Environmental Impact of Automatic Fire,part two原文

Environmental Impact of Automatic Fire Sprinklers:Part 2.Experimental Study
Christopher J.Wieczorek*,Benjamin Ditch and Robert G.Bill Jr.,FM Global,
1151Boston-Providence Turnpike,Norwood,MA 02062,USA
Received:25May 2010/Accepted:1October 2010
Abstract.A recent study on the environmental impact of automatic fire sprinklers is documented in a two part series.The present paper examines the relationship of automatic fire sprinkler technology to environmental rge-scale fire tests were conducted using identically constructed and furnished living rooms.In one test,fire extinguishment was achieved solely by fire service intervention,and in the other,a single residential automatic fire sprinkler was used to control the fire until final extinguishment was achieved by the fire parisons of the total green-house gas production,quantity of water required to extinguish the fire,quality of water runoff,potential impact of wastewater runoffon groundwater and surface water,and mass of materials requiring disposal between the two tests were made.The results show that in addition to providing life safety and limiting property damage,the use of automatic fire sprinklers is a key factor in achieving sustainability.
Keywords :Risk factors ,Environmental impact ,Greenhouse gas emissions
1.Introduction and Background
Current efforts to improve sustainability of new or existing buildings are focused on achieving improvements during normal operations.The importance and contri-bution of risk factors,i.e.,the potential for hazards and their consequences,for achieving sustainable development has been assessed in two recent studies [1,2].Included in these studies are assessments of the lifecycle carbon emissions (LCE)for office and residential buildings,and moderate hazard industrial facilities.The impact of risk factors on lifecycle carbon emission,LCE,is illustrated in Figure 1.The plot indicates the carbon emission for a building as a function of time.Note that proportions are not to scale,but are expanded for readability.The lower curve may be considered the carbon emissions under normal conditions;the upper curve shows the deviation from that of normal conditions due to a fire.
For residential occupancies,the contribution of fire risk to the total lifecycle carbon emissions of a home without sprinklers is between 0.4%and 3.7%.The contribution of a fire risk to the total lifecycle carbon emissions of a home is reduced to 0.2%when sprinklers are used,as all large fires are eliminated [3].
*Correspondence should be addressed to:Christopher J.Wieczorek,E-mail:Christopher.wieczorek@
Fire Technology,47,765–779,2011
Ó2010Springer Science+Business Media,LLC.Manufactured in The United States
DOI:10.1007/s10694-010-0192-7
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2.Fire Test Setup and Procedures
Testing was conducted under the20-MW calorimeter in the Large Burn Labora-tory(LBL)of the Fire Technology Laboratory located at the FM Global Research Campus in West Glocester,Rhode Island.The20-MW calorimeter con-sists of a10.7m(35ft)diameter inlet that tapers down to a3.05m(10ft)diame-ter duct.The inlet to the calorimeter is at an elevation of11.3m(37ft)from the floor.Measurements are made within the duct downstream of an orifice.Beyond the measurement location,the exhaust duct connects to a wet electrostatic precipi-tator(WESP)prior to cleaned gases venting to the atmosphere.All tests were conducted with the ventilation rate set to94.4m3/s(200,000scfm).The rooms were positioned under the20-MW calorimeter and the room centerline was offset relative to the calorimeter bell centerline by approximately1.1m(3.75ft)in the north-south direction to ensure that the gases exiting the room were collected within the calorimeter.
The living room was constructed by an outside contractor using standard indus-try practices.The room measured4.6m(15ft)wide by6.1m(20ft)long,and had a2.4m(8ft)high ceiling.To simulate a single room of a larger house,two of the walls were considered exterior walls and included windows and an exterior door.The other two walls were considered interior house walls,with one being solid with no openings and the other having a1.2m wide92.1m tall(4ft97ft) archway.
The two exterior walls and the ceiling were insulated using R13and R19fiber-glass insulation respectively.The windows installed in the room were double hung, replacement windows measuring0.9m by1.47m(3ft by4ft10in.).The win-dows were constructed of PVC frames with double-pane glass.The exterior door was steel clad with an insulated core and had dimensions of0.9m by 2.0m (36in.by80in.).The door had a0.51m wide by0.9m tall(20in.by36in.)sin-gle pane window.The exact locations of the exterior door and windows are shown in Figure2,and each was installed with a203mm(8in.)sill.
