Obstructions and calcing Specific Application sprinklers

[Cidona]

Dear Forum members,
I would appreciate insight and experience in regards to layout and calculation of specific application sprinklers (e.g. Tyco Ultra K17).
When you are installing additional sprinklers due to obstructions, there doesn't seem to be any 'penalty' for using extra sprinklers. i.e. There is no need to add additional sprinklers in the calc (as you would with ESFR sprinklers). Can anyone confirm that you are just meant to calc the 15 heads in the 'high level', and ignore the ones below the obstruction?
Secondly, I have a scenario with obstructed construction. I can maintain the required 8' minimum spacing for the area in question (protecting every pocket); however at the end of the run there is a Stairwell which protrudes into part of the end bay which reduces the area to install a branchline such that the 8' is not possible. There will not be storage directly below here as this part of the space is going to be used for egress to the stair and elevators. Was wondering if people have found this type of situation to prohibit the use of these sprinklers, or if they have been able to get approval/find an allowance/exception for this.
Please see attached file for clarification.
Thank you for any insight you can shed.

 

[spkreng]

First off if the lower level spacing is the greater of the two or you are dropping down with say 1" lines you need to prove this pipe sizing. usually when in doubt I do an additional set of calc's. Now as to the stair, it is enclosed with a 2hr wall and door right, so it's a separate fire area, and you can use standard heads. oh i see your problem what is the depth of the beam, if it obstructs the heads from cold soldering your 8' minimum doesn't count, otherwise use regular heads and include in a proof calc.

spkreng, CET

 

[TravisMack]

But, does the 8' minimum matter even if not cold soldered. I know you can't do an ESFR system with heads in pockets at 6' on center while only calculating 12 heads. Even if they are protected from cold solder by a beam or something else, that is not the listing of the head.

Do the specific app sprinklers like this one have those same limitations?

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[Cidona]

My understanding is there is no exception on the 8' for baffles. Though it seems hard to imagine not being able to use them due to the very last bay.