Storage over 40'-0"

[KINGSPRINKLER]

We are in the process of bidding a rather large ESFR protected warehouse, ( almost 1 million sq.ft. ).
Only 10% of the building has a roof height over 40'-0". Our question, Is it acceptable to use K25 heads for the systems with roof heights over 40'-0" & K17 heads for systems with roof heights below 40'-0". System seperations would define the split between the different type of head.
We have yet to find any code sections that would prevent this design.

Thanks, Glen

 

[TravisMack]

I may be wrong, but I can't see where you would have a problem with that. You will have a "draft stop" for the area where the roof drops down to the lower height.

It will be interesting to hear the rest of the group on this item. Stookey..you out there????

 

[KINGSPRINKLER]

There is no drop in the roof structure, just the roof slope 1/4" in 12", No draft stop as well.

Glen

 

[stookeyfpe]

King Sprinkler and Travis:

Nothing in the 2002 edition of NFPA 13 or the 2006 IFC prohibits this. I reviewed Table 12.3.2.3.1 and Table 12.3.3.3.1 and the associated sections and what is proposed meets NFPA 13. Chapter 8 of NFPA 13 is also silent on this so the mixing of the k-factors is permitted.

Unless I'm missing something your storage height is limited to a maximum of 25 feet and in those areas above 40-0 one level of in-rack sprinklers are required.

The one thing you will probably need to explain to the fire code official is how your design complies with IFC Section 910.3.5. This section has an exception that states when a building has ESFR sprinklers, draft curtains are not required. Depending on the code official's level of understanding of ESFR sprinklers, they may want to require the installation of draft curtains between the areas protected by the different sprinklers. You will need to ensure they understand that all you are doing is changing k-factor - the sprinkler system is still protecting the building using ESFR sprinklers designed for suppression mode. NFPA 13, Section 8.4.6.4.1 substantiates this.

 

[stookeyfpe]

Oops, one more thing:

IFC Table 2306.2 does not require draft curtains in a sprinklered building with an area > 12,000 square feet housing high piled combustible storage.

 

[TravisMack]

Glen:

Ok..now, I see what you have. The only thing I can see that I would do is provide the K25s and their pressure for an area of 15' around the >40' roof.

I would not concerned about the different K factors because the heads are different thread sizes. There is no way some one could mix up the heads if one needed to be replaced.

T

 

[LCREP]

What is the commodity, Group A Plastic, be very careful?? K25 heads do not protect the same products as a K17. Exposed unexpanded AND cartoned expanded can NOT be protected by K 25 heads, see NFPA 13, 02, pg 140 table 12.3.3.3.1 and pg 157 table 12.3.5.3.1.

If you have other then cartoned unexpanded plastic K22-K25 is NOT an option.

Tom

 

[KINGSPRINKLER]

Again thanks to all that responded. We are aware of head limitations, It's just that the ridge height is 41'-4", We don't want to give them K25 throughtout if we don't have to.

 

[FFP1]

Consider the provision of a solid barrier across the peak to ensure the maximum ceiling height is 40 ft......then there is no need to use K25s.

Different ESFR heads can be installed adjacent to other ESFR heads because they are all considered "fast response" heads. The only problem I am aware of has to do with the hydraulically most remote area. Having K17 and K25 heads on the same system creates problems due to the volume of water flowing through the larger orifice heads in order to meet the minimum pressure requirements for the smaller orifice heads. If I am reviewing the plans, I would want to see several remote area calculations to ensure the water supply provides adequate flow and pressure regardless of which heads are used in the remote area.