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Schedule 120 Plastic Pipe by Bill Corey Pentair Water Training Institute Two years ago, I was asked by the State of Oregon to do a presentat on on p pe s z ng. I ve got my standard p pe s z ng presentat on, wh ch takes an hour or so, but they wanted someth ng d fferent. They spec f ca y asked me to address Schedu e (SCH) 120 p ast c p pe. Most pump compan es, nc ud ng the one I work for, use a p pe fr ct on oss chart wh ch has stee and p ast c p pe on t. Most a use the Hazen-W ams charts, wh ch states as p pe gets o der, t f s up, mak ng the ID ( ns de d ameter) sma er, so the ve oc ty w go up. Th s makes the fr ct on oss go up. More fr ct on oss, ess pressure. Aga n, most compan es use a chart w th stee and p ast c p pe on t. The p ast c p pe they use s SCH 40. The next s ze wou d be SCH 80, then 120, and 160. I have a chart wh ch shows the d fferent s zes for the d fferent p pes. The OD (outs de d ameter) s the same, wh ch means the ID s changed by the wa th ckness. SCH 40 PVC has the same ID as stee p pe. Th s makes the ve oc ty amost the same. One chart I use has stee p pe at 5.05 and SCH 40 PVC at 5.11. It s 1/6 of a second d fference, and when I ask my students f there s anyone who th nks they can te 1/6 of a second d fference n the speed of the water w thout a spec a too , no one answers. Yet when we ook at the fr ct on oss, the stee p pe has a most TWICE the fr ct on oss as the SCH 40 PVC p pe. Now here s where the prob em comes n; most peop e ook ng at the chart see the word PLASTIC p pe and don t stop to th nk the wa th ckness may have an effect on the fr ct on oss! So the adm n strators of the program n Oregon wanted someone - me - to show the r nsta ers why ook ng at wa th ckness was so mportant. So I took the Hazen-W ams formu a and broke t down nto each component. One of the th ngs you need to watch s what the eng neer used for the va ue of “C”. Abook we use has a va ue of C at 140; another has t at 150. It may not sound ke much, but the two charts are d fferent and someone a ways wants to know wh ch s r ght. The answer, of course, s both. It a depends on whether you be eve C s 140 or 150. The b g prob em w th the schedu e of a p pe s wa th ckness, wh ch effects the ve oc ty or speed of the water as t moves through the p p ng system. If the OD s a - ways the same for, say, a two- nch p pe, then the ID w aways be sma er. If the wa s th cker, the resu ts w be faster mov ng water, resu t ng n more fr ct on oss. The nsta ers n Oregon were sur- pr sed to f nd the fr ct on oss n SCH 120 p ast c p pe was a most the same as stee p pe. They, ke most, fe t p ast c p pe has a much better va ue of “C”, so t has to have ess fr ct on oss. True, unt you change the ID, wh ch ncreases the ve oc ty. You get the p cture, r ght? For more nformat on and a copy of the formu as w th nstruct ons on how to change them for the type of p pe you re us ng, contact me at the e-ma be ow. Bill michele@ worldwidedrillingresource.com B& >381 < 36 8.=; :A / C /: 2/ .: 6381 3 < ;38- */;< :+8509:< 663893; (& 9-+<398 7+36 <//4+A 73.?/;< 8/< +@ ( & '966 :// % %(" ' #) & % " % ' $ '##' & % & & C % "/? (8=;/. ,3<; 7/. <99<2 ;<366 38 ,9@ & ' ;<366 38 ,9@ 2:3;</8;/8 $ 66 90 <2/ +,9>/ +:/ ( & 7+8=0+-<=:/. !3.;/+;98 +:1+38; 23 WorldWide Drilling Resource ® AUGUST 2016