Domes 1

[cdafd]

Going to be looking at a submittal with a couple of 30 foot diameter domes, and about 15 feet high from the bottom of the opening to the top

Designer is first suggesting Sidewalls at the bottom

1. If a pendant is put at the top and pipe in wall, maybe a freeze problem

2. Very ornate building so exposed pipe may not fly

Any thoughts suggestions??


How have you protected domesin other ways???


Thanks

 

[TravisMack]

It is my understanding that NFPA 13 does not allow a sidewall sprinkler to be located at the low point of a slope and spraying up.

These domes present crazy challenges.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[cdafd]

My understanding is that they would be in normal orientation and protecting floor area

 

[TravisMack]

A couple things to consider:

What is the slope of the dome?
8.7.4.2.2 Sidewall sprinklers, where installed under a sloped
ceiling with a slope exceeding 2 in 12, shall be located at the
high point of the slope and positioned to discharge downward
along the slope.

How high is the dome?
Let's say that you can put them at the low point, are they going to be within 36" of the peak (isn't that the requirement, or is that just for SSU/SSP?).

Remember, we position sprinklers for coverage and activation. If you are at the low point of a high ceiling, you may be within 6" of the ceiling at the point of the sidewall, but if that head is still 48" below the peak, it may be very delayed in activating.

Again, these domes are very challenging to protect. I guess we should get the kid that wants to memorize everything to show us how easy this could be. ha ha..I couldn't resist.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[cdafd]

Dome from bottom of opening to the top is about fifteen feet

Think they are going to propose them at the bottom, along the edge, something like for escalator opening protection

With the idea protecting floor area, and not the dome itself


I need to check the book on voids, like skylights

My MEMORY dies not recall the parameters that allow no sprinklers in the voids

 

[TravisMack]

My gut says this is not going to be allowed per NFPA 13. I think too many people go right to the idea of "protecting floor space" and ignore the activation part of the sprinkler system. I would think it will take quite a while to fill that 15' void with heat so that it will come down and finally activate the sidewall sprinklers. If that is a reality, how do you account for that in your design area?

With regard to raised ceilings, we can only have a maximum 36" deep void space and 1000 cubic feet before sprinklers are required in the raised ceiling area.

I will admit that I always hate dealing with these dome structures because of exactly what you are describing.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[cdafd]

Thanks for the void reference, my memory is not working


Yes I have a great problem with heads to low

I call them air heads, and that is probably who installed them

Along with shields or pie pans, a couple of my pet peeves

But you look at escalator opening protection, I know it has been on the books forever, and do not know if the design has ever been tested , or if there has been an actual fire where they have worked???

 

[CPleasant]

I've only come across domes in the residential systems I’ve designed, but I believe we use concealed pendents near the top of the dome. If there is a chance that the pipe may freeze, is there a way to make that area a dry pipe system?

 

[pipesnpumps]

Just a thought.. Get the architect to design in a feature to hide a pipe drop to sidewalls. Like a round button in the top of the dome, but dropped down whatever distance is required. Have however many sidewalls you need to protect the dome, sprayed out radially. e.g. one sidewall for every 60 degrees (6 heads).

It would be best to conceal the pipe also, but I suppose you could use copper and polish the splatter off the joints. Bend the pipe to match the curvature of the dome and make it feature.. lol, i dunno just spitballing.. Where is that first year student genius when we need him? I'd bet there is a book that gives us the answer, this is a very common problem. Later today will search ebay for the terms "used book on how to sprinkle dome structures"



Real world knowledge doesn't fall out of the sky on a parachute, but rather is gained in small increments during moments of panic or curiosity.

 

[chillylulu]

I looked at a church with the same situation yesterday. And it has $120,000usd of paintings applied to all the walls. Sprinklers could do more harm than good.

I think I am going to suggest an alternate equivalent system as allowed by NFPA 13.

I am thinking of a couple of options:

1. Closely spaced heads along the outside of the dome, (equivalent containment) or
2. Perhaps a mist system? (Exceeds containment and extinguishes)

Clean agents wont work because of height and containment issues, aerosol would have issues with current listings because of volume.

What do you think about vertical sidewalls at the bottom ceiling, pointing in? Water spray could cover almost the whole area, activation time could be an issue. 3D analysis of the space by qualified PE or FPE?

 

[firepe]

Other than the exceptions for sidewalls underneath garage doors in NFPA 13, sidewall heads need a ceiling above them and a wall behind them.

I'd be curious to hear that equivalency suggestion.

Fire Sprinklers Save Lives.
Can You Live Without Them?

 

[SprinklerDesigner2]

But you look at escalator opening protection, I know it has been on the books forever, and do not know if the design has ever been tested , or if there has been an actual fire where they have worked???

I know the answer to this one!

Obtained from Ken Isman from a seminar in Savannah I think it was.

A number of instances were brought up, such as sprinklers in pockets, that we've always taken as gospel that upon testing proves false or event opposite of assumptions that were made.

The drawing of the escalator was done by the daughter of one of the old time committee members. When taking it out of the standard was proposed it was met with a lot of resistance because a key member wanted to keep it for sentimental value.

The escalator scheme has never been tested.

Decorative beams in ceilings was another one. Cris crossing 12" beams forming 6'x6' recessed panels. Wisdom through the ages dictated sprinklers be up in the panel space but testing showed sprinklers under the beams operated faster.

 

[cdafd]

so how about 8.5.7 2010 edition

if my domes are less than 32 sq ft, it appears no sprinklers, and does not seem to have, say bottom of dome to top of dome height limit.

 

[TravisMack]

I could see applying that. But, then you have an unprotected ceiling pocket and the QR reduction is no longer allowed.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[cdafd]

Per 8.5.7 2010 edition if it is under 32 sq ft it is not required to be protected

 

[TravisMack]

I can see your logic, but I would not want to put my name on the line by using a QR reduction in that scenario. I tend to be more conservative and would say that if I have an unprotected pocket (even if not req'd to be protected) then I can not use the QR reduction.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[cdafd]

I know I seen the reduction, but can you give me a section number for it, thanks

"then I can not use the QR reduction"""

 

[skdesigner]

Tmack,

what about when 13 2010 11.2.3.2.3.1 (4) specifically says: there are no unprotected ceiling pockets as allowed by 8.6.7 and 8.8.7 exceeding 32 sq. ft? Would an unprotected ceiling pocket less than or equal to 32 sq. ft. not be perfectly acceptable to use the QR redux with?

I note that it does NOT mention 8.5.7, so I make the assumption that skylights don't qualify for it.

 

[TravisMack]

CDAFD:

Here is the reference:
11.2.3.2.3.1 Where listed quick-response sprinklers, including
extended coverage quick-response sprinklers, are used
throughout a system or portion of a system having the same
hydraulic design basis, the system area of operation shall be
permitted to be reduced without revising the density as indicated
in Figure 11.2.3.2.3.1 when all of the following conditions
are satisfied:
(1) Wet pipe system
(2) Light hazard or ordinary hazard occupancy
(3) 20 ft (6.1 m) maximum ceiling height
(4) There are no unprotected ceiling pockets as allowed by
8.6.7 and 8.8.7 exceeding 32 ft2 (3 m2)

SKD:

It does seem that the QR reduction exceptions do not reference 8.5.7 as something to be an issue. You may be able to stand on solid ground to use the QR in that application. Like I said, I am probably too conservative on some issues.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com