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The study of the effectiveness of a screen to stifle diffusion flames

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The study of the effectiveness of a screen to stifle diffusion flames

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Content THE STUDY OP THE EFFECTIVENESS OF A ii SCREEN TO STIFLE DIFFUSION FLAMES by N a r in d e r S. Bed! A T h e s is P r e s e n t e d to th e FACULTY OF THE SCHOOL OF ENGINEERING UNIVERSITY OF SOUTHERN CALIFORNIA In P a r t i a l F u l f i l l m e n t o f th e R e q u ire m e n ts f o r th e D egree MASTER OF SCIENCE (C hem ical E n g in e e rin g ) June 1966 UMI Number: EP41785 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMI Dissertation Publishing UMI EP41785 Published by ProQuest LLC (2014). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQuest ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 C h B i - / z This dissertation, written by I * ? o a, under the guidance of hXs...Faculty Committee and approved by all its members, has been presented to and accepted by the School of Engineering in partial fulfillment of the re quirements for the degree of .M aster..of ..Science., i n ............................... Date jSm©..l?66 Faculty C om m ittee Chairman M A is Z . AC KNOWLEDGMENTS I w ish to o f f e r my th a n k s to my a d v ise r., Dr. < T . M. L e n o ir , f o r h i s g u id a n c e and a s s i s t a n c e i n t h i s work. I a l s o w ish to th a n k my co m m ittee members, Dr. C. J . H e b e rt and Dr. C o peland, f o r t h e i r re v ie w and a p p r a i s a l o f my work. I f u r t h e r w ish to acknow ledge th e e f f o r t s o f Mr. J . M. S c o t t , th e l a b o r a t o r y m ech an icj h i s r e a d y h e lp and e x p e r ie n c e d s u g g e s t i o n s made th e l a b o r a t o r y work e a s i e r . F i n a l l y , I want to e x p r e s s my g r a t i t u d e to Mrs. R uth Toyama whose h e l p and f r i e n d s h i p w ere e x tre m e ly v a l u - ab l e . TABLE OP CONTENTS Page ACKNOWLEDGMENTS.................................... i i LIST OP T A B L E S ............................................................................. .... . . . i v LIST OP ILLUSTRATIONS . . . . . ........................................ . . . v C h a p te r I . INTRODUCTION ................................................................................ 1 P u rp o se and Method B ackground M a t e r i a l : R e la te d E x p e rim e n ts and L i t e r a t u r e I I . HISTORY OF DESIGN DEVELOPMENT...................................... 13 The F i r s t T r i a l Runs Summary and D is c u s s io n E x p e rim e n ts w ith P ure A cetone D is c u s s io n on th e F e a t u r e s o f th e New S creen S t r u c t u r e I I I . A RESUME OP F I N D I N G S ........................................................... 36 The D evice BIBLIOGRAPHY................................................................................................... 42 i i i LIST OF TABLES T ab le Page 1. Quenching D is ta n c e and B u rn in g V e l o c i t y a t 10 5° C., 1 Atmos and c p = 1.0 f o r Some H y d ro c a rb o n -A ir Flam es . . . ...................................... 7 2. Com parison o f P r e d i c t e d and O bserved P r e s s u r e Dependence o f Quenching D is ta n c e . . . . . . 8 3. H ead in g s .......................................... 22 4. R e a d i n g s .......................................... 23 5 . R e a d in g s .. . . . . . . 27 6 . R e a d in g s ..................................................... . . .. . . . . 31 i v LIST OF ILLUSTRATIONS F ig u r e s Page 1. Equipm ent S e t- u p . . . . . . . . . . . . . . . 13 2. The D evice i n O p e r a t i o n ...................................................... 14 3. Back P r o p a g a tio n o f F l a m e s ................................................ 18 4. S c re e n w ith Aluminum Gauze S k i r t . . . . . . . 22 5. V a r i a t i o n o f M t n w ith M d ” ................................................ 25 6 . Double S c re e n S t r u c t u r e ............................................... . 28 7. Double S c re e n S t r u c t u r e i n O p e ra tio n .......................... 30 8. S c re e n S e a l . . . ..................................................... 32 9. S cre e n S e a l .......................................... 33 10. D evice w ith Copper W hisker S e a l ................................. 3^- P l a t e s I . The F o u r-p ro n g e d S t r u c t u r e .......................................... 15 11. The S creen . . . . . ..................................................... 15 I I I . The S creen and S t r u c t u r e ...................................................... 16 IV. The S creen * S t r u c t u r e and S k i r t ................................. 16 v CHAPTER I INTRODUCTION P urpose and Method The u se o f m e ta l gauze a s an im perm eable s c re e n to th e p a s s a g e o f fla m e s was f i r s t g iv e n a p r a c t i c a l a p p l i c a t i o n to th e Davy S a f e t y Lamp. The g r i d o f t h i s s a f e t y lamp p r e v e n te d th e fla m e s from p r o p a g a t i n g to th e o u t s i d e by s u p p o s e d ly a b s o r b in g th e h e a t n eed ed f o r t h i s p r o p a g a t i o n . The mechanism o f th e p r o p a g a tio n o f fla m e s on w hich th e " a b s o r p t i o n o f h e a t " depended was a p u re therm odynam ic o n e. T h is mechanism h a s been found to be in a d e q u a te by th e more r e c e n t i n v e s t i g a t o r s . Lewis and Yon E lb e i n 193^ o f f e r e d a more c o m p lete th e o r y o f flam e p r o p a g a t i o n j w r i t i n g : The phenomena o f in fla m m a tio n w ith which th e p r e s e n t p a p e r i s c o n c e rn e d h a s been t r e a t e d by s e v e r a l i n v e s t i g a t o r s on th e a s su m p tio n t h a t b e f o r e any r e a c t i o n o c c u r s th e u n b u rn ed g as p r e c e d in g th e flam e f r o n t i s r a i s e d to i t s " i g n i t i o n te m p e r a tu r e " by th e h e a t c o n d u c tio n from th e b u rn in g g a s e s . In th e l i g h t o f modern c h e m is tr y we b e l i e v e t h i s c o n c e p tio n i s in ad eq u ate,, s in c e i t o m its a l l c o n s i d e r a t i o n o f th e r o l e p la y e d by th e a c t i v e atoms and r a d i c a l s known to e x i s t in th e flam e f r o n t . I t i s q u i t e c o n c e iv a b le t h a t flam e p r o p a g a t i o n i s g o v ern ed by d i f f u s i o n o f th e s e a c t i v e r a d i c a l s i n t o th e u n b u rn ed m ix tu r e . . . . ( 3 0 ) T his p r o j e c t h a s i t s r o o t s i n t h i s more advanced c o n c e p t o f th e th e o r y o f flam e p r o p a g a t i o n . I t u n d e r to o k 1 to d e v e lo p a m e ta l g r i d d e v ic e to e x t i n g u i s h fla m e s on f u e l s u r f a c e s ^ th e f u e l b e in g c o n ta in e d i n a v e r t i c a l c y l i n d e r . T h is method would have an a d v a n ta g e o v e r th e e x i s t i n g f i r e - e x t i n g u i s h i n g m eth o d s. In th e e x i s t i n g m ethods th e b u rn in g f u e l and th e e x t i n g u i s h i n g a g e n t i n v a r i a b l y come i n t o co n t a c t w ith each o t h e r . T h is p h y s i c a l c o n t a c t r e s u l t s in th e c o n ta m in a tio n o f th e f u e l s a lv a g e d i f any. H e re in l i e s an o b j e c t i o n to th e u sa g e o f such e x t i n g u i s h i n g a g e n ts as water,, foam* carb o n d ioxide,, and c h e m ic a l pow d ers. A m e ta l g r i d d e v ic e does away w ith th e ch e m ic a l e x t i n g u i s h i n g a g e n t. I t a p p e a r s to be a p r o p e r t y o f m e t a l l i c s u r f a c e s t h a t th e y ab so rb h e a t and remove co m b u stio n p r o p a g a tin g r a d i c a l s (1 0 ). T his p r o p e r t y f u r t h e r d e - e n e r g i z e s th e space c o n t i guous to th e s u r f a c e and r e n d e r s i t dead to th e p r o p a g a t i o n o f c o m b u stio n . T h is sp ace I s c a l l e d "dead s p a c e ." I t s b o u n d ary i s d e te rm in e d by th e f u e l b e in g b u r n t . I f two m e t a l l i c s u r f a c e s a re b r o u g h t c lo s e enough such t h a t t h e i r dead sp a c e s o v erlap ,, th e n th e a r e a betw een them becomes Im p