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FIRE PROTECTIONFIRE PROTECTION

AUTOMATIC SPRIN-KLER SYSTEM RELIA-BILITY

PROJECT MANAGEMENTOF AN ESFR SPRINKLERINSTALLATION

MIC IN FIRE SPRIN-KLER SYSTEMS

7

39

14

PROVIDING PRACTICE-ORIENTED INFORMATION TO FPEs AND ALL IED PROFESSIONALS

WINTER 2001 Issue No.9

ALSO:

SPRINKLERNEW

TECHNOLOGYSPRINKLERNEW

TECHNOLOGYpage 25

Fire Protection Engineering 1

3 BOOK REVIEWSprinkler Hydraulics by Harold S. Wass, Jr.Russell P. Fleming, P.E.

5 LETTER TO THE EDITOR

7 AUTOMATIC SPRINKLER SYSTEM RELIABILITY This article provides a brief summary of published sprinkler reliability studies, and an attempt is made to address uncertainties in the reported failure rates.Edward K. Budnick, P.E.

14 MICROBIOLOGICALLY INFLUENCED CORROSION IN FIRESPRINKLER SYSTEMSMIC in fire sprinkler systems has grown from an obscure topic of regionaldiscussions to one now generating widespread concern and debate. Thisarticle describes the MIC process and analyzes current treatments.Bruce H. Clarke

39 PROJECT MANAGEMENT OF AN ESFR SPRINKLER INSTALLATIONThis article discusses the various aspects involved in managing an EarlySuppression Fast Response (ESFR) sprinkler construction project to ensure a successful outcome.William Fletcher, P.E.

44 CAREER CENTER

47 SFPE RESOURCES

52 FROM THE TECHNICAL DIRECTORChanges to the PE Licensing Model Law ProposedMorgan J. Hurley, P.E.

For more information about the Society of Fire Protection Engineering or FireProtection Engineering magazine, try us online at www.sfpe.org.

Cover photo ©2000 Factory Mutual Insurance Company. Reprinted with permission.

contents W I N T E R 2 0 0 1

25COVER STORYWHICH SPRINKLER TO CHOOSE?In the past, choosing a sprinkler was easy. Today, the fire protection engineerhas a multitude of choices – and issues – to consider when looking at newsprinkler technology.Kenneth E. Isman, P.E.

Subscription and address change correspondence should be sent to: Society of Fire Protection Engineers,Suite 1225 West, 7315 Wisconsin Avenue, Bethesda, MD 20814 USA. Tel: 301.718.2910. Fax: 301.718.2242.E-mail: [email protected].

Copyright © 2001, Society of Fire Protection Engineers. All rights reserved.

FIRE PROTECTIONFIRE PROTECTION

SFPE

Fire Protection Engineering (ISSN 1524-900X) is published quarterly by the Society of Fire ProtectionEngineers (SFPE). The mission of Fire ProtectionEngineering is to advance the practice of fire protectionengineering and to raise its visibility by providing information to fire protection engineers and allied professionals. The opinions and positions stated arethe authors’ and do not necessarily reflect those of SFPE.

Editorial Advisory BoardCarl F. Baldassarra, P.E., Schirmer EngineeringCorporation

Don Bathurst, P.E.

Russell P. Fleming, P.E., National Fire SprinklerAssociation

Douglas P. Forsman, Oklahoma State University

Morgan J. Hurley, P.E., Society of Fire ProtectionEngineers

William E. Koffel, P.E., Koffel Associates

Jane I. Lataille, P.E., Industrial Risk Insurers

Margaret Law, M.B.E., Arup Fire

Ronald K. Mengel, Honeywell, Inc.

Warren G. Stocker, Jr., Safeway, Inc.

Beth Tubbs, P.E., International Conference of BuildingOfficials

Regional Editors

U.S. HEARTLAND

John W. McCormick, P.E., Code Consultants, Inc.

U.S. MID-ATLANTIC

Robert F. Gagnon, P.E., Gagnon Engineering, Inc.

U.S. NEW ENGLAND

Thomas L. Caisse, P.E., C.S.P., Robert M. Currey &Associates, Inc.

U.S. SOUTHEAST

Jeffrey Harrington, P.E., The Harrington Group, Inc.

U.S. WEST COAST

Scott Todd, Gage-Babcock & Associates, Inc.

ASIA

Peter Bressington, P.Eng., Arup Fire

AUSTRALIA

Richard Custer, Custer Powell, Inc.

CANADA

J. Kenneth Richardson, P.Eng., Ken Richardson FireTechnologies, Inc.

NEW ZEALAND

Carol Caldwell, P.E., Caldwell Consulting

UNITED KINGDOM

Dr. Louise Jackman, Loss Prevention Council

Publishing Advisory BoardBruce Larcomb, P.E., BOCA International

Douglas J. Rollman, Gage-Babcock & Associates, Inc.

George E. Toth, Rolf Jensen & Associates

PersonnelPUBLISHER

Kathleen H. Almand, P.E., Executive Director, SFPE

TECHNICAL EDITOR

Morgan J. Hurley, P.E., Technical Director, SFPE

MANAGING EDITOR

Joe Pulizzi, Penton Custom Media

ART DIRECTOR

Pat Lang, Penton Custom Media

COVER DESIGN

Dave Bosak, Penton Custom Media

By Russell P. Fleming, P.E.

It is unusual to be given an oppor-tunity to review a second edition ofa book that includes, among the

changes from the first edition, com-ments on your original book review 17years earlier. This is the situation withthe new second edition of HaroldWass’s Sprinkler Hydraulics. In hisintroduction to the new edition, writ-ten shortly before his death in 1999,Mr. Wass noted that my original reviewwas generally favorable, but includeda caveat to the effect that it was writ-ten from an insurance authority’s pointof view. He indicated that this gavehim pause, since he considered him-self to be objective. The result of hisdeliberation was a conclusion that theinsurance industry’s bias is one of themore benign, noting that even fireprotection consultants may have abias, a bias toward complexity.

Actually, the book may not techni-cally be a true second edition since ithas a new expanded title: SprinklerHydraulics and What It’s All About.The book is updated to include anumber of changes in the NFPA 13sprinkler rules that have taken placesince the original book was publishedin 1983 by IRM Insurance, where Mr.Wass was a longtime employee. Thereare a number of references to the lat-est changes in the 1999 edition of thesprinkler standard, which incorporatessprinkler design criteria formerly foundwithin NFPA 231 and 231C for high-piled storage. The book also has anew publisher: the Society of FireProtection Engineers.

What remains the same is the abilityof the book to take the mystery out ofhydraulic calculations. Harold Wasswrote in a conversational style andbasically tried to help the readerunderstand how water flows throughpiping. The book starts with brief dis-cussions of the mathematics involvedand the units of measurements, moveson to some of the advances in sprin-kler technology, and then settles in onthe subject of hydraulic calculations.Sprinkler discharge, K-factors, designareas, friction loss formulae, equivalentlengths of fittings, and all the otherelements one would expect are includ-ed. One might argue that they are alladdressed in NFPA 13 as well, but thisbook provides a context for many ofthe rules of the standard. Sample setsof calculations are provided for treesystems, with and without velocitypressures, and for a system under asloped roof. The special flow charac-teristics of loops and grids are ana-lyzed. Appendices are also especiallyuseful. One provides friction losstables for Schedule 40 steel pipe usinga C-factor of 120, but modification fac-tors are included for other C-factors,

piping materials, and a number of spe-cial listed piping products.

Sprinkler Hydraulics is HaroldWass’s legacy, his gift to the fire pro-tection community. It is one of a veryfew texts dealing with the subject ofhydraulic calculations for sprinkler sys-tems and remains the best available.

Russell P. Fleming is with theNational Fire Sprinkler Association.

For ordering information, or for anonline version of this article, go towww.sfpe.org.

R e v i e w o f

by Harold S. Wass, Jr.

book review

WINTER 2001 Fire Protection Engineering 3

Recently, the SFPE Board ofDirectors decided to discontinueSFPE’s role as the Secretariat for

the International Association for FireSafety Science (IAFSS). For those whodo not know the IAFSS (www.iafss.org),it is an international organization topromote the dissemination of fireresearch and science. It does thisthrough triannual symposia, the next(7th) to be held in Worcester, MA, in2002. The IAFSS has a world-widemembership of about 300 with officersscattered about the globe. The IAFSSwill find another source of administra-tive services, but I was moved by thisevent to raise some issues to the fireprotection community on the role ofscience. Since the IAFSS embodies thescientific pursuit of the knowledge forfire safety and the SFPE embodies theuse of engineering tools to design andanalyze fire safety, we need to realizehow important they are to each other.

As a mechanical engineer by initialtraining, I have had the opportunity toview other engineering professionalorganizations, such as the ASME, andrealize that SFPE has a long way togrow. The traditional engineering pro-fessions are grounded in core curricula,using textbooks that have basic funda-

mental information approved by thescientific community. Fire protectionengineering is not at the same state. Itneeds the input of science, and it needsthe propagation of fundamental princi-ples within its applications to develop-ment and design. These features arerepresented by The SFPE Handbook ofFire Protection Engineering, 2nd edi-tion. (I note not much different fromthe first edition.) If one examines thecontents, one will see that about 30 per-cent of the authors are scientists whoare not members of SFPE. The scientificgrounding of the subject is being devel-oped outside of the profession. Thishas happened in other engineering dis-ciplines, but they are probably too oldto have an active memory of the originof the science. Most of the other disci-plines have grown due to technologicaladvances that have sparked industrialdevelopment and a market for profit.Safety does not have the same incen-tives.

Fire safety is bound in regulations.Knowledge of the rules makes fire pro-tection more of a legal exercise thanengineering. Many wish to change thatthrough the acceptance of performancecodes for fire safety. But examine thatprocess: (1) We needed credible sci-

ence that could be readily used, and(2) We needed recognition of the sci-ence. I think the SFPE Handbook wenta long way to establish that recognitionand its credibility. That science, whichfound its way into the Handbook, cameabout from a concerted U.S. govern-ment-funded program in the 1970s thatestablished a worldwide dialogue. The1980s saw this drop off and the 1990ssaw it sustained by those applying sci-ence rather than developing it. Indeed,the IAFSS would very eagerly move tohave symposia every 2 years, but manyfeel that there is not enough newresearch to warrant that frequency.

I think it’s time that members of thefire engineering profession realize theimportance of science and its shortagein the field. The science eventuallyneeds to be developed within the pro-fession. Ways must be found to enlistthe intellect of scientists to contributeonce again to fire research and its sci-ence. Fire safety is a federal govern-ment responsibility, since no individualor entity has the means to fully appre-ciate fire hazard and risk. I urge theSFPE and its membership to recognizethe need to enlist scientists and to workto establish the adequate fundingsources to make the profession grow tomaturity.

James G. Quintiere, Ph.D.John L. Bryan ProfessorThe Department of Fire Protection

EngineeringUniversity of MarylandCollege Park, MD


letter to the editor

CORRECTIONS

In the Fall 2000 issue, Joe Cappuccio’s name was misspelled, and AndrewBowman was not listed as being a pro-fessional engineer.

SCIENCE and

FIREPROTECTION

Engineering


By Edward K. Budnick, P.E.

INTRODUCTION

When automatic fire sprinklersystems, or any fire protec-tion safety features, are

included in a fire protection designpackage, it is assumed that, if needed,they will perform as expected. Onemeasure of expected performance is asystem’s reliability. Reliability is gener-ally reported as probabilistic, i.e., thepercent success rate for a given num-ber of systems over a fixed time peri-od. Put more simply, the reliability(i.e., probability of success) isexpressed as

(1)

Several published studies providereliability estimates for automatic sprin-kler systems. These estimates indicatethat, historically, sprinkler systems havebeen highly reliable. However, thereare biases and limitations in the dataand the analyses that restrict their use-fulness. Most of the published studiesdo not attempt to address these limita-tions or any other elements of uncer-tainty in the estimates. Also, most ofthe studies are more than ten years oldand, therefore, do not include morecurrent sprinkler technologies in thedatabases.

Simple statistical methods are avail-able to more accurately estimate auto-matic sprinkler system reliability andthe uncertainty associated with suchestimates. Some of these methods canhandle “sparse” databases, i.e., smalldata sets from a few systems or from asingle system over a relatively shortperiod of time. These methods and theresulting predictions are of value tomanufacturers (in developing newsprinkler technologies and identifyingpossible failure modes), the user (inoptimizing Inspection, Testing, andMaintenance (ITM) costs and insuring

a high level of operational reliability),and the designer (in performing proba-bilistic-based risk analyses for newdesign projects). Accurate estimates ofreliability are necessary inputs to risk-based analyses where failure rates andredundancy considerations must beevaluated.

This article provides a brief summa-ry of published sprinkler reliabilitystudies. An attempt is made to addressuncertainties in the reported failurerates in a systematic manner. Ratherthan report the results as a single esti-mate of sprinkler reliability, statisticalmethods are used to average the indi-vidual estimates within specified confi-dence limits. The value of this simpleanalysis lies in the limit estimates.While calculating the “average” valueamong several available data sourcesdoes not in itself improve the qualityof the estimate, the simple calculationof the range of possible estimates atleast allows the user to perform limitedsensitivity analyses. Such analyses pro-vide input to risk-based assessmentsfor existing or proposed fire safetydesigns.

