water pipe size and flow

7/21/2019 Water Pipe Size and Flow

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Water Pipe Size and Flow

name James

status studentgrade 9-12location TX

Question - I was designing a water system forcattle(4H) !asically I am going to ta" into a water "i"eline# and run a muc$ smaller "i"e to a storagetan% T$e "ressure would remain constant in t$e &ig "i"e since it is a $uge "i"e I could find t$e

"ressure in it also (2' "si) I %now lengt$ of my "i"e running off of t$e main line (2 miles)* t$ediameter (2 inc$es)# a te+t&oo% told me t$e ,iscosity(1%gms)# and t$e rise in t$e ele,ation 2 feetI found an e.uation &ut it tal%s a&out t$e ,elocityof t$e water and I do not %now $ow to add t$at into my e.uation I would li%e to %now $ow muc$ ,olume I will get at t$e end of t$e line---------------------------------------/i,il engineering co,ers $ydraulics# and may&e w$ilein sc$ool I could $a,e dealt wit$ t$e "ro&lem# now I would go to our $ydraulics or mec$anical "eo"le

0or w$ate,er $el" $ere are my t$oug$ts# t$ere are many factors affecting t$e flow# t$ere will &efriction losses in t$e 2 mile "i"e ,ercominggra,ity for a 2 foot rise will im"act t$e flow Itsounds li%e t$e "i"e is e+"osed# so t$at can addt$ermal im"acts ny loss in t$e 3ointing# t$at is

not one stretc$ of "i"e !eing a ta%e off fromt$e main "i"e# can add some flow effects t$at couldaffect t$e initial "ressure T$ere are tutorials ont$e we& for designing "um"s It may &e an a""roac$to wor% &ac%wards# find t$e "um" and t$erefore t$e "ressure to get t$e gallons "er minute to t$edestination

James 5r6ewo6ni%

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Hi James#

8ou wis$ to %now w$at flow rate# in gallons "er minute# you can e+"ect to disc$arge from t$e end ofyour new "i"e 0low mo,es t$roug$ "i"e due toa difference in "ressure &etween eac$ end 8ou $a,ea dri,ing force of 2' "si If we con,ert t$is tofeet of water# (multi"ly &y 21) we get a dri,ingforce of a&out '::' feet

;ow# flow t$roug$ t$e 2 "i"e will &e resisted &y &asically two maineffects (let us %ee" t$is sim"le <=) 8ou $a,e t$ec$ange in ele,ation#

and you $a,e t$e friction loss in t$e "i"e due to t$e water flowingt$roug$ it T$e ele,ation c$ange is sim"le# it is2 feet and since weare going u"$ill# we su&tract t$is directly from t$edri,ing force >o#now our dri,ing force is ::' feed of $ead as wecall it

0riction loss is a little more tric%y# I use anem"irical formula called Ha6en-?illiams for t$e calculation T$is formula is

H(friction) 7 2@ A B A (1/)C1@' A( g"mC1@'dC4@D'')

0riction loss is e.ual to a constant times B w$ic$ ist$e e.ui,alentlengt$ of straig$t "i"e / is a roug$ness factor oft$e "i"e in useIf you are using new steel "i"e or smoot$ "lastic#use 12 $ere for t$e,alue of / Bittle d is t$e inside diameter of your "i"e in inc$esE"m is your c$osen flow rate

>o# let us figure some of t$is out F.ui,alentlengt$ of "i"e e.uals t$e

total lengt$ of "i"e "lus con,ersion of fittings to "i"e lengt$ 0or



e+am"le# a 2 inc$ 9 degree el&ow $as t$e samefriction loss as ' feetof straig$t "i"e In your case# you $a,e two milesof "i"ing and I willassume not a lot of turns# etc Two miles is a&out11# feet of "i"eso not counting a few fittings really will not ma%etoo muc$ of adifference

Bittle d for 2 inc$ steel "i"e is 2D: inc$es

>ummary

B 7 11# feet

/ 7 12d 7 2D:

;ow# we cannot calculate t$e friction loss wit$outt$e flow and we cannotget t$e flow wit$out t$e friction loss >o# we will ma%e a gra"$ offlow ,s friction loss in feet of water Here is w$at you do# c$oose a

flow rate# say 1 g"m 5lug it into t$e e.uation wit$ all of t$e a&o,e,alues and get a friction loss Ge"eat at 2# #4# '# etc nceyou reac$ 1 g"m# ma%e a gra"$ wit$ flow on t$e +a+is and frictionloss in feet on t$e y-a+is 5lot t$e "oints and you will see t$at it ma%es a cur,e T$is is called t$e system cur,e andtells you $ow your "i"eline flow will react to c$anges in resistance

nce you $a,e your cur,e# find ::' feet on t$e y-a+is and ma%e astraig$t $ori6ontal line across t$e gra"$ t t$e "oint it intersectst$e system cur,e# mo,e straig$t down to t$e X-a+isand read t$e flowT$is will &e t$e flow you can e+"ect from your

system



Eood luc%# and contact me again to let me %now w$atyour answer is or ifyou $a,e any difficulties

!o& Hartwell====================================================================

water pipe size and flow

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