Got a general question for the FPE's

[SprinklerDesigner2]

No, I am not in trouble and not looking for a seal or signature but I do have a question regarding NFPA 13 Section 1.5 Equivalency.

A standard 1/2" sprinkler head is limited to 225 sq ft with 15' between sprinklers.

Could a FPE sign off for 16'x16' spacing if he could show density, wall wetting etc would meet the whatever requirments?

Of course you would have to show, or I suppose be prepared to show, equivalency but could it be done hupothetically speaking?

Like I said I wouldn't touch it with a ten foot pool but....

Thanks

 

[rbulsara]

You already know the answer. If you would not touch it with a 10 feet pole, why would you expect someone else to sign off on it?



Rafiq Bulsara

http://www.srengineersct.com

 

[SprinklerDesigner2]

I wouldn't touch it because not being an FPE I am not qualified.

 

[rbulsara]

ah OK. One can only read what you write. In that case it is up to the designer to back up his design.

Perhaps a FPE will chime in if sees enough detail to respond.

Rafiq Bulsara

http://www.srengineersct.com

 

[SprinklerDesigner2]

rbulsara,

Three years ago I was attending a series of continuing educion classes and one example given by an FPE instructor was a weird round building with a "parachute" ceiling made of canvas... a real strange building ot say the least.

About 20 layout techs with varying levels of experiene and non of us could come up with a solution. The FPE came up with a solution using the equivalency clause (something a layout tech can not do) and I am wondering if an FPE could do the same thing with spacing.

Reason I bring this up is yesterday I was on a final inspection of a 1,500 head job I laid out and walking into a storage room it looked to me as if one of the heads was over 7'6" from the wall. I say appeared because when I measured it it was exactly 7'-6" or within 1/4" of being 7'-6" and I don't think anyone is going to worry about 1/4". But this job had a static pressure of 145 psi, a residual of 90 at 750 gpm and in the area of calculation I had an 80 psi safety factor. Given these conditions would it not be reasonable to think the level of protection would be higher even had this head been 9' off the wall as opposed to one 7'-6" with a static of 55 psi and residual of 30 at 750 gpm?

 

[stookeyfpe]

Given what you've told us so far, this may be a candidate for an equivalent design. My intial concerns on why I would not want to do this include:

a) The design fire could change
b) The water supply could decay
c) I don't know if the water supply could promote tuberculation in the connection between the potable water source and sprinkler riser.

If this is high-piled storage, hazmat, or suppression mode sprinklers I won't even get out the pole to touch it. Those designs are typically what I call either/or fire protection: the sprinkler will either control the fire provided the design meets the letter of the design standard -or - the building can burn to the ground if the design does not meet the design standard.

I've only considered one equivalent design for ESFR and the only way I would approve it was after reviewing the results 40 hours of fire modeling. At the end of the day it was faster and less expensive to fix the system but that's what the owner wanted, and that's he got - and even after all the modeling (which I had someone else do), the engineer who sat up and ran the CFD model and I both concluded that it was too close to being on the edge of the sprinkler's design limits. That owner no longer uses me because he paid $8,500 in fees for modeling as well as the fees for reviewing and inspecting the required modifications. He was able to find some schmuck Industrial Engineer (nothing against any industrial engineers who read this) who sealed the design - that liability is him, not me.

I'll grant you that one foot does not seem like a lot, and it's probably not. But for me to seal an alternate equivalent design I would at a minimum want historical data on the water system and clear understanding of the building's limitations and uses.

And as I write this response, Johnny Cash is on the radio singing "Ring of Fire." That's karma and my gut telling me to be extremely prudent.

 

[ContractorDave]

Strictly speaking (and addressing your post) Yes. NFPA 13 is only a standard, and only becomes a binding code if the local building codes reference it as such. It is as critical to show that your example meets the 15' criteria as it is to meet some other hypothetical number. That being said, there are manufacturers listings to be considered as well.

Any sprinkler design may fail of course, regardless of whether the design meets all relevant standards, codes, listings and the like. Prudence though, in this litigation crazy world, suggests you carry a big umbrella, and in sprinkler design, that umbrella has as major components the NFPA, manufacturers listings, and local codes.

So, is the question 'would I risk my ass', or 'is it viable'?

Regards
Dave

 

[KGBeast42]

SD2,

I just wanted to clarify. After re-reading your post you were very specific in referencing the 15' X 15' spacing. Later you talked about the reasoning being noticing a head that looked to far of a wall in a "storage" area.
Now I am by no means any type of FPE but in NFPA13 2007 Table 8.6.2.2.1(b) it states that all Ordinary Hazard occupancies have a maximum spacing of 130 ft. With storage areas being ordinary hazard I would have to assume that your heads are at least 8.6' on center?
I know that you were posting a hypothetical question but I just had to point that out.

Chad Johnson

 

[SprinklerDesigner2]

Dave,

"So, is the question 'would I risk my ass', or 'is it viable'?"

I doubt any FPE in the country would "risk his ass" and I didn't mean to make the quetion a "would you" but a "could you". Big difference.

I got into sprinklers the strange way. Before I did this was a flight instructor and charter pilot. I got here because one of my student pilots owned a sprinker company and I needed a more stan;e income when I got married. Once having access to an aerobatic airplane I dabbled in that, did loops and rolls and spins etc. If you asked me if I could complete a loop starting at 300' above the ground my answer would have been yes but ask me if I would do a loop, starting 300' above ground, my answer have been no way in heck!

When I wrote the question I knew non of you FPE guys would but my question was could it be done in context of the equivelency clause?

It wasn't the best question in the world but I was just curious.

Could and would, big difference.

 

[ContractorDave]

SD2
Great response none the less! I imagine you have acquired an interesting perspective on 'risk'.

Chad, wouldn't that be 11.4' on center and 5.7' off a wall given 130' max spacing?

Regards
Dave

 

[KGBeast42]

Dave,

I had just finished laying out a grid system Core & Shell where the branch lines ran parallel to the main wall. When I read the description my mind thought branch line. I then assumed 7'-6" to the first line, 15' between lines and 8.666' between heads on the line.
I could be mistaken.

Chad

 

[ContractorDave]

Thanks Chad

It was I who wasn't paying attention.

Regards
Dave