AWWA M31-2008 Distribution System Requirements for Fire Protection (Fourth Edition)《消防分配系统需求 第4版》.pdf

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1、Distribution System Requirements for Fire ProtectionAWWA MANUAL M31Fourth EditionMANUAL OF WATER SUPPLY PRACTICES M31, Fourth EditionDistribution System Requirements for Fire ProtectionCopyright 1989, 1992, 1998, 2008 American Water Works AssociationAll rights reserved. No part of this publication m

2、ay be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information or retrieval system, except in the form of brief excerpts or quotations for review purposes, without the written permission of the publisher.DisclaimerThe authors

3、, contributors, editors, and publisher do not assume responsibility for the validity of the content or any consequences of their use. In no event will AWWA be liable for direct, indirect, special, incidental, or consequential damages arising out of the use of information presented in this book. In p

4、articular, AWWA will not be responsible for any costs, including, but not limited to, those incurred as a result of lost revenue. In no event shall AWWAs liability exceed the amount paid for the purchase of this book.Project Manager/Technical Editor: Martha Ripley Gray, Melissa ValentineProduction E

5、ditor: Darice Zimmermann, D M31)Includes bibliographical references and index.ISBN 1-58321-580-81. Fire extinction-Water-supply. 2. Water-Distribution. I. American Water Works Association. TH9311.D565 2008628.9252-dc222008006142Printed in the United States of AmericaAmerican Water Works Association6

6、666 West Quincy Ave.Denver, CO 80235 Printed on recycled paperContentsList of Figures, vList of Tables, viiPreface, ixAcknowledgments, xiChapter 1 Fire Flow Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Impact on Distribution System Design, 1Community Governance,

7、 2Fire Flow Requirements, 2Calculating Fire Flow Requirements, 2Practical Limits on Fire Flow, 13Nonpotable Water Sources for Fire Fighting, 15References, 16Chapter 2 System Demand and DesignFlow Criteria . . . . . . . . . . . . . . . . .17Methods of Distribution, 17Rates of Water Use, 18Distributio

8、n System Appurtenances, 19System Evaluation and Design, 21Determining Design Flow, 21Flow Metering, 22Standby Charges for Fire Protection Systems, 22Water Distribution Analysis Techniques, 22References, 23Chapter 3 Distribution System Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9、 . .25Functions of Distribution Storage, 25Elevated and Ground Storage, 27Pumping for Distribution Storage, 28Location of Storage, 28Storage Reservoir Overflow Level, 28References, 30Chapter 4 Adequacy and Reliability of Distribution Systems . . . . . . . . . . .31Determining Level of Reliability, 3

10、1Application of Reliability Considerations, 33Reliability of Major System Components, 34Operations, 36References, 37iiiChapter 5 Automatic Fire Sprinkler Systems . . . . . . . . . . . . . . . . . . . . . . . . .39Advantages of Sprinkler Systems, 39Water Supply Requirements for Sprinklered Properties

11、, 40Types of Sprinklers for Commercial Buildings, 42Standpipes, 43Backflow Prevention for Fire Sprinkler Systems, 43References, 45Appendix A Agencies Involved in Fire Protection . . . . . . . . . . . . . . . . . . . . .47Insurance Services Office Inc., 47Insurance Organizations With Fire Protection

12、Interests, 48National Fire Protection Association, 48National Fire Service Associations, 48Fire Research Laboratories, 48National Fire Sprinkler Association, 48American Fire Sprinkler Association, 49International Code Council, 49Insurance Bureau of Canada, 49Insurers Advisory Organization, 49Nationa

13、l Research Council, 49Underwriters Laboratories of Canada, 49Appendix B Water Supply and Fire Insurance Ratings . . . . . . . . . . . . . . . . .51Insurance Ratings, 51References, 54Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

14、. . . . . .55List of AWWA Manuals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59ivFigures1-1 Typical occupancy classificationsnonmanufacturing, 61-2 Typical occupancy classificationsmanufacturing, 71-3 Comparison of fire flow calculations, 121-4 Compa

15、rison of fire flow calculations, including three exposure buildings, 142-1 Typical small city distribution system, 193-1 System Ahydraulic gradient with no storage, 293-2 System Bhydraulic gradients with storage between pump station and load center, 293-3 System Chydraulic gradients with storage bey