Each of the rooms was carpeted and furnished with new furnishings and con-
tents.The items are grouped into four categories:primary fuel items,secondary
Environmental Impact of Automatic Fire Sprinklers767
Table1
Room Furnishings and Contents
Quantity Item Principle Combustible Material Primary fuel items
1Recliner Urethane foam,wood frame
1Sofa Polyurethane foam,wood frame 1Loveseat Polyurethane foam,wood frame Secondary fuel items
1Coffee table Rubberwood
1Console table Rubberwood
1End table Rubberwood
1TV stand with shelves Laminated composite wood
2Bookcase Laminated composite wood 137-inch LCD television Unexpanded plastic
fuel items,decorative items,and ignition package.The primary and secondary fuel items are listed in Table1.A schematic of the room with relative positions of the primary and secondary fuel items,and the ignition package is presented in Figure2.Decorative items included a table lamp,picture frames,mirror,clocks, magazines,hardcover books,CD boxes,and drapes.The decorative items were arranged throughout the room.The primary combustible materials of the decora-tive items were cotton,soft woods,polystyrene and polypropylene plastic,card-board,and paper.Thefire was initiated in a magazine rackfilled with three rolled up newspapers,which was positioned adjacent to the loveseat.The newspapers were ignited using a propane torch.
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3.Firefighting
Fire control and suppression was achieved in the non-sprinklered test by manual fire service intervention only;in the sprinklered test,a single residential sprinkler was used to control thefire untilfinal extinguishment was achieved by thefire ser-vice.
In both tests,thefire service response was initiated via smoke detector activa-tion.Upon activation a10-min response clock was started.The10-min delay accounted forfire service notification,dispatch,arrival,and setup and was based on nationally accepted standards[4–6].
In the sprinklered test,a single FM Approved Tyco Fire Suppression&Build-ing Products recessed residential sprinkler(TY4234),was installed at the ceiling center within the living room.The sprinkler was equipped with a fast-response fusible link,which had a temperature rating of68°C(155°F).A nominal oper-ating pressure of 1.3bar(19.0psig)was used,resulting in a 4.1mm/min (0.1gpm/ft2)water density,in accordance with FM Global Property Loss Preven-tion Data Sheet2-5,Installation Guidelines for Automatic Sprinklers in Residential Occupancies[7].
4.Instrumentation
Scientific measurements internal and external to the room were made in each test. Each room was instrumented with ceiling and elevation thermocouples,heatflux gages,and gas measurements.In addition,each room was instrumented with two smoke detectors,one ionization detector and one photoelectric detector.Detector operation was monitored and recorded by connecting the speaker signal to the data acquisition system.The detectors were installed on the interior wall with the centerline of the detectors22.9cm(9in.)below the ceiling.The photoelectric detector was20.3cm(8in.)inward from the edge of the archway and the ioniza-tion detector was35.6cm(14in.)from the edge.
Continuous real-time gas measurements within the20-MW calorimeter duct include oxygen,carbon monoxide,carbon dioxide,and total hydrocarbons.Stan-dard FM Global measurements within the duct were supplemented by an outside contractor and included the following[8]:
Criteria Pollutants
Volatile Organic Compounds(VOCs)
Greenhouse Gas Pollutants
Particulate Matter
Heavy Metals
Semi-Volatile Organic Compounds(SVOCs)
Other Organic and Inorganic compounds
Total Hydrocarbons
Oxygen
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4.1.Water Quality Analysis
The quality of the wastewater generated in each test was evaluated and the poten-tial environmental impacts on groundwater and surface water were determined. Analysis of the water samples included general chemistry parameters,heavy met-als,cyanide,volatile organic compounds,and semi-volatile organic compounds.
A special water collection system was constructed to collect the portion of the water exiting the living room via the archway.The system generally consisted of a stainless steel collection pan fastened to the base of the archway.Two sump pumps were located within the pan to transfer the water to a1040L(275gal) intermediate bulk container(IBC).Each test used a new IBC,and the stainless steel collection pan was scrubbed and triple rinsed with distilled water between tests to ensure there was no cross contamination.The collection pan was also cov-ered in plastic wrap until immediately before the start of each test.