An illustration of the use of selectedstatistical methods to evaluate reliabili-ty for small or “sparse” data sets is alsoprovided. As an example, limited ITMdata for several existing sprinkler sys-tems are analyzed. The results demon-strate the potential usefulness of smallor limited data sets in estimating thereliability of a specific automatic sprin-kler system as well as the effects of

changing ITM frequency on those esti-mates. These methods can be helpfulin evaluating the reliability of newersprinkler technologies with relativelyshort field experience.

RELIABILITY CONCEPTS

A detailed discussion of reliabilityengineering is outside the scope of thisarticle. Modarres1 provides a morecomplete review of the subject. Briefdescriptions of selected elements ofreliability are listed below to orient thereader to the value and limitationsassociated with published data onautomatic sprinkler system reliability.

Reliability is normally defined as anestimate of the probability that a sys-tem or component will function asdesigned over a designated time peri-od. There are two components tooverall reliability. Operational reliabil-ity is a measure of the probability thata system or component will operate asintended when called upon. It isdirectly affected by the types and fre-quency of testing and maintenanceperformed on the system.Performance reliability (i.e., capabili-ty) is a measure of the adequacy ofthe system, once it has operated, tosuccessfully perform its intended func-tion. For a sprinkler system, opera-tional reliability accounts for the“readiness” of the system components,while performance reliability address-es the “capability” of the system toperform satisfactorily under specific

AUTOMATIC SPRINKLER SYSTEM RELIABILITY

P successnumber of successes

total number of incidents( ) =

8 Fire Protection Engineering NUMBER 9

TABLE 1. Selected Automatic Sprinkler Reliability Studies (percent)

Reliability Value Occupancy Reference (of success)

Milne6 96.6/97.6/89.2NFPA7 90.8-98.2Miller7 86

Commercial Maybee4 99.5Kook3 87.6Taylor2 81.3Linder9 96

Miller8 95.8Miller8 94.8

General Powers10 96.2Richardson11 96

Finucane et al.12 96.9-97.9Marryat5 99.5

fire exposures. The capability of thesystem is related to the scope and ade-quacy of the engineering design stan-dards (e.g., NFPA 13) and the level ofcompliance of the system and its com-ponents with the standards.

Two other important concepts arefailed-safe and failed-dangerous.When a sprinkler system fails safe, itoperates when no fire event hasoccurred. An accidental discharge of asprinkler is an example of a failed-safecondition. A failed-dangerous condi-tion occurs when a system does notfunction when needed, e.g., a sprin-kler fails to open, or the water supplyis unavailable.

Studies that rely on fire incidentdata to estimate automatic sprinklersystem reliability mix both operationaland performance reliability elements.They also typically do not includefailed-safe incidents in the analysis. Onthe other hand, studies that rely ontesting and maintenance data are, forthe most part, providing estimates ofoperational reliability.

PUBLISHED STUDIES

Several studies have been publishedthat report estimates of automatic sprin-kler system “reliability.” For the mostpart, these studies provide estimatesbased on review of actual fire incidentswhere automatic sprinklers were pre-sent. As a group, they vary significantlyin terms of reporting periods, the typesof occupancies, and the level of detailregarding the types of fire incidents andsprinkler system design. Nevertheless,such studies are routinely referencedand provide some basis for estimatingsprinkler system reliability.

Table 1 provides a summary of thereported reliability estimates. The threeoccupancy categories reflect occupancytype variations in the reported esti-mates. Several studies provided reliabil-ity estimates for “commercial” occupan-cies. These are grouped accordingly inthe table. The estimates grouped underthe “general” occupancy category werefrom studies that grouped commercial,residential, and institutional occupan-cies into a single database.

The estimates indicate relatively highreliability for automatic fire sprinklersystems. However, significant variation

exists among the various studies. Thereported reliability estimates rangefrom 81.3 percent to 99.5 percent.These differences may be attributableto any number of variations in the pro-tocols or the databases used by eachstudy. For example, the relatively lowvalue of 81.3 percent2 as well as thesomewhat higher value of 87.6 percentreported by Kook3 appear to reflectbiases in the databases. In both stud-ies, the number of incidents was rela-tively small. And, while most of thesuppression systems in the databaseswere sprinkler systems, apparentlyother types of suppression systemswere also included. In addition, thehigh-end estimates of 99.5 percentreported by Maybee4 and Marryat5

reflect sprinkler system performance inoccupancies where inspection, testing,and maintenance were rigorous andexceeded customary requirements forITM activities. If these studies wereexcluded from the group, the range ofreliability estimates for the remainingstudies is from 86 percent to 97.9 per-cent, which still represents a significantrange.

An additional limitation in thereported sprinkler reliability estimatesis that most of the sprinkler systemswere more than 15 years old.Therefore, while the reliability esti-mates provide reasonable informationfor conventional spray sprinkler tech-

nology, it may not be appropriate torely on these estimates to evaluate thereliability of newer technologies suchas quick response, residential, andESFR sprinklers without addressingadditional factors.

LIMITED UNCERTAINTY ANALYSIS

Estimates of reliability are requiredinput to fire risk assessments. Theapplicability and accuracy of such esti-mates are perpetuated through the riskanalysis and directly reflected in theperformance outcomes. The estimatescompiled in Table 1 demonstrate vari-ability in sprinkler system reliabilityamong different studies. Unless theparameters of a particular study matchthose of interest, reliance on the esti-mate of reliability from a single studycan incorrectly alter the results of arisk assessment.

Relatively simple statistical methodsare employed here to provide both“estimates” of sprinkler system reliabil-ity and measures of “uncertainty” asso-ciated with the reported estimates.Uncertainty is reported as confidenceintervals, i.e., the upper and lowerbounds associated with the reliabilityestimate.

The estimates of reliability are sim-ple calculations of the “mean” of thevalues reported in Table 1. The confi-dence intervals are calculated based


on the degree of certainty required.There are many factors that areinvolved in selecting a degree of cer-tainty. In its simplest form, it is a mea-sure of the likelihood that the actualmean value falls within the confidenceintervals. Assuming normal distribu-tion, the higher the accuracy desired,the wider the confidence intervals(and the higher the required certainty).

Mean reliability estimates and 95percent confidence limits were calcu-lated for each of the occupancy cate-gories represented in the data sources.Similar estimates were calculated for acategory referred to as “combined,”which is simply combined estimatesfor both the commercial and generalcategories. The 95 percent confidencelimits were selected as representativeof confidence limits typically used forquality assurance estimates for manu-factured machine parts. Other confi-dence limits are routinely used,depending on the required certaintyassociated with a particular product orsystem. Table 2 provides a summary ofthe results of this analysis.

This relatively simple effort at esti-mating variance in reported dataimproves the statistical certainty of thereported reliability estimates. Forexample, for the three occupancy cate-gories presented in Table 2, the“mean” reliability estimates range from93.1 to 96.0 percent, a relatively smallrange, and much smaller than therange associated with the raw reliabili-ty estimates in Table 1. Greater confi-dence in the estimates is also providedby reporting a range of estimates usingupper and lower confidence limits.This information reduces the uncer-tainty in estimating the impact ofsprinkler system reliability in risk-based design evaluations.

ANALYSIS OF SMALL DATA SETS

Field performance data for newsprinkler technologies are limited.Therefore, in order to estimate the reli-ability of these systems or components,methods must be used that can handlesmall data sets. The results from a pilotstudy13 of several existing automaticsprinkler systems are used to demon-strate the usefulness of such analyses.

Selection of the Pilot StudySystem(s)

An important step in the pilot studywas the selection of the sprinkler sys-tems and collection of the data to bestudied. This was accomplished byreviewing existing sprinkler systemITM data, in addition to available sys-tem drawings and documentation.Detailed ITM records were obtainedfor a 66-month period for severalsprinkler systems in the same complexof buildings.

Development of System andComponent ITM Database

The second element of the studywas the development of a database.The raw ITM data collected for thesprinkler systems were reviewed andan appropriate database scheme devel-oped. The data obtained from the ITMreports were placed in a spreadsheetdatabase in the statistical package.14

This statistical package offers the abili-ty to serve as a database and a statisti-cal tool for analysis.

Table 2. Reliability Estimates for Sprinkler Systems

Note: Combined = Commercial and General

Commercial General Combined

Lower confidence limit (95%) 88.1 93.9 92.2Mean (%) 93.1 96.0 94.6Upper confidence limit (95%) 98.1 98.1 97.1Number of referenced studies 9 7 16

Sprinkler1

Sprinkler6

Sprinkler5

Sprinkler2

Sprinkler4

Sprinkler3

SprinklerFailure

Sprinkler SystemOperational Failure

PipeRupture

8" AlarmCheckValve

Figure 1. Simplified Automatic SprinklerFault Tree

The database spreadsheet set up eachinspection form as an individual case.The ITM results were entered for eachcomponent in each system identified bythe test record. The results for all com-ponent tests were either “pass” or “fail.”

Development of System Fault TreesOnce component failure rates were

developed, system schematics wereused to develop fault trees for individ-ual systems. Figure 1 provides a sum-marized version of the fault treedesign. The fault tree structures wereprogrammed into spreadsheets. Thespreadsheet programs allowed failureprobability and reliability informationto be propagated through the systemsusing the fault tree models, resulting inan overall system reliability estimate.

Once the baseline system reliabilityinformation was obtained, furtheranalysis was performed to examinetesting and inspection intervals andhow altering these intervals affectedthe system’s reliability. The use of faulttrees provided information that offersinsight into testing and inspection fre-quencies and established a means totrack system performance.

Fault trees were constructed foreach sprinkler system. For the faulttree models, the system’s boundarieswere defined as the base of the systemriser to the sprinkler grid. Defining the

system with boundaries at the riserand sprinkler grid assumed that thewater supply was 100 percent reliable.

Component Failure RatesThe model used to develop compo-

nent failure rates was the ExponentialModel for Life Testing (EMLT).13 TheEMLT model defines the estimate ofthe mean life (µ) of a component as

(2)

whereTr = accumulated time on test, andr = number of component fires.

The confidence interval about themean is given by

(3)

where is dependent on thedegrees of freedom (DF) and foundin statistical tables, andDF = 2(r).

The 95 percent confidence intervalabout the estimated mean was calcu-lated for each component failure rate.The individual system components’failure rates are provided in Table 3along with the industry reported fail-ure rates for similar components.

Reliability EstimatesTable 4 provides the reliability esti-

mates and associated uncertainty of thesystem fault tree model calculations.The analysis was performed using theexisting ITM frequencies, checkingmanual valve positions, and sprinklerand pipe inspections conducted eachmonth. The existing frequency tests allother system components quarterly.The system fault tree models were thenused to estimate the reliability of thesprinkler system if the monthly inspec-tions were extended to quarterly fre-quencies. In addition to the actualcomponent failure data, industry com-ponent failure data for similar compo-nents were used in the fault trees. Thereported confidence intervals were alsopropagated to allow for comparison.

The uncertainty intervals reportedfor the system reliability estimatesreflect the propagation of the 95 per-cent confidence interval about themean component failure rates throughthe fault tree models. This was accom-plished by quantifying the componentfailure rate distributions as fuzzy setsand using interval arithmetic in thefault tree model. Singer16 presents thetheory and methodology for this quan-tification and propagation.

The mean reliability estimates illus-trate the reduction in system reliabilitythat occurs when ITM frequencies are

Number of Total Hours Pilot Systems ITM Data IndustryComponent Components in System 95% Confidence Interval Failure Rate

in Database Failure Rate (failures/hour) (failures/hour)

PIV 10 480,480 0 N/A

ACV 10 480,480 0 14.0 x 10-6

OSY 172 8,264,256 7.5x10-8 < 3.6x10-7 < 8.7x10-7 14.0 x 10-6

Main Drain 10 480,480 0 4.0 x 10-6

Inspector’s Test 10 480,480 2.3x10-6 < 8.3x10-6 < 1.8x10-5 4.0 x 10-6

Flow Alarm 10 480,480 5.8x10-6 < 1.5x10-5 < 2.7x10-5 24.6 x 10-8

Motor Gong 10 480,480 4.1x10-5 < 2.5x10-5 < 1.3x10-5 22.0 x 10-6

Fire Department Connection 10 480,480 0 N/A

Piping (gasket failure) 10 480,480 5.0x10-7 < 4.0x10-6 < 1.2x10-5 11.0 x 10-6

Note: 1 from Finucane and Pickney12

2 from WASH-140015

Table 3. Component Failure Rates

µ = T

rr

2 2

22

1 22

T

X

T

Xr r

α α

µ/ /

< <−

Xα / 22



reduced. Not only does system reliabili-ty decrease with reduced ITM frequen-cies, but also the uncertainty associatedin the lower reliability direction of theuncertainty interval becomes larger. Thisis an element of system reliability analy-sis that is often overlooked but greatlyaffects the interpretation of the resultsand clearly demonstrates the limitationsof a given database. As the database isexpanded, uncertainty associated withthe reliability estimates will be reduced.

The results of this effort suggest thatmeaningful reliability estimates can beobtained for sprinkler systems withlimited data. This capability is helpfulin addressing specific types of systems(including those using newer technolo-gies) or systems exposed to similarenvironments. Based on the results ofsuch analysis, ITM frequencies or sys-tem components can be tailored toachieve a desired reliability based onthe specific system in question ratherthan general industry values.

ACKNOWLEDGMENTS

This article is based on work sup-ported by the U.S. Department ofEnergy and the National Institute ofStandards and Technology. The authorthanks Mr. Christopher Schemel, whoworked on both of these projects andperformed analyses that were reliedupon in preparing this article.

Edward K. Budnick, P.E., is withHughes Associates.