16、ond load center, 305-1 Sprinkler system design curves, 41B-1 Water supply evaluation, 53vTables1-1 Fire flow durations, 31-2 Values of coefficient (F) construction class, 41-3 Occupancy factors for selected combustibility classes, 51-4 Factor for exposure (Xi), 81-5 Factor for communications (Pi), 9

17、1-6 Needed fire flow for one- and two-family dwellings, 92-1 Values commonly used in distribution piping, 203-1 Water use and storage depletion for maximum day in a typical city, 265-1 Hazard classification schedule, 42viiPrefaceWater distribution systems have been developed and operated for a varie

18、ty of rea-sons. In the past, many communities recognized the need for safe, potable water that could be used for drinking and cooking. Governmental agencies or private enterprise promptly took on the responsibility of providing safe water to meet these basic human requirements.The need for nonpotabl

19、e water arose because of an increasingly sophisticated lifestyle. In many cases, the water systems established to provide potable water were augmented and enlarged to provide water for irrigation, car washing, industrial pro-cesses, and other purposes. It also became necessary to provide an adequate

20、 supply of water for fire protection and suppression. Systems that provide for fire protection needs have frequently been incorporated into the systems that provide potable water service as well as nonpotable service. As technology advances, many alternatives to this basic water supply configuration

21、 can be found. A notable alternative is the use of dual distribution systems.The American Water Works Association has published standards for materials used in the field of fire protection for many decades. However, it was not until the early 1980s that AWWAs Committee on Fire Protection developed t

22、he first edition of this manual, which addresses the planning, design, and maintenance of distribution systems that supply water for fire protection and suppression.This manual provides specific guidance on the design, operation, and mainte-nance of water distribution systems as they relate to fire

23、protection and fire suppres-sion activities. When the governing body of a community makes a conscious decision to use the available water supply system for fire suppression purposes, this manual should be consulted, judiciously applied, and tempered as local conditions require.This edition of the ma

24、nual updates the information, clarifies some topics, and deletes material that is no longer essential. The manual still closely parallels the first edition prepared by the Fire Protection Committee.As was the case with the first edition, this fourth edition does not intend to de-scribe how firefight

25、ers should use water to control fires, but rather how water utilities should design and operate their systems to maximize fire protection benefits while delivering safe, potable water to customers. The emphasis is on public wa ter systems and not on water systems exclusively designed for fire protec

26、tion. Similarly, this man-ual does not intend to reproduce material available elsewhere in AWWA publications such as Manual M17, Installation, Field Testing, and Maintenance of Fire Hydrants, or Standards C502, Dry-Barrel Fire Hydrants, and C503, Wet-Barrel Fire Hydrants.The adequacy of a water dist

27、ribution system for fire protection depends on the fire flows required. Chapter 1 describes several methods for determining required fire flows. Once fire flow requirements are determined, these are added to the other water system demand requirements. Chapter 2 discusses the impact of fire protectio

28、n on dis-tribution system design. Chapter 3 focuses on distribution storage in terms of both siz-ing and location. Chapter 4 discusses reliability issues arising because systems must remain in operation even when individual components are out of service. Chapter 5 describes fire suppression sprinkle

29、r systems and their effect on water requirements, particularly because they affect how water is used for fire fighting.ixAppendix A lists organizations involved in fire protection and describes the or-ganizations and their roles. Appendix B describes the relationship between the water supply system

30、and fire insurance ratings, because one benefit of supplying needed fire flow is an improved fire insurance rating for a community.The water utility has important partners in fire protection. The water utility must work together with local fire officials, building code officials, and others to effec

31、tively and efficiently promote fire protection. Good communication between all involved parties is essential to protect property and life.xAcknowledgmentsThe members of the AWWA Fire Protection Committee at the time this edition was prepared included:Kevin Kelly, ChairDoug Bayles, Pittsburg Tank the

32、 steam can deprive the fire of oxygen, and in the case of miscible or dense fluids, water can disperse the fuel. The key question for water utilities is how large must distribution system components be to provide sufficient water for fire protection. The remainder of this manual presents methods for