4.2.Solid Waste Analysis
In addition,the solid waste generated in each test was evaluated to determine if the debris exhibited the hazardous waste characteristics of toxicity.Samples of ash and/or charred materials were collected after each test and analyzed per the Uni-ted States Environmental Protection Agency’s(USEPA)Toxicity Characteristic Leaching Procedure(TCLP),Method1311.Details of the water and solid waste analyses are reported in Ref.[9].
5.Experimental Results
On September17,2009,thefirst fully instrumented,non-sprinklered test was con-ducted.The comparison burn,a fully instrumented sprinklered test was conducted on October1,2009.Thefire test chronologies for the two tests are provided in Table2.In the non-sprinklered test,fire spread from the magazine rack to the curtains and loveseat was noticeably slower compared to the sprinklered test,as seen in the time for theflames to reach the ceiling.The slowerfire development does not impact any of thefinal results and conclusions.
The chemical heat release rate of eachfire was calculated from calorimetry tech-niques based on carbon monoxide and carbon dioxide generation.The total chemical energy released during eachfire was determined by integrating the time-resolved heat release rate data.The peak heat release rates were300kW and 13,200kW respectively.The total energy released in the non-sprinklered test was 5,169MJ,76times greater than that of the sprinklered test,which was68MJ. Flashover is defined by the International Standards Organization as‘‘the rapid transition to a state of total surface involvement in afire of combustible material within an enclosure’’[10].Although not precise,the typical quantitative criteria for flashover are room temperatures between500°C(932°F)and600°C(1112°F),or radiation to thefloor of the compartment from the gas layer between15kW/m2 and20kW/m2(1.3BTU/ft2s to1.8BTU/ft2s).A more subjective demarcation of flashover is the visual observation offlames external to the enclosure.
770Fire Technology2011 Table2
Fire Test Chronologies
Event Sprinklered(min:s)Non-sprinklered(min:s) Ignition00
Smoke detector activation(ionization)0:250:25
Flames reach the ceiling2.4m(8ft)0:351:55 Sprinkler activation0:44–
Smoke detector activation(photoelectric)1:100:33
Window1breaks–4:00
Window2breaks–4:42
Flames extend out of archway–4:48
Window4breaks–5:12
Window3breaks–5:32
Flames exit around exterior door seam–5:42
Window in exterior door falls out–6:18
Fire service pries open door10:30–
Fire service applies hose stream10:3810:30
Fire service enters room10:5811:42
Fire out13:4024:44
Note:Windows are numbered as East Wall,North(#1),East Wall,South(#2),South Wall,East(#3),and South Wall,West(#4).
Using these criteria,the time toflashover in the non-sprinklered test was deter-mined to be between271s and327s.The occurrence offlashover prior tofire ser-vice response is an indication that thefire would have progressed to adjoining rooms,thus increasing the volume of materials consumed by thefire and the quantity of water required to extinguish thefire.In the sprinklered test the tem-perature near the ceiling at the archway did not exceed136°C(277°F),the heat flux at thefloor did not exceed0.3kW/m2(0.03BTU/ft2s),and noflames were observed exiting the enclosure.All of the data indicate thatflashover did not occur in this case and thefire was contained completely to the room of origin. The total volume of water discharged in the sprinklered and non-sprinklered test was1,938L(512gal)and3,835L(1013gal)paring the vol-ume of water for the non-sprinklered test to the total combined sprinkler and hose stream volume,for the sprinklered test,it is seen that50%less water was used in the sprinklered test compared to the non-sprinklered test.Furthermore, thefire with the sprinkler was extinguished3min and17s faster than the non-sprinkleredfire.This comparison is conservative,i.e.,expected values for the non-sprinklered case will be larger,because in the non-sprinklered tests thefire would have propagated to adjacent rooms,if not the entire house,requiring more time and water to extinguish thefire.Conversely,thefire was contained to the ignition area in the sprinklered room making the results independent of any additional rooms.Extrapolation of the water usage data to larger occupancies will be made in a later section.
