PRELIMINARY STUDIES ON THERMAL SENSITIVITY OF FUSABLE LINKS WITH A WIND TUNNEL

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1 Inerninl Jurnl n Enineerin Perfrmnce-Bed Fire Cde, Vlume 9, Number 1, p.1-6, 2007 PRELIMINARY SUDIES ON HERMAL SENSIIVIY OF FUSABLE LINKS WIH A WIND UNNEL W.K. Chw nd Anu C.K. Chen Reerch Cenre fr Fire Enineerin, Deprmen f Buildin Service Enineerin Are f Srenh: Fire Sfey Enineerin he Hn Kn Plyechnic Univeriy, Hn Kn, Chin (Received 17 Auu 2006; Acceped 15 Nvember 2006) ABSRAC hi i repr n jin feibiliy udy wih he Fire Service Deprmen n explrin hw herml eniiviy f fuble link cn be eed. Five mple f fuble link prvided were eed by fllwin UL-33 n He repnive link fr fire-precin ervice wih mdified wind unnel. A wind unnel fr udyin he herml repne f prinkler hed he Hn Kn Plyechnic Univeriy w ued. In he e, he fuble link mple were lded under 0.4 kf. he wrk-ecin f he unnel w e ir emperure f 135ºC nd ir peed f 2.54 m -1. Reul ueed h i i feible e he herml eniiviy f fuble link by fllwin UL INRODUCION here re inere in ein he herml eniiviy f fuble link mde lclly. Fr quliy cnrl, cmmn e i meure he civin emperure f fuble link by h wer bh. Hwever, he reul f hi e cn nly e wheher he fuble link cn be cived he pecified emperure. here i n indicin n hw ln he fuble link will be cived. In her wrd, herml eniiviy f he fuble link h be eed. here re vere ndrd n ein he herml eniiviy f fuble link wih wind unnel. Exmple re UL-33 n He repnive link fr fire-precin ervice [1] nd AS n Preliminry udie n herml eniiviy f fuble link [2]. he Fire Service Deprmen (FSD) i inereed in inveiin wheher uch ein prcedure fr fuble link cn be crried u in Hn Kn. A jin feibiliy udy prjec f ein he herml eniiviy f fuble link w hen wrked u wih Prfer W.K. Chw, Chir Prfer f Archiecurl Science nd Fire Enineerin he Hn Kn Plyechnic Univeriy (PlyU) in Sepember, A em w hen e up wih me enineer frm FSD in Fi. 1. In fc, herml eniiviy f prinkler hed h been udied by Prfer Chw fr 20 yer. Afer erie f meein wih he enineer frm FSD, i i reed h UL-33 will be fllwed. I i pible e fuble link in Hn Kn by fllwin hi ndrd wind unnel cn be develped eily. Five mple f fuble link were delivered Prfer Chw nd eed. Fi. 1: he em nd wind unnel e n 25 Jnury ESING PROCEDURE A wind unnel w cnruced under he uperviin f Prfer Chw PlyU fer hi rinin Fire Reerch Sin (FRS), Brehmwd, UK in Sepember h w ne f he reerch nd develpmen ucme f chmen exercie he lden e f plyechnic. Advice frm dicuin wih he pineer exper, Mr. C. hebld FRS, n ein he herml eniiviy f prinkler were pplied build he unnel PlyU in Deiled decripin were repred in he lierure 1

2 Inerninl Jurnl n Enineerin Perfrmnce-Bed Fire Cde [3,4]. A chemic dirm f he wind unnel i hwn in Fi. 2. Ech fuble link wuld be plced in he wrkin ecin f he wind unnel in Fi. 3. here, he ir emperure nd peed cn be djued. In fllwin UL-33, he ir emperure h be djued 135ºC, nd ir peed 2.54 m -1. Five mple f fuble link f 68 C rin were upplied by FSD. Fur f hem re hwn in Fi. 4. An exernl ldin f 0.4 kf w pplied he fuble link in Fi. 5. A ril run n ne mple w cnduced n 20 Jnury, he her fur mple were eed eher wih hree enineer frm FSD nd ne fire exper n 25 Jnury, he plne f he fuble link w riened eiher ln r perpendiculr he ir flw. hi wuld chne he he rnfer prce lihly. he ppernce f he fur mple fer ein re hwn in Fi RESULS he ein cndiin nd reul n he meured civin ime re hwn in ble 1. I i berved h he 68 C-red fuble link wuld be cived 30 73, ll lyin wihin he rne f UL-pecificin frm under he ldin f 0.4 kf, when pluned by h ir 135 C nd peed 2.54 m -1. CENRIFUGAL FAN INSULAION HEAER EXPANSION CHAMBER CONRACION PIO UBE HERMOCOUPLE WAER PIPES FREQUENCY INVERER WORKING SECION CONROL PANEL () Dirm (b) Picure Fi. 2: Schemic f he wind unnel 2

