On backflow testing, NFPA 13 (2019) 16.14.5.1 states the backflow needs to be tested at system demand. I have a hard cover copy, and in it the question was asked, if a 2" main drain would be sufficient, to do the backflow test. After their explanation, they say it basically needs to be the same size as your system riser, and using a larger drain valve would be a waste since the drain test is to be done more often. So what we've been doing is running a pipe outside the same size as the backflow, using a normally closed butterfly valve. Sometime routing around the FDC if it's a Storz. model.
Our thought now is why not run several 2" drains out the wall. With 2½" & 3" backflows, we increase the main drain to 2" which is usually enough for system demand. Can always run a separate 1" insp. test also. With 4" backflows, you already need (1) 2" main drain, why not run a separate one for testing, that will give you (2) 2" openings, and run a third if you have a 6" backflow. And with multiple systems, run the main drains out separately instead of combining them together before you go out. Does this sound feasible, since all we're really trying to do is exercise the springs in the checks? From: Ed Kramer <[email protected]> Sent: Friday, November 18, 2022 11:19 AM To: [email protected] Subject: [Sprinklerforum] BFP on underground supply NFPA 13 is pretty clear that some method of forward flow testing a fire sprinkler system backflow preventer shall be provided. If the BFP is located at the system riser (very common in these parts), we provide the required means. So, who is responsible for providing the means if the BFP is located in a pit on the underground fire service, and the UG fire service (along with the pit/BFP) is "by others"? From a practical viewpoint, it's easy enough for us to provide that at our system riser, but are we required to do so? Or does that responsibility fall on whomever installs the BFP? I've not seen this addressed anywhere in bid/contract documents. Ed Kramer Bamford Fire
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