e rv io u s to th e p r o p a g a t i o n o f fla m e s . A m e t a l l i c s c re e n can be c o n s id e r e d to be an a g g r e g a te o f num erous such dead s p a c e s . Now as long as t h e s e dead s p a c e s do n o t ex ceed th e q u en c h in g d i s t a n c e o f th e f u e l b e in g e x tin g u is h e d ,, th e fla m e s w i l l n o t p e n e t r a t e th e s c re e n from one s id e to th e o t h e r . The equipm ent u s e d was o r i e n t e d tow ard d e v e lo p in g a w o rk ab le d e s ig n f o r th e d e v ic e . The s tu d y was a l s o d i r e c t e d tow ard u n c o v e r in g any r e l a t i o n s h i p s betw een v a r i a b l e s t h a t c o u ld be d e te rm in e d . The d ev elo p m en t o f th e s c re e n s t r u c t u r e was a g r a d u a l e v o l u t i o n . The f i n a l d e s ig n was th e c u m u la tiv e r e s u l t o f th e numerous m o d i f i c a t i o n s t h a t were t e s t e d and r e j e c t e d o r f u r t h e r m o d ifie d . T h is d evelopm ent i s p r e s e n t e d i n i t s c h r o n o l o g i c a l o r d e r to show th e c o n n e c t i o n betw een each m o d i f i c a t i o n and i t s a n t e c e d e n t . B ackground M a t e r i a l : R e la te d E x p e rim e n ts and L i t e r a t u r e The e x p e r im e n ta l d evelopm ent o f th e d e v ic e was com p le m e n te d w ith l i t e r a t u r e r e s e a r c h i n t o th e p r i n c i p l e s o f i t s o p e r a t i o n . The d i s c u s s i o n t h a t f o llo w s b e a r s on t h e o r i e s and c o n c e p ts w hich e x p l a i n th e s c ie n c e o f th e d e v ic e . The o l d e r th e o r y o f c o m b u stio n , u s in g th e c o n c e p t o f i g n i t i o n te m p e r a tu r e , was found to be in a d e q u a te to e x p l a i n ( l ) th e e x i s t e n c e o f r a d i c a l s i n th e un b u rn ed g a s and (2) th e e x i s t e n c e o f an i n d u c t i o n p e r i o d i n th e c a se o f many h y d ro c a rb o n f la m e s . The more modern t h e o r y o f com bustion s h i f t e d i t s c e n t e r o f a t t e n t i o n from th e c o n c e p t o f " i g n i t i o n te m p e r a tu r e " to t h a t o f " th e d i f f u s i o n o f flam e p r o p a g a t i o n c e n t e r s . " T a n fo rd w ro te i n 19^7: Thus two a l t e r n a t i v e p i c t u r e s o f com bustion p r o c e s s e s p r e s e n t th e m s e lv e s : l ) t h a t th e u n b u r n t g as i s i g n i t e d by f r e e r a d i c a l s p ro d u c e d l o c a l l y by th e rm a l d i s s o c i a t i o n f o llo w in g h e a t c o n d u c tio n , and 2) t h a t i t i s i g n i t e d by f r e e r a d i c a l s s u p p li e d to th e u n b u r n t gas by d i f f u s i o n from th e flam e f r o n t . ( 25) 4 By 1952 i t was more th a n e v i d e n t th at,, a t l e a s t in th e c ase o f h y d ro c a rb o n f l a m e s d i f f u s i o n p la y e d a more p ro m in e n t p a r t th a n c o n d u c tio n . But even to d a y t h e r e does n o t e x i s t a com p lete u n d e r s t a n d i n g o f th e phenomenon o f c o m b u stio n . H ydrocarbon Com bustion Chain c a r r i e r s have been found to p l a y an im p o r ta n t p a r t in th e co m bustion o f h y d r o c a rb o n s . Lewis and Von E lbe ( 1 3 ) p o i n t o u t t h a t " t h e r e i s no d o ubt t h a t th e h y d ro c a rb o n o x i d a t i o n i s a c h a in r e a c t i o n . " On t h i s b a s i s th e y e x p l a i n th e p r e s e n c e o f r a d i c a l s i n th e u n b u r n t r e g i o n and th e i n d u c tio n p e r i o d in th e co m b u stio n o f h y d r o c a rb o n s . The p a r t i c i p a t i n g r a d i c a l s a r e r e f e r r e d to as " c h a in c a r r i e r s " o r " a c t i v e s u b s t a n c e s ." Levy (12) s t u d i e d c h a in r e a c t i o n s and c h a i n - c a r - r i e r s in c o n n e c tio n w ith f l a m e - i n h i b i t i n g e f f e c t s o f h a l o g e n s . He b ro k e up th e c h a in r e a c t i o n o f co m b u stio n i n t o f o u r se q u e n c e s and p o i n t e d o u t t h a t flam e p r o p a g a t i o n c o u ld be t e r m i n a t e d by t e r m i n a t i n g th e c h a in r e a c t i o n . H is sim p l i f i e d mechanism f o r th e i n i t i a t i o n and t e r m i n a t i o n o f th e c o m b u stio n o f CH^ i s a s f o ll o w s : ( A ll below a r e r a d i c a l s and n o t i o n s . ) 1. I n i t i a t i o n CH4 + o 2 = OH + ch3o 5 2. P r o p a g a tio n CH^ + OH = CH^ + HOH CH^ + 0 2 = HCHO + OH 3• B ra n c h in g 0Ho + 0 o = CH + 20H D ^ CH^ + 0 2 = CHO + H + OH 4. T e rm in a tio n HX + A = HA + X (A I s th e a c t i v e r a d i c a l and X i s th e h a l o g e n .) T h is l e a d s to th e I n f e r e n c e t h a t any s u b s ta n c e w hich h a s th e p r o p e r t y o f rem oving a c t l v e - f l a m e - p r o p a g a t i n g c e n t e r s w i l l t e r m i n a t e c o m b u stio n . A m e ta l s u r f a c e h as such a p r o p e r t y . The Blame S t r u c t u r e and th e Concept o f Dead Space The flame,, b r o a d l y s p e a k in g , i s th e b o u n d ary b e tween th e b u r n t and th e u n b u r n t r e g i o n s . The flam e f r o n t , where i t i s s t a b l e , r e s t s on s u r f a c e s w hich have th e p r o p e r t y o f a b s o rb in g h e a t and a c t i v e r a d i c a l s . T h is r e d u c e s th e w a ll speed o f th e flam e to z e ro . A d jo in in g th e w a ll t h e r e i s a sp ace th ro u g h w hich no flam e can p r o p a g a te and 6 t h i s i s c a l l e d dead s p a c e . W ith in t h i s space th e c o n c e n t r a t i o n o f th e a c t i v e r a d i c a l s i s n o t h ig h enough to s u p p o r t a f l a m e . The q u en ch in g o f fla m e s Toy g r i d s i s made p o s s i b l e by th e j o i n i n g o f dead sp ace t h a t e x i s t s betw een two p a r a l l e l m e t a l l i c s u r f a c e s . Lewis and Von E lb e say : E v id e n tly ,, when two h e a t s sink., such as two s o l i d p la te s ,, a p p ro ach each o th er,, th e dead s p a c e s must u l t i m a t e l y merge and th e co m bustion wave c a n n o t p r o p a g a te p a s t th e zone o f q u en c h in g t h a t i s th u s form ed. On t h i s p r i n c i p l e i t i s p o s s i b l e to d e s ig n flam e t r a p s w hich a r e g r i d s o r p o ro u s p a r t i t i o n s whose c h a n n e l w id th does n o t exceed th e d i s t a n c e c a l l e d th e q u en ch in g d i s t a n c e . . . . ( 13) Quenching d i s t a n c e s have been s t u d i e d s c i e n t i f i c a l l y by many. Quenching d i s t a n c e i s a v a r i a b l e q u a n t i t y d ep en d in g upon th e f o llo w in g f a c t o r s : A. Type o f f u e l B. Flame te m p e r a tu r e C. P r e s s u r e D . A i r - f u e l r a t i o E. B u rn in g v e l o c i t y A. Type o f f u e l . - - P o t t e r and B e r la d ( 3 ) worked w ith p ro p a n e j b e n z e n e , is o - o c ta n e ,, d ec e n e , n -h e x a n e and b u t y l - b en zen e ( a l l 97^ p u re ) to d e te rm in e th e e f f e c t o f f u e l ty p e on flam e q u e n c h in g . T h e ir p r e s s u r e was f ix e d a t 1 atm. and t h e i r te m p e r a tu r e a t 105° C b u t th e y v a r i e d th e a i r - f u e l e q u i v a l e n t r a t i o . Below i s a r e p r o d u c t i o n o f th e t a b l e o f t h e i r r e s u l t s . 