REFERENCES

1 Modarres, M. Reliability and RiskAnalysis, University of Maryland, MarcelDekker, Inc., New York, NY, 1993.

2 Taylor, K.T. “Office Building Fires...ACase for Automatic Fire Protection,” FireJournal, 84 (1), January/February 1990,pp. 52-54.

3 Kook, K.W. “Exterior Fire Propagation ina High-Rise Building,” Master’s Thesis,Worcester Polytechnic Institute,Worcester, MA, November 1990.

4 Maybee, W.W. “Summary of FireProtection Programs in the U.S.Department of Energy – Calendar Year1987,” U.S. Department of Energy,Frederick, MD, August 1988.

5 Marryat, H.W. Fire: A Century ofAutomatic Sprinkler Protection inAustralia and New Zealand 1886-1986,Australian Fire Protection Association,Melbourne, Australia, 1988.

6 Milne, W.D. “Automatic SprinklerProtection Record,” Factors in SpecialFire Risk Analysis, Chapter 9, pp. 73-89.

7 NFPA. “Automatic Sprinkler PerformanceTables, 1970 Edition,” Fire Journal, July1970, pp. 35-39.

8 Miller, M.J. “Reliability of Fire ProtectionSystems,” Loss Prevention ACEPTechnical Manual, 8, 1974.

9 Linder, K.W. “Field Probability of FireDetection Systems,” Balanced DesignConcepts Workshop, NISTIR 5264, R.W.Bukowski (Ed.), Building and FireResearch Laboratory, National Institute ofStandards and Technology, September1993.

10 Powers, R.W. “Sprinkler Experience inHigh-Rise Buildings (1969-1979),” SFPETechnology Report 79-1, Society of FireProtection Engineers, Boston, MA, 1979.

11 Richardson, J.K. “The Reliability ofAutomatic Sprinkler Systems,” CanadianBuilding Digest, Vol. 238, July 1985.

12 Finucane, M, and Pickney, D. “Reliabilityof Fire Protection and DetectionSystems,” United Kingdom AtomicEnergy Authority, University ofEdinburgh, Scotland.

13 Hughes Associates, Inc. “Pilot Study:Automatic Sprinkler System ReliabilityAnalysis,” Hughes Associates, Inc.,Baltimore, MD, September 30, 1998.

14 SYSTAT, SYSTAT 6.0 for WINDOWSTM,SPSS, Inc.

15 WASH-1400, “Reactor Safety Study, anAssessment of Accident Risks in U.S.Commercial Nuclear Power Plants,”WASH-1400, United States AtomicEnergy Commission, August 1974.

16 Singer, D. “A Fuzzy Set Approach toFault Tree and Reliability Analysis,”Fuzzy Sets and Systems, 34, pp. 145-155.

17 Schemel, C.F., and Budnick, E.K. “PilotStudy: Analyzing Fire Protection SystemReliability Using Limited Databases,”Proceedings of the Fire Suppression andDetection Research ApplicationsSymposium, Fire Protection ResearchFoundation, Quincy, MA, February 1999.

Table 4. Sprinkler System Reliability Estimates and 95% Confidence Limits for Six Existing Sprinkler Systems13

System Reliability System Reliability System Reliability System Reliability Using Industry for All ITM at for All ITM at

System at Current Component Failure Rate Data 3-Month Frequency 3-Month FrequencyComponent Testing and Current Testing Using Pilot Component Using Industry Component

Frequency1 Frequency Failure Rate Data Failure Rate Data

System 1 0.949<0.993<0.999 0.864<0.984<0.997 0.854<0.978<0.998 0.684<0.971<0.996

System 2 0.949<0.993<0.999 0.840<0.971<0.994 0.854<0.978<0.998 0.665<0.963<0.993

System 3 0.949<0.993<0.999 0.864<0.984<0.997 0.854<0.978<0.998 0.684<0.971<0.996

System 4 0.949<0.993<0.999 0.864<0.984<0.997 0.854<0.978<0.998 0.684<0.971<0.996

System 5 0.949<0.993<0.999 0.864<0.984<0.997 0.854<0.978<0.998 0.684<0.971<0.996

System 6 0.948<0.993<0.999 0.856<0.981<0.996 0.852<0.978<0.997 0.665<0.963<0.993

Note:1 Monthly tests of manual valves, sprinklers, and piping; quarterly frequency for other components.

For an online version of this article, goto www.sfpe.org.


By Bruce H. Clarke

INTRODUCTION

Numerous reports in the pastdecade have described therapid development of pinhole-

sized leaks and highly obstructive interior growth developments in sprin-kler system piping, fittings, and supplytanks. Some occurrences have beenreported after less than one year ofsystem service.1 In many of these cases,the cause has been found to be micro-biologically influenced corrosion (MIC).

MIC in fire sprinkler systems hasgrown from an obscure topic ofregional discussions in the early 1990sto one now generating widespreadconcern, speculation, and debatethroughout several countries.Unfortunately the building owner, fireprotection engineer, and contractorfaced with addressing this problem stillhave relatively few universally accept-ed practices within our industry to ref-erence. In fact, many calls for help arestill answered with theoretical treat-ment solutions and, in some cases,inaccuracies. And while most fire pro-tection professionals have now heardof this problem, proper diagnosis andtreatment are still not fully understood.

MIC DEFINED

Corrosion occurs in many forms andcan be defined from many scientificviewpoints. Microbiologically influ-enced corrosion is one type. For thefire protection discipline, it can specifi-cally be defined as:

An electrochemical corrosion processthat is concentrated and acceleratedby the activity of specific bacteria with-in a fire sprinkler system, which resultsin the premature failure of metallicsystem components.

This definition fully captures bothcause and effect. But a more detailedreview is required to fully clarify thetrue nature of MIC and the complexi-ties in addressing this problem.

Electrochemical Corrosion Process Metallic materials can degrade and

fail from various causes including cor-rosion. In general, corrosion can bedefined as the “wearing away of mate-rial.” As in other forms of corrosion,with MIC the “wearing away” orremoval of material occurs through aseries of electrochemical interactions.Thus both an “electrical” and a “chemi-cal” component are required for MIC.The electrical component occursthrough electron transfer.2 This is basi-

cally the removal of pipe wall materialone electron at a time. Electrons arestripped away from pipe materialatoms through various forms of oxida-tion which are dependent on the bac-teria involved. The chemical compo-nent is the result of the bacterial meta-bolic process that occurs. This createsvarious organic and mineral acidswhich chemically decompose metallicsurfaces from direct contact.3 The sec-tion on THE MIC PROCESS willdescribe this in more detail.

Concentrated and Accelerated The MIC process is both concentrat-

ed and accelerated in comparison totypical corrosion seen in sprinkler sys-tems. All metallic systems normallybegin to corrode from the instantmoisture meets metal. This is calledgeneral or uniform corrosion.

With general corrosion, a thin layerof oxidation occurs relatively evenlythroughout the entire pipe wall sur-face. This type of corrosion is typicallynot treated nor a significant concern infire sprinkler systems. This is becauseit does not significantly change a pipe’sinterior surface roughness (i.e., “C-fac-tor”), and the rate of decay is naturallyself-limiting. A typical corrosion rate insprinkler pipe is highly dependent on

MICROBIOLOGICALLY INFLUENCED

CORROSION

IN FIRE SPRINKLER SYSTEMS


water quality but is usually negligibleat under 1.0 mil/year. With MIC, thisrelatively slow corrosion rate is abnor-mally accelerated up to 10 mils/year.Put in perspective, schedule 40 pipehas a wall thickness of approximately20 mils.

When microbiologically influencedcorrosion occurs, general corrosionalso becomes concentrated, or local-ized, into high-activity pockets or cells.This causes pitting, which can drasti-cally change a previously smooth inte-rior pipe wall surface and its associat-ed “C-factor.”

Activity of Specific BacteriaAs defined, MIC is from the activity

of specific bacteria. Various bacteriaare present in all ecosystems. Sprinklersystems also normally have manykinds, but only a relatively small num-ber have the potential to cause rapidsystem destruction. Only a few specificbacteria concentrate and accelerate thegeneral corrosion process. Thus a high“general” bacteria count is meaning-less. It is important to understand thatthe bacteria associated with MIC donot produce a new corrosion processbut, as stated, simply concentrate and

accelerate general corrosion which isalready occuring.3 Microbiology influ-ences, not induces, corrosion.

How are these “specific” bacteriadefined? MIC-related bacteria are pri-marily classified by oxygen tolerance:being aerobic or anaerobic. Aerobicbacteria require oxygen to flourish andreproduce. Anaerobic bacteria arethose that do not require oxygen toflourish and reproduce.1 And, whilemost species only flourish with oneatmosphere and find the other toxic,facultative bacteria can survive in bothaerobic and anaerobic environments.All three types play a role in the rela-tively complex and random interac-tions that can occur in microbiological-ly influenced corrosion.4

In defining bacteria further, classifi-cation is not absolute and can becomerelatively confusing. The most com-monly used method of categorizingbacteria associated with MIC further isby metabolism. These labels are basi-cally definitions of what each bacteria

type eats (or metabolizes) and excretesas a byproduct. As these terms imply,where plants use photosynthesis (i.e.,light) to develop energy, bacteria usechemosynthesis (i.e., eating/breathingvarious chemicals or minerals).

However, use of these metabolictags are not universally replicated andcan be somewhat confusing. A singlebacteria type may fall under more thanone metabolic definition. Some of thecommonly referenced categoriesinclude Sulfur-Reducing Bacteria,Metal-Reducing Bacteria, Acid-Producing Bacteria, Iron-DepositingBacteria, Low-Nutrient Bacteria, Iron-Related Bacteria, Iron-ReducingBacteria, Iron-Oxidizing Bacteria,Sulfate-Oxidizing Bacteria, Slime-Forming Bacteria, Sulfate-ReducingBacteria, and Iron Bacteria.1,2,4

Finally, all bacteria can be classifiedby their scientific name under phylum,class, order, family, genus, or species.5

For example, one type of sulfate-reducing bacteria is anaerobic andmetabolizes sulphate to sulphide. Thesulfate-reducing bacteria groupincludes the genera desulfovibrio,desulfobacter, and desulformaculum.2

All are of the phylum Thiopneutes,which interestingly translates fromGreek to “sulfur-breathers.”

Within a Fire Sprinkler SystemThe specific source of MIC is con-

sciously omitted from the captioneddefinition. Bacteria is only indicated tobe within the fire sprinkler system.Typically, a sprinkler system’s water

supply is incorrectly consid-ered to be the onlysource for bacteria.Although there currentlyare no conclusive relation-

al studies in the fire pro-tection industry, there are

growing beliefs this is not theonly source of bacterial infec-

tion. Besides all water sources,bacteria capable of causing MIC arepotentially present in all soil, air, andcutting oils. Thus the manufacture,shipping, storage, and flushing of sys-tem materials should be addressed inall MIC investigations.

Obstructive growth from MIC


MIC does not only occur in water-filled systems. Dry pipe systems arealso susceptible.1 In fact, evidenceshows that dry systems may be moresusceptible to damage than fully wetsystems due to the humidified atmos-phere that is created after a first triptest. This could create the right atmos-pheric moisture content for some bac-terial types to thrive.

Premature FailureThe ultimate effect of MIC is the

premature failure of metallic compo-nents. This failure can take two forms.First is the failure of a system to holdwater (i.e., leakage requiring compo-nent replacement). This is most oftenseen in the development of the pin-hole-sized leaks often referenced as aprimary MIC infection indicator. This isalso typically the only concern inmany treatment investigations.

Second, and more concerning, is thefailure of a system to achieve itsdesigned purpose: that of fire control.Several systems with MIC have beenfound with sprinkler drops completelyplugged with the debris generated as abyproduct of the MIC process (calledbiofilm or biosludge). Sprinkler systemfeed mains have also been found withup to 60% obstruction from biologicalgrowth.6 This could present an obvioushydraulic concern as many sprinklersystems today will not provide fire con-trol with just a 15%-20% flow reductiondue to design.

What is considered premature ? Withregard to system function, at any

time a system is “in service” andfails to operate as

designed, it has

experienced “premature failure.” If asystem is operational and properlymaintained, it is always expected towork as intended. This is the founda-tion for the public’s trust we buildupon in selling the value of sprinklers.Unfortunately, like the recent Omegasprinkler which was recalled after itdid not perform as expected in everyinstance, the effects of MIC could con-ceivably be the next large public rela-tions problem our industry will haveto address.

What constitutes premature withregard to the integrity of specific sys-tem components must also be dis-cussed. Long-term warranties are nottypical with system components, butwith proper maintenance, a sprinklersystem is typically expected to last fora minimum of 30-60 years beforemajor repairs are required.

Metallic System ComponentsThe word components and not sim-

ply “pipe” is used as the captionedpoint-of-failure. While pipe is the typi-cally seen failure point, there areincreasing reports that sprinkler orificecaps, control valves, fittings, and sup-ply tanks are also being damaged.Only metallic components are succept-able to MIC, while plastic materials

are not directly susceptible.Plastic components are, how-

ever, subject to bacterialdebris blockage fromupstream bacterial activi-ty in metallic compo-nents. The term metal-lic is also chosen oversteel. With the excep-tion of a possibly veryselect few steel alloys,virtually all metallic

materials currently in usetoday are susceptible to

biological corrosion.

THE MIC PROCESS

The corrosion process can be verycomplex with many variable interac-tions at a cellular level between aero-bic, anaerobic, and facultative bacteria.However, several steps in the processare somewhat universal: 1, 2, 3, 4

Above Top: Interior pitting androughness created by MIC.Bottom: Exterior pinhole.