Of the123species analyzed in the air emissions,only76were detected in either the sprinklered or non-sprinklered test.There were24species detected at ratios in
Environmental Impact of Automatic Fire Sprinklers771 excess of10:1,of which11were detected at ratios in excess of50:1,and of those six were detected at ratios in excess of100:1.Four species,NH3,1,2,3-trichlo-ropropane,carbon tetrachloride,and o(rtho)-xylene,were detected in the non-sprinklered test but not in the sprinklered test.Similarly,four species,ethanol, hydrogen chloride(HCl),isopropyl alcohol(IPA),and bromoform,were detected in the sprinklered test but not the non-sprinklered test.The data indicate that ‘‘The total emissions from the Sprinkler controlled burn were lower than the emis-sions from the No Sprinkler controlled burn’’[8].
The following results and discussion related to the wastewater analysis have been extracted from Ref.[8].The water analysis includes water samples from each of thefire tests.In addition,since FM Global uses a closed-loop recycled water system forfirefighting purposes,samples of the recycled water on each day were also analyzed to establish a baseline.Because various constituents were detected in the recycledfirefighting water samples,the concentrations of constitutes detected in each wastewater sample were adjusted.This adjusted,or net,concentration rep-resents the difference between the detected level of a constituent in wastewater and the corresponding detected level in the recycled water sample.The results pre-sented in this paper are based on the net concentrations,unadjusted values and data on the recycled water samples can be found in Ref.[2].
5.1.Sprinklered Controlled Burn
Acetone,benzene,and chloroform were detected in the sample obtained from the sprinklered test.Both chloroform and acetone levels were lower than those of the recycled water sample collected on the same sample date.No SVOCs were detec-ted in the sprinklered sample.Total and dissolved copper,mercury,and zinc were detected in the sample;lead was detected only in total form in this sample.
5.2.Non-Sprinklered Controlled Burn
Chloroform,styrene,acetone,and several phenolic compounds were detected; both acetone and chloroform levels were lower than those detected in the recycled water sample.Heavy metals,including antimony,arsenic,chromium,lead,mer-cury,and silver,were also detected.Of the metals,only antimony and mercury were detected in dissolved form implying that most of the detected metals are likely associated with suspended particulate matter.Three SVOCs were detected in the non-sprinklered sample.
Both chloroform and acetone concentrations were highest in the recycled water sample compared to concentrations detected in the sprinklered and non-sprin-klered samples.However,the sprinklered and non-sprinklered samples contained higher levels of total suspended and dissolved solids,organic carbon,and nutri-ents(nitrogen and phosphorous).In general,the non-sprinklered water sample contained the highest levels of solids and TOC,and a higher pH.This is expected, considering the high generation of ash resulting from the non-sprinklered test compared to the sprinklered test.Of all of the wastewater samples,the total cyanide concentration was highest in the sprinklered sample.Cyanide gas can be
772Fire Technology2011 generated from burning synthetic polymers in building materials and furnishings, as well as natural materials such as wood.
Metals concentrations were variable between the sprinklered and non-sprin-klered test samples,with no clear bias shown by either sample.In general,how-ever,the differences in concentration between the two tests were less than an order of magnitude.Of the eight metals analyzed(as total metals),six metals were detected in the non-sprinklered sample at concentrations higher than that of the sprinklered sample.However,dissolved copper,mercury,and zinc concentrations were highest in the sprinklered test.Dissolved antimony concentrations were high-est in the non-sprinklered sample.
The pH of the composite wastewater samples from the non-sprinklered test was 12.1versus pH of7.9for the wastewater sample from the sprinklered test.Thus, the wastewater from the non-sprinklered controlled burns was approximately four orders of magnitude higher in alkalinity than the wastewater from the sprinklered test.The discharge of any wastewater with pH values of higher than10would be a serious environmental concern.Wastewaters exhibiting pH values of greater than9.0would be exceeding the allowable discharge range of pH 5.5to9.0 required by most environmental regulatory agencies.
Solid waste from each of the tests was analyzed as described previously.The results of the analysis indicate that the samples‘‘would not be considered‘hazard-ous waste’under USEPA regulations’’.Furthermore,‘‘the wastes are not antici-pated to significantly leach once landfilled’’[8].