7 TABUS 1 QUENCHING DISTANCE AND BURNING VELOCITY* AT 105°C, 1 ATMOS AND c p - 1.0 FOR SOME HYDROCARBON-AIR FLAMES d U dU F u e l cm cm /sec cm / s e c H exene-1 0 .1 6 6 6 5 .6 1 0 .9 Benzene o. 171 6 3 .4 1 0 .8 D ecene-1 0 .1 7 5 5 0 .3 10.4 n-H exane 0 .1 8 2 5 9 .1 10.8 n-D ecane O . I 83 5 5 .5 1 0 .2 P ropane 0 .1 8 4 6 0 .1 1 1 .1 n - B u ty l b en zen e 0 .2 0 3 5 3 .2 10 .8 I s o o c t a n e 0 .2 3 3 4 3 .4 10 .1 * C a l c u l a t e d from d a ta o f Dugger,, Simon., and Wagner and Dugger., a l l s e t s o f d a t a u s e d c o n ta in e d a v a lu e f o r p ro p a n e j so t h a t a l l d a t a were n o r m a liz e d to p ro p an e = 40 cm /sec a t 25° C . T h e ir c o n c lu s io n was t h a t th e "q u en ch in g d i s t a n c e I s p r i m a r il y a f u n c t i o n o f th e m o le c u la r w e ig h t o f th e h y d r o carb o n . . . q u e n c h in g d i s t a n c e d e c r e a s e s as th e m o le c u la r w e ig h t i n c r e a s e s . " Friedm an and Johnson (10) a ls o h o ld th e same c o n c l u s io n s . B. Flame t e m p e r a t u r e . --T h e h i g h e r th e flam e tem p e r a t u r e th e s m a l l e r i s th e q u e n ch in g d i s t a n c e . The e x p l a n a t i o n i s t h a t more s u r f a c e a r e a i s n eed ed to a b so rb th e i o n s and th e h e a t r e l e a s e d to make i t im p o s s ib le f o r th e flam e to p r o p a g a te . C. P r e s s u r e . --T he r e l a t i o n s h i p betw een p r e s s u r e and q u en ch in g d i s t a n c e i s t h a t o f i n v e r s e p r o p o r t i o n though n o t s im p le p r o p o r t i o n . The q u en c h in g d i s t a n c e d e c r e a s e s w ith th e i n c r e a s e o f p r e s s u r e . B e r la d (2) e x p r e s s e s t h i s / \ “P dependency t h u s l y : d (q u e n c h in g d i s t a n c e ) a P , Below i s a t a b l e o f h i s r e s u l t s . TABLE 2 COMPARISON OP PREDICTED AND OBSERVED PRESSURE DEPENDENCE OP QUENCHING DISTANCE Oxygen E q u iv a le n c e P r e s s u r e Dependence o f F r a c t i o n R a tio Quenching D istan ce,, 7 a 9 Obsd. P r e d i c t e d 0 .1 7 0 .9 4 3 0 .9 0 0 .8 8 1.000 .89 .85 1.340 .84 .75 1.530 .71 .75 0 .2 1 0 .7 3 8 O.85 0 .8 6 .864 .84 .89 1.000 .89 • 93 1.240 .95 .78 1.490 .98 .76 0 .3 0 0 .5 6 6 0 .7 6 0 .8 7 . 662 .93 .89 .773 1.06 .92 1.000 0 .9 8 .94 1.380 .93 . 86 1 .903 .74 .76 0 .5 0 0 .4 7 6 1.01 0 .9 1 .544 1 .0 1 .93 .680 0 .9 6 .96 1.000 .93 .97 1 .358 .91 .95 1.940 .88 .82 TABLE 2 - -C o n tin u e d 9 Oxygen E q u iv a le n c e P r e s s u r e Dependence o f F r a c t i o n R a tio Quenching D is ta n c e , 7 a T O bsd. P r e d i c t e d 0 -n 0 0 .3 4 5 1 .1 2 0 .9 1 .395 1 .1 2 .93 .494 1 .0 2 .96 1.000 1 .0 1 .98 1.234 1.07 .98 1 .8 2 9 0 .6 0 .89 D e f i n i t i o n o f te rm s: a i s th e oxygen f r a c t i o n in f u e l - v a p o r m ix tu r e . _ _____ Amount o f f u e l p r e s e n t ________________ ~ T h e o r e t i c a l a m t. o f f u e l f o r co m p le te r e a c t i o n w ith Og p r e s e n t 7 = Power o f P i n th e r e l a t i o n s h i p d = kP r . The n u m e r ic a l v a lu e o f r ra n g e d from 0 .7 5 to 1 .0 5 . F r i e d man and Johnson a l s o d e r i v e d th e same k in d o f e x p r e s s i o n , — n d a P , t h e i r v a lu e f o r n b e in g a p p r o x im a te ly 0 .9 1 . D. A i r - f u e l r a t i o . --T h e q u en ch in g d i s t a n c e v a r i e s w ith th e a i r - f u e l r a t i o in a manner such t h a t i t h a s i t s minimum p o i n t a t a b o u t th e s t o i c h i o m e t r i c a i r - f u e l r a t i o . Friedm an and Johnson (10) s t u d i e d a i r - p r o p a n e co m bustion v a r y in g th e r a t i o from 11 to 24. T h e ir r e s u l t s a r e shown i n th e f i g u r e below . 10 J_L -r- i _ _ _ The quenching of propane-air flames at various pressures. N ote: The c r i t i c a l s l i t o p en in g I s th e same as th e q u e n c h in g d i s t a n c e . M a rk ste ln ( l4 ) a l s o to o k d a t a on a i r - p r o p a n e co m bustion and came up w ith r e s u l t s s i m i l a r to th o s e o f th e a b o v e -m e n tio n e d a u t h o r s . Both th e a r t i c l e s p o i n t e d o u t t h a t no e v i d e n t i n f lu e n c e was e x e r c i s e d by th e n a t u r e o f th e s u r f a c e o f th e e x t i n g u i s h i n g m e t a l l i c p l a t e s . M a rk s te ln sa y s: No m e a s u ra b le d i f f e r e n c e s i n q u en ch in g b e h a v i o r were o b s e rv e d f o r e i t h e r le a n o r r i c h m ix tu res,, f o r any o f th e f o llo w in g ty p e s o f s u r f a c e s : n ic k e l,, platinum ,, b r i g h t gold,, ro u g h en ed gold,, KC1, and w a te r g l a s s . T h is r e s u l t i n d i c a t e s t h a t n e i t h e r th e c a t a l y t i c power o f s u r f a c e n o r i t s a b s o r p t i v i t y f o r r a d i a t i o n s i g n i f i c a n t l y a f f e c t s th e q u en ch in g phenomenon. ( 1 '4 ) 11 Hence th e most in e x p e n s iv e m e ta l i s as e f f e c t i v e as th e most e x p e n s iv e i n q u en c h in g th e p r o p a g a tio n o f fla m e s . E. B u rn in g v e l o c i t y . - - F o r h y d r o c a r b o n - a i r fla m e s "q uenching d i s t a n c e sh o u ld v a ry i n v e r s e l y a s th e b u rn in g v e l o c i t y " (14) . Summary The m a t e r i a l s t h a t have been c i t e d h i t h e r t o a re b a s e d on e x p e r im e n ta l work done w ith p re -m ix e d f la m e s . The work t h i s p r o j e c t u n d e r to o k c o n c e rn e d i t s e l f o n ly w ith d i f f u s i o n fla m e s . U n f o r t u n a t e l y no such scope o f e x p e r im e n ta l work i s a v a i l a b l e in th e c a se o f d i f f u s i o n f la m e s . Hie th e o r ie s ,, th e d e f i n i t i o n s * and th e d i f f e r e n t c o n c e p ts men t i o n e d have been t e s t e d f o r v e r i f i c a t i o n w ith p re -m ix e d fla m e s . There i s a g r e a t a d v a n ta g e in t h i s ; i . e . * th e d i f f u s i o n flam e i s n o t as c o n t r o l l a b l e as th e p r e -m ix e d flam e and c o n s e q u e n tly f o r th e p u rp o se o f r e p r o d u c in g a c c e p ta b le * a c c u r a t e r e s u l t s u n d e r c o n t r o l l e d c o n d itio n s * th e p re -m ix e d flam e i s most s u i t a b l e . These d e f i n i t i o n s and c o n c e p ts were u s e d in t h i s p r o j e c t w ith a p p r o p r i a t e r e s e r v a t i o n s . The D i f f u s i o n Flame D e f i n i t i o n . - - The com bustion o f a f u e l em erging from an o r i f i c e mixed w ith no o r i n s u f f i c i e n t oxygen r e q u i r e s th e d i f f u s i o n o f oxygen i n t o th e s tre a m o f g as c o n t a i n i n g u n b u r n t f u e l and co m b u stio n p r o d u c t s . T his d i f f u s i o n c o n t r o l s th e r a t e o f h e a t r e l e a s e from th e r e a c t i o n o v e r a wide ra n g e o f c o n d i t i o n s — hence th e term d i f f u s i o n fla m e s . ( 28 ) 12 A d i f f u s i o n flam e depends more on d i f f u s i o n (m o le c u la r o r t u r b u l e n t eddy) f o r i t s p r o p a g a tio n th a n does a p re -m ix e d fla m e . I t s b o u n d ary i s a lo n g th e l i n e o f th e s t o i c h i o m e t r i c p r o p o r t i o n s o f v a p o r and a i r . To g e t a s i m p l i f i e d p i c t u r e o f a d i f f u s i o n flam e i t can be assumed t h a t on th e u n b u r n t s id e t h e r e i s no a i r and on th e b u r n t s id e no f u e l v a p o r. U n lik e th e p re -m ix e d flam e th e h e a t o f d i f f u s i o n flam e b u r n in g from a l i q u i d s u r f a c e p e rfo rm s two f u n c t i o n s : ( l ) i t e v a p o r a t e s th e l i q u i d to form v a p o r and (2) i t h e a t s up th e v a p o r. T h is v a p o r th e n m ixes w ith oxygen to form a s t o i c h i o m e t r i c c o m b u s tib le m ix tu re w hich b u rn s a t th e flam e f r o n t . To b u i l d a flam e t r a p f o r a d i f f u s i o n flam e b u rn in g from a f u e l s u r f a c e i s n o t e a sy ; th e flam e s i t s d i r e c t l y on th e s o u rc e o f th e fe e d and m oreover w ith r e s p e c t to sp ace I s im m obile. Our d e v ic e overcom es t h i s d i f f i c u l t y by s e p a r a t i n g th e flam e from th e f u e l w ith th e flam e t r a p and th e n l e t t i n g th e fla m e s e x t i n g u i s h th e m se lv e s in t r y i n g to p e n e t r a t e th e t r a p . As long as th e mesh d im e n sio n s o f th e g r i d - t r a p a re k e p t l e s s th a n th e q u en ch in g d i s t a n c e f o r th e fuel,, th e fla m e s c a n n o t p e n e t r a t e . CHAPTER I I HISTORY OP DESIGN DEVELOPMENT The s c h e m a tic d ia g ra m below g iv e s a s i m p l i f i e d piC' t u r e o f th e ite m s o f equipm ent u s e d to p e rfo rm th e t e s t s . l i f t i n g rod. c y lin d er flames f u e l surface fla m e-ex tin g u ish ing screen P ig . 1 . --E q u ip m e n t s e t - u p As shown in P ig . 1 th e s c re e n i s k e p t immersed i n th e f u e l . T his i s i t s norm al p o s i t i o n o f r e s t . A l i f t i n g d e v ic e i s a t t a c h e d to t h e s c re e n such t h a t i t can he moved v e r t i c a l l y th ro u g h th e f u e l . The f u e l s u r f a c e i s i g n i t e d and th e n th e s c re e n r a i s e d up s lo w ly . As i t r i s e s above th e s u r f a c e o f th e f u e l i t l i f t s th e fla m e s and p r e v e n t s them from b a c k p r o p a g a t i n g . The d ia g ra m below shows th e s c re e n a t I t s 13 h i g h e s t p o i n t o f d is p la c e m e n t. 14 l i f t i n g rod flames screen f u e l surface P ig . 