Left: Interior biofilm growth and exterior pinholeleak – at approximate two o’clock point on pipe wall.

Above: Interior biofilm buildupwith clearly seen corrosion celltubercle shell.


1. Bacteria enter the system, attach tometallic components, and begin torapidly colonize and reproduce.

2. Aerobic colonies metabolize nutri-ents from the water and/or themetal surfaces they are attached to,and subsequently excrete a polymerfilm byproduct that bonds togetherto form crustaceous nodules calledtubercles.

3. Tubercles and associated biofilmscreate microenvironments on themetallic material surface (under thetubercles).

4. The underdeposit area (i.e., underthe tubercles) becomes oxygen-depleted (i.e., anaerobic and anod-ic) in relation to the surroundingsystem water or air (which remainsaerobic and cathodic).

5. Underdeposit anaerobic bacteriametabolize pipe wall materials andexcrete an acidic byproduct.Relative acidity and alkalinity levelswithin the tubercle shells arereduced to an approximate 2-4 pH,which chemically attacks the metal-lic component surface. The described corrosion process can

continue indefinitely until the aerobicand anaerobic bacteria in the systemare killed. The tubercles created fromcolonization must also be brokendown to destroy the underdepositmicroenvironment. This is becauseeven without bacteria in the under-deposit of a corrosion cell, the processcan still continue indefinitely as thecorrosion chain in its final phases isno longer reliant on their activity.

CURRENT TREATMENT REFERENCES

Currently, the fire protection industryhas a very limited amount of usablereferences supported by scientific data.However, several allied groups canprovide excellent information on datafrom other industries.

The National Association of CorrosionEngineers (NACE) has many publishedstudies and overviews about MIC detec-tion and treatment. The AmericanSociety for Testing and Materials (ASTM)offers several publications on properbacterial testing practices.

The American Water WorksAssociation offers standards describingthe proper management of the some-what hazardous chemicals typicallyused in injection devices attached tosprinkler systems for microbial control.Depending on how a facility’s water issupplied, this may be a very importantreference to maintain compliance withthe nationally mandated Safe WaterDrinking Act. The B300 series of publi-cations specifically address disaffectionchemicals (such as hypochlorites com-monly used in treatment), and theB500 series of documents specificallyaddresses scale and corrosion controlchemicals (such as the phosphatescommonly used in treatment).

The National Fire ProtectionAssociation (NFPA) fire codes alsoaddress MIC. But these references arestill very limited. The most impactingto our industry thus far was a sectionadded to the 1999 edition of NFPA 13:Standard for the Installation ofSprinkler Systems. Section 9-1.5 cover-ing water supply treatment states:

In areas with water supplies knownto have contributed to microbiological-ly influenced corrosion (MIC) of sprin-kler system piping, water supplies shallbe tested and appropriately treatedprior to filling or testing of metallic pip-ing systems.

While this has generated a flood ofneeded curiosity, it does little toaddress the resulting questions aboutproper treatment. First, there is noexplanation as to what is consideredan area “known to have contributed tomicrobiologically influenced corro-sion.” Data indicates data thus far onconfirmed cases have been widelyinconsistent, varying within city blocksand even within building complexesfed off common loops. If one case isfound in a given municipal area, is theentire community served by the samewater supply now considered a “bio-logical activity area?”

It also requires that building ownersbe fully familiar with the sources oftheir fire protection water. This can bevery difficult as many municipalitiesswitch between and blend multiplesources such as canals, various wells,rivers, lakes, and reservoirs. It also

does not address the fact that contami-nation can come from sources otherthan the water supply, as already dis-cussed.

Finally, this section indicates thatsprinkler systems “shall be tested andappropriately treated prior to filling.”The “who,” “how,” and “when” arestill in debate by those addressing thisissue. Who is truly qualified to makethe determination of when a failure isthe result of MIC and if a biocidaltreatment program will prevent allfuture failures? And how is a systembest tested (i.e., most accurately andcost-effectively) to confirm MIC?Almost anything requiring laboratorywork can be overtested... at a price.These are questions where answersare still evolving.

National Fire Code 25: Standard forthe Inspection, Testing, andMaintenance of Water-Based FireProtection Systems, 1998 Edition,Section 10 and Appendix 10 discussMIC treatment and detection in somedetail. NFPA 25 also provides otherinspection requirements that can beuseful. These include:

Section 7-3.4.1 stating “...system pip-ing and fittings shall be inspectedquarterly for external conditions (e.g.,missing or damaged paint or coatings,rust, and corrosion.”

Section 7-3.6 stating “...the depend-ability of the water supply shall beensured by regular inspection andmaintenance, whether furnished by amunicipal source, on-site storagetanks, a fire pump, or private under-ground piping systems.”

TREATMENT

The analysis required to properlyselect a course of action to addressMIC is typically outside of the scopeof work that most sprinkler contractorsand engineers are competent to direct-ly provide. Thus, until treatment meth-ods become universally proven andstandardized, the most critical step inproper mitigation begins with theselection of a qualified corrosion con-trol consultant.

With the wrong choice, a buildingowner could spend a large amount of


money on a problem that will likelyrecur. And a poor treatment choicecould actually accelerate the corrosionrate and affected area beyond thatexperienced before treatment.

The company chosen to determinetreatment must have a detailed knowl-edge not only of microbial corrosioncontrol but also of metallurgy andsprinkler system dynamics. Fire sprin-kler systems have flow characteristicsand concerns that are much differentfrom most common industrial processsystems where MIC is typicallyaddressed.

Most other industries deal with MICin systems containing fluids that areeither always static or always flowing.And unlike sprinkler systems, dynamicsystems have flow rates that are rela-tively constant, making prescribedchemical dose rates constant. A con-stant flow rate does not occur in sprin-kler systems. Variable differences areseen with system drains and refills,inspectors testing, and main draintests. The dose rate for each of theseflows must be considered to ensurethe chemical injection rate is alwayseffective. Most other industrial systemsalso have multiple points where bioci-dal chemicals can be injected.Sprinkler system water can realisticallyonly be treated at system risers, backflow apparatus, or suction tanks.

Finally, as previously stated, it iscritical to understand that prematuresystem failure can be a function ofboth bacterial infection and a waterquality that is incompatible with com-ponents. In fact, in the majority of pre-mature system failure cases, waterchemistry is likely to also be a majorfactor. A high bacterial count does notalways indicate MIC will occur, andconversely, a low bacterial count doesnot discount that MIC has occurred inthe past in a given system and will notoccur in the near future.

AnalysisIn systems suspected of already

being infected, the first step is to haveall possible water supply sources(tank, city mains, ponds, rivers, etc.)and the interior of each system testedfor bacterial levels and activity. While

this detection is not difficult with cur-rent technology, analysis of theseresults is somewhat complex. And, aspreviously stated, in determining treat-ment, bacterial detection is worthlesswithout factoring in water quality.

The laboratory used for analysisshould be capable of giving conclusivedetails of water supply mineral andchemical levels, pipe wall depositcompositions, and type-specific bacter-ial counts. Multiple tests are used inthese analyses from simple bacterialincubation with visual inspection tosulfur print or DNA testing. Obviously,not all tests are required nor are nec-essarily needed. Current preferredanalysis methods run the spectrum,depending on the consultant chosen.Costs for such testing can also varywidely.

In new systems, if MIC-causing bac-teria could be present, all sourcesshould be tested. It is critical that sus-ceptibility be determined before anysystems are filled or tested in any way.This is because if water tests are posi-tive, a chemical injection system mustbe installed and used immediately aftercompletion – including in hydrostatictesting and preliminary fills.

Once a system is filled with infectedwater, treatment can become exponen-tially more complex as any futuretreatment from a chemical injectionsystem must now be effective inremote and stagnate system legs. Inbacteria-positive areas, several addi-tional water quality tests should becompleted throughout the first year ofservice to ensure contamination hasnot occurred from any other sources.

Mitigation in Affected SystemsWhen MIC is confirmed in opera-

tional systems, the building owner isfirst faced with a fundamental ques-tion. Can the system be salvaged (i.e.,cleaned) or does it have to bereplaced? Currently, this decision is notsupported by documented best prac-tices in our industry.

Who is qualified to determine if asystem can be cleaned or must bereplaced? Pipe cleaning is typically anoption when corrosion (i.e., pitting) isnot excessive. However, excessive is a

relative term. To answer this question,the resulting after-cleaning quality ofthe pipe must be considered – bothfor future longevity and systemhydraulics. The resulting frictional lossfrom numerous pits after cleaningcould affect system performance. This,of course, is typically outside of thescope-of-work of most corrosion con-trol consultants. Who is actually quali-fied is currently interpreted in manyways. When replacement materials arechosen that are different than those ofthe original system, this also must beaccounted for in hydraulics analysis ofthe post-treated system.

Chemical InjectionOnce system components have been

cleaned or replaced and sterilized, achemical injection system must beinstalled to prevent recurrence. Onceinstalled, this system will be requiredto be operational continuously. Aswith any other mechanical system, thiswill require continuous system preven-tive maintenance.

When such a system is chosen, theapplicable AHJ should be consulted.In addition to frictional loss concernsmentioned from changes in pipe sur-face roughness, increased back flowprevention hardware may be required.This could mean a 10 psi (0.7 bar) ormore pressure drop to sprinkler sys-tems in addition to that created by pit-ting if cleaning is chosen. In new sys-tem design, added alarm system con-tacts must also be planned to monitorinjection system chemical levels, oper-ational status, and trouble signals.Many pre-engineered systems availabletoday have readily available contactpoints for these signals. As with detec-tion, the perceived “best choice”depends on the person choosing andis highly variable.

Several commercially availablechemical injection systems have beenspecifically designed for installation onfire protection systems. Some simplyuse existing hardware and chemicalsmodified from MIC treatment in otherutilities, such as cooling towers. Noneof the systems currently available arebelieved to be UL-listed or FM-approved specifically for use as a


sprinkler system components. Andwhile most appear to be effectivewhen properly installed and main-tained, reliability and effectivenesshave not been time-proven when com-pared with most industrial systembenchmarks. Past references shouldalways be investigated with anychoice.

Most injection systems currentlyavailable are designed to work withspecific chemicals. These selectedchemicals and dose rates are critical.Some bacteria can develop chemicalresistance over time if doses are notstrong enough and bacteria are notquickly killed. A small number of MIC-related bacteria (such as the generaBacillus and Clostridium) also have theability to convert to a spore state whenthey encounter adverse conditionswhich are not lethal.3, 4 Spores areimpervious to chemical penetrationand thus can then survive biocidaltreatments indefinitely. And while sub-sequent treatments may then slow orstop their activity, they will reappearwhen/if treatments are stopped andresume colonization. With a weakchemical attack, bacteria may also be-come resistant to the chemicals chosen.

As with most other parts of thetreatment system, the choice of chemi-cal depends on the consultant. Thesegenerally include penetrants andbiodispersants to break up the tuber-cles which protect underdepositcolonies, a biocide to kill the bacteriain the colonies, and a corrosioninhibitor to protect of the interior sys-tem surface.

Unlike most other industrial systemstreated for microbiologically influencedcorrosion, several chemical interactionsmust be considered. First, sprinklersystems are typically located directlyover people. Chemicals used musttherefore be nontoxic in contemplationof accidental discharge. Second, sys-tem designs typically place water dis-charge (such as from inspector’s testports) into foliage or biologically sensi-tive drains. Most municipal wastewater treatment plants (to which typi-cal drains ultimately flow) require bac-terial activity to decompose waste. Too

large a quantity of biocides in munici-pal drains could be a problem.

In conclusion, a complete toxicityreview with the highest possible bioci-dal chemical concentration must becompleted. As much as possible, thesechemicals should be noncombustible,colorless, odorless, and nontoxic.These must also be nondeteriorating torubbers and polymers such as thoseused on pipe couplings and sprinklero-rings. Chemical storage should alsobe reviewed, as several currently usedcan degrade rapidly with heat and maycreate relatively toxic vapors.

Some of the more common chemi-cals currently in use specifically formicrobial control in sprinkler systemsinclude quaternary ammonium com-pounds, organo-sulfur compounds,bromines, carbamates, isothiazalone,phosphates, and chlorines. Sodium sili-cate is effectively used in bulk quanti-ties by several municipalities as aninhibitor but this should be avoidedfor individual systems due to thepotential sprinkler head plugging over-dosing can cause.

FUTURE ACTIVITY

The National Fire SprinklerAssociation formed an “MIC TaskGroup” in 1996 to address these asso-ciated issues. Their work continues,and they currently have the onlyknown Internet-accessible Web site forreporting suspected MIC cases. TheNational Association of CorrosionEngineers (NACE) recently formed atask group specifically to investigateMIC fire sprinkler systems – a problemthey have been addressing for years inother industries. And NFPA recentlyformed an “MIC Task Group” as anextension of the NFPA 13 NewTechnology Task Group. This group isworking to develop a report contain-ing specific recommendations for theprevention and treatment of MIC. It isplanned for inclusion in the next edi-tion of NFPA 13.

Studies by many universities, gov-ernment, and private industry groupswill also continue to research micro-bial control in other industries as they

have for the past several decades. Thisshould continue to provide improvedtreatment options in our industry.Some currently being investigatedinclude in situ steam sterilization andgas fumigation as possible alternativesto chemical cleaning and sterilization.Other studies are looking at usingengineered bacteria to control corro-sion-causing bacteria through variousinteractive means. And studies into thedevelopment of bacterial-resistantmaterials such as chemically impreg-nated steel or plastic-coated pipes alsohold promise. This may include workwith biostat coatings. These are films,paints, and coatings that do not killorganisms but simply inhibit theirgrowth or attachment to metallic com-ponents.

