detec- tion system is enhanced by providing inform
35、ation to occu- pants. This situation is often the case in stay-in-place or defend-in-place strategies or partial evacuation/relocation strategies. The detection system is used to provide infor- mation about the location and extent of the fire. Instruc- tions are then given to the target audience. Pr
36、operty protection goals are principally economic. The objective is to limit damage to the building structure and contents. Maximum acceptable losses are established by the property owner or risk manager. The goal of the system is to detect a fire soon enough to allow manual or automatic extinguishme
37、nt before the fire exceeds accept- able damage levels. Goals for the protection of a mission or business are determined in a manner similar to that used in property protection. Here, fire damages are limited to prevent un- desirable effects on the business or mission. Some items that need to be cons
38、idered are the effects of loss of raw or finished goods, loss of key operations and processes, and loss of business to competitors during downtime. Other concerns include the availability and lead time for obtaining replacement parts. If the equipment to be pro- tected is no longer available or requ
39、ires several months for replacement, the ability to stay in business during and af- ter an extended period of downtime may be jeopardized. Protection of the environment is also a fire protection concern. Two examples are (1) toxicity of products of combustion and (2) contamination by fire protection
40、 run- off water. Should large quantities of contaminants be ex- pected from a large fire, the goal of the system may well be to detect a fire and initiate appropriate response prior to reaching a predetermined mass loss from burning ma- terials or quantity of fire suppression agent discharged. Once
41、the overall goals have been set, specific per- formance and design objectives for a performance-based design can be established.35Performance-based fire pro- tection design requires that specific performance ob- jectives, rather than generic prescriptive requirements, be met. A typical prescriptive
42、requirement would be to provide a smoke detector for every 84 m2(900 ft2) or 9-m (30-ft) spacing. In prescriptive design, speed of detection and the fire size at detection for such an installation are not known or considered explicitly. In addition, if some action must be taken in response to the al
43、arm in order to control the fire, the expected damage is also unknown. Implementation of a fire safety performance objec- tive requires that the objective be stated first by the client in terms of acceptable loss. The client loss objectives must then be (1) expressed in engineering terms that can be
44、 quantified using fire dynamics, and (2) related to design fires, design fire environments, and the performance characteristics of fire suppression equipment. For exam- ple, the client loss objective may be to prevent damage to essential electronic equipment in the compartment of origin. To meet thi
45、s objective, one must first define what damage is. This damage could be expressed in terms of the thickness of the smoke layer. Other criteria, such as temperature or concentration of corrosive combustion products, or a combination of criteria, could also be used. Based on a study of the likelihood
46、of ignition and fire growth scenarios, a design fire needs to be established. The design fire is characterized by its heat release rate, Q g, at any moment in time; its growth rate, dq/dt; a combus- tion product rate dcp/dt, such as smoke particulate, toxic or corrosive species, and so forth; and pr
47、oduction rate, dp/dt. The design fire may be determined by (1) a combi- nation of small- and large-scale testing specific to the ap- plication or (2) analysis of data taken from studies reported in the literature. For a given fire safety design objective, there will be a point, Q g do,on the design
48、fire curve where the energy and product release rates will produce conditions representa- tive of the design objective. Given that there will be de- lays in detecting the fire, notifying the occupants, accomplishing evacuation, or initiating suppression ac- tions, the fire will need to be detected a
49、t some time in advance of Q g do. In order to account for these delays, a critical fire size, Q g cr,can be defined as the point on the de- sign fire curve at which the fire must be detected in order to meet the design objectives for a given spacing or radial distance from the fire. There are two types of delays that influence the size of the fire at detection: (1) those that are variable and (2) those that are fixed. Variable delays represent trans- port lag and are related to radial distance of the detector from the fire, ceiling height, and the convective heat re- lease rate of the fir