2 . --T he d e v ic e i n o p e r a t i o n The s c re e n was made from a s t a i n l e s s s t e e l gauze and was 3 1 /2 in c h e s i n d ia m e te r . Running v e r t i c a l l y down from th e c ir c u m fe r e n c e o f th e s c r e e n , and, h e ld to i t f ir m l y by sc re w s, was a c o m p le te ly e n c i r c l i n g aluminum f o i l s k i r t r e a c h in g t h r e e in c h e s i n t o th e v e s s e l . The f u e l c o n t a i n e r was a c y l i n d r i c a l g l a s s b a t t e r y j a r m e a su rin g 4 in c h e s in d ia m e te r and 6 i n c h e s in h e i g h t . The fram e i n w hich th e s c re e n s a t , was made o u t o f 1/8 in c h ( d i a . ) s t e e l ro d s and i s shown in th e p h o to g ra p h s t h a t f o llo w . 17 A cetone was chosen a s th e e x p e r im e n ta l f u e l b e c a u s e i t h as a r e l a t i v e l y slow b u r n in g flame,, a c o n v e n ie n t v a p o r p r e s s u r e ^ and c o u ld be c o m f o rta b ly h a n d le d . To f u r t h e r l e s s e n th e r i s k s in v o lv e d i n e x t i n g u i s h i n g a flam e on i t s su rfa c e ,, a 50-50 m ix tu re o f w a te r and a c e to n e was u s e d as th e i n i t i a l e x p e r im e n ta l f u e l . The F i r s t T r i a l Runs The e x p e r im e n ts were c o n d u c te d u n d e r a tm o s p h e ric c o n d i t i o n s in a d a rk room., and th e v e s s e l was k e p t u n c o v e re d th ro u g h o u t th e t r i a l s . The 50-50 f u e l was p o u red i n t o th e v e s s e l u n t i l th e l e v e l s to o d 4 1 /2 in c h e s i n v e r t i c a l h e i g h t . The s c re e n and th e a t t a c h e d s k i r t were th e n lo w ered i n t o th e v e s s e l u n t i l th e s c r e e n s u r f a c e r e s t e d an in c h below th e l e v e l o f th e f u e l . (T hroughout th e l e n g t h o f th e p r o j e c t th e s c r e e n was lo w ered and r a i s e d by hand w ith th e h e lp o f th e w ire a t t a c h e d to th e u p p e r end o f th e l i f t i n g r o d . ) A b u c k e t f i l l e d w ith w a te r was p la c e d a d j a c e n t to th e equipm ent to m eet any em ergency and a ls o f o r th e p u rp o se o f c o o lin g th e m e ta l s c r e e n and th e s u p p o r tin g s t r u c t u r e . A flam e was th e n s t a r t e d and a llo w e d to s t a b i l i z e f o r te n s e c o n d s. The s c re e n was th e n g e n t l y r a i s e d th ro u g h th e f u e l to th e to p o f th e v e s s e l . T h is movement was n o t r a p i d . The flam e was l i f t e d o f f th e s u r f a c e o f th e f u e l . 18 O b s e r v a t i o n s . --A s th e s c re e n was moved up above th e f u e l th e v a p o rs c o n tin u e d to burn on th e s c re e n s u r f a c e w i th o u t p e n e t r a t i n g I t . D uring th e f i r s t ru n th e aluminum s k i r t was moved to above th e s u r f a c e o f th e fuel., and,, th e fla m e s managed to p r o p a g a te b ack to th e s u r f a c e th ro u g h th e sp ace betw een th e s k i r t and th e w a l l s o f th e v e s s e l . The d ia g ra m below i l l u s t r a t e s th e p a th of p r o p a g a t i o n . aluminum s k ir t The s c re e n mesh s i z e was u n d o u b te d ly w it h i n th e q u en ch in g d i s t a n c e l i m i t . But th e v a c a n t space betw een th e s k i r t and th e w a l l s o f th e v e s s e l was too l a r g e to p r e v e n t th e fla m e s from p r o p a g a tin g th ro u g h t h a t sp a c e . For th e n e x t ru n th e s c re e n was l i f t e d to a p o i n t such t h a t th e low er edge o f th e s k i r t j u s t c o n t a c t e d th e f u e l s u r f a c e . The s c re e n was k e p t p e r f e c t l y s t i l l a t t h i s h e i g h t . In 25 s e c s , th e flam e was e x t i n g u i s h e d . T h is r e p r e s e n t e d a s u c c e s s f u l e x t i n g u i s h i n g p r o c e d u r e . 19 I t was now d e s i r e d to e x p e rim e n t w ith d i f f e r e n t mesh s i z e s to d e te rm in e th e a p p ro x im a te maximum q uenching d i s ta n c e o f a c e t o n e . The gauze u s e d in th e f i r s t t r i a l was o f s t a i n l e s s s t e e l w ith l6 meshes p e r i n c h . Two s t a i n l e s s s t e e l g a u z e s were procured., one h a v in g 10 m eshes p e r in c h and th e o t h e r 6 m eshes p e r in c h . 1. S t a i n l e s s s t e e l gauze w ith 10 m eshes p e r in c h . a. D ia . o f w ir e ; 0 .0 2 5 7 i n s . b. Mesh s i z e ; 0 .0 6 5 3 i n s . 2. S t a i n l e s s s t e e l gauze w ith 6 m eshes p e r in c h . a. D ia. o f w ire ; 0 .0 3 5 0 i n s . b . Mesh s i z e ; 0 .1 2 5 2 i n s . The 16 meshes p e r in c h s c re e n was r e p l a c e d by a s i m i l a r s c re e n made o u t o f th e 10 meshes p e r In c h g a u z e . O b s e r v a tio n s f o r th e 10 mesh s c r e e n . — The fla m e s l i f t e d o n to th e u p p e r s u r f a c e o f th e s c re e n and c o n tin u e d to b u rn t h e r e f o r a p p r o x im a te ly 50 s e c s . The fla m e s th e n e x t i n g u i s h e d . T h is was r e p e a t e d t h r e e tim e s w ith th e same r e s u l t s . I t i s p o i n t e d o u t t h a t th e fla m e s c o n tin u e to bu rn even a f t e r b e in g removed from th e f u e l s u r f a c e b e c a u se th e f u e l d ro p s t r a p p e d i n th e meshes v a p o r iz e and s u p p o rt th e fla m e s . By sh a k in g th e gauze up and down w h ile l i f t i n g i t , I t was found t h a t some d ro p s f e l l o f f and th e tim e o f e x tin g u is h m e n t d e c r e a s e d s l i g h t l y . O b s e r v a tio n s f o r th e 6 mesh s c r e e n .--T h e mesh s i z e f o r t h i s s c re e n was 0 .1 2 5 2 in c h e s . I t was s u s p e c te d t h a t 20 th e fla m e s would p e n e t r a t e t h i s mesh. The 50-50 f u e l was i g n i t e d a t i t s s u r f a c e and th e s c re e n r a i s e d up. The s c re e n l i f t e d th e fla m e s; th e tr a p p e d d r o p l e t s o f th e f u e l m ix tu re were c l e a r l y v i s i b l e in th e m eshes. A f t e r a p p r o x im a te ly 35 to 40 s e c s , th e fla m e s s u b s id e d to s m a ll b l u i s h fla m e s j u s t v i s i b l e above th e s c re e n s u r f a c e ; th e n a f t e r a n o t h e r te n seco n d s th e fla m e s e x t i n g u i s h e d . T h is i n d i c a t e d t h a t we were s t i l l w i t h i n th e l i m i t o f th e quen ch in g d i s t a n c e f o r a 5 0 -5 0 m ix tu re o f w a te r and a c e to n e . Summary and D is c u s s io n 1. The fla m e s do n o t e x t i n g u i s h im m e d ia te ly a f t e r b e in g l i f t e d o f f th e f u e l s u r f a c e . 2. The fla m e s when removed from th e s u r f a c e a r e s u p p o rte d by th e f u e l d r o p l e t s tr a p p e d in th e s c re e n m eshes. 3 . The m ost v u l n e r a b l e p a r t o f th e s t r u c t u r e i s th e gap betw een th e s c re e n c ir c u m fe r e n c e and th e i n n e r p e r i m e t e r o f th e v e s s e l . As f a r a s e x t i n g u i s h i n g th e fla m e s was c o n c e rn e d , th e s c re e n and d e v ic e p ro v e d e f f e c t i v e , b u t th e tim e o f e x tin g u is h m e n t was u n s a t i s f a c t o r y . When th e t r a p p e d d r o p l e t s were e v a p o r a te d , th e y s u s t a i n e d th e fla m e s and c o n s e q u e n t ly e x te n d e d th e tim e o f e x tin g u is h m e n t. Two i n t e r e s t i n g p o i n t s were n o te d : ( l ) th e s c re e n rem ain ed r e l a t i v e l y c o o l w h ile th e d r o p l e t s e v a p o r a te d , b e c a u se th e h e a t co n d u c te d to th e s c re e n was a b s o rb e d by th e f u e l d ro p s 21 w hich th e n e v a p o r a te d ; and, (2) th e w a l l s o f th e v e s s e l b e came h o t b e c a u s e o f h e a t t r a n s f e r from flam e to w a l l . E x p e rim e n ts w ith Pure A cetone As th e 6 mesh s c re e n had p ro v e d s u c c e s s f u l w ith th e 50 -5 0 f u e l m ix tu re i t was t e s t e d on a t e c h n i c a l g ra d e a c e to n e f u e l . When th e s c re e n was r a i s e d th e fla m e s l i f t e d , , b u t a f t e r a s h o r t tim e th e y p e n e t r a t e d th e s c r e e n . T h is h a p pened each tim e th e e x p e rim e n t was r e p e a t e d . E v i d e n t l y f o r th e p u re a c e to n e th e m eshes were n o t w i t h i n th e q u en ch in g d i s t a n c e maximum. The 6 mesh s c re e n was r e p l a c e d by th e 10 mesh s c r e e n . I t was p ro p o se d t h a t th e r e l a t i o n s h i p , , i f any, b e tween th e tim e M t M t h a t th e fla m e s to o k to e x t i n g u i s h , and, th e d i s t a n c e M d n betw een th e s c re e n and th e f u e l s u r f a c e s be exam ined. The e x p e r im e n ts c o n d u c te d to f i n d th e v a r i a t i o n o f ”t" ( s e c s . ) w ith "d" ( in c h e s ) u s e d th e f o llo w in g : 1. Pure a c e to n e . 