Bruce H. Clarke is with IndustrialRisk Insurers.

REFERENCES

1. Bsharat, Trariq K., “Detection, Treatment,and Prevention of MicrobiologicallyInfluenced Corrosion in Water Based FireProtection Systems”, National FireSprinkler Association, Inc. June 1998.

2. Borenstein, Susan Watkins,Microbiologically Influenced CorrosionHandbook, Woodhead Publications, Ltd.1994

3. Pope, Daniel H., Duquette, David J.,Johannes, Arland H., Wayner, Peter C.“Microbiologically Influenced Corrosionof Industrial Alloys.” MaterialsPerformance, July 1984.

4. Little, Brenda J., Ray, Richard I., andWagner, Patricia A. “TameMicrobiologically Influenced Corrosion,”Chemical Engineering Progress,September 1998.

5. Marshall, Roy, “Iowa Authorities SuspectsM.I.C.” Sprinkler Age, September 1998,Volume 17, No. 9.

6. Kammen, Joh, “Bacteria Spell Doom forFire Sprinklers,” The Arizona Republic.Oct. 24, 1999.


By Kenneth E. Isman, P.E.

Once it has been decided that a buildingis going to be sprinklered, one of thefundamental decisions that needs to be

made is which type of sprinkler to choose. From1955 to 1981, the choice was relatively simple.There were only two types of sprinklers, the con-ventional sprinkler (sometimes called the old-style sprinkler) and the spray sprinkler. In NorthAmerica, the spray sprinkler was the sprinkler ofchoice except for fur storage vaults, piers, andwharves. In these special areas, fire tests had

Which Sprinkler to

CHOOSE?


shown some advantage to using con-ventional sprinklers. Outside NorthAmerica, much of the world continuedto use conventional sprinklers, onlyallowing spray sprinklers to be usedwhen pressed by some American firmdoing business overseas, and then usual-ly only under a noncombustible ceiling.

As the spray sprinkler received moreand more attention in North America,it became the “standard” sprinkler ref-erenced by NFPA 13. So many spraysprinklers were installed after 1955that the sprinkler actually becamereferred to as the Standard SpraySprinkler. The letters SSP (for StandardSpray Pendent) and SSU (for StandardSpray Upright) were stamped on thesprinkler for easier identification. Sucha high percentage of spray sprinklerswere installed that the fire protectionindustry considered the term “sprin-kler” and the term “Standard SpraySprinkler” to be synonymous.

In 1981, a revolution (or evolution,depending on how you look at it) insprinkler technology occurred. The fireprotection industry decided that itmight be better off developing a spe-cific type of sprinkler for a specificoccupancy. Rather than rely on thespray sprinkler’s “one-size-fits-most”approach to developing water dropletsof different sizes and velocities andspray patterns that distribute water tofight most fires, the ResidentialSprinkler was developed to combatthe types of fires found specifically inresidential occupancies while makingthe most efficient use of the waterthrough development of specificdroplet sizes and distribution of thewater. The recognition that a sprinklercould be developed for a specific typeof occupancy opened a floodgate ofnew types of sprinklers that have thecapability of fighting fires more effi-ciently than the spray sprinkler, or ofachieving different design goals thanthe spray sprinkler, in the occupancyfor which they were designed.

ORGANIZING THE TECHNOLOGY

In order to see how these newsprinklers fit into the “big picture” of

fire protection, some organizationneeds to be given to the differenttypes of sprinklers. There are three dif-ferent parts of the sprinkler that can bevaried to get different performancefrom the sprinkler: the activationmechanism (link), the deflector, andthe orifice.

NFPA 131 defines two different typesof activation mechanisms, FastResponse and Standard Response. AFast Response sprinkler is defined asone having a Response Time Index(RTI) of 90 (ft-s)1/2 [50 (m-s)1/2] or less.A Standard Response sprinkler isdefined as one having an RTI of 145(ft-s)1/2 [80 (m-s)1/2] or more. The RTI ofa sprinkler is a quantitative method ofmeasuring the sensitivity of the link toany given fire and is a function of thelink material’s thermal capacity, mass,and surface area. The method bywhich the link is attached to the restof the sprinkler and the conductivity ofthis connection are also taken intoaccount in the calculation of RTI.

Note that a “no man’s land” existsbetween the RTI values for FastResponse and Standard Response. Thecommittees responsible for writing thisdefinition wanted a clear distinctionbetween the Fast Response andStandard Response sprinklers. In theo-ry, a sprinkler with an RTI between 90and 145 (ft-s)1/2 [50 and 80 (m-s)1/2]could be developed and given theterm Special Response sprinkler, butno strategic advantage can be seen forsuch a device, and its presence doesnot seem necessary at this time.

The rest of this article will focus onthe different deflectors that are current-ly being installed on sprinklers and theeffect of the different orifice sizes.These two variables are independent.Note that a spray sprinkler can have anorifice size of K=11.2 (KM=160) and thata large drop sprinkler can also have anorifice with K=11.2 (KM=160). This doesnot make the sprinklers the same. Eventhough the orifice is the same size, thedeflectors on the sprinklers are verydifferent and can produce very differ-ent size water droplets and differentareas of water distribution.

Over the last 15 years, sprinkler ori-

fice sizes have been growing larger andlarger. There are several factors drivingthe use of larger orifice sprinklers, ofwhich the most important is the abilityto achieve higher flows than smallerorifice sprinklers at the same pressure.Another way of expressing this conceptis the ability to achieve flows necessaryfor fire control at lower pressures thanwhat is generally required from a small-er orifice sprinkler. As the fires getmore challenging (aerosols, flammableliquids, high-piled storage of plastics),the amount of water we need to getfrom the sprinkler to control the fireincreases. As the flow increases, sodoes the pressure necessary to pushthat water out of the sprinkler. Therelationship between the flow and thepressure at an orifice can be expressedby the formula

Q = K (P)1/2 (1)where:

Q = flow in gpm or l/minK = measure of the ease of getting

water out of the orifice, relatedto size and shape of the orificein units of gpm per (psi)1/2 or KM

in units of l/min per (bar)1/2

P = pressure in psi or bar

Table 1 shows the relative necessityof having sprinklers with bigger ori-fices. The table shows how muchpressure is necessary to achieve a den-sity of 0.85 gpm/ft2 (35 mm/min) (nec-essary for protection of certain high-piled plastic storage) over a coveragearea of 100 ft2 (9.3 m2). In order toachieve this density over this area, aflow of 85 gpm (300 l/min) would benecessary from the sprinkler. Using theformula above, the Table was devel-oped to show the pressures necessaryfrom each of the different orifice sizespray sprinklers.

Table 1 shows a number of interest-ing concepts. It is clear that the largerorifice sprinklers are necessary. If anengineer wanted to get 85 gpm (300l/min) from a sprinkler with a K=5.6(KM=80), a pressure of 230 psi (16 bar)would need to be applied at thatsprinkler – clearly not a practical fireprotection solution. But with a K=14


(KM=200) spray sprinkler, the flow of85 gpm (300 l/min) can be achievedwith only 37 psi (2.5 bar).

The Table also shows the nominalorifice size. Prior to 1996, this washow sprinklers were described byNFPA 13. However, in light of the factthat nothing on the sprinkler can actu-ally be measured to these dimensions,and because metric conversions weregetting more difficult, this method ofidentifying orifice sizes was aban-doned in 1996.

The Table also shows the orificenames used in NFPA 13. Prior to 1999,the name helped to define the orificesize. However, in developing the 1999edition of NFPA 13, the committeeneeded to come up with a name foran orifice larger than “Very ExtraLarge.” The committee had a hard timedeveloping a suitable name. In themeantime, the committee was alsoaware that even larger orifice sprin-klers were coming in the future. In theend, the committee decided to aban-don the concept of using sprinklernames and describe sprinklers by theirK-factors.

In writing the 1999 edition of NFPA13, the committee also decided to stan-dardize the K-factors that were beingused to describe orifice sizes. In thepast, manufacturers were allowed topick any K-factor from a range. Thisled to the situation where some sprin-klers had K-factors of 5.75 (KM=82)while others had K-factors of 5.4(KM=77), yet these were supposed to bethe same orifice size sprinklers. Withthe 1999 edition of NFPA 13, the manu-facturers will have to change their liter-ature and possibly even their sprinklers.

The published K-factors will have to beconsistent with those used in Table 1.The listing and approval laboratorieswill work out with the manufacturerswhat the allowable tolerance from thatK-factor will be.

The most variable of all of the thingsthat can be changed on a sprinkler isthe deflector. Once the water comesout of the sprinkler, the deflectorbreaks the water up into different sizedroplets and distributes those dropletsin a predetermined pattern. In someoccupancies, large water droplets areneeded to penetrate high-velocity fireplumes. In other occupancies, lots oflittle droplets are necessary so that theheat from the fire can be absorbed. Insome occupancies, the water needs tobe thrown straight down at the floor.In other occupancies, the water needsto be distributed to the side of thesprinkler as well as below it.

There are currently at least eight dif-ferent kinds of deflectors being put onsprinklers. Figure 1 shows how all ofthe different types of sprinklers can becategorized by the type of deflector.

Conventional Sprinklers – As dis-cussed above, these sprinklers are pri-marily used outside of North America.Approximately half of the dischargefrom these sprinklers is up towards theceiling while the other half is downtowards the floor.

Residential Sprinklers – These deflec-tors are designed to produce manysmall and medium-sized waterdroplets. Large droplets are not neces-sary because residential fires do nottend to develop high-velocity vertical

fire plumes. However, residential firesdo produce a great deal of heat, whichis absorbed by the small waterdroplets. Medium-sized droplets dopenetrate the outer edges of the fireplume to pre-wet adjacent com-bustibles, making it harder for the fireto spread. This sprinkler maximizes theefficiency of absorbing heat from a fireand, therefore, can operate at lowerflows than Spray Sprinklers. However,the NFPA committees responsible forvarious residential occupancies haveexpressed concern about allowing list-ed flows to get too low. In a decisionto take effect soon, the manufacturerswill not be allowed to list sprinklers atdensities less than 0.1 gpm/ft2 (4.1mm/min) for NFPA 13 applications orless than 0.05 gpm/ft2 (2.0 mm/min)for NFPA 13D or NFPA 13R applica-tions. If order for the residential sprin-kler to be successful, it needs to openbefore the fire gets very large. To dothis, a fast response link is put on thesprinkler. However, this should not beconfused with a Quick ResponseSprinkler. As covered later in this arti-cle, a Quick Response Sprinkler has avery specific spray pattern. While theresidential sprinkler is Fast Response, itis not Quick Response.

Spray Sprinklers – Still the mostpopular type of sprinkler, the SpraySprinkler discharges 100% of its waterdown towards the floor in an umbrel-la-shaped discharge pattern. Thedeflector is designed to produce waterdroplets in three specific size ranges.Small droplets help absorb the heatfrom the fire and maintain cool ceilingtemperatures. Medium-sized dropletspenetrate the edges of the fire plumeto pre-wet adjacent surfaces making itmore difficult for the fire to spread.Large-sized droplets penetrate the fireplume to get to the surface of theburning fuel to control or suppress thefire. There are at least four differenttypes of Spray Sprinklers as represent-ed by the four boxes on the bottomlevel of the Figure. All of the greenboxes in Figure 1 are considered typesof Spray Sprinklers.

Nominal Size Name K (KM) Flow Pressureinches (mm) gpm/(psi)1/2 gpm psi (bar)

[l/min-(bar)1/2] (l/min)

1/2 (13) Standard 5.6 (80) 85 (300) 230 (16)

17/32 (13.5) Large 8.0 (110) 85 (300) 113 (7.7)

5/8 (16) Extra Large 11.2 (160) 85 (300) 58 (3.9)

3/4 (19) Very Extra Large 14.0 (200) 85 (300) 37 (2.5)

16.8 (235) 85 (300) 26 (1.8)

Table 1 - Pressures to Achieve 85 gpm from Various Orifice Size Spray Sprinklers


Large Drop Sprinklers – Developedspecifically for high-challenge storageoccupancies, these sprinklers producea greater amount of large waterdroplets than spray sprinklers. Thelarge droplets penetrate the fireplumes more easily and help controlthe fire.

Early Suppression Fast Response(ESFR) Sprinklers – The ESFR Sprinklerswere developed to specifically sup-press fires in high-challenge storageoccupancies. In most cases, they cando so without the need of in-racksprinklers. All of the other sprinklersdiscussed here are designed to controlfires, but ESFR Sprinklers, if designedand installed properly, will suppressfires. The ESFR Sprinkler producesmany large droplets and gives thosedroplets a high velocity as they traveldown towards the floor. This, com-bined with the fast response element,helps them suppress fires while theyare still small.

Special Sprinklers – There are manysprinklers that are being developed foruse in specific applications that call forunusual spray patterns. The AtticSprinkler is one example. The AtticSprinkler has a deflector designed todischarge water down the typical

Sprinklers

Conventional(Old Style) Residential Spray

LargeDrop

EarlySuppression

FastResponse

Special

StandardResponse

Spray

QuickResponse

ExtendedCoverage

QuickResponseExtendedCoverage

Figure 1 - Relationship of Different Sprinklers by Deflector


Standard Response Spray Sprinklers –More than 90% of the sprinklers installedfrom 1955 to 1981 in North America werethis type of sprinkler. Today, they are stillused extensively, but hold less than 75% ofthe market. These sprinklers produce thespray pattern and droplet sizes discussedabove for Spray Sprinklers, are intended tobe installed at the maximum distances andareas covered by NFPA 13, and are avail-able in a variety of orifice sizes.

