FM Global Property Loss Prevention Data Sheets 8-9 - Table 8. Ceiling-Level Protection Guidelines

[SprinklerDesigner2]

The building in question is existing and your standard rigid frame and 8" bent metal purlin building that is exactly 35'-0" tall at the peak having a 1" in 12" pitch.

Unlike all other rigid frame buildings this one has 24'-0" bays. This is so unusual that tomorrow I am driving 220 just north of Atlanta to double check the bay spacing just to make double sure they are all 24' bays.

Rack storage and the FM rep told me to use Table 8 found in 8.9.

I would like to use the Tyco K25.2EC upright sprinklers and it appears to me that 8 sprinklers discharging at 40 psi would be an acceptable alternative design.

It appears, and I can certainly be wrong here, that Reliable is the only one that manufactures and FM approved EC25.2 pendent? With the maximum spacing of 12' between heads you can understand why it is so important for me to verify that we do have all bays at 24' and that a 25' bay isn't hidden in on me somewhere.

And I believe the maximum size of line I can have is 2 1/2" for the upright K25.2EC. I don't think anything larger than 2 1/2" can be used on an upright sprinkler unless it is on a sprig up that would be massive.

And for some reason I believe it is calculating four open sprinklers on two branch lines?

The water supply could certainly be better but hat we have is a 1,500 gpm 50 psi booster pump taking suction from a city water main. What I have to work with is 110 psi at churn, 84 psi @ 1,500, 71 psi @ 1,700, 63 psi @ 1,800 and 59 psi @ 1,900. I wish it was a 100 psi booster and not a 50 psi but that is what I have to work with so you can see the sprinklers I have to work with is rather limited. Reality tells me it is going to be the K25.2 EC or the K22.4.

So, am I reading the table correctly that I can use a Tyco K25.2EC UPRIGHT discharging 8 sprinklers at 40 psi with 250 gpm hose? That I would be discharging 4 sprinklers from two lines?

I know this is just a forum but I want everyone to rest assured I will certainly talk to the FM representative before I do anything (like give a price) just to make sure it is all clear in my head.

 

[stookeyfpe]

SD2:

Don't take this wrong but did you look in the lower right hand portion of the table at footnote a? It states the 8 sprinklers @ 40 PSIG is acceptable provided the maximum linear spacing dimension of 12 feet is not exceeded. And I have never found an explanation as to why certain cells of the table are green. I'm hoping Spaddler may offer an opinion.

 

[SprinklerDesigner2]

I never take anything wrong.

The footnote in the lower left corner that reads "a An acceptable alternative design is 8 @ 40 (2.8) when a 12 ft (3.6 m) maximum linear spacing is used."

The way I take it is the footnote only applies to the K25.2EC (K360EC) pendents, I couldn't find where Tyco has any approval for the pendent and the the only approval I could find was Reliable. This said the Tyco K25.2EC upright does have FM approval and it does appear I can use that even though it isn't green. The upright does not have the green or the note that it is limited to 12' spacing.

The green is confusing to say the least.

I think I am going to try to get a hold at someone at Tyco.

PS This is NOT the sort of thing you want to make a mistake on.

 

[skdesigner]

From FM-DS 8-9 2.3.3.7.1 General

...

"In each table, the ceiling-level protection options highlighted in green represent those for which the hose stream demand is 250 gpm and the duration is 1 hour. These highlighted options have the potential result in less fire, smoke, and water damage than other acceptable options and thus may, from a sustainability standpoint, be preferable."

R M Arsenault Engineering Inc.

http://www.rmae.ca

 

[Sdpaddler50]

I don't do a lot of HPS anymore, but I will see if I can answer some of your questions;

As noted, the green demands are 250 hose because these are essentially "suppression mode" designs. IE, FM does not use the term ESFR anymore, its now either a storage, or non storage mode sprinkler per DS 8-9. With that said, think of the green demands as ESFR, and based on suppression occurring, you only need 250 hose, as opposed to 500. Less mop up, etc.

Some background, these new tables were developed after extensive full scale fire testing. Basic conclusion - big head, big drops, pendent position, low RTI, results in suppression if the other key parameters are present.

I did not confirm, but I believe you are correct that there is only the one Reliable head for that particular demand.

2.5 in branchline, requiring a sprig - sorry, forgot that answer.

I believe 4 heads on 2 lines may work, but you should verify its not 3, 3, 2 to get a more uniform DA.

You do a lot of FM jobs, and I appreciate the fact you will check with the FM Engineer who is involved. I would suggest you send them this exact list of questions. Sometimes contractors wait until everything is done, and send in plans and calcs for review. For complex projects like this, I think a couple emails/calls is a good thing as you both go through the process together, to ensure you are on the same page.

 

[TravisMack]

When I have done these, I did 4x2. There is an FM datasheet on selecting your remote area and determining length along branch lines and such. You may want to check that just to be sure. It is the FM datasheet on hydraulic calculations.

And correct..3" branch lines equals sprigs. You want to avoid that if at all possible.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

"Follow" us at

https://www.facebook.com/pages/MFP-Design-LLC/92218417692

 

[SprinklerDesigner2]

Thank you to everyone who had input.

After spending the past four days doing nothing but reading 2-0 and 8-9 I know more now than what I did. At least now I know what the green means.

After talking with the FM rep I felt confident enough to bid the job ending up having to change the fire pump and go with the 12 22.4 pendents discharging 40 psi each. Yes, originally I was told the building was 35' but that was revised to 36' so there you go on that.

The site has a 1,500 gpm @ 50 psi booster pump which sort of sounds fine until you discover the city water is 50 psi static and 25 psi residual at 150% of pump capacity.

Working with the 35' height I tried everything possible to make it work using every reasonable scenario (this was not wasted time, it was good practice time spent with the FM data sheets) and I still couldn't make it. The closest I got was 11 psi over the line and my pipe size to get there was idiocy. A rigid frame bent metal purlin building and I don't like hanging 8" mains from that building type unless I call in a structural engineer and I already know what he will tell me.

Pricing got ridiculous and I was still failing to get to where I had to be.

I gave up when the FM rep told me the building was considered over 35' deciding to look at the fire pump.

Success at last; turns out I can give the owner a new fire pump with new controllers and all new pipe and valves at less money than what the inside would have cost if I had been able to make it work which I couldn't All the pipe was at least one size smaller and in some cases two sizes. It was one of those "get a new pump and save $20,000 on the overall price" things.

Years ago when I was up north I dealt with FM a lot; lots of factories and lots of FM risks but down south there isn't anywhere near the presence FM has up north. To say FM data sheets have changed is an understatement.