2. 10 mesh s t a i n l e s s s t e e l s c r e e n . 3 . A r u l e r to m easure th e d i s t a n c e betw een th e s c re e n and th e f u e l s u r f a c e s . 4. A s to p w atch to c lo c k th e tim e of e x t i n g u i s h - men t . 5 . A new s k i r t made o u t o f f l e x i b l e aluminum 18 mesh gauze a t t a c h e d to th e s c re e n a lo n g th e c ir c u m fe r e n c e w ith th e h e lp o f i r o n w ire s t r a n d s . 22 6 . G la s s j a r . screen s k i r t k n itte d to th e scree n circum fe re n c e s k i r t F i g . 4 The s u r f a c e a r e a o f th e f u e l was 1 1.05 sq. i n . TABLE 3 READINGS Run No. nt" ( s e c s .) "d n ( in c h e s ) 1 a 21.44 2 .0 b 2 0 .0 0 2 .0 c 1 9 .0 0 Av. 20.45 2 .0 2 a 27.40 1 .5 b 2 5 .2 0 1 .5 c 28.30 Av. 2 6 . 0O 1 .5 3 a 2 9 .6 0 1 .0 b 2 7 .8 0 1 .0 c 3 1 .2 0 Av. 29.50 1 .0 4 a Did n o t e x t . 0 .5 b Did n o t e x t . 0 .5 c Did n o t e x t . 0 .5 23 The same e x p e rim e n t was done u s in g a 8 mesh s c re e n i n s t e a d o f th e 10 mesh s c re e n ; th e o t h e r com ponents o f th e a p p a r a t u s re m a in e d u nchanged. TABLE 4 READINGS Run No. "t M ( s e c s .) M d ” (in ch e s) 1 a 4 l .6 o 2 .0 b 4 9 .2 0 2 .0 c 4 0 .5 0 2 .0 d 4 5 .5 0 Av. 4 4 .2 0 2 .0 2 a 53.50 1 .5 b 4 4 .2 0 1 .5 c 4 2 .3 0 1 .5 d 4 8 .0 0 Av. 4 7 .0 0 1 .5 3 a 8 5 .1 0 1.0 b 5 7 .5 0 1 .0 c 7 4 .5 0 1 .0 d 56.40 Av. 6 8 .4 0 1 .0 4 a P e n e tr a te d 0 .5 b P e n e tr a te d 0 .5 c P e n e tr a te d 0 .5 The combined g ra p h i s shown on p. 25. O b s e r v a t i o n s . --T h e fla m e s a t f i r s t a p p e a re d a s l u m inous cones w ith r a p i d l y v a r y in g f i g u r a t i o n s . They th en sank i n t o th e s c re e n and c o l l e c t e d i n b l u i s h p o o ls on th e f u e l d r o p l e t s t r a p p e d i n th e m eshes. B e fo re e x t i n g u i s h i n g th e y m ig r a te d to th e edge o f th e s c re e n and b u rn e d alo n g 24 th e l i n e o f c o n t a c t o f th e s k i n t and th e s c r e e n . They t r i e d to p e n e t r a t e betw een th e s k i r t and th e v e s s e l w a l l s b u t w ith o u t s u c c e s s , e x c e p t in the c a se o f th e f o u r t h r u n s . Here th e y managed to p r o p a g a te b ack th ro u g h th e space b e tween th e s k i r t and th e w a l l s . R e s u l t s . --A . From a p r e l i m i n a r y s tu d y o f th e n a t u r e o f th e r e l a t i o n s h i p betw een " t " and nd,n " t n v a r i e s i n v e r s e l y to "d" w i t h i n a c e r t a i n h e i g h t r a n g e . When th e s c re e n i s q u i t e removed from th e f u e l s u r f a c e th e tim e i s f a r s m a l l e r th a n when i t i s j u s t above th e s u r f a c e . B e tween th e s e two e x tre m e s t h e r e i s no s h a rp o r d e f i n i t e p r e d i c t a b i l i t y o f d e c r e a s e o f " t " w ith i n c r e a s e o f " d , " as o b s e rv e d by com paring th e i n d i v i d u a l r e a d i n g s o f ru n no. 2 and ru n no. 3 . B. The tim e r e q u i r e d f o r e x t i n g u i s h i n g th e flam e w ith th e l a r g e r mesh s c re e n i s l e s s th a n t h a t o f th e s m a l l e r mesh screen,, a s o b s e rv e d by th e g ra p h on th e f o llo w in g p a g e . E x p l a n a t i o n . --T he tim e r e q u i r e d f o r e x tin g u is h m e n t depends upon th e amount o f f u e l v a p o r t h a t can be e v a p o r a te d p e r u n i t tim e to s u s t a i n th e fla m e s . T h is am ount, in i t s t u r n , depends upon th e d i s t a n c e b etw een th e s c re e n s u r f a c e on which th e flam e s i t s and th e f u e l s u r f a c e . As t h i s d i s ta n c e i n c r e a s e s , th e h e a t t r a n s f e r r e d to th e f u e l d i r e c t l y by r a d i a t i o n o r i n d i r e c t l y by c o n v e c tio n c u r r e n t s , d e c r e a s e s . Time t in seconds 25 8 0 lOMeshes/ in SMeshes/ in 7 0 6 0 5 0 4 0 - 3 0 20 0-5 Distance d " in inches VARIATION OF " t " AND " d " Fi g 5 26 The i n t e n s i t y o f th e h e a t t h a t i s r a d i a t e d to th e l i q u i d from th e fla m e s i s p r o p o r t i o n a l to th e i n v e r s e s q u a re o f " d ." As "d" i n c r e a s e s th e i n t e n s i t y o f t h i s h e a t d e c r e a s e s and c o n s e q u e n tly v a p o r i z e s l e s s f u e l to fe e d th e f l a m e s . The tim e v a r i a t i o n w ith mesh s i z e i s more e v i d e n t f o r l a r g e " d 's " th a n f o r s m a ll " d 's * " f o r two r e a s o n s . As th e fla m e s a r e s u p p o rte d by th e f u e l d ro p s e n tr a p p e d i n th e meshes th e g r e a t e r th e mesh s i z e th e l a r g e r q u a n t i t y o f f u e l tr a p p e d i n th e m eshes. The more th e f u e l a v a i l a b l e th e lo n g e r th e tim e o f e x tin g u is h m e n t. The 8 mesh s c re e n h a s a mesh s id e o f 0 .0 9 inches,, and th e 10 mesh s c re e n h as a mesh s id e o f 0 .0 6 5 3 i n c h e s . The tim e o f e x tin g u is h m e n t o f th e fo rm e r i s g r e a t e r th a n o f th e l a t t e r . Secondly* th e s m a l l e r mesh s id e th e g r e a t e r th e s u r f a c e a r e a o f th e mesh w i r e s . T his i n c r e a s e s th e amount and th e r a t e o f th e h e a t c o n d u c te d away from th e fla m e s . For s m a ll " d ’ s*" th e f u e l d ro p s tr a p p e d in th e mesh o f th e s c r e e n a re no l o n g e r th e m ajo r s o u rc e o f f u e l - v a p o r su p p ly to th e fla m e s: c o n s e q u e n tly th e tim e d i f f e r e n c e owing to mesh s i z e s t a r t s to n arro w . The n e x t v a r i a b l e to be c o n s id e r e d was th e s u r f a c e a r e a o f th e f u e l . The s u r f a c e in th e g l a s s j a r was 11.05 sq. i n . I t was d e c id e d to i n c r e a s e t h i s a r e a and n o te th e s u b s e q u e n t e f f e c t on th e tim e o f e x tin g u is h m e n t. A m e t a l l i c 27 c y l i n d e r was u s e d . I t had a p r o t r u d i n g o u t l e t a t th e s id e n e a r th e b a se to w hich was a t t a c h e d a hollo w g l a s s ro d by means o f a r u b b e r tu b e . The g l a s s ro d was g r a d u a te d to m easure th e d i s t a n c e " d ." D ata and d im e n s io n s : H t ......................................................................................... D i a ...................................................................................... Depth o f s c re e n from to p o f v e s s e l . . H t. o f s c re e n s u r f a c e from b o tto m o f v e s s e l ............................................................... Length o f aluminum gauze s k i r t . . . . A rea o f f u e l s u r f a c e ..................................... (The s c re e n was made o f a s t a i n l e s s s t e e l 8 in c h mesh g au ze) Mesh s i z e .................................................................... TABLE 5 READINGS Run No. " t " ( s e c s .) "d" ( in c h e s ) 1 a P e n e t r a t e d 2 .0 b P e n e t r a t e d 2 .0 c P e n e t r a t e d 2 .0 O b s e rv a tio n s and d i s c u s s i o n . --T he s c re e n f a i l e d to p r e v e n t th e p e n e t r a t i o n o f th e fla m e s . They f i r s t s u b s id e d i n t o th e s c re e n w ith o u t p e n e t r a t i o n and th en moved to v a r i ous p o i n t s ( a p p a r e n t l y to p o i n t s where e x c e s s f u e l was t r a p ped in th e m e s h e s ) , and f i n a l l y m ig r a te d to th e edge o f th e s c r e e n . The fla m e s th e n t r a v e l l e d down th e s k ir t ., betw een th e s k i r