Document wqjXMJ5aZjy8KmrLrv6nwLRYV

a b l e 2. C ir c u l a r E q u iv a l e n t s of R e c t a n g u la r D ucts fo r E q u a l F r ic t io n a n d C a p .T Dimensions in Inches ;:' 676 CHAPTER 31 1952 Guide ill 8338 3833 SSSS .'.SSSg SEES SSSS 3ESR SESS SSSg SSg J : ; : .; K Si i : -. ; * 9999 999 : ssss sss j . o.o exec, ; ' : . -as ssss ssg ; 9999 9"99 999 3333 5338 sss K1 . s. S< S' ------- ---~ . 3 3 EE SSSS ssssj; SSS toc*-' oeeo " ' REEK SE8E SSSS'SSS ;. . , .. . ;- 99 ;S.S 9999 ...SSSS 9 999 s ssss 99 .9999 .9999 ?9"9 . sc sees ecss .esss/sss ri-Nn-N r-r-r-n- .wrioa .,.( ;SSS: :sscs KCSS'^SSR - gs's ranrato rareCT- 9999 9999 999 SSSS SSSE CESS:C.SEK CEE .""n9999 9999 9999 '999- SSSS. SSSS SSEC EEEE REE 9999 :999 9999 9999- 999 ssss ssss ssss sees RES '.a9s9 ssss s99s"s9s,s9s9s9s9 s9s9s9s9 "99-. ssec "99 ere 999 9999 -.999 "999 9999 999 999 SES ssss ssss ssss ssss ssss esc . 9999 SSgS s9s9s9s9 s9s9s9s9 s9s9s9s9 :s9.9s9s9s. s9s9s9s9 s"s9s9 " 7" as-. a>aso.CO oooot-t- evw .ooco-ff nonv ^oovo 'eT .. ,v5:85 .SSSS SSSS . SSSS SSSS, SSSS.. SSS oooo ooooooco mciQv nnoo ono :<enON oC ; ?S^:;.S.SSS SSSS, SSSS -SSSS ssss':,SSSS- SSS 999 'SSS 9ss9s9s9 ' 9S9S9S9S.S9E9S9S9 s9s9s9s9 9999 SSSS s"s9s9s9 9999 SESS 9ss9s9s9 9999 SEES s9s9s99s; 9999 SSSS 9999 9999 SSSS.SSSS 9s9s9s 999 SSS .'3 's s 3 ; ; S Isis^sliS 3s2s isis ssss es3s .:.bsss ,sis ------------- ; oo. ooo=>. '999 9999 9999 9999 9999. 9999 :999' . 3S'ssss ssss ssss ssss ssss ssss ssss sss - .-. .' `9.9.9.99.99. 9999 9999_9999 9999.19999 9999 999" . 333 3333: 3333 SSSS ' SSSS SSSS SESS S3.SS SSS . .9999,9999,-9999' 9999 '9999 9999 ! 9999 '. 999" 999 ; r. SESS ; 333.3 .3S3S E.3SS SSSS :.S.SS3 SSSS. BESS '8SS_ ssss.9 9999: 9999 99"9 9999 9999 9999 9999 9999 |. g.88ES-8SS8;:.3533 SSSS SSSE.f.ESSS ssgs::sss_ "9 :9999,9999:.-9999. 9999 S3 SSSS.SSSS 3333 3333 ----- 999 9999 9999 9999 9999 SSS 3383 SESS 8333 3353 9999 9999 9999 9999 9999 SSSS SSSS 333E 3SS8 SSSS 9999 9999 SEES-'SSSS 9999 9999 SSSS SEES 9999 9999 3533 SSSS 9999 9999 ,999 5SSS.S3SS SSS 9999 9999 9-7T SSS5 5SSS SSS 9999 9999 999" SSSS.SSSS SSS_ ifl 3333 SSSS SSSS SSSS SESS SSSS SEES SSSS SSSS.SSS Air Duct'Design 677 tKe air; and are therefore conveniently expressed as a fraction of the:velocity head: ' U : -.9.;.::;..;. h. (4) and for standard air where hy = dynamic pressure loss, feet of fluid flowing. , Hv = dynamic pressure loss, inches of water. v = velocity of fluid, feet per second: :;<s) Fig. 4. Relation Between Velocity and Velocity Head for Standard Air f ^ = the velocity pressure corresponding to the mean velocity of flow, feet of fluid flowing. .j - .; - ...,: , ; ' . V = mean velocity of standard air, feet per minute. . j,,,.. C = an experimentally determined constant (dynamic loss coefficient). , . , It can be seen from Equation 4 that the dynamic loss coefficient is' inde pendent of both density and the units used, and that it representa 'the number , of velocity heads lost at the conduit transition or bend. Yalues of the dynamic loss coefficient for various duct elements are sometimes tabulated,'7- * though it should be kept in mind that absolutely: reliable dynamic loss coefficients have not yet been fully established;, for all duct elements. ... , Fig. 4, which shows the relation of velocity pressure to velocity for stand ard air (Y = m5VHy), can be conveniently used to find the total dynamic pressure loss for any duct element with known dynamic loss coeflikent C. This coefficient is nearly independent of the air velocity and the roughness of the duct walls; therefore dynamic losses cannot theoretically be computed as friction losses. For duct components where intense eddying flow is not IfiL