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We are converting approximately 100 extended coverage, ordinary hazard upright sprinklers (off of a 1x3/4 bushing) to standard spray chrome pendents (light hazard). The ceilings are approximately 6'-0" below the existing branchlines at the deck. We are planning to use "2-Stage" drops where we add a 1" double elbow ( with a 1" close nipple) off the branchline, then drop down about 5'-0" to get down near the ceiling and terminate this with a 1" plugged elbow. Then when the time comes, we will add a flexible sprinkler connector to this and fix the sprinkler in the suspended ceiling (ASTM C635 & C636).  If I use a 72" flexible connector, I understand I don't need a hanger per 17.4.1.3.3.3 (NFPA 13 2019).
If I use a 23" starter piece of pipe off the bottom of the drop, would I need to catch a hanger due to the total length of this assembly? Or, since the flexible connector is 6'-0" and the starter pipe is 23" (Section 17.4.3.5.1) could I get away without an additional hanger? Not that I'm planning to do this but just curious what people think? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
16 Comments
Alex
12/12/2022 05:53:40 am
I can’t imagine any AHJ seeing that drop without a hanger and approving it. I’m not at my desk so can’t do the code research, but I feel you need a hanger!
Glenn Berger
12/12/2022 08:09:30 am
The more pipe segments that I see, it would cause me to want a pipe hanger or two installed.
Bill
12/12/2022 08:16:31 am
Section 17.4.3.5.1 states the "cumulative horizontal length of an unsupported armover to a sprinkler." That would include all piping, not just your 23" starter piece, and an inspector could include the flexible hose. I think a hanger is clearly required
Daniel LeFave
12/12/2022 08:17:00 am
I'm curious as to why you don't just put the 1'11 piece up above before the drop? I feel like this would be easier to get an AHJ to approve without a hanger and would eliminate almost 100 elbows.
Chris
12/12/2022 08:21:23 am
Why would you do it in two stages? The nice thing about flex drops is that you can hook them up and tie them out of the way, without having to plug that coupling. Just curious why you’d do this in two separate stages.
James Phifer
12/12/2022 08:24:58 am
Per the appendix, The maximum unsupported length of 6 ft of flex hose was based on the weight of the water filled pipe and what the ceiling grid could safely support. With the addition of the 23" of hard pipe, you've added more weight. I think a hanger should be required.
Ed
12/12/2022 08:26:23 am
Per 17.4.3.5.1 The cumulative horizontal length of an unsupported
Jesse
12/12/2022 08:36:20 am
If you use the 23" piece you'll need a hanger IMO
Anthony
12/12/2022 08:42:18 am
I've done what you're showing but with 1'-0 starter pieces and 60'' whips.
Cliff Schulze
12/12/2022 12:47:40 pm
That was my thought as well. adding the horizontal run at the bottom of the 5'-0" drop seems unnecessary when you are using a flex connection.
Danial Bartle
12/12/2022 08:47:18 am
We did a remodel and changed uprights similarly because ACT was added along with a couple of clouds. As they added the drops, the weight caused the branch to turn in the direction of the added weight because of the type of grooved couplings in the branch line. For that reason, supports were added to the arm overs.
Chris
12/12/2022 01:06:04 pm
If you do want a hanger on the bottom arm over, swing the gooseneck away from the head's new location and then support the arm over from the branchline ring to ring. I'd probably use a longer top arm over than a close nipple.
Rob Castro
12/12/2022 02:59:07 pm
Why don't you just eliminate the armover all together since you are using a 5ft drop for a 6ft flex hose? Your drop is only a foot or so above your ceiling so the 6ft hose is more than enough to reach where your placing it... Just a thought...
Mark B
12/14/2022 10:13:05 am
Thinking a little larger than just the individual drops. If all drops were off the same side of the branchline like this, you will want a hanger regardless if code requires to help keep the torque created from the additional weight off the fittings of the branchline. I have had grooved branchlines rotate overtime due to this setup, while maintaining code requirements.
Janak Patel
12/14/2022 03:34:49 pm
17.4.1.3.3.3* Where flexible sprinkler hose fittings exceed 6 ft
chris
12/15/2022 09:30:11 pm
at the bottom of the drop try incorporating 45 deg fittings instead of 90s when you go land the head its a much smoother transition for your flex line and much easier to work with your fitters in the field will thank you Leave a Reply. |
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