t and th e v e s s e l w alls* and c o n tin u e d to b u rn in 7 3 / 8 n 4 3 /4 " 3 7 /8 " 3 1/ 2 " 3 1/2 " 1 7 .6 9 s q . i n 0 .0 9 " 28 t h a t s p a c e . T his b u rn in g was s u p p o rte d by th e v a p o r i z a t i o n o f th e f u e l d ro p s i n t h e s k i r t m eshes. T his c o n tin u e d b u r n in g h e a t e d th e s k i r t to a p o i n t where i t was u n a b le to p r e v e n t th e p e n e t r a t i o n o f th e fla m e s. The d i s t a n c e betw een th e w a l l s and th e s k i r t was too l a r g e and p e r m i t t e d th e p e n e t r a t i o n o f th e fla m e s and t h e i r s u b se q u e n t b u r n in g in t h i s sp a c e . I t was s u g g e s te d t h a t th e s k i r t be r e d e s i g n e d and made to s c ra p e th e w a lls^ th u s k e e p in g th e fla m e s from sq u e e z in g th ro u g h . A new s t r u c t u r e was d e v e lo p e d and was a p p r o p r i a t e l y named th e tw o - s c r e e n s - tw o s k i r t s s t r u c t u r e . T his do u b le s c r e e n was c o n s id e r e d as a p o s s i b l e s a f e t y f a c t o r to t r a p fla m e s t h a t managed to p e n e t r a t e th e p rim a ry s c r e e n . >l i p "C > prim ary screen >1 * ■ ¥ * tt HftK ■ > secondary screen ---- * >■ * ■ W>f KXKi H- W f i V i fo n r-p ro n g ed s tr u c tu r e ■ v s k i r t F i g . 6 29 The p rim a ry s c r e e n , " A ," was made o u t o f 10 meshes p e r in c h s t a i n l e s s s t e e l g a u z e . The d ia m e te r o f th e s c re e n was 4 1 /2 in c h e s and i t s ed g es were tu r n e d up to form a l i p ,fC" 7 /8 in c h e s h ig h . The edges o f th e l i p were d e s ig n e d to s c ra p e th e i n s i d e o f th e v e s s e l w a l l s , th u s c l o s i n g th e gap w hich had h i t h e r t o l e t th e fla m e s sq u eeze th ro u g h betw een th e v e r t i c a l s k i r t and th e w a l l s . To th e p rim a ry s c re e n was a t t a c h e d a v e r t i c a l s k i r t r u n n in g 3 3 /8 in c h e s in h e i g h t and h a v in g th e same d ia m e te r as th e s c r e e n . One in c h below th e p rim a ry s c r e e n , and p a r a l l e l to i t , a se c o n d a ry s c re e n was a t t a c h e d to th e s k i r t . B oth th e se c o n d a ry s c re e n and th e s k i r t were made o u t o f a 10 mesh g a u z e . D is c u s s io n on th e F e a t u r e s o f th e New S creen S t r u c t u r e The a n g le d s k i r t was d e s ig n e d to p r e v e n t ; ( l ) th e s q u e e z in g o f th e fla m e s betw een th e s k i r t and th e v e s s e l w a l l s ; and, ( 2 ) th e fla m e s from g e t t i n g too c l o s e to th e w a l l s . As had been n o t i c e d on th e p r e v io u s s t u d i e s , th e v u l n e r a b l e p a r t o f th e s t r u c t u r e was th e j o i n t o f th e s c re e n and th e s k i r t . The se c o n d a ry s c re e n was f ix e d an i n c h b e low th e p rim a ry to a r r e s t any fla m e s t h a t managed to p e n e t r a t e th e v u l n e r a b l e j o i n t . 30 Runs and o b s e r v a t i o n s . --T he c u p -sh a p e d p rim a ry s c re e n c o n ta in e d th e fla m e s s i m i l a r to a cup c o n t a i n i n g w a te r . The fla m e s were th u s p r e v e n te d from a p p ro a c h in g too c l o s e to th e w a l l s . —» p rim ary scree n 'lip ■>the v e s s e l w a ll : fc«-- 'Vx-y*x*,v v x * h y XK*X*j<)<X^fry x-j secondary screen s k i r t ■fuel su rfa c e F ig . 7 D uring th e t e s t s th e fla m e s e x tin g u is h e d ,, b u t one p a r t i c u l a r tim e th e y d id n o t . The s c re e n was j e r k e d up, w hich c a u se d some p h y s i c a l d i s t u r b a n c e s . The fla m e s p e n e t r a t e d th e p rim a ry s c re e n and were s to p p e d by th e s e c o n d a ry s c r e e n . Here th e y c o n tin u e d to b u rn i n a form o f v e r t i c a l snaky w a l l s bounded by th e two s c r e e n s , w ith th e p rim a ry on to p and th e se c o n d a ry below . They were b l u i s h in c o l o r and had a v e ry s m a ll h o r i z o n t a l w id th . They u n d u l a t e d h o r i z o n t a l l y . They f i n a l l y p e n e t r a t e d th e s e c o n d a ry s c r e e n . 31 TABIE 6 READINGS Run No. " t" ( s e c s .) "d" ( in c h e s ) D is ta n c e o f P r i mary S c re e n from Top o f V e s s e l 1 17.50 2 1/4 1 M below 2 1 7 .8 0 2 1 /4 1 " below 3 1 6 .7 0 2 3 /8 7/ 8 ” below 4 16.40 3 3/ 8 ” below 5 21.40 3 1A 0 6 2 1 .0 0 3 1/4 0 7 1 6 .0 0 3 1/4 0 8 2 8 .1 0 3 1 /2 1 / 4 ” above 9 3 0 .2 0 3 1 /2 1 / 4 ” above 10 P e n e t r a t e d In 25 s e c s . 4 1 /8 7/ 8 ” above 11 P e n e t r a t e d i n 20 s e c s . 4 1 /2 1 1 / 4 ” above The fla m e s d u rin g th e tim e o f e x tin g u is h m e n t f i r s t a p p e a re d r i c h and lum inous and s p re a d o v e r th e e n t i r e screen . Then h a v in g s u b s id e d to many b l u i s h subdued f la m es, th e y t r a v e l l e d e r r a t i c a l l y a c r o s s th e s u r f a c e o f th e s c r e e n . F i n a l l y j u s t p r i o r to e x tin g u is h m e n t, th e y s e t t l e d n e a r th e lo w e s t p o i n t on th e s u r f a c e o f th e p rim a ry s c r e e n . The p o s i t i o n o f th e p rim a ry s c re e n w ith r e s p e c t to th e to p rim o f th e v e s s e l a p p e a re d to make a d i f f e r e n c e i n th e tim e o f e x t i n g u is h m e n t. When th e s c re e n was p l a c e d too f a r above th e rim (ru n s n o s . 10 and 11 i n T ab le 6 ), th e se c o n d a ry s c re e n was u n a b le to p r e v e n t th e p e n e t r a t i o n o f th e fla m e s . The e f f e c t o f th e s c re e n p o s i t i o n w ith r e s p e c t to th e rim o f th e v e s s e l a p p a r e n t l y may be th e r e s u l t o f th e 32 amount o f oxygen a v a i l a b l e a t the d i f f e r e n t p o s i t i o n s . When the prim ary sc ree n i s p la c e d above the rim., a i r s u r rounds the e n t i r e sc re e n and makes a v a i l a b l e oxygen to sup p o r t th e combustion by d i f f u s i o n . C onsequently even though the d i s ta n c e "d" i s i n c r e a s in g the time o f ex tin g u ish m en t does no t d e c re a se ; in fact,, i t i n c r e a s e s . But i f the screen su rfa c e i s below th e rim , " t" d e c re a se s w ith in c r e a s e o f nd. u The new sc ree n s t r u c t u r e w ith th e a n g led s k i r t and secondary sc ree n proved s a t i s f a c t o r y f o r e x tin g u is h in g flam es on aceto n e c o n ta in e d in a m e t a l l i c v e s s e l . But the com plicated,, awkward n a tu r e o f th e c o n s tr u c tio n v i t i a t e d the u s e f u l n e s s o f the d e v ic e . I t was proposed t h a t the v e r t i c a l s k i r t and the secondary sc ree n be e lim in a te d and i n s t e a d a means be found whereby an e f f e c t i v e s e a l could be formed between the sc ree n and the w a lls o f th e v e s s e l . Development o f an E f f e c t i v e S eal scree n s e a l w a l l o f th e v e s s e l ^ f u e l P i g . 8 33 The s e a l n eed s to f i t th e e n t i r e le n g t h o f th e s c re e n c ir c u m fe r e n c e and to be sq u eezed a g a i n s t th e v e s s e l w a l l s ; y e t th e f r i c t i o n betw een th e w a l l s and th e s e a l I s to be k e p t as low as p o s s i b l e so t h a t th e s c re e n I s a b le to r i s e w ith e a s e . T h is p r o p e r t y was c o n s id e r e d I m p o r ta n t as i t was s u g g e s te d t h a t th e d e v ic e be f l o a t e d up th ro u g h th e f u e l I f e v e r u s e d I n d u s t r i a l l y . The new s c re e n s t r u c t u r e used,, c o n s i s t e d o f a s t a i n l e s s s t e e l 10 meshes p e r in c h gauze c u t i n t o a d i s c m eas u r i n g 5 7 /8 in c h e s i n d ia m e te r . The d i s c was d e p r e s s e d in th e c e n t e r to make t h i s p a r t th e lo w e s t on th e s u r f a c e o f th e s c r e e n . As i t had been p r e v i o u s l y o b s e rv e d t h a t th e dy ing fla m e s te n d e d to s e t t l e on th e lo w e s t p o i n t o f th e s c r e e n , th e c e n t e r was d e p r e s s e d to h e lp m ig ra te th e fla m e s away from th e e d g e s . A t i n a n n u l a r s t r i p was s o ld e r e d to th e s c re e n a lo n g i t s edge,, th e n , t h i n c o p p e r w ir e s Y5' 000 i n c h i n d ia m e te r were s o ld e r e d to th e t i n s t r i p r a d i a l l y o u tw a rd s a lo n g th e c ir c u m fe r e n c e o f th e s c r e e n . T his form ed a c i r c l e o f s u rr o u n d in g w ire w h is k e rs p r e s s e d a g a i n s t th e s i d e s o f th e v e s s e l , and r e s u l t e d i n an e f f e c t i v e s e a l w ith n o t too much f r i c t i o n . copper -whiskers xxxxxxxxxyxyx xx xxx xxxtyxsoooo 00* I ^ ^ * t i n s t r i p s ^ screen F i g . 