Quick Response Spray Sprinklers – Thesesprinklers are identical to the StandardResponse Spray Sprinklers except for theactuating mechanism. As Fast ResponseSprinklers, they react while the fire issmaller and can control the fire with feweroperating sprinklers, allowing for smallerwater supplies, smaller pipe, and less waterdamage. These sprinklers are intended tobe installed using the allowable distancesand areas of NFPA 13.

Extended Coverage Sprinklers – Thesesprinklers produce the same umbrella-shaped distribution and three differentsized water droplets as the Spray Sprinkler;however, they spread that spray patternover a larger area. Extended CoverageSprinklers are intended for use in areaslarger than the distances and maximumareas of NFPA 13. The limitation on the

area of coverage for each individualsprinkler is contained in the speciallisting of the sprinkler, not NFPA 13. Inorder to obtain these listings, the man-ufacturer frequently needs to utilizegreater flows and pressures thanwould normally be used under NFPA13. In order to utilize these sprinklers,hydraulic calculations need to ensurethat these higher flows and pressuresare available. These sprinklers are notinterchangeable, since some modelsmay need higher pressures and flowsto cover similar areas as other models.These sprinklers are consideredStandard Response Sprinklers eventhough some of them employ a fastresponse link. They use fasterresponse to compensate for the possi-ble increased distance to a fire.

Quick Response Extended CoverageSprinklers – Similar to the ExtendedCoverage Sprinkler, these sprinklerscan cover more area than normallyallowed by NFPA 13. In addition, thelinks are sensitive enough to be con-sidered Quick Response even at theextended spacings. As with ExtendedCoverage Sprinklers, Quick ResponseExtended Coverage Sprinklers are notinterchangeable due to differing flowand pressure requirements.

TYPES OF SPRAY SPRINKLERS


slope of an attic roof/ceiling. Otherexamples include window sprinklersand concealed space sprinklers andare discussed later in this article.

NEW SPRINKLERS ON THE MARKET

Now that the terminology has beenexplained, it will be easier to discussthe new types of sprinklers that are onthe market and where they fit in to the“big picture.”

One of the recent trends in newtypes of sprinklers has been the produc-tion of larger and larger orifice SpraySprinklers. While the sprinkler with a K-factor of 16.8 (KM=235) is currently thelargest orifice spray sprinkler, it is only amatter of time before one with a K-fac-tor of 22 (KM=315) or 25 (KM=350) isdeveloped. One of the things that theNFPA committee was concerned aboutwas the proliferation of different K-fac-tors, so they limited the manufacturersto the following sizes: 16.8, 19.6, 22.4,25.2, and 28.0. In metric units, thesewill be 235, 275, 315, 350, and 400. Itshould be noted that the sprinklers witha K-factor of 16.8 are being marketed asK=17. While 17 may be a “sexier” num-ber to market the device, NFPA 13 willrequire the use of K=16.8 in thehydraulic calculations.

There are currently two differentways that Spray Sprinklers are beinglisted for use. The first method is as aregular Spray Sprinkler. The sprinklercan be used with any of the area/den-sity curves of NFPA 13, although to beused in storage occupancies, it needsto be listed as a “Storage Sprinkler.”NFPA 13 is trying to encourage the useof these larger-orifice sprinklers.

In the 1999 edition, a new section(5-4.1.2) was added for storage occu-pancies. This new section only allowsK=5.6 (KM=80) sprinklers to be used ifthe design density is 0.2 gpm/ft2 (8.2mm/min) or less. Similarly, K=8.0(KM=110) sprinklers will only beallowed if the design density is 0.34gpm/ft2 (13.9 mm/min) or less. Anystorage commodity that needs a designdensity of more than 0.34 gpm/ft2

(13.9 mm/min) will need to utilize asprinkler with an orifice size of K=11.2(KM=160) or more.

The second method by which bigorifice Spray Sprinklers are allowed tobe used is through the SpecificApplication listing. NFPA 13 allowssprinkler manufacturers to get speciallistings to protect certain size storagearrangements of certain commodities.The limitations as to what kind ofcommodities can be protected andhow they can be stored are up to themanufacturer to define and become apart of the listing of the sprinkler.When sprinklers are used in confor-mance with the Specific Applicationlisting, much of the sprinkler installa-tion, hydraulic calculation, and watersupply information needs to be foundin the listing, not NFPA 13. Thedesigner and plan reviewer need to becompletely familiar with the SpecificApplication listing in order to get thesprinkler system installed correctly.

Another big trend in the sprinklerindustry has been the development ofdifferent types of ESFR Sprinklers. Theoriginal ESFR Sprinkler was a pendentsprinkler with an orifice of K=14.0(KM=200). A few years after that, anupright sprinkler with a K=11.2(KM=160) was recognized as an ESFRSprinkler for protection of storage inslightly smaller buildings than theK=14 (KM=200). More recently, pendentESFR Sprinklers were recognized withan orifice size of K=25.2 (KM=350).

There are two methods in which touse the K=25.2 (KM=350) ESFRSprinkler. The first method is to usethe rules of NFPA 13. The 1999 editioncontains information on the protectionof Class I-IV commodities as well ascartoned unexpanded plastic.Minimum pressures vary from 20 to 50psi (1.4 to 3.4 bar) based on the stor-age height and the ceiling height inthe building.

The second method under whichthe K=25.2 (KM=350) ESFR Sprinklerscan be used is through the SpecificApplication listing process. One manu-facturer of an ESFR Sprinkler with aK=25.2 (KM=350) has received a speciallisting for use with pressures lowerthan those required by NFPA 13. Useof this sprinkler is allowed due to thespecial listing; however, the listing isspecific to one manufacturer, not allsprinklers with that orifice size.

Another development in the evolu-tion of ESFR Sprinklers is the uprightESFR with a K=14.0 (KM=200).Although not yet listed or approved,this sprinkler has undergone fire testsand shown impressive performance.As an upright sprinkler, the manufac-turer knew that the pipe under thesprinkler would be an obstruction anddesigned the sprinkler to be much lesssusceptible to minor obstructions com-pletely below the sprinkler. Hopefully,this sprinkler will pass the rest of itstests and join the ranks of acceptableESFR Sprinklers.

The last trend that will be coveredin terms of new products in this articlewill be the Special Sprinklers. Newsprinklers are being developed forspecific applications where perfor-mance can be optimized by takingadvantage of the geometry of thespace. As previously discussed, theAttic Sprinkler has been developedspecifically for the typical sloped ceil-ing configuration of an attic.

Another special sprinkler that hasbeen developed for a specific applica-tion is the Window Sprinkler. Thissprinkler discharges water in a spraypattern against glass to give itimproved fire resistance. The windowsprinkler gives architects more flexibili-ty in the products they choose, whilemaintaining the integrity of the firecompartment.

The last new type of sprinkler thatthis article will cover is the ConcealedSpace Sprinkler. Just listed in May2000, this sprinkler will not be foundin NFPA 13, but may be used in accor-dance with its special listing. Thesprinkler is intended for use in flatconcealed spaces between 12 and 32inches (300 to 800 mm) in depth.Rather than throw its water down, likea spray sprinkler, this sprinkler isdesigned to discharge most of its waterto the sides. The sprinkler is designedto operate at a density of 0.1 gpm/ft2

(4 mm/min) over a design area of 1000ft2 (90 m2). Each individual sprinklerhas a K-factor of 3.0 (KM=40) and mustdischarge at a minimum of 10 psi (0.7bar). The maximum allowable distancebetween sprinklers is 10 ft (3.1m) andthe minimum allowable distancebetween sprinklers is 6 ft (1.8m).


One of the unique things about theConcealed Space Sprinkler is that itallows CPVC pipe to be installed inthe concealed space with it. Prior tothis, CPVC was not allowed in a con-cealed space that required sprinklers.Now, with special additional designrules covered in the manufacturer’sdata sheet, the sprinkler can protectthe concealed space and the exposedCPVC pipe at the same time.

OLD DOG, NEW TRICKS

In addition to the development ofnew sprinklers, there is constantly on-going research expanding our knowl-edge of what we can protect withexisting sprinkler technology. In the1996 edition of NFPA 30 – Flammableand Combustible Liquids Code, exten-sive use of new information aboutsprinklers was used to revise Chapter

4 and give definitive criteria on how toprotect certain flammable and com-bustible liquid storage with spraysprinklers. In the 2000 edition of NFPA30, even more information has beenadded to define even more commodi-ties that can be protected with spraysprinklers (including some flammableliquids in plastic containers) and a fewcommodities that can be protectedwith ESFR Sprinklers.

In addition to flammable and com-bustible liquids, work has continuedon expanding the list of commoditiesthat can be protected with ESFRSprinklers. Recent work has includedthe protection of rubber tires, rollpaper, and higher racks of plastic com-modities than could be protected afew years ago. It is clear that buildingowners enjoy the flexibility that ESFRSprinklers give them, and they contin-ue to press for research into additionalarrangements that can be protectedwith these sprinklers.

Even the sidewall sprinkler is havingits application expanded. A new excep-tion to section 5-4.2 in NFPA 13 allowsthe Sidewall Sprinkler to be used toprotect below overhead doors. Whilemany Authorities Having Jurisdictionallowed this application in the past,some did not because it technically vio-lated the rule that sidewall sprinklersbe no more than 6 inches (150 mm)down from the ceiling. While someextended coverage Sidewall Sprinklershad special listings allowing them toget as far as 18 inches (450 mm) downfrom the ceiling, this did not allow forprotection under an overhead door.The sprinkler committee was sympa-thetic to the problem of how to protectunder such an overhead door andrevised the standard. It is anticipatedthat the sidewall sprinkler will bebetween 4 and 6 inches (100 to 150mm) below the plane of the overheaddoor once it is in the open position.

Kenneth E. Isman, P.E. is with theNational Fire Sprinkler Association.

REFERENCE

1 NFPA 13, Standard for the Installation ofSprinkler Systems. National Fire ProtectionAssociation, Quincy, MA, 1999.



By William Fletcher, P.E.

INTRODUCTION

The managing of a constructionproject in which EarlySuppression Fast Response

(ESFR) Sprinklers are to be usedrequires careful planning by the con-struction project team to ensure the sys-tem is designed and installed properly.This involves a coordinated effort bythe various disciplines (fire protection,architectural, structural, mechanical, andelectrical) in the conceptual designstage as well as during construction.This article discusses the variousaspects involved in managing such aproject to ensure a successful outcome.

SUPPRESSION MODE VS. CONTROL MODE

Suppression Mode, Fast ResponseSprinklers were developed in the 1980sfor use against severe fire challenges.These sprinklers were developed fromthe design concepts of two of their pre-decessors; the Large Drop andResidential Sprinklers. They are intend-ed for use in certain occupancies inwhich fire suppression is possible. Theterm “suppression” relates to sprinklersystem performance where the first fewoperating sprinklers provide sufficientwater to the fire to reduce it to anacceptable level, if not extinguish it.Based on extensive testing, there canbe no ESFR Sprinklers obstructed by

the building structure or equipmentsuch as lights, ducts, cable trays, etc. Inthe case where objects such as ducts,conveyors, and walkways are unavoid-able, the option of providing moresprinklers to compensate for themwhen they shield sprinkler water distri-bution is available. The obstruction ofeven one ESFR Sprinkler could result inthe lack of fire suppression. The avoid-ance of obstructed sprinklers is one ofthe greatest challenges to overcomewhen ESFR systems are involved.

The Suppression Mode Sprinkler isdifferent from the Standard ControlMode Sprinkler (these include standard

Above: ESFR sprinkler head inoperation.

PROJECT MANAGEMENT OF AN

ESFR SPRINKLER INSTALLATION


spray upright and pendent, Extra LargeOrifice, and Large Drop type sprin-klers). In full-scale fire testing involv-ing control mode sprinklers, as manyas 20 to 30 sprinklers can operate inorder to achieve fire control. The con-trol mode sprinkler prevents firespread by slowly reducing its intensityand prewetting surrounding com-bustibles so they do not ignite. Theperformance of a control mode systemis therefore not as susceptible toobstructions as ESFR systems.

CURRENT APPLICATIONS

ESFR Sprinklers are intended to pro-tect a wide range of storage and arebeing installed throughout the UnitedStates and in many parts of the world.There are two major benefits for usingESFR Sprinklers in warehouse facilities.The primary reason is that ESFR sys-

tems eliminate the need for in-racksprinklers for specific rack storagearrangements up to 40 ft (12.2 m) highin maximum 45 ft (13.7 m) high build-ings. They also provide greater flexibil-ity in warehousing operations sincethe cost of removing and reinstallingin-rack sprinklers, as the storage layoutchanges, is not a factor. ESFR systemsare intended solely for warehouse stor-age occupancies and should not beused in buildings involving manufac-turing occupancies.

ESFR – THE RIGHT CHOICE FORYOUR APPLICATION?

One of the first things to consider iswhether the use of ESFR Sprinklers arean appropriate choice for the hazardand building construction involved.This involves the gathering of data onthe proposed storage and building con-

struction details. This information ismore important when ESFR Sprinklersare being used than Standard Sprinklerssince the ESFR system is relying on firesuppression in the incipient stage of afire as opposed to the control modeconcept previously discussed. There is,therefore, less tolerance for certaindesign and installation factors whenESFR Sprinklers are involved.

