hudrulically pipe sizing 1

[crb7]

hi guys
I want to choose pipe sizes for fire sprinkler system. The Hazan-Williams formula have flow rate, pressure loss and pipe diameter. For determining the pipe diameter, the value of flow rate and pressure loss have to be known. We have flow rate from the required flow rate for each sprinkler. But what about pressure loss per length of pipe? how much shall we consider that?

 

[UFT12]

You do not approach the situation like that. You need to determine the pipe sizes based mainly on experience and start calculations from least favorable head back to source. Some iterations will be required to balance other branch lines. If you do not know the least favorable head, calculations should be run from any candidate head that may appear as least favorable. Based on the design and sizes you choose, the total pressure exhibited on the source point should fall below your water supply line. Otherwise you re-run calculations with some pipe sizes larger or by re-evaluating the design by simplify it if possible.

You should consult literature about hydraulic calculations. It s a rather complicate & cumbersome procedure which requires diligence and good understanding of the subject.

 

[TravisMack]

This is all spelled out pretty clear in NFPA 13. Do you have a copy of it?



Travis Mack, SET, CWBSP, RME-G, CFPS
MFP Design, LLC

http://www.mfpdesign.com

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[crb7]

Thank you Travis
Yes I have. I guess you mean chapter 11 of NFPA 13. But I need a solved example to understand the calculations.

 

[TravisMack]

Yes I have. I guess you mean chapter 11 of NFPA 13. But I need a solved example to understand the calculations.

Check out my web page. There is a blog section. I have a video up of an impromptu hydraulics tutorial up that I did for a customer. That may help you.

Travis Mack, SET, CWBSP, RME-G, CFPS
MFP Design, LLC

http://www.mfpdesign.com

"Follow" us at

https://www.facebook.com/pages/MFP-Design-LLC/92218417692

 

[UFT12]

Here is a comprehensive presentation which may be also handy. It describes all steps about hydraulic calculations per NFPA 13. One thing however that I do not agree with is the determination of No. of heads (see pg. 62). To me this should be a more thorough process wich starts from building corner and taking acount of the actual distances from building and btw heads.

Hydraulics for Fire Protection

 

[crb7]

thank you so much for your precious information.