9 34 >. copper w hiskers ■ > scree n w a ll ^ lo w est p o in t in th e c e n te r > aceto n e P i g . 10 Runs and o b s e r v a t i o n s . - - F o r th e f i r s t t r y th e s c re e n ■was moved to 5 in c h e s above th e l e v e l o f a c e t o n e . The i n i t i a l fla m e s were lum inous o ra n g e and e v e n ly d i s t r i b u t e d o v e r th e e n t i r e s u r f a c e o f th e s c r e e n . A f t e r 22 s e c s , th e fla m e s changed to b l u i s h y e llo w and m ig r a te d to th e e d g e. They c o n tin u e d to move a b o u t r a p i d l y and e r r a t i c a l l y and th en a f t e r a n o t h e r 10 s e c s , e x t i n g u i s h e d . The e a s e w ith which th e s c re e n had been r a i s e d was j u s t what was d e s i r e d . In th e second ru n th e s c re e n was r a i s e d 3 in c h e s above th e f u e l and i t to o k 25 s e c s , f o r th e fla m e s to e x t i n g u i s h . D i s c u s s i o n . --T h e s e a l form ed by th e c o p p e r w h is k e rs had th e n e c e s s a r y a t t r i b u t e s . B eing f l e x i b l e th e y d id n o t e x e r t too much p r e s s u r e on th e w a l l s and b e in g c l o s e enough th e y p r e v e n t e d th e fla m e s from p e n e t r a t i n g betw een th e s c re e n and th e w a l l s . T his same s t r u c t u r e was th en u s e d to e x p e rim e n t w ith th e fla m e s o f t o l u e n e and b e n z e n e . F i r s t t o l u e n e was e x p e rim e n te d w ith ; i t had a mild,, luminous., s o o ty fla m e . When th e s c re e n was l i f t e d above th e fuel., th e fla m e s l i f t e d and c o n tin u e d to b u rn on th e s c r e e n w ith r e l e a s e o f e x c e s s i v e amount o f s o o t. A f t e r a la p s e o f a b o u t 20 seco n d s th e fla m e s p e n e t r a t e d r i g h t th ro u g h th e c e n t e r o f th e s c r e e n . T h is a l s o o c c u r r e d e ach tim e th e e x p e rim e n t was ru n u s in g th e 10 mesh s c r e e n , The 10 mesh s c re e n was th e n r e p l a c e d by 25 mesh s t a i n l e s s s t e e l s c r e e n . As th e s c r e e n was moved up i t l i f t e d th e fla m e s . The fla m e s co n t i n u e d to b u rn f o r anywhere b etw een 80 to 120 s e c s , b e f o r e e x t i n g u i s h i n g d u rin g th e t h r e e r u n s w hich were made. T his tim e was found to be too lo n g . The 25 mesh s c re e n was a p p a r e n t l y too s m a ll f o r t o l u e n e . An 18 mesh s c re e n was th en u s e d . The fla m e s e x t i n g u i s h e d in 45 s e c s . The tim e o f e x tin g u is h m e n t was found to v a ry betw een 45 and 65 s e c s . For b en zen e th e same s c re e n r e s u l t e d in an a v e ra g e tim e o f 40 s e c s . The n e x t f u e l to be t e s t e d was e t h y l g a s o l i n e . The fla m e s e x t i n g u i s h e d each tim e a ru n was made. The tim e o f e x tin g u is h m e n t ra n g e d from 52 to 75 s e c s . CHAPTER I I I A RESUME OF FINDINGS 1. The s c re e n can l i f t th e fla m e s o f f th e f u e l s u r f a c e , and p r e v e n t t h e i r p r o p a g a tin g h a c k to th e fuel., i f th e mesh s i z e s o f th e s c r e e n m easure l e s s th a n th e f u e l ' s q u en ch in g d i s t a n c e . 2. Even a f t e r th e s c r e e n h a s l i f t e d th e fla m e s , th e y c o n tin u e to b u r n . D uring t h i s p o s t - b u r n i n g p e rio d s th e fla m e s a r e s u p p o rte d m ain ly by th e f u e l tr a p p e d i n th e m eshes. 3 . The h i g h e r th e s c re e n above th e f u e l s u r f a c e th e s h o r t e r th e tim e o f p o s t b u r n in g ; th e l a r g e s t d i s ta n c e b etw een th e s c re e n and th e f u e l s u r f a c e , d u r in g th e s tu d y , was 3 1 /4 " . 4. B e fo re e x t i n g u i s h i n g , th e fla m e s te n d to m ig ra te to th e lo w e s t p o i n t on th e s c re e n s u r f a c e . 5. The v u l n e r a b l e p o i n t in th e mechanism I s th e space betw een th e s c r e e n c ir c u m fe r e n c e and th e v e s s e l w a l l s . T h is sp ace must be l e s s th a n th e quen ch in g d i s t a n c e o f th e f u e l b e in g e x t i n g u i s h e d . These f i n d i n g s a r e now i n c o r p o r a t e d In a d e v ic e which s h o u ld p r a c t i c a l l y be u s e f u l f o r flam e e x t i n g u i s h i n g . 36 37 The D evice The main elem en t o f th e u n i t i s th e s t a i n l e s s s t e e l s c r e e n . The s c re e n i s made from a 10 meshes p e r in c h g r i d as th e mesh s i z e f o r t h i s g r i d i s w ith in th e q u en ch in g d i s ta n c e o f a c e to n e . T h is i s v e ry e s s e n t i a l * i . e . * th e mesh s i z e o f th e s c re e n must he below th e q u en ch in g d i s t a n c e o f th e f u e l f o r which th e d e v ic e i s d e s ig n e d . The d ia m e te r o f th e s c re e n i s 19 fe e t* le a v in g a p e r i p h e r a l c l e a r a n c e o f 6 in c h e s betw een th e c ir c u m fe r e n c e and th e w a l l s o f th e ta n k . The c e n t e r o f th e s c re e n i s 6 in c h e s below th e h o r i z o n t a l a c r o s s th e s c re e n c ir c u m f e r e n c e . T h is i s to keep th e fla m e s from a p p ro a c h in g too c lo s e to th e w a l l s . In th e l a b o r a t o r y i t was o b s e rv e d t h a t th e fla m e s te n d e d to m ig r a te to th e lo w e s t p o i n t o f th e s c r e e n . The 6 i n c h d e p r e s s io n w i l l p r o v id e enough o f an a n g le to t r a v e l th e fla m e s down to th e c e n t e r . I t i s p r e d i c t e d t h a t a n y th in g l e s s th an t h i s w i l l f a i 1 . To h o ld th e s c re e n r i g i d * two s t e e l s t r i p s ( l 1 /2 in c h e s i n w id th and 1 /2 in c h in t h i c k n e s s ) a re w elded to th e convex s u r f a c e o f th e screen* p e r p e n d i c u l a r to each o t h e r . T h is a ls o p r o v id e s a s u p p o rt to th e g r i d w hich o th e r w is e would te n d to sa g . Along th e c irc u m fe r e n c e o f th e s c re e n a n o t h e r s i m i l a r s t r i p i s welded* s e r v in g two p u rp o s e s : F i r s t * i t g iv e s a d e f i n e d and r i g i d o u t l i n e to th e s c re e n s t r u c t u r e * and secondly* i t forms a p l a t f o r m to w hich th e s e a l betw een th e s c r e e n and th e v e s s e l w a l l s 38 i s w elded. The w a ll s e a l i s formed by f l e x i b l e m e ta l t i n s e l s w elded to th e above p l a t f o r m alo n g th e e n t i r e c irc u m f e r e n c e o f th e s c r e e n . T his s e a l i s im p o r ta n t a s th e space betw een th e edge o f th e s c re e n and th e v e s s e l w a l l s i s most v u l n e r a b l e to th e p e n e t r a t i o n o f fla m e s. At th e same tim e i t i s n o t d e s i r a b l e t h a t t h i s s e a l sh o u ld i n t e r f e r e w ith th e f l o a t i n g up o f th e s c r e e n ; hence th e u se o f f l e x i b l e m e ta l t i n s e l s to form th e s e a l . The e n t i r e s c re e n s t r u c t u r e r e s t s on f o u r s t e e l r o d s . These ro d s a r e w elded to th e s c re e n a t i t s c irc u m ference,, and 90 d e g r e e s from each o t h e r . The r o d s m easure 5 f e e t in h e i g h t . As l a b o r a t o r y t r i a l s have shown t h a t tim e o f e x tin g u is h m e n t d e c r e a s e s w ith i n c r e a s e o f d i s t a n c e b e tween th e s c re e n and th e f u e l su rface,, i t would be d e s i r a b l e to have ro d s m easure more th an 5 f e e t . But f o r p r a c t i c a l r e a s o n s a n y th in g more th a n 5 f e e t i s n o t recommended. The low er ends o f th e ro d s a r e w elded to a CO^ a n n u la r f l o a t . The f l o a t d e v ic e i s a h o r i z o n t a l a n n u la r tu b e p r e f i l l e d w ith The s t r u c t u r e i s h e l d below th e f u e l s u r f a c e by wedges "X” as shown in th e d ra w in g s. These wedges a r e