Is there any benefit to having the backflow preventer on the discharge side of the fire pump? We've seen several RFPs recently that are requiring the backflow to be on the discharge side of the fire pump.
To me it seems as though this arrangement unnecessarily leaves more pipe and mechanical components exposed to the public water supply, but I'd be interested in others' opinions. Posted anonymously by a member for discussion. Discuss this | Subscribe
11 Comments
Brian Gerdwagen FPE
2/19/2019 10:08:35 am
This seems to be a hold-over from an older version of UFC 3-600-01. The newer versions do not require this and defer to NFPA 20.
Reply
JOE MEYER
2/19/2019 10:42:02 am
Where I've seen it - it has been military requirements for the backflow to be on the discharge side, but only required on a specific project. As you've mentioned UFC 3-600-01 doesn't require this arrangement.
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James
2/19/2019 10:11:59 am
From my experience, almost every water utility company will require a backflow device at the incoming service location after the house control valve. I would imagine not having one until after the fire pump be a big "no-no".
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James
2/19/2019 10:14:24 am
Ah I might have misread what you asked. Is this a BFP that is additional to the one at the incoming service? I personally have never installed a BFP after a fire pump, just single check valves as per NFPA 20 diagrams.
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2/19/2019 10:14:46 am
There is only one probable answer to this that I can think of.
Reply
PETE
2/19/2019 11:35:17 am
PIERRE- The backflow pressure drops are consistent with their listings. Any instantaneous cavitation that may occur on pump-run, is addressed in NFPA 20 with a 10 x suction nominal diameter distance upstream of the pump suction flange to the backflow discharge.
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Franck Orset
2/19/2019 10:36:07 am
As it has been said, a check valve is necessary on the discharge side of a pump.
Reply
2/19/2019 12:40:17 pm
Backflow Prevention Assemblies (BFPA), by definition, protect the potable water supply from contaminants. Ref: Manual of Cross-Connection Control developed by the Foundation for Cross-Connection Control & Hydraulic Research.
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J. Diaz
2/19/2019 03:40:00 pm
This is one of the "suggestions" from Factory Mutual. Depending on the reviewer, it could be seen as the only approved installation method. Generally, they are open and could accept the conventional way.
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Ed Glynn
2/19/2019 05:48:00 pm
There is an issue where the sole source of potable water is strictly a tank that has head pressure only.
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Todd Delisle
12/24/2020 10:23:03 am
NFPA does not require the installation of BFPs.
Reply
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