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We are getting a plumbing department reviewer's comment that the combined sprinkler/domestic water service cannot exceed a flow of 5 feet per second.
Their justification is that flow above 5 ft/s will negatively impact the "coating" on the inner surface of the copper pipe. I've never heard of such a concern, and 5 ft/s is far slower than the hydraulic calculations can support. This is for small diameter services on an NFPA 13R project that is 3 stories in height. The difference in tap fees between a 2-inch combined service (with an automatic domestic shutoff in this case) and a 3-inch ductile iron is at least ten thousand to the owner. Is there some truth or justification to limit fire sprinkler flow to 5 ft/s on copper pipe? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
7 Comments
Jon Sullivan
6/16/2021 08:19:19 am
Validity of the requirement aside, do they have written design guidelines that you are obligated to follow to connect to their system? You could push back try and push back if not. I would also contact the piping/coating manufacturer for their opinion. Good luck!
OP
6/16/2021 08:31:00 am
The "interim" plumbing code (a legacy code that's getting revised) carries over some old rules on this, specific to water that supplies domestic hot and cold water supply.
Mike
6/16/2021 08:25:59 am
I have never heard of such a limitation. My first thought is they are gouging owner's for fees. Most cities are broke.
Art
6/16/2021 08:34:25 am
Appendix E in the International Plumbing Code includes information on sizing domestic water piping and as per the friction loss figures (i.e. Figure E-103.3(3)) you should be limiting the flow to 5-8 fps. In my interpretation this is for the "everyday" domestic use, which includes the typical domestic water use of the building, and exceeding these velocities can deteriorate the copper material. In my opinion, including the sprinkler flows which will occur extremely rarely and consequently oversizing the copper piping is not reasonable and is not the intention of the code.
Matthew King
6/16/2021 08:43:17 am
California plumbing code says 8 fps cold water, 5 fps hit water up to 140F, and 1.5 fps above 140 F. 6/16/2021 08:44:53 am
1. They need to provide the code reference so you can evaluate
schulman
6/16/2021 08:57:25 am
I"m with Art and Paul ... Leave a Reply. |
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