r e t r a c t a b l e and a r e c o n t r o l l e d by a h e a t se n so ry d e v ic e . In c ase o f f i r e th e s e n s in g d e v ic e sends o u t ap p r o p r i a t e s i g n a l s to r e t r a c t th e w edges. The s c re e n th en r i s e s th ro u g h th e f u e l , th e s p r i n g s "Yn p r e v e n t any h o r i z o n t a l d is p la c e m e n t, and I t s s u r f a c e comes to r e s t 5 f e e t above th e s u r f a c e o f th e f u e l . A f t e r th e f i r e i s e x t i n 3 9 guished the fu el i s pumped in to another tank to allow the screen to re tu rn to i t s o rig in a l p o s itio n . The wedges s lip in to th e ir holds and the device i s ready to be used again. At the p resen t time an e a s ie r way of re tu rn in g the device to i t s o r ig in a l p o sitio n cannot be recommended. In concluding i t should be pointed out th a t the mesh siz e of the screen w ill vary according to the fuel contained in the tank. But apart from this., the other e s s e n tia l fe a tu re s of th is device w ill not vary from fu el to f u e l . * A« * + 0 SID E V IE W SCREEN- S T A IN L E S S ST E E L IO M E S H /IN D I A - O F WIRE-0-0257" .M E S H SIDE-0-0653" S T A IN L E S S S T E E L S T R IP W E L D E D T O T H E R I M O F T H E SCREEN-W IDTH-1/2 : T H IC K N E SS— 1/2 * T H IN M E T A L STR IPS W E L D E D T O T H fe I '/2 " ST R IP A L O N G . T H E R IM - L-0 25 W D- '/8 D IS T - B E T * A D J ;, STRIPS-0-06 >4 ST A IN L E SS STE E L ST R IP W IDE- 15 4 " TH IC K N ESS- %" - S U P P O R T ROD-STAINLESS STEEL- D IA * X } H T 5' T W O SU P PO R T R O D S C O , IN L E T X. \5" ± 8 - 6* - C02 F L O A T , H O R IZ O N T A L A N N U L A R T U B E -, S M A L L E R D I A — 1 3 -1 1 * 8 THE DEVICE •b* T O P V IE W S U P P O R T R O D S S T R IP R U N N IN G T H E E N T IR E C IR C U M F E R E N C E VOF T H E SC R E E N M E T A L S T R IP S F O R M I N G A S E A L M E S H ST E E L ST R IP S \ S U P P O R T IN G T H E M E S H S C R E E N T H E SC R E E N IS W E L D E D O N T O T N E [strips C02 INLET A N N U L A R F L O A T V T H E D E V IC E IN S T A L L E D I N T H E T A N K F U E L S U R F A C E F U E L S T R IP S T H A T SE A L S P A C E B E T W E E N S C R E E N A M D W A L L O F V E S S E L SC R E E N S U P P O R T F O U R S P R IN G S A T F O U R E N D S O F T W Q P E R P . D IA . T O P R E V E N T H O R I Z - D IS P L . O F T H E S C R E E N ____________ W E D G E — R E T R A C T A B L E A N D T R IG G E R E D B Y A H E A T S E N S O R Y D E V IC E B I B L I O G R A P H Y h 3 BIBLIOGRAPHY 1. Barr,, John,, " D if f u s io n F l a m e s / ' F o u rth Symp. ( i n t . ) on C o m b u stio n , 1952, pp. 7 6 5 - 2. B e r l a d , A. L. , "Flame Quenching by a Y a r i a b l e - - W i d t h R e c ta n g u la r - - C h a n n e l B u rn e r a s a F u n c tio n o f P r e s s u r e f o r V a rio u s Propane-O ^-N ^ M ix t u r e s ," J o u r n a l o f P h y s i c a l Chem. , 5 8 , 1023 (November, 1954). 3 . B e r l a d , A. L ., and P o t t e r , A. E . , "The E f f e c t o f F u e l Type and P r e s s u r e on Flame Q u e n c h in g ," S i x t h Symp. ( i n t . ) on C om bustion, 1 9 5 6 . 4. C a l c o t e , H. E . , "On P r o d u c tio n and on R em oval," E i g h t h Symp. ( i n t . ) on Com bustion, S ep tem b er, i 9 6 0, p p . 1 8 4 - ' 19B7 5 . Emmons, H. ¥ . , and M urgai, M. P ., " N a tu r a l C o n v ec tio n F i r e s , " J o u r n a l o f F l u i d M ech an ics, 8, P t. 4, 611-624 ( i 9 6 0 ). 6. F r i s t r o m , R o b e rt M., "The S t r u c t u r e o f Lam inar Flames," S i x t h Symp. ( i n t . ) on C o m bustion, 1956, p. 9 6 . 7. Gaydon and W o lfh ard , " F la m e s," New Y ork, i 9 6 0 . 8. G risw o ld , Jo h n , " F u e ls , Com bustion and F u r n a c e s ," M cG raw -H ill, 1946. 9. H i r s t , K ., and S u tto n , D ., "The E f f e c t o f Reduced P r e s s u r e and A irflo w on L iq u id S u r fa c e D i f f u s i o n F la m e s," Com bustion and F lam es, V, 319-331 (December, 1 96 1 ). 10. Jo h n so n , ¥ . C ., and F riedm an, R ., "The ¥ a ll-Q u e n c h In g o f Lam inar Propane Flam es as a F u n c tio n o f P r e s s u r e , T e m p e ra tu re and A i r - F u e l R a t i o n , " J o u r n a l o f A p p lie d P h y s i c s , 21 (A u g u st, 195 0 ). 11. , " P r e s s u r e Dependence o f Quenching D is ta n c e o f Normal H e ta n e , I s o - O c ta n e , B enzene, and E th y l E t h e r , " J o u r n a l o f P h y s i c a l Chem. , 20, 919 (May, 1952). 44 45 12. Levy,, A r th u r , "The Mechanism o f Flame I n h i b i t i o n , " E ig h th Symp. ( i n t . ) on C om bustion, S ep tem b er, i 9 6 0 . 1 3 . Lew is, B ., and Von E lb e , G ., "Com bustion, Flam es and E x p lo s io n o f G a s e s ," 1938* 14. M a rk s te in , J o u r n a l o f P h y s i c a l Chem., Y] > no . 20 (1 9 4 9 ). 15. M i l l e r , R o s s e r, and W ise, "Mechanism o f Com bustion I n h i b i t i o n by Compounds C o n ta in in g H a lo g e n s ," S ev en th Symp. ( i n t . ) on C om bustion, 1958., pp. 175-182. 16. P alm er, K. N ., "The Quenching o f Flam es by Wire G a u z e s," S e v e n th Symp. ( i n t . ) on C om bustion, 1958, pp. 497-5 0 3 . 17. P e a se , R. N ., and T a n fo rd , C ., " E q u ilib r iu m Atom and F ree R a d ic a l C o n c e n tr a t i o n s in Carbon Monoxide Flames and C o r r e l a t i o n w ith B u rn in g V e l o c i t i e s , " J o u r n a l o f P h y s i c a l Chem. , 15 ( J u l y , 1 9 4 7 ). 18. P e r r y , John H ., "Chem ical E n g in e e rs H andbook," 3d e d . , M cG raw -H ill, New York, 19 , pp, 244-246. 19. P o t t e r , A. E . , and A nagn o sto u , E ., " R e a c tio n O rder in th e H ydrogen-B rom ine Flame from th e P r e s s u r e Symposium ( i n t . ) on C om b u stio n , 1958, p . 347* 20. S avage, L. D ., "The E n c lo s e d Lam inar D i f f u s i o n F la m e ," Com bustion and F lam e, 6 , 77-87 (Ju n e , 1 9 6 2) . 21. S h a p la n d , J . D ., " F i r e - F i g h t i n g I n s t a l l a t i o n i n th e Chem ical I n d u s t r y , " C hem ical and P ro c e s s E n g in e e r in g , 43, 5 -8 ( J a n u a r y , 1 9 6 2). 22. Simmons, R. F . , and W o lfh a rd , H. G ., "Some L im itin g 0^ C o n c e n tr a t i o n s f o r D i f f u s i o n Flam es In A ir D i l u t e d w ith N^," Com bustion and F lam e, 1, no. 2 (Ju n e , 1957). 2 3 . S k r o t z k i , B. G. A ., "What I s New in F i r e P r o t e c t i o n ? " Power, 106, 57-63 (S ep te m b e r, 1 9 6 2). 24. S m ith, M. L ., and S t i n s o n , K. W., " F u e ls and Combus t i o n , " 1 s t e d . , 1952. 2 5 . T a n fo rd , C ., "Theory o f B u rn in g V e l o c i t y , I , " J o u r n a l o f P h y s i c a l Chem., 15* 8 6 1 (December, 19 4 7 ). 46 26. T a n fo rd , 0. , and Pease,, R. N ., "Theory o f B u rn in g V e l o c i t y , I I , " J o u r n a l o f P h y s i c a l Chem.,, 15* 8 6 l (December, 19477^ ~ 27. Thomas, P. H ., and H e s e ld e n , A. J . M ., "B e h a v io r o f F u l l y D eveloped F i r e i n an E n c l o s u r e ," Combustion and F lam e, 6 , 133-137 (S ep te m b e r, 1 9 6 2) . 28. Thomas, P. H ., W e b ste r, C. T ., and R a f t e r y , M. M., "Some E x p e rim e n ts on B uoyant D i f f u s i o n F la m e s," Com bustion and F lam e, 5> 359-367 (December, 196 1) . 29. Van K re v e le n , D. W., and Cherm in, H. A. G ., " G e n e ra l i z e d Flame S t a b i l i t y D iag ram ," S ev e n th Symp. ( i n t . ) on C o m bustion, 1958, p . 359. 30. Von E lb e , G ., and Lew is, B ., "On th e Theory o f Flame P r o p a g a t i o n ," J o u r n a l o f P h y s i c a l Chem. , 2, 537 (A u g u st, 193^)•

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Creator Bedi, Narinder Singh (author)

Core Title The study of the effectiveness of a screen to stifle diffusion flames

Degree Master of Science

Degree Program Chemical Engineering

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag engineering, chemical,OAI-PMH Harvest

Language English

Contributor Digitized by ProQuest (provenance)

Advisor Lenoir, John M. (committee chair), Copeland, Charles S. (committee member), Rebert, Charles J. (committee member)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c20-311583

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Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

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