ANALYSIS OF PREDICTED SPRINKLER ACTIVATION TIME IN AUTOMATED CAR PARKINGS

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1 Bulletin of the rnsilvni University of Brşov CIBv 2014 Vol. 7 (56) Specil Issue No ANALYSIS OF PREDICED SPRINKLER ACIVAION IME IN AUOMAED CAR PARKINGS B. BRĂNIȘEANU D. M. ȘERBAN D. D. SOLOMON Abstrct: In the pst few yers cr prkin hs evelope ifferent technoloies. Protection inst fire must to evelop properly to ensure the minimum level of security n protection. Mny stuies rerin fire behvior on n enclose cr prkin were me. Fire suppression n smoke control it s commonly issue of this stuies. his pper is focuse on the clcultion methos n computtionl flui ynmics moels tht cn preict the ctivtion time of sprinkler systems mounte on n enclose utomte cr prkin. Key wors: sprinkler, cr stcker, stnr response, test plune 1. Introuction In cr prkin fire cn spre esily becuse of the smller istnce between the crs n the hiher quntity of flmmble liquis n combustible mterils such plstics. A prticulr cse of cr prkin is represente by multiprkin cr stckers. Serious concerns were expresse rerin the fire sfety of stckers. hese re utomte cr prkin evices of vrious types were crs re locte bove one nother with no fire resistin floor or ceilin between them. 2. Fire behvior on cr stckers Automte cr prks like stckers re becomin incresinly common n there re vriety of ifferent utomte cr prks types, some involvin hollow, other usin simple jck rmps to ouble cpcity. his equipment llows two or more crs to be prke on the plce of sinle cr. Such innovtions hve implictions for fire fihters ue to the very rpi evelopment of fire in the secon cr. Stuies [1] emonstrte tht the fire rowin fster in the lower cr on stcker n spre very rpily to the cr bove in bout 5 or 6 minutes. he complexity of stcker structures my lso cuse ifficulties in the ppliction of wter. Potentil benefits of instllin sprinkler systems on cr prks hve been emonstrte by mny stuies [2], but esin fire enineerin coes on t tke into ccount the ctivtion time. Becuse the istnce between crs is very smll fire cn spre rpily from cr to nother n the ctivtion time of 1 Generl Inspectorte of Emerency Situtions 2 Police Acemy Al. Ion Cuz Firefihters Fculty

352 Bulletin of the rnsilvni University of Brşov Vol. 7 (56) Specil Issue No. 1-

2 352 Bulletin of the rnsilvni University of Brşov Vol. 7 (56) Specil Issue No sprinkler system become n essentil prmeter in this cse. Fi. 1. Automte cr prkin Durin the rowth ste of fire, the smoke environment in n enclose cr prkin cn be represente by two lyers, hot upper lyer n cool lower lyer. In erly stes of fire evelopment, the temperture of the lower lyer is close to mbient. he temperture of the upper lyer rises s the plume bove the fire trnsports smoke n hot ses into the upper lyer lon with sinificnt volume of entrine ir. Once the plume reches the ceilin in ril irection wy from the plume. his hot s flow is known s the ceilin jet, the properties of which stronly influence the opertion of sprinkler systems. he ctivtion time of the sprinkler is the time t which the temperture of the sprinkler link reches the nominl ctivtion temperture. Convective het trnsfer from the flowin ses in the ceilin jet to the sprinkler link is the primry het trnsfer mechnism. However, for n enclosure where the ceilin jet is immerse in hot lyer, itionl het trnsfer from the hot lyer to the sprinkler occurs. he opertion of sprinkler epens on severl fctors other thn the iven ctivtion temperture, Nsh n Youn [3] escribe the fctors s: - ctul opertin temperture of sprinkler. - therml cpcity of those prts of the sprinkler which ffect opertion is quntifie by RI n c-fctor. - ese of trnsfer of het from the ir to the ffecte prts of the sprinkler (RI/cfctor). - rte of rowth of the fire in terms of its convective het output. - heiht of the ceilin below which the sprinkler is mounte. - ceilin confiurtion below which the sprinkler is mounte. - therml qulities of the ceilin ssembly. - istnce between sprinkler n ceilin. - horizontl istnce of sprinkler from fire. - extrneous fctors ffectin the pttern of flow of the ses from the fire to the sprinkler. - rte of rise of ir temperture surrounin the sprinkler. he sensitivity of sprinkler he epens on the RI n conuction fctor. Bsiclly the more sensitive the sprinkler he, the quicker it will ctivte t iven fire. 3. Response ime Inex (RI) he RI is mesure of therml sensitivity, which inictes how fst the sprinkler cn bsorb het from its surrounins sufficient to cuse ctivtion. he RI is clculte tkin ccount of the ctul function time of link mounte in sprinkler or other evices in iven stnr conitions n its usully etermine by

