Yes but when the computer hashes it out you can't tell how much of an imbalance you have. The computer adjusts the end head pressure so things balance at the connection causing overflow in one system or the other, unless you get really lucky. I would always calc each system, make sure they balance at the connection then let the computer hash it out. I've seen rack systems that require 420 gpm minimum use over 600 gpm and the designer says "well it's balanced at the base of riser".
Ron Fletcher Aero Automatic Phoenix, AZ -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Matt Grise Sent: Wednesday, April 20, 2011 7:33 AM To: '[email protected]' Subject: RE: Balancing Rack Calc's 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) _______________________________________________ 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)
