Jimmy- We're not on 07 yet so I'm not intimate with it yet. But you're asking a conceptual question that I think I can answer.
If you have 5 heads each side of a tree, and a length demanding 7 heads flowing, you flow the 5 on one side, and 2 more on the other side. This will flow all the water needed thru the RN. If you have same piping as above, and you need to flow 12 heads, you flow the 10 per line and just come back as many lines as needed to pick up the entire MRA. When you get to the last line with partial heads flowing, the ones closest to the RN will overdischarge more than others so they're your most demanding. glc -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Jimmy Waite Sent: Tuesday, January 20, 2009 6:33 PM To: [email protected] Subject: 1.2 Leg of Remote Area Good afternoon everyone, or evening for East coasters. I would like to get a second opinion about a matter dealing with the commentary and 22.4.4.1.1 of the '07 edition. 22.4.4.1.1.1 says that I have to have my 1.2 length of my remote area parallel with the branch lines. My question is how do you approach a situation where the branch line is of insufficient length to meet the 1.2 length. For example, (this is not based on real numbers, so hopefully my guess-timation doesn't further complicate the issue, if I have a center-fed tree system, and I am calculating 1500 sf. I would typically be required to have the longer length of my remote area be at least 47 feet long. What do I do if my branch line is only 40 feet long (and say containing 7 heads)? I have always understood that I would include all seven heads on the branch line, then continue adding heads until I get to 1500 sf. So, I would calc 3 branch lines and an additional 3 heads. This wouldn't satisfy the 1.2 requirement. BUT, figure A.22.4.4.1(a) example D shows this type of configuration. The commentary also says "To required more water to flow through a smaller number of individual branch lines is hydraulically more demanding than to require the same demand to be supplied by more branch lines with fewer operating sprinklers." We are working with a free-lance designer that is arguing the 1.2 length MUST be met. So, in the example I gave he would treat the situation oppositely than I would. He is arguing it is necessary to meet the 1.2 length, and will pick up more branch lines, but with fewer heads. His argument is that the commentary after 22.4.4.1.1.3 only applies to that section and not 22.4.4.1.1.1. And, near the end of the commentary is says, "the requirements . are illustrated by System D if Figure A.22.4.4.1(a). Note that the design area's longer dimension is along the cross main." He was also taught to do it this way from one of the few FPE's in the state. So, I would really appreciate it if I could get some feedback on this example. Thank you all for your time, I know you all don't have much of it to spare. Thanks, Jimmy Waite _______________________________________________ Sprinklerforum mailing list http://lists.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 http://lists.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)
