P.S. Just realized you're replacing sch 10 w/ sch40... why not just replace the black sch10 w/ galv sch 10? That way you're ID's are the same but you're getting the added benefit of a HWC of 120.
On 6/5/08, IPA <[EMAIL PROTECTED]> wrote: > > Todd, based on the fact that this is a repair, as mentioned, AND the fact > that you're replacing pipe that *should* have been calculated with a > hazen-williams c-factor of 100 (black steel) with piping that has a c-factor > of 120 (galvanized) - I would say you're probably going to be alright - but > better safe than sorry - so why not run calcs? > > -B- > > > > On 6/5/08, Todd Williams - FPDC <[EMAIL PROTECTED]> wrote: >> >> To do this job correctly (operative word) will require a lot more than >> just pipe replacement and thus will need to be recalculated. As an example, >> to properly pitch the pipe will require replacement of most of the dry >> pendents feeding the floor below. The additional 30% increase and a few >> other things have already been mentioned to the contractor. However, the job >> spec treats this as a repair and doesn't really try to solve the problem of >> water trapped in mains (except they want an add for an air dryer in the >> quote) >> >> My question was more academic in that if you replace one pipe with a >> different type of pipe with a similar loss per foot and make no other >> changes, would it necessarily have to be recalculated. When does repair >> become modification? >> >> >> >> At 12:31 AM 6/5/2008, you wrote: >> >>> If I had high confidence of all the following, I wouldn't see the need >>> for >>> new calcs: >>> - Strictly pipe replacement (no added offsets, elbows, riser >>> nipples, etc) >>> - The original calcs were accurate (done properly and reflect 'as >>> built' conditions) >>> - Water supply hasn't deteriorated. >>> >>> A bit of a side note - if the attic has a roof with slope greater than >>> 2/12, >>> the design area very likely didn't include a 30% increase for the slope. >>> That requirement didn't appear in 13 until 1996. But since the pipe >>> replacement is legitimately a repair, you probably don't need to meet any >>> standard other than what was in effect 17 years ago. >>> >>> Ed Kramer >>> Littleton, CO >>> >>> >>> > I walked through an attic this afternoon where all of the existing >>> > mains need to be replaced. The piping is 3" schedule 10 black steel, >>> > that is developing leaks after 17 years (we found another one on our >>> > tour). The proposal is out there to replace the existing with 3" >>> > schedule 40 galvanized (and provide proper pitch). I did a couple of >>> > quick calculations and at 250 gpm, the friction loss per foot for the >>> > two pipes is very close to the same. (.077 for the sch 10 black v. >>> > .075 for the sch 40 galv). My guess is that the difference in >>> > pressure would be about 0.75 psi. The calc has about 12 psi >>> > remaining. If this was strictly a pipe replacement (no other >>> > modifications), would you recommend new hydraulic calculations? >>> > >>> > Todd G. Williams, PE >>> > Fire Protection Design/Consulting >>> > Stonington, Connecticut >>> > www.fpdc.com >>> > 860.535.2080 >>> >>> _______________________________________________ >>> Sprinklerforum mailing list >>> [email protected] >>> http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum >>> >>> To Unsubscribe, send an email >>> to:[EMAIL PROTECTED]<[EMAIL PROTECTED]> >>> (Put the word unsubscribe in the subject field) >>> >> >> Todd G. Williams, PE >> Fire Protection Design/Consulting >> Stonington, Connecticut >> www.fpdc.com >> 860.535.2080 _______________________________________________ >> Sprinklerforum mailing list >> [email protected] >> http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum >> >> To Unsubscribe, send an email to:[EMAIL PROTECTED]<[EMAIL PROTECTED]> >> (Put the word unsubscribe in the subject field) >> > > _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