3 BRĂNIȘEANU, B., et l.: Anlysis of preicte sprinkler ctivtion time in utomte cr prkins plunin into hete lminr irflow within test oven. It is clculte usin the followin: - opertin time of the sprinkler; - opertin temperture of the sprinkler s het responsive element which is etermine in bth test; - ir temperture of the test oven; - ir velocity of the test oven; - sprinkler s conuctivity (c) fctor, which is the mesure of conuctnce between the sprinkler s het responsive element n the sprinkler mounte oven; A clssifiction of sprinkler hes rerin RI n conuctivity c - fctor it s been presente in SR EN A1:2002, Fixe firefihtin systems Components for sprinkler n wter spry systems Prt 1: Sprinklers. Sprinklers efine s fst response hve therml element with n RI of 50 m 1/2 s 1/2 or less, efine s specil response hve therml element with n RI between 50 m 1/2 s 1/2 n 80 m 1/2 s 1/2, efine s stnr response A hve therml element with n RI between 80 m 1/2 s 1/2 n 200 m 1/2 s 1/2 n efine s stnr response B hve therml element with n RI of 200 m 1/2 s 1/2 or more. Fctory Mutul Reserch Institute evelope test pprtus to etermine the RI of sprinkler hes. In the test, clle plune test, the sprinkler he is plune into the flow of hete ir. he temperture n velocity of the s re known n re constnt urin the test. he eqution for the chne in the link temperture is t 1 (1) 353 Since the s temperture is constnt urin the test, the solution to this eqution is t exp 1 (2) Rerrnin the eqution ives t (3) ln In therms of the response time inex, eqution becomes RI ln r 0 t u r (4) Sprinkler t sheets presents RI vlue for every sprinkler he. Knowin the RI, the chne in temperture of similr units cn be clculte for ny history of fire ses flowin pst it. he form of the het trnsfer eqution is: t u RI (5) his eqution is use to clculte the temperture of sprinkler he expose to fire ses. It cn be use to etermine the time t which the sprinkler bulb or link reches its opertin temperture. Alpert [4] present fire moel with ceilin jets hvin ner constnt s temperture n velocity wich cn be moele usin the followin series of equtions

4 354 Bulletin of the rnsilvni University of Brşov Vol. 7 (56) Specil Issue No Q 4.74 Q r r o C 0 F (6) H H Where r/h > 0.18, n Q 14.9Q o C o F (7) 5 / 3 5 / 3 H H Where r/h 0.18, n 1/ 3 1/ Q H 0.25Q H u m / s ft / s 5 / 6 5 / 6 r r (8) Where r/h his moel ssumes tht the temperture n velocity of the fire ses t point wy form the source re relte to the instntneous het relese rte of the fire. For constnt s temperture n constnt s velocity, the bsic het trnsfer eqution cn be t (9) t (10) t 0 exp C 1 (11) or, substitutin the eqution for RI tu 0 1 exp C RI (12) he RI is the prouct of the therml time constnt of the het responsive element n the squre root of the ssocite s velocity.