33、 estimating these requirements.IMPACT ON DISTRIBUTION SYSTEM DESIGN _The decision to provide water for fire protection means that a utility must explicitly consider fire flow requirements in sizing pipes, pumps, and storage tanks. In larger systems, fire protection has a marginal effect on sizing de

34、cisions, but in smaller sys-tems these requirements can correspond to a significant increase in the size of many compo nents. In general, the impact of providing water for fire protection ranges from being minimal in large components of major urban systems to being very significant in smaller distri

35、bution system pipes and small distribution systems. The most significant impacts are installing and maintaining fire hydrants, pro-viding adequate storage capacity, and meeting requirements for minimum pipe sizes (e.g., 6-in. 150-mm pipes in loops and 8-in. 200-mm dead ends) in neighborhood distribu

36、tion mains when much smaller pipes would suffice for delivery of potable water only. These requirements make designing distribution systems easier for the engineer but more costly for the water utility. Other impacts include providing extra treatment capacity at plants and extra pumping capacity at

37、pump stations.2 FIre PrOTeCTIONCOMMUNITY GOVERNANCE _The decision of whether or not to size distribution system components, including water lines, appurtenances, and storage facilities, for fire protection must be made by the governing body of the community. This decision is made in conjunction with

38、 the water utility if the utility is privately owned. However, there is no legal requirement that a governing body must size its water distribution system to provide fire protection. In some instances, this undertaking may be prohibitively expensive. For privately owned utilities, the distribution s

39、ystem would not be sized for fire protection unless such an undertaking could be shown to be commercially profitable.The governing bodies of most communities do provide water for fire protection for a variety of reasons, including protection of the tax base from destruction by fire, preservation of

40、jobs that would be lost in the event of a large fire, preservation of human life, and reduction of human suffering.When a communitys governing body provides fire protection, it must do so in accordance with a well-thought-out plan that will provide adequate supplies for the in-tended purpose. An ina

41、dequate fire protection system provides a false sense of security and is potentially more dangerous than no system at all.FIRE FLOW REQUIREMENTS _When establishing a fire protection plan, the governing body must first select a well-documented procedure for determining the fire flow requirement. Cent

42、ral to provid-ing “enough” water is a determination of how much water should be made available for any given situation. The following definition of required fire flow will be used in this manual: the rate of water flow, at a residual pressure of 20 psi (138 kPa) and for a specified duration, that is

43、 necessary to control a major fire in a specific structure. A complete definition of required fire flow requires a determination of both the rate of flow required and the total amount of water that must be applied to control the fire. The rate of flow and the duration of flow required may be specifi

44、ed by the simple equation:quantity = rate duration (Eq. 1-1)Understanding Water UseThe importance of flow rate and total quantity must be realized when attempting to understand the ways in which water is used to suppress fire. Water applied to a fire ac-complishes two things. First, it removes the h

45、eat produced by the fire, thereby prevent-ing that heat from raising the temperature of unignited material to the ignition point. Water absorbs the heat of the fire when it changes from a liquid to a gaseous state as the heat is released as steam. Second, water not converted to steam by the heat of

46、the fire is available to cool material not yet ignited. Water also blankets unignited mate-rial, excluding the oxygen required to initiate and sustain combustion.CALCULATING FIRE FLOW REQUIREMENTS _All fires are basically different because of random variations in the structure and con tents of the b

47、urning building, exposures (configuration of adjacent structures not involved in a fire but that are to be protected to prevent the fire from spreading), weather, temperature, and length of time the fire has been burning. Consequently, numerous methods have been proposed for determining how much wat

48、er is enough to suppress a fire. The following sections describe four methods for calculating fire flow requirements. These methods have been developed by the Insurance Services Office FIre FlOW reQUIreMeNTS 3Inc. (ISO),*Iowa State University (ISU),the National Fire Academy,and the Illinois Institut

49、e of Technology Research Institute (IITRI).Responsibility for determining needed fire flows for individual structures usually rests with the local fire officials based on information provided by the owner. Rating services such as ISO may determine this flow during an evaluation for insurance pur-poses. For planning purposes, water departments may determine representative fire flow requirements in portions of towns for system planning, hydraulic analysis, and des