How to Sprinkler a Dome?

1/6/2022

How do I go about designing protection below a dome?

We have a church project, and the dome is 30'-0" in diameter and is about 15'-0" high. It's basically a hemisphere.

Looking for tips/guidance/creativity on getting this one started. Thanks.

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12 Comments

Mike L

1/6/2022 07:39:33 am

The layout of the sprinklers should follow the requirements for steeped pitched roofs.

Use back-to-back 90 degree elbows to allow the sections of branch piping to follow the contour of the dome.

Jesse

1/6/2022 08:06:52 am

You can protect using the requirements for steep / pitched roofs in NFPA 13 chapter 8. If its within your hydraulically remote area, remember you may need to increase the size of the design are due to the slope.

Glenn Berger

1/6/2022 08:09:13 am

Dependent on the slope, just follow standard NFPA 13 rules. I had to sprinkler a Jefferson-style dome years ago and enjoyed watching the Contractor figure out the exact lengths of pipes required before each "swing joint" to follow the curve of the ceiling.

Alex

1/6/2022 08:30:18 am

Agreed with the responses above! Make sure you increase your remote area based on the pitch. Ensure you work closely with the contractors when it comes to installation that heads are not too far off the dome.

Emil Ohler

1/6/2022 08:34:02 am

If hydraulics allow, use flexible sprinkler drops. Your installers will appreciate it.

Dan Wilder

1/6/2022 08:49:54 am

Having done a retrofit on the NAU Walkup Sky Dome...

My layout was heavily dictated by the structure (triangles with 36" deep beams, segmented into slices by reducing beam sizes down to 12"). Sprinkler layout started around the perimeter walls for spacing, then I filled in moving up.

Do not layout everything flat at max spacing, as soon as it gets elevated the distance between sprinklers will exceed maximum spacing. If the dome is typical (structure), laying out a section and then copying that around will save a lot of time 1/4 or 1/5 typical sections have worked out well for me.

I've seen both concentric rings and a spoke pattern for domes so whatever works with your layout.

Jessica Lutz

1/6/2022 09:33:20 am

This is my jam!

My suggestion would be to first figure out what all of your "deal-breakers" are...i.e. new or existing architecture?, can the pipe be exposed/concealed?, what are my hanger/seismic attachments limitations?, is there an architect's aesthetic which should be considered?, are there any pipe type/material limitations?, are there lighting obstructions?, what's my deflector distance/spacing going to be?, etc.

THEN, get creative & brainstorm!
I start roughly modeling my ideas, and the solutions start to reveal themselves...

Also, if this is at the contractor/installation phase, I highly recommend getting the opinion of your Super/Foreman...

Good Luck!

David

1/6/2022 10:15:18 am

I agree with all the comments but no one touched on attachment fasteners. I recommend the Sammy Swivel attachments for dome applications.

Dave

1/6/2022 10:50:09 am

I concur with Jessica’s excellent points and approach - Where you can run, hang, and brace/restrain the pipe is where I would start. Is there a conditioned space above the dome? If so, concealed sprinklers (perhaps one of the smaller-diameter ones that are available), custom-painted, if necessary, would look decent. Put on your architect cap for an acceptable, code-compliant sprinkler layout. If the piping must be exposed below, then it gets tricky, but sprinkler pipe is beautiful. Bending of pipe, as allowed in NFPA 13 can lead to impressive installations. (Check out photos of the main hall at LeMay / America’s Car Museum.) I am aware of dome structure similar to yours where the AHJ allowed protection by a ring of sidewalls down low, on an electrically-activated deluge system.

CONNOR

1/6/2022 11:52:04 am

For aesthetic purposes, I would like to add a caution on using back-to-back elbows to make the bends. Especially with grooved fittings and mechanical couplings, it can quickly become busy and distracting compared to other installation methods.

If bending pipe is not an option, another solution for making low-angle bends in piping is a short braided flexible hose. There are UL-Certified flexible hoses which are suitable for use on mains and branch lines. One example is here: https://mason-ind.com/gwn-gwn-ul/

If the hydraulics are accounted for, a few strategically placed flexible bends may make fabrication easier, and most models can even be painted to match the pipe.

Anthony

1/6/2022 12:52:00 pm

8.6.3.2.5 Under curved surfaces, the horizontal distance shall
be measured at the floor level from the wall, or the intersection of the curved surface and the floor to the nearest sprinkler shall not be greater than one-half the allowable distance between sprinklers.

fyi

sean

1/7/2022 02:17:20 pm

no matter what it will suck, but a consistent design look will over better if exposed

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How to Sprinkler a Dome?

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