Multiple Sprinklers for Dry System Return Bend?

9/30/2025

I'm working on an office fit-up, which is being fed from a dry system in an industrial facility.

I've already talked to them about providing a wet system, but that is not what they want to do. So, we've got a dry system feeding pendent sprinklers coming down to an acoustic ceiling.

When using pendents on a dry system, we need to provide return bends.

Does a return bend have to be for only one sprinkler, or could there be multiple heads on a single return bend?

I'm picturing the pipe extending up from the main, then across horizontally, with multiple drops coming off of the horizontal.

Is this an allowed approach?

Thanks in advance.

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9 Comments

Pete H

9/30/2025 06:07:57 am

Are you past budgeting?

Cause I'm not sure there are many pendents listed for dry systems that aren't "dry sprinklers" and those are more expensive.

[WSF] Dan Wilder

9/30/2025 08:19:32 am

You're describing a branch line on a riser nipple, and each sprinkler would need its own return bend....ironically "Drop" is not specifically defined in Chapter 3 until the 2022 version and "Return Bend" is not defined directly at all through the 2025 version.

3.3.9 Arm-Over - A horizontal pipe that extends from the branch line to a single sprinkler or a sprinkler above and below a ceiling. (AUT-SSI)
3.3.23 Branch Lines - The pipes supplying sprinklers, either directly or through sprigs, drops, return bends, or arm-overs. (AUT-SSI)
3.3.64 Drop - A vertical pipe supplying one sprinkler from above. (AUT-SSI)
3.3.180 Riser Nipple - A vertical pipe between the cross main and branch line.

For the dry system requirement of a return bend
8.3.2.5 (3) - Pendent sprinklers installed on return bends

franck

9/30/2025 08:27:50 am

It may be under the hand of the AHJ.
Technically it is possible if you are looking for the reason behind the requirement: it is to avoid blocking the opening of the sprinkler with sediment end sludge (same requirement for wet system fed by raw water supply, by the way).
One return bend can then feed several sprinklers.
Note one downside: if you provide pendent sprinklers that way, you will need to remove all of them to fully dry the piping system everytime the dry pipe system has been activated (which is at least once every 3 years from the ITC). And additional downside : this will greatly increase the corrosion rate of the system.

Colin Lusher

9/30/2025 08:29:43 am

No. As soon as you add another sprinkler, it becomes a 'branchline' with a 'riser nipple'. And since a 'return bend' is part of an 'armover', it can't be a return bend once you add a second sprinkler. Look at the piping definitions in chapter 3 of NFPA 13, they're very specific.

Anthony

9/30/2025 09:47:34 am

I concur with colin here.

also, I think some of the vernacular is getting fuzzy here. I would believe you'd need dry barrel sprinklers here.

Glenn Berger

9/30/2025 08:50:24 am

The project that is being discussed here is an office-type space within an overall industrial occupancy that is provided with a dry-pipe sprinkler system.

The office area will be not be subjected to freezing conditions.

The project will use standard sprinklers in lieu of dry sprinklers and hence the requirement for the return bend arrangement.

As others have said, there appears to be some confusion with definitions of what to call specific portions of the piping system.

My reading of the requirement is that one return bend assembly is required for each sprinkler. See NFPA 13 (2025) Section 8.2.2.1.1 (3) and the enhanced content provided in NFPA Link.

R. Jackson link

9/30/2025 09:59:44 am

Everyone has made very good points, but let me sum up, the AHJ makes the final decision. You might be able to sway their opinion one way or another and maybe this time but not next time.

Jesse

9/30/2025 01:41:39 pm

Each pendent needs its own return bend. I wouldn't like supplying more than 1 sprinkler from 1 outlet

Jack G

10/1/2025 10:11:39 am

It becomes a branch line and if a heated area rbl are required. If a cold area, dry pendants are required. Keep in mind dry pendants are required to be installed in tees.

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Multiple Sprinklers for Dry System Return Bend?

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