6.Discussion
In the following sections,the reduction in the environmental impact due to the use of automaticfire sprinklers in afire will be discussed.Quantification of the environmental impact will be based on analysis of greenhouse gases,water usage, potential environmental impacts of wastewater runoff,fire damage,and solid waste material disposed in landfills.
6.1.Impact on Greenhouse Gases
This section discusses the impact of sprinkler protection on the generation of greenhouse gases.The measured greenhouse gases, e.g.,carbon dioxide(CO2), methane(CH4),nitrous oxide(N2O),can be converted to an equivalent mass of carbon dioxide:
CO2;equivalent¼GWP gasÁm gasð1Þwhere CO2,equivalent is the equivalent mass of carbon dioxide for a gas,m gas is the mass of the greenhouse gas,and GWP gas is the global warming potential of the gas.The global warming potentials(GWP)‘‘are a measure of the relative radia-tive effect of a given substance compared to another,integrated over a chosen time horizon’’[11].A common time horizon used by regulators is100years.
The global warming potential,measured masses of greenhouse gases,and calcu-lated equivalent carbon dioxide levels are listed in Table 3.The equivalent mass of CO 2generated in the non-sprinklered test was 404.4kg (890.7lb)versus 8.7kg (19.2lb)generated in the sprinklered test.This indicates that in the event of a fire,the use of sprinklers can reduce the greenhouse gas emissions by 97.8%.It should be noted that this is a conservative value,i.e.,the expected values will be larger,since in the non-sprinklered test the fire would have propagated to adjacent rooms,if not the entire house,before firefighting intervention commenced.
6.2.Water Use Extrapolation
In this section,the quantity of water needed to extinguish a fire in structures lar-ger than the one used in this study will be estimated.The key assumption in this analysis is that the quantity of water needed to extinguish the fire is directly pro-portional to the area of the room.Based on the area of the room used in this study the quantity of water per unit area needed to extinguish the fire without a sprinkler was 138L/m 2(3.4gal/ft 2).
Assuming various percentages of damage to a typical sized residence,the pro-jected quantity of water required by firefighters can be determined and the percent reduction achieved by using a sprinkler can be estimated.The estimates in Table 4indicate that,in the event of a fire,for an average sized home of 164m 2(1,765ft 2)using sprinklers can reduce the water usage between 50%and 91%.Table 3Equivalent Carbon Dioxide Values for Measured Greenhouse Gases
Gas
GWP a Measured mass
Equivalent CO 2Non-sprinklered,kg (lb)Sprinklered,kg (lb)Non-sprinklered,kg (lb)Sprinklered,kg (lb)CO 2
1360.1(794) 5.9(13.0)360.1(794) 5.9(13.0)CH 4
250.82(1.8)0.004(0.019)20.5(45.2)0.1(0.22)N 2O
2980.08(0.17)0.009(0.02)23.8(52.5) 2.7(6.0)Total
404.4(890.7)8.7(19.2)a Based on a 100-year time interval.
Table 4
Water Usage Estimates
Percentage
damaged
Area damaged,m 2(ft 2)Estimated water usage by firefighters,L (gal)Reduction achieved by using sprinklers (%)25
41(441)5,644(1,491)6650
82(883)11,292(2,983)8375
123(1,324)16,936(4,474)89100164(1,765)22,584(5,966)91
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6.3.Fire Damage
The combustible loading within each living room consisted of the primary and secondary fuel items,decorative items,and ignition package comprising a com-bined mass of309.8kg(683.0lb).The carpet,carpet padding,and plastic window frames are also considered part of the combustible loading,adding an additional 130kg(287lb)of combustible material.Therefore,the total mass of combustible material in each living room was440kg(970lb).
In the sprinklered test,the items that sustainedfire damage included the recli-ner,loveseat,magazine rack,carpet,and carpet padding.The initial andfinal mass of each of these items is listed in Table5.Thefinal mass of the magazine rack,carpet,and carpet padding was not recorded;however,based on the post test images,it is assumed that80%of the magazine rack was consumed in the fire,and a457mm9457mm(1.5ft by1.5ft)area,or0.75%,of carpet and car-pet padding was damaged in thefire.Based on the values listed in Table5,and the initial weight of all the combustibles in the room,the fraction of material burned in the sprinklered test was3.0%.