3 Inerninl Jurnl n Enineerin Perfrmnce-Bed Fire Cde Cnrl pnel Fi. 3: Wrk-ecin f he Wind unnel Fi. 4: he fur fuible link eed n 25 Jnury 2006 Hlder Fuble link Weih Fi. 5: Fuible link under ldin f 0.4 kf 3

4 Inerninl Jurnl n Enineerin Perfrmnce-Bed Fire Cde () Smple 2 (b) Smple 3 (c) Smple 3 (d) Smple 4 Fi. 6: Appernce f he mple eed n 25 Jnury 2006 ble 1: e reul Smple ein De Orienin wih Air / C / C V /m -1 Acivin ime / 1 20 Jnury 2006 Aln Jnury 2006 Aln Jnury 2006 Perpendiculr Jnury 2006 Aln Jnury 2006 Aln RESPONSE IME INDEX he ein prcedure under UL-33 i imilr he Fcry Meril (FM) plune e [5] n ein he herml enin elemen f prinkler hed. Suppe h ir cnn emperure nd cnn ir peed V i mvin wrd herml enin elemen f rin, m M, pecific he C, urfce re A nd urfce he rnfer cefficien h. he iniil emperure f he herml enin elemen i. he emperure f he herml enin elemen ime cn be bined by lvin he he blnce equin: d ( ) = ha ( ) (1) d Rerrnin: ( ) d ha = d ( ) hi cn be rewrien in erm f ime cnn : ha (2) = (3) 4

5 Inerninl Jurnl n Enineerin Perfrmnce-Bed Fire Cde Slvin i wuld ive he civin ime, when heed up : d( ) d = (4) ( ) 0 r ( ) ( )( / 1 e ) = (5) / = x he ime cnn i n nly prpery f he herml enin elemen becue h i reled 1 V. herefre, depend n V. A prmeer clled repne ime index RI w defined by muliplyin by V : x Fi. 7: Fiin fr RI RI = V (6) In hi wy, RI i prpery f he herml enin elemen nly. i hen iven by: = 1 e ( ) ( ) hi cn be rrned : RI n V Le V RI (7) 1 = l (8) 1 V x = l n (9) hi ive: = RI x (10) Plin in x wuld ive rih line f lpe RI. Reul n re pled in Fi. 7 wih he be fiin line f crrelin cefficien 0.56: = x (11) he vlue f RI re vryin frm m, wih men f m m 5. CONCLUSIONS Frm he bve udy, i i feible e he herml eniiviy f fuble link by UL-33 [1]. Such wind unnel [3,4] cn be develped erly in ny lbrry f Hn Kn. REFERENCES 1. UL-33, He repnive link fr fire-precin ervice, Underwrier Lbrrie (2003). 2. AS , hermlly releed link, Aurlin Sndrd, Aurli (1999). 3. W.K. Chw nd P.L. H, herml repne f prinkler hed, Buildin Service Enineerin Reerch nd echnly, Vl. 11, N. 2, p (1990). 4. W.K. Chw nd P.L. H, herml repne f prinkler hed in h ir rem wih peed le hn 1 m -1, Fire Science nd echnly, Vl. 12, N. 1, pp (1992). 5. G. Heked nd R.G. Bill, Qunificin f herml repnivene f umic prinkler includin cnducin effec, Fire Sfey Jurnl, Vl. 14, N. 1-2, p (1988). APPENDIX A: HEA BALANCE EQUAION (1) he he blnce equin i: ( ) d = ha ( ) (A1) d Definin : 5

6 Inerninl Jurnl n Enineerin Perfrmnce-Bed Fire Cde = (A2) ha Inerin (, ) frm (0, ) (, ): d( ) d = (A3) 0 d (2) Dimenin f : 1 1 k Jk K [] ~ Wm K m J ~ W ~ Rerrnin: ( ) = e ( ) = + e ( ) = e ( ) ( ) = e ( ) ( ) = [1 e ] (A6) RI = V (A7) (3) Inerin LHS f equin (A3): Le = θ d = dθ d( ) d dθ l ( ) l ( ) = n + C ( ) = = = nθ+ C θ θ d = n + C l ( ) ( ) ln( ) l n( ) = = l n (4) Inerin RHS f equin (A3): 0 d = (5) LHS = RHS: l n = (A4) ( ) ( ) V RI = [1 e ] (A8) (6) Rerrnin: ( ) ( ) = 1 e V RI e = 1 e V RI = V RI RI l n V = (7) A rih line cn be bined by plin V x: 1 = RI l n V (A9) y lpe x he lpe i RI. l n = = e (A5) 6