PROJECT MANAGEMENT

The project management aspectsrelating to fire protection in a buildingthat will use ESFR Sprinklers are veryimportant. There are many individualsinvolved with the construction of abuilding, and each has their own par-ticular area of expertise. It is essentialto bring these individuals together toreview the proposed fire protectiongoals in the conceptual stages of plan-ning. The proper design and installa-tion of an ESFR system can be compli-cated, and everyone involved mustwork closely together prior to theonset of construction as well as duringthe construction process.

Periodic meetings should be held atthe construction site with the Architect,Structural, Mechanical, and ElectricalEngineers as well as the foremen rep-resenting the various trades. A build-ing survey can then be done prior toeach meeting to review the ESFRinstallation progress and identify anyproblems. In the fast-paced world ofconstruction, the early identification ofdeficiencies involving the sprinklerinstallation is important in order tomake the appropriate changes. Forexample, three experienced sprinklerfitters can complete the installation ofthe ceiling piping for a 120,000 ft2

(11,000 m2) building (3 systems) inapproximately three weeks. Frequentsite visits are therefore necessary dueto the fast pace of work involved. Thekey points involved in successfullymanaging an ESFR project include thefollowing:

Storage DetailsExtensive testing and analysis back

ESFR application for various storagearrangements and commodities. It istherefore important to know the pro-posed storage type and racking config-

Fire Test at Factory Mutual Research Center

uration that will be used early in thedesign process. This will usuallyrequire some investigation andresearch. The commodity type, storageconfiguration, rack dimensions, etc., allneed to be known in advance. Thebest source of this information is gen-erally the building occupant (end-user). This information is also neededfor the local jurisdiction to obtain anyneeded permits (high-pile permit, forexample). Determining this informa-tion for a multitenant leased building,“Spec building” may not be possiblesince tenants for these types of build-ings are usually signed up after thebuilding construction and sprinklerinstallation are complete. It should benoted that not all storage types arecompatible for use with an ESFR sys-tem. For example, when racking isused, the racks must have “open”shelves as opposed to “solid” shelving.The end-user (warehouse occupant)must also understand the importanceof maintaining flue spaces within theracks. These spaces can becomeblocked in such applications as pickracks where boxes are packed tightlyon wire shelving. Open-top, five-sidedcombustible containers cannot be usedwithin racks since they can preventwater from running across the top ofstorage and down the flues and canalso collect sprinkler water. The appro-priate guidelines referenced for theproject must therefore be carefullyreviewed for a complete list of suchrestrictions depending on the pro-posed storage.

Roof Construction Roof construction and roof height

are some of the aspects of buildingdesign that must be closely coordinat-ed. Some types of roof constructioncan present inherent problems withESFR sprinklers being obstructed bystructural members. A recurring chal-lenge in designing ESFR sprinkler sys-tems has been to design a layoutwhich eliminates obstruction to distrib-ution, satisfies guidelines for spacingbetween sprinklers on or betweenbranch lines, and satisfies guidelinesfor maximum area of coverage persprinkler. This has been a commonproblem with construction using openbar joists or steel trusses. The layout of

the sprinkler system must therefore bedone in a concerted effort with theStructural Engineer’s plans. A roof/ceil-ing slope up to and including 2 in/ft(17%) is acceptable. If the ceiling slopeis in excess of 2 in/ft (17%), a suspend-ed ceiling with an acceptable slopemay be installed above the storagewith sprinklers installed below the ceil-ing.

Design Specifications and Fire Sprinkler Plans

Specification of design criteria forthe sprinkler system will include sys-tem hydraulic design, undergroundmain layout, location of hydrants, and

sprinkler piping earthquake bracing (inspecific geographic areas where need-ed). Since obstructions to sprinkler dis-charge will significantly affect the abili-ty of the system to suppress the fire,all potential obstructions must be iden-tified prior to the submittal of sprinklershop drawings. In order to accomplishthis, it would be desirable to have thefire sprinkler contractor on the designteam at the project inception. Pipingshould not be fabricated or installeduntil all the necessary approvals areobtained via the plan review process.

The water supply to be used is alsoof critical importance. Quite often thelarger building developments are locat-

ESFR Sprinkler system with obstructed sprinklers due to electrical junction boxand conduit located directly below sprinklers.

ESFR Sprinkler system with no obstructed sprinklers.



ed on the “outskirts” of town wherethe water supply details are not com-pletely known. In most cases, thewater department should be contactedand a meeting should be held to deter-mine the supply characteristics. Forexample, some areas can experience adrop in the available water pressureduring certain times of day or night. A24-hour. monitoring device can behooked up to a public hydrant todetermine the minimum static pressurein such cases. Hydrant flow testsshould be conducted well in advanceof sprinkler design beginning. A com-mon practice is to subtract 10% off thestatic and residual hydrant test pres-sures to account for future pressurefluctuations and growth in the area.Since ESFR systems require high oper-ating pressures for the sprinklers, thereis a good chance a booster pump willbe needed for the public supply. Inareas subject to a high frequency ofearthquakes and/or areas with watersupply reliability concerns, considera-tion should be given to the provisionof a secondary, on-site water supply.

Installation of Equipment by Contractors

As the building construction pro-gresses, it is likely that changes in thelocation of equipment that will beinstalled at or near the roof level willoccur. This is prevalent during the ten-ant improvement stage of the project.Aside from building constructionissues, the second most likely cause ofobstruction to ESFR Sprinklers is due toequipment being added by contractors.This includes lights, ducts, heaters,cable trays, conduit, draft curtains, etc.The best way to deal with this is toinvolve the foreman from the varioustrades in all of the project meetings.Everyone must understand the obstruc-tion rules and these guidelines shouldbe presented in writing to all parties.

SUMMARY

The benefits of a properly designedand installed ESFR Sprinkler systemare very attractive. Since they respondfaster to a fire than standard sprinklers,fewer sprinklers will operate to mini-mize fire, smoke, and heat damage.ESFR protection eliminates the need

for in-rack sprinklers, in many cases,allowing users to handle material with-in racks more easily. The system pro-vides greater storage flexibility thanstandard sprinklers since users canstore a variety of products anywherein the warehouse.

However, there are many questionsthat need to be asked in the concep-tual design stage, such as whether theuse of ESFR sprinklers are an appro-priate choice for the hazard and build-ing construction involved. There aremany pitfalls that can be encounteredduring the design and subsequentinstallation of these systems. Carefulproject management is thereforeessential to ensure all members of theconstruction project team understandthe applicable guidelines. Finally, fre-quent site visits should be conductedto ensure the ESFR system is installed“obstruction free.”

William Fletcher, P.E., is with FM Global.

REFERENCES

FM Global Data Sheet 2-2 “InstallationGuidelines for Early Suppression - FastResponse Sprinklers”

FM Global Data Sheet 8-9 “Storage ofClass 1-4 & Plastic Commodities”

FM Global ESFR Technology, FacingToday’s Challenges; Form P9202

FM Global ESFR Installation Alert,Understand Before You Install; FormP9709

FM Global Record Magazine, ESFR Around the World

Factory Mutual Research Approval Guide2000 - Fire Protection

These publications can be orderedthrough FM Global Customer Serviceat (781) 255-6681 and toll-free in theU.S. & Canada at (877) 364-6726.


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Arup Fire has immediate openings for fire protection engineers inNew York. Successful candidates will play a very active role in

developing the practice in the USA and will work closely with manyof the world’s leading architects and building owners developinginnovative design solutions for a wide range of building, industrial,and transport projects.

Candidates should possess a Fire Protection Engineering degree,approximately five years of experience, and preferably an FPE – PE.Risk management, industrial fire engineering, and computer model-ing skills will be highly regarded.

Similar opportunities available in London, Leeds, Dublin, HongKong, and Australia, with opportunities available in Boston, SanFrancisco, and Los Angeles in the near future.

Arup Fire offers competitive salaries and benefit packages. Pleasesubmit résumé and salary history to:

Chris Marrion, PEArup Fire Ove Arup & Partners 155 Avenue of the AmericasNew York, NY 10013Telephone: +1.212.896.3269Fax: +1.212.229.1986E-mail: [email protected]

EQUAL OPPORTUNITY EMPLOYER

Harrington Group, Inc., is focused on continuous, profitable growthand currently has openings in Atlanta for fire protection engineers.

For full details on current job openings, please visit our Web site atwww.hgi-fire.com or submit your résumé via e-mail or fax to:

Ms. Patsy Sweeney [email protected] Fax: 770.564.3509 Phone: 770.564.3505

Harrington Group is a full-service fire protection engineering designand consulting firm. Founded in 1986, Harrington Group has con-sistently provided a high level of quality and value to clientsthroughout North America, South America, and Germany.

Should you be interested in us? YES! If:

• You want a career with increasing responsibility and compensation.• You care about quality and service delivered to the client.• You have strong engineering skills and people skills.• You are creative and desire to use your creativity.• You are honest and hard-working.• You want to be trusted and respected by your company.• You want to participate in the financial aspects of your company – like owners do.• You are in a dead-end where you are now.

Check us out, and discover whatmakes Harrington Group such anexcellent career opportunity.

Fire ProtectionEngineers






As the global leader in fire protection, security, and life safety solutions, Rolf Jensen & Associates, Inc., is always looking for

talented, dynamic individuals. Opportunities exist throughout oureleven offices for engineering and design professionals looking forgrowth. We are looking for engineers with experience in fire alarm,sprinkler, and security design; code analysis; and business develop-ment.

Check out our Web site at www.rjagroup.com for more details. Send your résumé to:

Ralph Transue, PEThe RJA Group, Inc.549 W. Randolph St., 5th FloorChicago, IL 60661

RJA EmploymentOpportunities

RJA EmploymentOpportunities


Founded in 1973, Code Consultants, Inc. (CCI), is a nationally recog-nized fire protection engineering firm providing professional con-

sulting and design services to developers, owners, architects, and othersignificant clients throughout the United States. With a staff of 55, CCIis a dynamic, growing firm that has an unmatched reputation fordeveloping innovative fire protection and life safety solutions, codecompliance guidance, and cost-effective designs which are equallywell received by clients and governing officials. CCI’s projects includesome of the nation’s largest shopping malls, retail stores, stadiums andarenas, hospitals, convention centers, detention/correctional facilities,transportation (air and rail) facilities, warehouses, and theaters for theperforming arts, to name a few.

The firm is seeking degreed fire protection engineers and otherdegreed individuals with a high level of experience applying ModelCodes and NFPA standards to service clients and projects throughoutthe country.

These positions offer a unique income opportunity, including partici-pation in CCI’s lucrative performance incentive program. The positionrequires residency in the St. Louis area.

Code Consultants, Inc.1804 Borman Circle Dr.St. Louis, MO 63146314.991.2633

Koffel Associates, Inc., is a fire protection engineering and codeconsulting firm with offices in Connecticut, Maryland, and

Tennessee that provides services internationally. Positions are avail-able at the following levels:

Senior Fire Protection EngineerRegistered Fire Protection EngineerFire Protection Engineers (BS or MS in FPE)Fire Protection Engineering Technician (AutoCAD experience,

NICET, or technology degree desirable)

Responsibilities may include:• Fire protection engineering and life safety surveys• Design and analysis of fire protection systems including automatic sprin-

klers, clean agent, fire alarm and detection, water supply, and smoke man-agement systems

• Code consultation with architects, engineers, developers, and owners during design and construction

• Post-fire analysis and investigation• Computer fire modeling• Fire risk and hazard assessments• Codes and standards development

Koffel Associates, Inc., personnel actively participate in the activitiesof professional engineering organizations and the codes and stan-dards writing organizations. The firm offers a competitive salary andbenefits package including conducting its own in-house professionaldevelopment conference for all employees.





Established in 1939, Schirmer Engineering was the first independent fireprotection engineering firm to assist insurance companies in analyzing

and minimizing risk to life and property. Since then, Schirmer Engineeringhas been a leader in the evolution of the industry, innovating for tomor-row with science and technology, using insight from tradition and experi-ences of our past. Today, Schirmer Engineering, with a staff of 180employees, is synonymous with providing high-quality engineering andtechnical services to both national and international clients.

Career growth opportunities are currently available for entry-level andsenior-level fire protection engineers, design professionals, and codeconsultants. Opportunities available in the Chicago, San Francisco, SanDiego, Los Angeles, Dallas, Las Vegas, Washington, DC, and Miamiareas. Our firm offers a competitive salary and benefits package,including 401(k). EOE.

Send résumé to:

G. JohnsonSchirmer Engineering Corporation707 Lake Cook Rd.Deerfield, IL 60015-4997

Fax: 847.272.2365e-mail: [email protected]



Fire SafetyEngineeringFire SafetyEngineering

UNC Charlotte Department of Engineering Technology invitesapplications for the position of Assistant Professor of FireSafety Engineering Technology. The person selected will helpin developing detailed curricula in fire protection and safety, aswell as teach and perform research in the discipline. The suc-cessful candidate should hold at least a Masters Degree in FireProtection/Safety Engineering, or another appropriate disci-pline, or Engineering Technology and three years’ relevantexperience. A record of scholarly achievement, and Internetand Distance Education experience are desirable. The positionwill be available in August 2001. U.S. citizenship or a perma-nent visa is required. Nominations and applications, includinga letter of interest that addresses the qualifications, a curricu-lum vitae, and a list of four professional references withaddresses and phone numbers, should be sent to:

ChairpersonFaculty Search CommitteeDepartment of Engineering TechnologyThe University of North Carolina Charlotte9201 University City Blvd.Charlotte, NC 28223-0001

UNC Charlotte is an AA/EOE.

