Rack storage design 1

[MitchellCons]

NFPA 13 2002 EDITION States

8.16.5 Hose Connections.

8.16.5.1.3 Hose connections shall be supplied from one of
the following:
(5) In rack storage areas, the ceiling sprinkler system in the same area (as long as in-rack sprinklers are provided in
the same area and are separately controlled)

Does this mean if I have a Rack system(valve controled Riser) supplied from the bottom of the 6" riser that covers dericly over the racks, I can supply the hose valves from that system?

Also can someone tell me, if I supply the rack system off the bottom of the (E) 6" riser with new control valve and flow switch do I have to calc both systems flowing together?
Can I just calc the racks per FM Global Standards @ 8 sprinklers in one level @ 30 psi and leave the Clg. Sprinkler system @ .60/2000.

Thanks for everything

 

[SprinklerDesigner2]

Yes, feed the rack from the overhead.

Yes.

Always calc both systems together. The .60/2000 is high for a system with sprinklers in the rack though. Depending on what you got the overhead might be half that density or even less.

 

[MitchellCons]

Your response was much needed! Funny because there is an (E) system out there with an (E) rack system riser off the bottom of the Overhead 6" riser. The rack system calc plate reads 8 sprinklers @ 15psi and the overhead system riser reads .60/2000.
Should the riser calc plate show the demand of both flowing together? This is what has me confused.

Also I know what you mean, the CMDA .60/2000 is required per FM Global data sheets 8-9 Dated May 2008 with 1 row of IRAS for plastics stored up to 25'.

 

[MitchellCons]

SprinklerDesigner2
Yes, feed the rack from the overhead

You mean the Hose rack and not the rack storage correct?


Thanks again!

 

[SprinklerDesigner2]

"Yes, feed the rack from the overhead
"You mean the Hose rack and not the rack storage correct?"

Yes, hose rack from the overhead.

Rack sprinkler system must be fed from a separate riser (manifold does this well) so if overhead is turned off the rack sprinklers will still operate; if rack sprinkler is disabled, as often happens with fork lifts, the overhead sprinkler system and hose racks will remain in service providing partial protection.

With a density of ,60/2000 it appears the overhead sprinkler was designed before storage racks came into the picture. Maybe someone can correct me but I can't think of a situation where that kind of density would be needed in conjunction with in-rack sprinklers. I am almost positive the requirement will be much lower than what's on the placard.

Overhead and in-rack sprinklers must be added together at the point of connection which, in this case, is near the base of the riser.

Assume your overhead requires 550 gpm @ 102 psi (at the manifold connection) and your in-rack sprinkler requires 225 gpm @ 52 psi.

Total water requirement is going to be a lot more than 775 gpm.

k=q/sqrt p
k=31.20

q=k*sqrt p
q=315.1

In this scenario the total water requirement, at the point of overhead and in-rack sprinkler connection, will be 865.1 gpm.

 

[MitchellCons]

Here is the FM Global Data sheet I am talking about.

The design is for 25' max storage. 30' max Bldg. height.

Im really looking @ .60/1500 with 1 row of IRAS(E).

(E) means sprinklers located in every transverse flue space.

Sorry for the miscommunication but is still a very high demand required.
Also the new FM data sheets require that the 8 IRAS be calced @ 30 psi instead of the 15psi shown. The existing calc plate on the riser was performed in May of 06.