Scissor stairways

[Mr.Denis]

Hi everyone,

Just wondering... how do you design standpipe in an interlocking/scissor stairs ?
Let's put aside the fact that we need a vertical shaft with the same fire rating as the stairway.
we have a high rise building, incombustible construction, residential type, design per NFPA 14.
i see 2 options...
1. 1 standpipe on let's say the North side of the stairway, and we put an angle valve at each lvl floor we cross.
2. 2 standpipes, 1 on the north and other on the south side of the stair and we put angle valve at each floor lvl we cross. At the end, we should have angle valve at every floor lvl.

My 2 options may be wrong, any tips on the deisgn for this?
If there's something specific about it in NFPA 14 let me know, i didn't find it!

Thanks,

 

[OremusFire]

By interlocking do you mean dedicated stairwells (side by side but staggered), one for up-going traffic and one for down? If so, in my opinion it would make the most sense to put it in the up-going stairwell since that's how the FD would access the upper levels. I'm not aware of anything in '14 specifically addressing this so you might just want to run it by your AHJ and see what they have to say. If it's not dedicated traffic in one direction or the other perhaps you could run one standpipe and armover hose connections at each landing on the opposing stairwell - your option #1.