Introduction to Performance-Based Fire Safety, byRichard L. P. Custer and Brian J. Meacham, 1997. This 11-chapter, illustrated book presents the basicconcepts of performance-based fire safety engineer-ing and includes chapters on design vs. codes, firedynamics and modeling, hazard analysis and riskassessment, performance criteria, human factors, andcase studies illustrating the process. 260 pages. (Item No. F6-PBFS-97) AVAILABLE ONLY THROUGHNFPA (800) 344-3555 and outside the U.S. (508) 895-8300.

Price: SFPE Member, $66.75; Nonmember, $74.25

Enclosure Fire Dynamics, by Bjorn Karlsson andJames G. Quintiere, 1999. This 300-page text hasbeen developed to serve as a framework and ref-erence for how to estimate the environmentalconsequences of a fire in an enclosure. It isbased in part on the work in this area developedby Professor Magnusson, Lund University, and isexpanded upon with new topics and informationfrom authors. Ten chapters and three appendicescover such subjects as fire plumes and flameheights, pressure profiles and vent flows, heattransfer and computer modeling, as well as sug-gestions for educators.


Sprinkler Hydraulics and What It’s All About, 2nd edition, by Harold S. Wass, Jr.Significantly expanded and updated to the 1999 edition of NFPA 13, this com-prehensive reference on sprinkler hydraulics contains practical information onall aspects of hydraulic design including sprinkler discharge; friction losses;backflow prevention; relationships to water supply; examples of dead-end, loop,grid, and in-rack sprinkler designs and inspection; and reliability. Written in aneasy-to-understand format by one of the industry’s acknowledged experts onsprinkler hydraulics.


Design of Smoke ManagementSystems by J. H. Klote, Ph.D., andJ. A. Milke, Ph.D., 1992. Offersstate-of-the-art information foranyone who has been challengedwith the design of smoke man-agement systems. Includes sec-tions on the nature of smoke, itsmovement in buildings, andanalysis methods for the designof smoke control systems withsample calculations. Published byASHRAE. 225 pages.


Comprehensive Fireproof BuildingDesign Methods is a translation ofthe Japanese Methodology forBuilding & Fire PerformanceEvaluation under Article 38 of theBuilding Standard Law of Japan.A publication of the InternationalForum for Fire Research, this doc-ument summarizes a comprehen-sive research effort by theConstruction Ministry of Japan todevelop rational design methodsfor attaining enhanced fireproofdesign in various building condi-tions. 400 pages.

Price: $50.00

BOOKSBOOKS

BOOKS


GUIDES

Reference Manual/AnswerManual for the P.E. Exam inFire Protection Engineering, 1stedition, 1996. This study guideincludes practical informationon engineering licensing in theUnited States, problems andsolutions on every technicalsubject in the PE exam syllabus,and detailed appendices includ-ing a reference list. 545 pages.

Price: SFPE Member, $125.00;Nonmember, $175.00

GUIDES

GUIDESSFPE Engineering Guide to Performance-BasedFire Protection Analysis and Design of Buildingsby the SFPE Task Group on Performance-BasedAnalysis and Design, 2000. This guide outlinesa process for carrying out these designs and isessential for anyone who will apply, approve,or be affected by performance-based codes andstandards. Chapters cover such topics as defin-ing your project scope and identifying goals,specifying stakeholders and design objectives,developing performance criteria, creatingdesign fire scenarios and trial designs, evaluat-ing trial designs, and documentation and speci-fications. Equip yourself for the coming era of performance-basedcodes with this unique guide!


Engineering Guide – Assessing Flame Radiation to External Targets from Pool Fires by the SFPE Task Group on Engineering Practices, 1999.Summarizes accepted calculation methods for radi-ant heat transfer from pool fires to targets locatedoutside of a flame. For each method, the datarequirements, data sources, inherent assumptions,and limitations are summarized.


Guide to the 1997 UBC Smoke-Control Provisions – An Illustrative Commentaryby Douglas H. Evans, P.E., published by ICBO, 1999. This sixty-page interpretiveguide provides the basics on smoke management systems as well as detailedinformation for implementing the smoke-control provisions in accordance withsection 905 of the 1997 Uniform Building Code.



The F.P. Connection

An electronic, full-service fire protection resource Web site.

The F.P. Connection offers posting of employment opportunitiesand résumés of fire protection professionals. If, as a fire protec-

tion service provider or equipment manufacturer, your Web site is dif-ficult to locate using search engines and keywords, let us post yourbanner and provide a direct link for use by our visitors who mayrequire your services.

Please visit us at www.fpconnect.com or call 724.746.8855.

For posting information, e-mail [email protected].

Fax: 724.746.8856

The F.P. Connection

SFPE

AN INVITATION TO JOINBENEFITS OF MEMBERSHIP

• Recognition of your professional qualifications by your peers •• Chapter membership •

• Fire Protection Engineering magazine •• SFPE Today, a bi-monthly newsletter •

• The peer-reviewed Journal of Fire Protection Engineering •• Professional Liability and Group Insurance Plans •• Short Courses, Symposia, Tutorials & Seminars •

• Representation with international and U.S.A. engineering communities •

Ask for our membership applicationSociety of Fire Protection Engineers

7315 Wisconsin Avenue, Suite 1225W • Bethesda, MD 20814

301-718-2910www.sfpe.org [email protected]

Society of Fire Protection EngineersA growing association of professionals involved in advancing the

science and practice of fire protection engineering

FIRES-T3: A Guide for Practicing Engineers by the SFPE Task Groupon Documentation of Computer Models, 1995. A practical user’sguide to Fires-T3, a three-dimensional heat-transfer model applicableto analyzing heat transfer through fire barriers and structural elements. 82 pages.

Price: $36.00

The SFPE Engineering Guide to Predicting 1st and 2nd Degree Skin Burnsfrom Thermal Radiation summarizes accepted calculation methods for pre-dicting pain, and first- and superficial second-degree burns from radiant heattransfer. Calculation methods are presented that range from simple algorithmsto more detailed calculation methods. For each method, the data require-ments, possible data sources, inherent assumptions, and limitations are presented. The guide also provides an overview of the physiology of the skinas it relates to thermal injury.



• Ansul .....................................................Page 13

• Advanced Fire Technology, Inc. ..........Page 43

• Ansul, Inc.................................................Page 2

• Central Sprinkler ...................................Page 46

• Edward Systems Technology ..........Page 26-27

• Fenwal Protection Systems ...Inside Back Cover

• Fike Protection Systems..........................Page 4

• Fire Control Instruments, Inc. ................Page 6

• Gem Sprinkler Company.................Back Cover

• Grinnell Fire Protection Systems..........Page 51

• Koffel Associates ...................................Page 29

• Master Control Systems ........................Page 35

• Metraflex ................................................Page 36

• NOTIFIER Fire Systems.........................Page 21

• Potter Electric Signal Company............Page 13

• Protection Knowledge Concepts..........Page 23

• The RJA Group ....................Inside Front Cover

• Reliable Automatic Sprinkler...Page 18 and 31

• Seabury & Smith ...................................Page 37

• Siemens..................................................Page 17

• Simplex ..................................................Page 42

• TVA Fire & Life Safety, Inc. ..................Page 32

• Viking Corporation ...............................Page 38

• Vision Systems.........................................Page 9

• Wheelock, Inc. ......................................Page 24

Index of Advertisers

ADT, Inc.Arup Fire Automatic Fire Alarm AssociationBFPE InternationalBourgeois & Associates, Inc.Central Sprinkler Corp.The Code Consortium, Inc.Code Consultants, Inc.Copper Development AssociationDemers Associates, Inc.Draka USADuke Engineering and ServicesEdwards Systems TechnologyFactory Mutual Research Corp.Fike CorporationFire Consulting Associates, Inc.Fire Suppression Systems AssociationGage-Babcock & Associates, Inc.Grinnell IncorporatedHarrington Group, Inc.HSB Professional Loss ControlHubbell Industrial ControlsHughes Associates, Inc.Industrial Risk InsurersJames W. Nolan Company (emeritus)Joslyn Clark Controls, Inc.Koffel Associates, Inc.

Marsh Risk ConsultingMountainStar EnterprisesNational Electrical Manufacturers AssociationNational Fire Protection AssociationNational Fire Sprinkler AssociationNuclear Energy InstitutePoole Fire Protection Engineering, Inc.The Protectowire Co., Inc.The Reliable Automatic Sprinkler Co., Inc.Reliable Fire Equipment CompanyRisk Technologies, LLCRolf Jensen & AssociatesSafeway, Inc.Schirmer Engineering CorporationSiemens, Cerberus DivisionSimplex Time Recorder CompanyS.S. Dannaway Associates, Inc.Starwood Hotels and ResortsTVA Fire and Life Safety, Inc.Tyco Laboratories Asia Pacific Pty., Ltd.Underwriters Laboratories, Inc.Vanderweil EngineersVan Rickley & AssociatesVision Systems, Inc.Wheelock, Inc.W.R. Grace Company

The SFPE Corporate 100 Program was founded in 1976 to strengthen the rela-tionship between industry and the fire protection engineering community.Membership in the program recognizes those who support the objectives ofSFPE and have a genuine concern for the safety of life and property from fire.


C O R P O R A T E 1 0 0

Solution to last issue’s brainteaser

A wire loop is constructed with enough wire so that the loop justtouches the top of Mt. Everest when the loop’s center coincides withthat of the earth’s center (i.e., it wraps all the way around the earth).You are placed at the top of Everest and asked to cut the wire andinsert a 10-meter section.

Assuming that the radius of the loop is 20,000 km, how far abovethe top of the mountain will this large wire loop rise?

With a radius of 20,000 km, the circumference of the loop is:

With the addition of the 10-meter section, the circumference wouldbecome 125,674 km, which would correspond to a radius of 20,001.6km. Therefore, the loop would rise 1.6 km above the top of themountain.

What is the smallest positivenumber (N) that leaves remaindersof 3, 4, 5, and 6 when divided by8, 9, 11, and 13, respectively?

Thanks to Jane Lataille, P.E., forproviding this issue’s brainteaser.

C r= = × × =2 2 20 000π π , km 125,664 km

B R A I N T E A S E R

The National Society ofProfessional Engineers (NSPE)has developed a new model for

the process by which engineers wouldbecome licensed as professional engi-neers.1 NSPE cited their goal of havingall engineers licensed as PEs and theirbelief that the current licensing proce-dures are inadequate for engineersworking in a number of specializedareas of engineering as their reasons fordeveloping the new model. Accordingto NSPE, today only approximately 20%of all engineers are licensed as a PE.

Under the current model licensinglaw, there are four requirements forbecoming licensed as a PE:

• Graduation from a four-year academic program accredited by the Engineering AccreditationCommission of the AccreditationBoard for Engineering andTechnology

• Passing the Fundamentals ofEngineering Exam, which is alsoreferred to as the “engineer-in-train-ing” exam

• Four or more years of engineeringexperience

• Successful completion of thePrinciples and Practices ofEngineering Exam, which is alsocalled the “professional-engineering”exam.

As with many model rules, therequirements for becoming licensed mayvary in some states from the require-ments of the model law.

The new model proposed by NSPEwould include two separate paths tolicensure as a professional engineer.Under the first path, the first three stepswould be similar to those under the cur-rent model law: engineers would berequired to earn an Bachelor of Sciencedegree from an engineering school, passthe Fundamentals of Engineering exam,and have four years of engineeringexperience. However, the final step tolicensure would require a credentialsand portfolio review, and if the engi-neer’s credentials and portfolio aredeemed acceptable, completion of anew “Professional Licensing Exam.”

The proposed credentials and portfo-lio review is intended to judge whetheran engineer has sufficient experience forlicensure. Also, since the new proposedProfessional Licensing Exam is nontech-nical in nature, it is presumably intend-ed to determine whether the engineerhas sufficient understanding of theapplication of engineering principles.

Instead of testing technical subjects,the new Professional Licensing Examwould focus on ethics and codes andstandards that are applicable to theengineer’s area of practice. The pro-posed change in subject matter for theexam reflects that most of the problemsfaced by state licensing boards dealwith professional ethics, such as whenan engineer practices outside of his orher area of expertise, or how they pro-mote themselves in advertising. As withthe current Principles and Practices ofEngineering Exam, under the new mod-el, SFPE would define what should becovered in the Professional LicensingExam for Fire Protection Engineering.

Under the second path of the newlicensure model, engineers whoreceived an advanced degree in engi-neering, such as a Master of Science ora Ph.D., would not be required to passthe Fundamentals of Engineering Exam.Additionally, for engineers with a mas-ter’s degree, only three years of engi-neering experience would be required,and for those with a doctorate, onlytwo years’ experience would berequired. Engineers with advanceddegrees would also be required toundergo a credentials and portfolioreview and pass the ProfessionalLicensing Exam.

The next step for NSPE is to receiveendorsements of their proposed modelfrom other engineering societies, such asSFPE. If you have opinions on this newmodel, please do not hesitate to sendthem to [email protected].

1 Anon. “NSPE Proposes Changes to ModelLaw for Licensing of Engineers,”Engineering Times, Vol. 22, No. 10,National Society of Professional Engineers,Alexandria, VA, November, 2000.

Changes to the PE Licensing Model Law Proposed

Morgan J. Hurley, P.E.Technical DirectorSociety of Fire Protection Engineers


from the technical director

newsprinkler technology€¦ · kler system relia-bility project management of an esfr sprinkler...

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