Dry Pipe System Size

[Ehendrix]

I have an old 3 story hotel that has a walkway that loops the entire building for 3 floors and is exposed to the elements. Think of an old hotel where the stairs are exposed and so is the wrap around covered walkway.

Our thought we be to install a new dry system that is installed and loops this walkway and then run lines into each room. They are converting it to homeless shelter. My issue is with the system size, the Dry system will easily be over 750 gallons per floor so I am thinking about diving each floor into 2 systems.

But then I run in NFPA 13 (2013) section 7.2.3.1.1 which states that any dry pipe system protecting dwelling unit portions of any occupancy shall deliver water in 15 seconds to the test connection. It also states that I cannot use sections 7.2.3.2, 7.2.3.3, 7.2.3.4, but I can use 7.2.3.5 which talks about dry pipe systems being calculated for delivery times per Table 7.2.3.6.1

So am I going to be stuck with 15 seconds or can I use the table under light hazard for 60 seconds delivery time?

Thanks for the help!

 

[TravisMack]

Your system sounds residential, so you I believe you are going to be stuck with 15 seconds delivery time.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

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[Ehendrix]

My thoughts exactly. Thanks buddy.

 

[cdafd]

Wow thanks Travis

Those little standard secreats no one talks about.

But, I don't think I have personally seen a dwelling dry pipe system, plus it just started in 2010

 

[Ehendrix]

We are only thinking about a Dry system due to the fact it is existing and it would be easier to run the pipe outside and then shoot a 2 head line into the room.

 

[LCREP]

How about antifreeze system?

 

[Ehendrix]

The locals are having issues with the use of Antifreeze systems. Might not approve it. But that would be one big antifreeze system.

Thanks,

 

[MatthewJWillis]

Not sure you will find anti-freeze.

 

[LCREP]

Just something to explore, yea I know it is a pain to deal with, you can always make the systems smaller. Just throwing ideas at the wall, see what sticks.


Here is another one how about insulation on the pipes using UL listed tape for the pipes. I think you can get heat tape for up to 6".

 

[MatthewJWillis]

Anti-freeze was banned. Specifically due to it's use in residential systems.
To even use in in a 13 system, it must be listed. To date, there are none when I last checked.

 

[Ehendrix]

Ok so back to my original question, it appears I am stuck with the 15 second trip time correct?

 

[MatthewJWillis]

Yes.

Your system is residential so 7.2.3.1.1 applies.

Do you have a copy a FDT? It might save you a lot of guess work...

R/
Matt

 

[Ehendrix]

No I dont.

 

[MatthewJWillis]

Tyco has it. Not sure of the price.

Now I get to thinking, can you use computer trip times for Residential...?

 

[stookeyfpe]

I am going to approach this with a different strategy. I always thought it was interesting that the NFPA 13 TC used the phrase dwelling unit, which is a defined term in NFPA 5000 (the referenced building code in NFPA 13):

DWELLING UNIT: One or more rooms arranged for complete, independent housekeeping purposes, with space for eating, living, and sleeping; facilities for cooking; and provisions for sanitation.

In my world I would not treat the exterior egress path as part of the dwelling unit for the purpose of water delivery time because the loss history data in NFPA 13R Table A.1.2 clearly shows this area is where the fires occur. I understand this is a NFPA 13 system and the exterior walkways would require AS protection. However, possibly excluding those areas by dividing your design for the dwelling units with one set of DPVs and the balconies with another could make the 15 second delivery time easier to achieve.

It would be a question to your AHJ.

 

[TravisMack]

Again, thinking outside the box, what if you were to use decoshield in the interior to conceal the piping, yet run below the ceiling? That may make an interior installation easier. You could also then just use a dry sidewall from the interior to protect that wrap around walk way. This eliminates the dry system and the 15 sec trip time.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

"Follow" us at

https://www.facebook.com/pages/MFP-Design-LLC/92218417692

 

[Ehendrix]

Travis,

That is something I will be recommending to the owner.

Thanks,