Dry System section 7.2 NFPA 2002

[SPKR]

Hello everyone,
Need an opinion on a sprinkler system design.

Code states dry pipe system should only be installed where there is not adequate heat for a wet system.

Here is my dilema.....
Building owner has a one story building with a would attic/dead space.
The drywall ceiling is tight to the bottom of the wood trusses and the lay-in insulation is ran in between the trusses and layed on top of the drywall.

The area below the ceiling is light hazard.

Owner stipulated that he did not want any exposed pipe below his ceiling.
Only place left to run piping is in the unconditioned attic space.

I designed a dry pipe system which served to protect the attic with upright sprinklers and the ceiling area below attic.

Even though the entire area where the pendent sprinklers are located below is heated, the piping is ran in an unheated space so I had to make it a dry system.

In your opinion do you feel this is in accordance with NFPA 13, section 7.2, 2002 edition?

 

[LCREP]

Unless the attic is heated, which it is not, you can not use the pendent heads in the heated area. Why? because the 1st time u trip the system u will fill the drop nipple with water, it will freeze and no one will be happy with you. The only way you can do this is with a dry type sprinkler, option #2 in 7.2.2., not a cheap option, but the only one you have. Also dry type sprinklers representative sample has to be tested every 10 years as per NFPA 25, 2002.

 

[SPKR]

Sorry, I should have specified that I am using Quick Response Dry Pendents on return bends.

 

[LCREP]

Why on a return bend? Why not a T from the dry sprinkler to pipe. A return bend will trap water and freeze IF in the attic??

 

[FFP1]

Tell the owner he has two options.......provide a reliable heat source for the attic area (only has to be capable of maintaining 40 degrees during the coldest days of the year) so you can use a wet system for the attic and occupied areas OR convince the owner that he must accept the fact that the sprinkler piping will be exposed in the occupied areas.

This is much better approach than dealing with the aggravation and cost associated with numerous broken sprinkler lines when several sections of pipe freeze and burst.

P.S. A third option(probably unrealistic due to the increased cost) is to provide the sprinkler piping under the ceiling and have a second ceiling installed to "hide" the sprinkler piping. You could go with drywall or suspended ceiling tiles. There is more than one way to skin a cat......sometimes you must think outside of the box!!

Good Luck

 

[stookeyfpe]

Is an anti-freeze loop an option?

Sorry I am traveling so I don't have NFPA 13 in my travel library.

 

[SPKR]

I agree FFP1, but the owner and the Architect do not want to budge on their design.

stookeyfpe, I asked the AHJ about anti-freeze, and even though it is allowable per code, they won't accept it.

 

[TravisMack]

SPKR:

If you are stuck between a rock and a hard place, it doesn't matter if the AHJ just doesn't like it. He can only enforce what is the adopted code / standard with any local amendments. Therefore, if NFPA 13 would allow an antifreeze system, then you could push the issue for it. However, it may mean winning the battle and losing the war on any future projects with that AHJ.

NFPA 13 did remove the 40 gallon maximum capacity recommendation in either the 99 or 2002 edition. So, the AHJ doesn't have a leg to stand on by saying they won't approve it, unless it is written in their local amendments.

Since you are the contractor and the Architect will not budge, I would make the architect appeal the case to the AHJ to allow an anti-freeze system. That way, you are out of the loop.

Good luck on it!

T

 

[firepe]

Just a thought,

You could go with two layers of protection. Wetpipe under tented insulation, with dry for the attic, and get rid of the dry pendents.

The extra piping for the second wet layer will most likely be cheaper than the cost for all of the dry pendents.

 

[TravisMack]

Going with the tented insulation, if your attic is not overly tall, you go could with dry uprights (max 48") for that as well.

T

 

[SeaColl]

This is a very interesting post. I ran into this situation several times over the past year on single and multi-story buildings. In my opinion do not let the Architect/owner push you into a compromise which will make you responsible for any freezing or code issues and more impotently issues with the AHJ. In the end it is better to outline their options with respect to the codes and AHJ rulings and advise that your hands are tied based on the codes and AHJ rulings. It is better for them to be frustrated by the building codes and AHJ. In the end some kind of compromise will have to be reached be it additional costs, bulkheads etc.

Here is a possible option if the ceiling is not installed yet:
We hade a system where the wet piping was installed under the trusses/vapour barrier. In order to get the drywall below the piping, the drywall strapping was 2x4 giving some more clearance. This could limit the amount of bulkheads required. We also had a common wall running the length of the building (non load bearing, engineered trusses). The wall thickness was increased using 2x6 material. This allowed us to get most of the piping either in the wall or above the 2x4 strapping.

Hope this helps
Seacoll

 

[fireguy519345]

Soffits can hide the wet sprinkler piping, with upright dry heads protecting the attic area. Also, there is a requirement to have a certain amount of the dry barrel of the dry sprinkler heads to be in a warm area. I think this is part of the mfg listing of the dry heads. I knew I should have kept that notification from the NFSA that came in yesterdays mail.

fireguy