5 BRĂNIȘEANU, B., et l.: Anlysis of preicte sprinkler ctivtion time in utomte cr prkins RI u 1/ 2 (13) m c (14) h A c he conuctivity c - fctor is mesure of how much of the het picke up from 355 the surrounin s is conucte into the sprinkler frme from the lss bulb. Computtionl prorms such s Fire Dynmics Simultor or BrnzFire tht cn preict the ctivtion time of sprinkler he uses moel bse on ifferentil eqution incluin convective hetin of the sensin element n conuctive losses to the sprinkler frme. t c C2 u u m. (15) RI RI RI 4. Experimentl conition n proceures For the experiments two stnr response sprinkler hes with sme chrcteristics were plce in 5,5 x 3,1 x 2,3 m fire comprtment me form concrete of 10 mm thickness. here ws no open vents in the experimentl construction n to brin oxyen urin the fire tests oor with 1,4x2,0 m imensions ws open 20 cm from the close position. Sprinkler hes were mounte t 35 cm bellow the ceilin t 1 m istnce from ech other. For the first test 10 l ethnol pn ws plce into the corner of the room to simulte sinle cr fire n then the sme pn with ethnol ws covere with 5 mm steel flne t 90 cm bove the floor to simulte simple two crs stcker. o recor tempertures insie the fire comprtment three thermocouples type K were plce into the wll t 30, 60 n 90 cm bove the floor. 5. Conclusions n results he im of this stuy ws to investite the sprinkler ctivtion time in utomte cr prkin n to ientify ll criticl prmeters tht cn influence it. Fi. 2 emperture evolution insie the fire comprtment

6 356 Bulletin of the rnsilvni University of Brşov Vol. 7 (56) Specil Issue No he results s shown in the tble 1, le to the followin observtions rerin to the ctivtion time: - the steel flne influence the movement of the hot ses insie the fire comprtment; - sprinkler ctivtion time ws bier in the stcker cse; - fire sfety enineers shoul crefully clculte the ctivtion time of sprinkler systems especilly in utomte cr prks becuse the ctivtion ely in such fire comprtments cn cuse rpi evelopment of fire n extinuish process cn file; - in rck sprinkler system must be instlle to ecrese the ctivtion time; - fst response sprinkler hes woul be more efficiently thn other sprinkler he types; - when people presence is not necessry to prk the crs n pproprite fire prevention system shoul be tke into ccount t fire sfety esinin. Experimentl results ble 1 Activtion time [sec] Cr stckers Reulr cr prk FDS Cr stckers FDS Reulr cr prk Sprinkler no Sprinkler no After the experimentl work the results show tht the ifference between Fire Dynmics Simultor n fire comprtment test is not bier thn 25 %. Fire Dynmics Simultor ctivtion times is resonbly well, bein within 25 % of the ctul times n it ten to be conservtive. Nomenclture A re of the sprinkler boy (m 2 ) c conuctivity fctor (m/s) 1/2 C 2 Di Mrzo constnt empiriclly etermine to be 6 x 10 6 k/(m/s) 1/2 H comprtment heiht (m) h c convective het trnsfer (kw/m 2 0 C) M mss of sprinkler boy (k) Q - totl het relese rte (kw) r ril istnce from the xis of the fire plume (m) 1/2 RI response time inex (m s) time (s) mbient temperture ( 0 C) - link temperture ( 0 C) s temperture ( 0 C) m temperture of the sprinkler mount ( 0 C) u s velocity (m/s) u 0 s test velocity (m/s) - volume frction of wter in the s strem - time constnt References 1. SP echnicl Reserch Institute of Sween: Report 2008:41, Bus Fire, Li, Y.: Assessment of Vehicle Fires in New Zeln Prkin Builins. Fire Enineerin Reserch Report 04/2, University of Cnterbury, New Zeln, My Nsh, P., Youn, R.: Automtic Sprinkler Systems for Fire Protection. 3 r E., Prmount Publishin Limite, Enln, Alpert, R.L.: Clcultion of Response ime of Ceilin-Mounte Fire Detectors. In: Fire echnoloy, 1972.

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