NFPA 14 - Looped Standpipes and Flow Splitting 1

[Haldorson]

For looped standpipes within the fire department pumping capability, is the standpipe hydraulic calculation allowed to take into account the loop design configuration to reduce friction loss in the system? If so, is it stated anywhere in NFPA 14 (2024 or earlier versions) to support this argument?

 

[UFT12]

The 2024 edition has section 9.4 to address this. Section 9.4.3 seems to imply that multiple interconnections for wet systems are allowed and the rest of the requirements are not against it. In the 2019 edition, there was a limitation that required check valves be installed at the bottom of the risers. This did not, of course, allowed improved (looped) hydraulics. The 2024 edition does not have this requirement and therefor I take it the advantage of a looped design should be allowed. Note, no example in the explanatory material shows a looped configuration for full FD capacity systems but I guess this does not necessarily mean it's not allowed.

 

[cdafd]

1 is this in the USA?

2. Is this inside a building?

3. Is this tied into a fire sprinkler system?

 

[Haldorson]

In response:

1. Canada.
2. Yes.
3. Yes.

 

[cdafd]

I am not a engineer or designer or

Sounds like you have a combination fire sprinkler standpipe system.

I cannot talk to how that helps your hydraulics,,,you still have to meet nfpa 14 for flow and pressure

 

[skdesigner]

The section requiring check valves to prevent circulation when standpipes are interconnected at the top and bottom was removed between the 2019 edition and the 2024 edition during the First Revision cycle.

This change was logged as FR-47, with the following NFPA 14 committee statement:

'There is no reason to prevent or prohibit circulation of water within the standpipe system when standpipes are connected at the top and bottom. Hydraulically there’s an advantage to having looped pipes where water can circulate through the most advantageous path. Omitting the need for check valves will reduce maintenance required by NFPA 25 that would periodically take the standpipe system or portions of the standpipe system out of service.'

The item passed with 31 affirmative votes, and 0 negative votes, so it is safe to say that many agree with your position.

 

[Haldorson]

Thank you so much skdesigner. I have been looking but can't find the document. Do you know where I can find it?

 

[skdesigner]

https://submittalsarchive.nfpa.org/TerraViewWeb/ViewerPage.jsp?id=14-2019.ditamap&pubStatus=FDR

Go to 9.4.3 where the section has been struck out and click the hyperlink to FR-47.

 

[Haldorson]

Thank you so much. This was helpful. Have a great day.

 

[skdesigner]

My pleasure. Always nice to run into another Canadian on here.