Steve:
Unfortunately, this is that same project. The standpipe system all
drains to a common drain at the lead-in location. The drain riser is
solely for the 1" floor system drains. Since this is designed per NFPA
13R, the requirement to upsize is not there. However, it was upsized out
of common practice. That upsize requirement is only in NFPA 13.
Travis Mack, SET
MFP Design, LLC
2508 E Lodgepole Drive
Gilbert, AZ 85298
480-505-9271
fax: 866-430-6107
email:[email protected]
On 8/12/2014 10:13 AM, Steve Leyton wrote:
Travis - we've already talked about this project, I think. The requirement
for the collection drain is that it be one nominal pipe size larger than the
largest discharge connected to it. If the standpipe has a drain that's
connected to this collection riser, then I'd agree with the AHJ. But if the
standpipe is being drained independently from a hose valve or an aux drain,
then I believe you've met the intent of the standard(s).
The foregoing is my opinion only and does not necessarily represent the opinion
or intent of the NFPA 14 Technical Committee on Standpipe and Hose Systems, or
the NFPA 13 Committee on Residential Sprinkler Systems.
Steve Leyton
Protection Design & Consulting
San Diego, CA
-----Original Message-----
From: Sprinklerforum [mailto:[email protected]] On
Behalf Of Travis Mack
Sent: Tuesday, August 12, 2014 10:06 AM
To: [email protected]
Subject: Drain riser NFPA 13R
We have a project that has a combination standpipe. Due to an issue with the AHJ interpreting
the minimum sizing for a combination standpipe, we have installed the standpipe as 6".
This is a project designed per NFPA 13R. Each floor control valve coming off the combination
standpipe is a 2" floor control valve assembly (b'fly valve, check valve, flow switch,
gauge, test-n-drain). The test-n-drain is 1"
per NFPA 13R. Each 1" drain line ties into a common drain riser. The common drain riser was indicated as
1¼" and approved this way. Now, the inspector is stating that is has to be a minimum of 2". They are
stating that since it is attached to a standpipe "riser" that is larger than 4", the drain riser
must be 2".
I believe this is an incorrect rationale and that technically a 1" drain riser would
be acceptable because NFPA 13R only says that you must do a minimum of 1" drain.
The drain was upsized to 1¼ because of the requirement in NFPA 13, but it is technically
not applicable.
What is the general forum consensus on this? Is a 1¼" common drain riser acceptable
because it is connected to 1" floor control drains.
Or, is the common drain riser required to be 2" because the floor control assembly
is connected to a 6" standpipe?
It would not have been an issue earlier, but all drain risers are installed.
--
Travis Mack, SET
MFP Design, LLC
2508 E Lodgepole Drive
Gilbert, AZ 85298
480-505-9271
fax: 866-430-6107
email:[email protected]
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