First, lessening the pressure differential between flowing heads on a line will reduce overdischarge.
2nd, larger K-factor heads tend to accentuate overdischarge between flowing heads. Keeping the original K factor while upping the end pces to 1.25", and likely switching from Sch 40 to Sch10 in doing this, you'll have less demand if the MRA is uniform. That's elementary hydraulics. And this is one of those occasions when I'm glad I had to learn hand calcs, cause if you don't understand the interrelationship of the variables, you'd spend an hour or two going the wrong way- instead of making a quick change, hitting CALC, and seeing the result go up or down. Yes, I'm aware of what happens in irregular MRAs. Did a presentation years back on this, where tossing in a couple 90's on a BL n the MRA caused a 2 PSI increase in demand for that line, a contractor could argue that the 5 PSI cushion covered this. Except that this was the only line in the MRA with the added offsets, so virtually every other head in the MRA overdischarged, and it was a 7 PSI impact to the MRA, and the 5 PSI buffer went to 2 PSI over the curve. I believe some of the plan reviewers in the room followed my point. The inspectors had been asleep for an hour, once the seminar moved to hydraulics. -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Russell Sent: Wednesday, May 12, 2010 12:19 PM To: [email protected] Subject: RE: Pipe Size Well, what I'm getting at is that the more water that is flowing from the remote area the less residual pressure you have available at the source. The less residual, the less the safety factor. The same as trying to use sprinklers with a k-factor of 8.0 in a light hazard design. It'll kill your calc's. Russell _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
