Smart questions
Smart answers
Smart people
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Member Login
Remember Me
Forgot Password?
Join Us!

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips now!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
Join Eng-Tips
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

LINK TO THIS FORUM!

Add Stickiness To Your Site By Linking To This Professionally Managed Technical Forum.
Just copy and paste the
code below into your site.

Eng-Tips LinkedIn® Group

Partner With Us!

"Best Of Breed" Forums Add Stickiness To Your Site
Partner Button
(Download This Button Today!)

Feedback

"...Really appreciate your site. Really good site for learning what others do when they run into problems. You guy's are great!!!..."
More...

Geography

Where in the world do Eng-Tips members come from?
Click Here To Find Out!

Eng-Tips Shirts!

Get Eng-Tips Swag
Get your
Eng-Tips Forums
SWAG here!
Home > Forums > Engineering Codes, Standards & Certifications > Engineering Codes, Standards & Certifications > NFPA (fire) Code Issues Forum

Water flow equationHelpful Member! 

thread184-328195
Read More Threads Like This One
skdesigner (Mechanical)
20 Aug 12 11:35
I had it written down, lost it and for the life of me I can't remember how it goes.

Equation to figure out flow at a certain pressure when given static and residual. For example, I do a flow test and come up with x static and y residual pressure at some flow. I need to determine how much flow will be available at 20 psi.

I know that I can just use 1.85 graph paper, but for the sake of precision, does anyone have this equation handy?

Thanks in advance!

Steve
Helpful Member!  cdafd (Specifier/Regulator)
20 Aug 12 11:53
maybe:

sorry cannot copy but:

Qr = Qf x hr(.54) power divided by hf (.54) power


where:
QR = flow predicted at desired residual pressure
QF = total flow measured during test
hr = pressure drop to desired residual pressure
hf = pressure drop measured during test

check this link for the formula:::


http://developmentservices.cityofoxnard.org/Upload...
cdafd (Specifier/Regulator)
20 Aug 12 11:54
http://www.scribd.com/doc/63723117/NFPA-291-Recomm...
skdesigner (Mechanical)
20 Aug 12 11:57
Much appreciated!
NewtonFP (Automotive)
20 Aug 12 12:02
Qf=Qr((Hr^0.54/Hf^0.54)

Qf=flow at desired pressure (gpm)
Qr=flow at residual pressure (gpm)
Hr=(static - desired pressure) (psi)
Hf=(static - residual pressure) (psi)
cdafd (Specifier/Regulator)
20 Aug 12 12:17
forgot about the "delta" symbol!!!!
TravisMack (Mechanical)
20 Aug 12 13:59
Hey SK, shoot me an email and I will send you a flow test form in MS Excel that does the graphs and also gives you the flows at 20 psi. I got it from OSU's website long ago, so I don't believe it is an proprietary information or spreadsheet.

Travis Mack
MFP Design, LLC
www.mfpdesign.com
Read More Threads Like This One

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!

Back To Forum

Back To NFPA (fire) Code Issues

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close