1/ 29/ 2013 Winte r Ca mping And Ba c kpa c king Co ld We a the r Da ng e rs › Hypothe rmia - is a c o nditio n in whic h c o re te mpe ra ture dro ps b e lo w the re q uire d te mpe ra ture fo r no rma l me ta b o lism a nd b o dy func tio ns whic h is de fine d a s 95.0 °F . › F ostbite - is the me dic a l r c o nditio n whe re lo c a lize d da ma g e is c a use d to skin a nd o the r tissue s due to e xtre me c o ld. 1
1/ 29/ 2013 De c iding Wha t to Bring › Che c k the lo c a l we a the r fo re c a st fo r the time pe rio d yo u will b e in the b a c kc o untry – we t, dry, wind, te mpe ra ture e xtre me s. › Co nside r whe re yo u will b e g o ing in the b a c kc o untry – wa te r fro nt, mo unta ins, a lpine . I n dry we a the r, the te mpe ra ture dro ps a b o ut 5.5 F pe r 1000 fe e t in e le va tio n g a in (3.2 F fo r mo ist we a the r). › Co nside r ho w lo ng yo u will b e in the b a c kc o untry. › Co nside r yo ur o wn se nsitivity to lo w te mpe ra ture s. › Co nside r the e xte nt o f yo ur physic a l e xe rtio n a t the e nd o f the da y. Me c ha nisms o f He a t L o ss › Co nduc tio n › Co nve c tio n › Ra dia tio n › E va po ra tio n › Re spira tio n – Co mb ina tio n o f c o nve c tio n a nd e va po ra tio n 2
1/ 29/ 2013 Thermal conductivity Material [W/(m·K)] I nsula tio n Vacuum 0 0.016 Water (vapor) Air (sea level) 0.025 › T Silica Aerogel 0.026 he rma l c onduc tivity , k , is the Polyurethane Foam 0.02 - 0.03 Feathers 0.034 Fiberglas 0.035 pro pe rty o f a ma te ria l's a b ility Wool 0.03 - 0.04 Polystyrene Foam 0.03 - 0.05 to c o nduc t he a t. Cotton 0.04 Hollow Fill Fiber Insulation 0.042 Paper 0.04 - 0.09 0.05 Polyester Straw 0.05 Felt 0.06 Wood 0.09 - 0.14 › He a t tra nsfe r a c ro ss ma te ria ls Mineral oil 0.138 Particle Board 0.15 0.15 - 0.45 Neoprene Rubber 0.16 o f hig h the rma l c o nduc tivity Snow 0.16 Polypropylene 0.25 o c c urs a t a hig he r ra te tha n Teflon 0.25 0.27 Sand Cement, Portland 0.29 a c ro ss ma te ria ls o f lo w the rma l Water (liquid) 0.561 Thermal grease 0.7 - 3 c o nduc tivity. Glass 1.1 Soil 1.5 Concrete, stone 1.7 Water (ice) 2.2 Sandstone 2.4 Mercury 8.3 Stainless steel 14 › Ma te ria ls o f lo w the rma l Titanium 21.9 Lead 35.3 Steel 45 - 65 c o nduc tivity a re use d a s Iron 80.2 Aluminum 237 Gold 318 the rma l insula tio n. Copper 401 Silver 429 Diamond 895 I nsula tio n › T e sistivity , R , is the pro duc t he r ma l r o f the ma te ria l thic kne ss a nd re c ipro c a l o f the the rma l c o nduc tivity. › Go o d the rma l insula to rs ha ve la rg e R va lue s. › An insula ting ma te ria l will ha ve a la rg e R va lue whe n the the rma l c o nduc tivity o f tha t ma te ria l is sma ll a nd the thic kne ss is wide . 1 t R t k › I n la ye re d ma te ria ls, R-va lue s c a n k b e a dde d. 3
1/ 29/ 2013 I nsula tio n › T he the rma l insula tio n o f c lo thing is pro po rtio na l to the thic kne ss o f the de a d a ir spa c e e nc lo se d. › De a d a ir is de fine d a s a ny e nc lo se d unit o f a ir tha t is sma ll e no ug h tha t na tura l c o nve c tio n c urre nts wo uld no t a rise in it. › T he de a d a ir ne xt to the skin is he a te d up b y the b o dy a nd pro vide s a la ye r o f wa rmth a ro und the b o dy. › T he c lo thing is no t wha t is ke e ping yo u wa rm it is the de a d a ir. T he L a ye ring Princ iple › T he ke y to pro viding this de a d a ir spa c e is thro ug h ha ving a numb e r o f la ye rs o f c lo thing . › I f yo u ha ve to o muc h c lo thing o n, yo u will o ve rhe a t a nd sta rt to swe a t. Yo u ne e d to find the pro pe r he a t b a la nc e b e twe e n the numb e r a nd type s o f la ye rs a nd yo ur a c tivity le ve l. › He a t lo ss fro m a we t surfa c e c a n b e up to 25 time s g re a te r tha n a dry surfa c e (due to the hig he r de nsity o f wa te r). › I f yo u swe a t a nd g e t so a ke d, yo u will lo se he a t muc h mo re q uic kly thro ug h e va po ra tio n o f the wa te r. › So yo u wa nt to c o ntro l yo ur la ye rs so a s to b e wa rm a t the a c tivity le ve l yo u a re in b ut no t swe a ting pro fuse ly. › Co nve c tio n ma y a c c o unt fo r the g re a te st a mo unt o f he a t lo ss unde r mo st c o nditio ns. I n o rde r to pro pe rly insula te , yo u ne e d to ha ve a n o ute r la ye r tha t is windpro o f. 4
