Ron:
That is just some one that is not willing to play the tweak game to get
things sized better. Allowing the computer to do the balancing is a
great tool, but you can't forget the most important tool, then one
between your ears.
On 4/20/2011 8:23 AM, Ronl.Fletcher wrote:
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
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