In the non-sprinklered test,following thefire extinguishment,none of the items within the room were recognizable and thefinal mass of individual items could not be determined directly.The mass of materials consumed is,therefore,esti-mated based on the total energy released and an assumption for the chemical heat of combustion.The total energy released from thefire was calculated to be 5,ing the chemical heat of combustion for pine,i.e.,12,400kJ/kg,as the lower bound and that offlexible polyurethane foam,i.e.,19,000kJ/kg,as the upper bound,it is calculated that the mass of material consumed in thefire was between272kg(600lb)and417kg(919lb),or62%to95%of the total room fuel load,for thefire scenario used in this study.In an actual home,thefire would almost certainly have propagated to adjacent rooms increasing the mass of materials damaged.
The increasedfire damage,in the non-sprinklered test,will have a direct impact on a building’s sustainability via the embodied carbon associated with materials necessary for reconstruction.Norman et al.[12]estimated that the average equiva-lent annual embodied greenhouse gases per unit area for construction materials
for residential dwellings is7:4kg co
2=m2Àyear.Estimates of the embodied carbon
associated with furnishings,contents,and carpet were not addressed in this study. Table5
Mass of Combustibles Consumed in Sprinklered Test
Item Initial weight,kg(lb)Final weight,kg(lb)Mass consumed,kg(lb) Recliner44.5(98.1)40.8(90) 3.7(8.1) Loveseat56.9(125.5)49.9(110)7.0(15.4) Carpet+carpet padding94.0(207)93.3(205.7)0.7(1.3) Magazine rack 1.7(3.75)0.34(0.75) 1.4(3.0)
Total197.1(434.5)184.3(406.4)12.8(28.5)
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6.4.Potential Environmental Impacts of Fire Water Runoff1
Fire water runoffcarries with it numerous contaminants and solids that may enter soil,groundwater,or a water body and potentially pose a health risk or cause ecological harm.To evaluate the difference in pollutant loading and associated environmental hazards between the sprinklered and non-sprinklered tests,waste-water results were compared to two types of US federal water quality standards: Maximum Contaminant Levels(MCLs)and National Recommended Water Qual-ity Criteria(WQC).Although MCLs and WQC are not directly applicable to wastewater,these criteria can be used as tools to assess potential environmental impacts that may be associated withfire wastewater runoff.
The net concentrations in the wastewater represent a worst-case estimate of ground or surface water contamination.Under a more typical scenario,one would expect that only a portion of the totalfire wastewater volume would percolate through the ground into an underlying aquifer or migrate overland and discharge into a water body.Because there are a variety of environmental factors(such as soil type,volume of the receiving water body,depth to groundwater etc.)that could affect the extent of dilution of wastewater into either surface water or a groundwater aquifer,a generic10-fold dilution factor was applied to the net wastewater concentrations of constituents in order to estimate hypothetical surface or groundwater concentrations[9].
Under a worst-case scenario,where all of the wastewater from afire runs offor percolates into a potable water source and assuming that there is no decrease in the concentration of contaminants,the resultant concentrations of three parame-ters or contaminants could exceed drinking water standards for the sprinklered test.Five parameters or contaminants could exceed drinking water standards for the non-sprinklered test.This suggests that the wastewater could potentially pose a health risk to users of an impacted water supply.Under a more realistic scenario,assuming that a10-fold dilution of contaminant concentrations in waste-water would occur once wastewater enters a drinking water supply,fewer constit-uents exceed the MCLs,these are summarized in Table6.
Detected concentrations and diluted concentrations of constituents in each wastewater sample were compared to WQC.Under a worst-case scenario,assum-ing that the water source would contain100%of the initial concentration of a contaminant present in the wastewater,more constituents were detected in the non-sprinklered test sample(in particular,heavy metals)that exceed WQC com-pared to the sprinklered test sample.Again,assuming that a10-fold dilution of pollutant concentrations would occur once the wastewater entered a water body, several constituents remain at levels exceeding WQC in the non-sprinklered test, whereas fewer constituents under the sprinklered test exceed WQC.The diluted concentrations that exceed the WQC are summarized in the Table7.
1The following results and discussion related to the wastewater analysis are based on results and discussions presented in Ref.[9].。