1/ 29/ 2013 T he 3 L a ye r Syste m › T a ye r - wic k he Ba se L mo isture a wa y fro m the b o dy a llo wing yo u to re ma in dry a nd wa rm. › T a ye r - pro vide he Middle L the rma l pro te c tio n fro m the wind a nd the c o ld. › T he Oute r L a ye r - pro te c t a g a inst ra in a nd wind, b ut a llo wing yo u to b re a th. › E xtre mitie s - he a ds, ha nds a nd fe e t. Up to 40% o f the b o die s he a t c a n b e lo st thro ug h the e xtre mitie s. No Co tto n - Co tto n K ills! › Co tto n is b a sic a lly use le ss in winte r time . › Pro b le ms with c o tto n o c c ur whe n the c o tto n g e ts we t. › Co tto n a b so rb s this mo isture a nd the wa te r o c c upie s the spa c e pre vio usly o c c upie d b y de a d a ir. › Whe n wa te r o c c upie s the spa c e pre vio usly o c c upie d b y de a d a ir, c o tto n lo se s a ll insula ting pro pe rtie s. › Be c a use c o tto n ho lds so muc h mo isture , it c a n ho ld tha t mo isture a g a inst yo ur b o dy a nd sa p b o dy he a t fro m yo u b y hig h e va po ra tive c o o ling a nd c o nduc tio n. T his c a n q uic kly le a d to hypo the rmia . › A c o tto n g a rme nt is a lmo st impo ssib le to dry o ut. › Co tto n b e c o me s a b ra sive whe n we t. 5
1/ 29/ 2013 Na tura l F ib e rs › Silk lo se s its insula ting pro pe rtie s whe n it g e ts we t a nd do e s no t wic k like mo de rn hydro pho b ic fa b ric s. › Wo o l insula te s re la tive ly we ll whe n we t. But while so me we a ve s do she d wa te r fo r a pe rio d o f time , it will e ve ntua lly a b so rb a g re a t de a l mo re mo isture tha n c o mpa ra b ly we ig hte d synthe tic g a rme nts a nd b e c o me ve ry he a vy. › All o f the se na tura l fib e r fa b ric s ta ke muc h lo ng e r to dry o nc e we t tha n c o mpa ra b ly we ig hte d synthe tic fa b ric s. Ba se L a ye r › L ig ht We ig ht – Ca pile ne 2 › Me d ium We ig ht – Ca pile ne 3 › E xpe ditio n We ig ht – Ca pile ne 4 6
1/ 29/ 2013 Mid (I nsula ting ) L a ye r › F le e c e , ma de fro m po lye thyle ne o r o the r synthe tic s ha s ma ny o f the fe a ture s o f wo o l, b ut is lig hte r. I t pro vide s g o o d insula tio n e ve n whe n we t, a b so rb s ve ry little mo isture , a nd drie s q uic kly. – 100 We ig ht – 200 We ig ht – 300 We ig ht Mid (I nsula ting ) L a ye r › Down F ill ha s ve ry g o o d wa rmth to we ig ht ra tio , a nd c a n b e pa c ke d do wn (sq ue e ze d) to ta ke ve ry little ro o m. I t is e xpe nsive , ma ke s a thic k g a rme nt, drie s slo wly, lo se s its insula ting pro pe rtie s whe n we t o r c o mpre sse d, a nd sto ps lo fting pro pe rly a fte r b e ing wa she d se ve ra l time s. 7
1/ 29/ 2013 Mid (I nsula ting ) L a ye r › F ill powe r is a me a sure o f the lo ft o r "fluffine ss" o f a do wn pro duc t tha t is lo o se ly re la te d to the insula ting va lue o f the do wn. › T he hig he r the fill po we r the mo re insula ting a ir po c ke ts the do wn ha s a nd the b e tte r insula ting a b ility. › F ill po we r is e xpre sse d a s c ub ic inc he s pe r o unc e (in³/ o z). Technically speaking fill power is a measurement of the amount of space one › F (1) ounce of down (as shown on the right) will occupy in cubic inches when ill po we r ra ng e s fro m a b o ut allowed to reach its maximum loft. 300 in³/ o z fo r fe a the rs to For example, one (1) ounce of 800 fill power goose down will loft to 800 cubic a ro und 900 in³/ o z fo r the inches. The higher the fill power the larger the down cluster. Larger down clusters will loft higher, last longer and sleep warmer. hig he st q ua lity do wn. › A lo fting po we r o f 400-450 is c o nside re d me dium q ua lity, 500-550 is c o nside re d g o o d, 550-750 is c o nside re d ve ry g o o d, a nd 750+ is c o nside re d e xc e lle nt. Mid (I nsula ting ) L a ye r › Synthe tic F ill is po lye ste r fib e r (suc h a s Po la rg ua rd, Ho llo fil, Qua llo fil) use d simila rly to do wn, b ut do e s no t ha ve a s g o o d a wa rmth to we ig ht ra tio . › I t is le ss e xpe nsive , pro vide s g o o d insula tio n (fa irly e ffic ie nt a t pro viding de a d a ir spa c e tho ug h no t ne a rly a s e ffic ie nt a s do wn) e ve n whe n we t, drie s q uic kly, a nd a b so rb s ve ry little Down mo isture . › Ove r time with re pe a te d c o mpre ssio ns, the fib e rs b e c o me da ma g e d a nd b e c o me le ss e ffe c tive a s a n insula to r. › Primaloft - the princ ipa l b e hind supe r thin fib e rs is tha t b y ma king the fib e r thinne r yo u c a n inc re a se the a mo unt o f de a d a ir spa c e in a g ive n vo lume o f ma te ria l. Othe r supe r thin fib e rs inc lude Mic ro lo ft a nd T hinsula te . Prima loft One 8
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