Brian, I have seen that it matters which has the higher pressure for exactly the reason you are describing (when adding racks to an overhead system). If one requires too high a pressure, it may overflow the other enough to blow the calc.
I agree with the others though... if you can, just build the entire system into one model and let the computer hash it out. Matt Grisé PE*, LEED AP Sales Engineer Alliance Fire Protection 130 w 9th Ave. North Kansas City, MO 64116 *Licensed in KS & MO 913.888.0647 ph 913.888.0618 f 913.927.0222 cell www. AFPsprink.com -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Wednesday, April 20, 2011 9:25 AM To: [email protected] Subject: RE: Balancing Rack Calc's Brian, If this is a new system with roof & rack systems,then calc them as 1 system,adjust pipe size to give the required demand at each area and no other balancing is needed.It's when you are adding a rack system to an existing roof system riser that balancing is required.I was told by F.M. years ago that if the 2 systems were within 1 PSI of each other,they would not ask for a seperate balancing calc.Good luck. Lamar Vaughn,SET On Wed, Apr 20, 2011 at 10:12 AM, Brian Harris wrote: > Travis- > I'm using HydraCalc > > Brian Harris > FDFP Inc. > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Travis > Mack, > SET > Sent: Wednesday, April 20, 2011 10:10 AM > To: [email protected] > Subject: Re: Balancing Rack Calc's > > What calc program are you using? Just put both the rack and overhead > system > in the calc file and let the computer balance. > It has been over a decade since I did a 'separate' calc for each. > Travis Mack, SET > MFP Design, LLC > www.mfpdesign.com > > Sent on the SprintR Now Network from my BlackBerryR > > -----Original Message----- > From: "Brian Harris" <[email protected]> > Sender: [email protected]: Wed, 20 Apr 2011 > 10:06:42 To: <[email protected]> > Reply-To: [email protected] > Subject: Balancing Rack Calc's > > I knew sooner or later my luck would run out and I'd have a job with > racks, > yes ladies and gentlemen this is the first time I've had to do an in > rack > system. I've searched through code, searched past archives, and still > am not > all warm and fuzzy with my conclusion, if someone would be so kind as > to > either give me either an amen or send me to the corner with a dunce > cap I > would greatly appreciate it. > > > I have done my overhead calc's, done my rack calc's, they are balanced > to > within .5 psi of each other at a common point on the riser. My > question is > this: does it matter which calc has the higher of the two pressures? > The > reason I ask is when it comes to the combined calc and you balance the > flow > at the common point on the riser I have tried two scenarios, if the > higher > pressure is on the rack system and you plug in the "balance" formula I > get > 981 gallons I need to add to the rack system which will work. If I > tweak a > couple things and the overhead system is the higher pressure and plug > that > into the "balance" formula I get 181 gallons that I need to add to the > overhead system and that will not work. What is the consensus of the > forum? > > > Brian Harris > > First Defense Fire Protection > > 11957 Ramah Church Road > > Huntersville, NC 28078 > > Phone: 704.948.3506 > > Fax: 704.948.3507 > > Nicet # 128476 > > > > > > > ======= > Email scanned by PC Tools - No viruses or spyware found. > (Email Guard: 7.0.0.21, Virus/Spyware Database: 6.17320) > http://www.pctools.com/ > ======= > _______________________________________________ > 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) > > > > > > ======= > Email scanned by PC Tools - No viruses or spyware found. > (Email Guard: 7.0.0.21, Virus/Spyware Database: 6.17320) > http://www.pctools.com/ > ======= > > > > > > ======= > Email scanned by PC Tools - No viruses or spyware found. > (Email Guard: 7.0.0.21, Virus/Spyware Database: 6.17320) > http://www.pctools.com/ > ======= > _______________________________________________ > 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) _______________________________________________ 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)
