design areas 2

[pipesnpumps]

I am often baffled by the simplest jokes because I read too much into it.

This may also be the case with something related to design areas. I have a contractor who is required to design to 1,800 ft2 design area.

He chose two design areas on the same floor. An 1,800 ft2 light hazard area. In a separate design area, he chose 1,200 ft2 of Ordinary 1, the limits of a mechanical rooom, withOUT any adjacent light hazard area

The project must meet UFC 3-600-01 which disallows the room design method. He is claiming that 11.1.2 (extension of design area into adjacent ceiling space) somehow means he only has to calculate for 1,200 ft2 design area.

To me this is patently wrong, however since the result of my review comments will result in chaning out the fire pump and possibly changes to the underground, I wanted to be double dang sure since this is a NICET IV. I am not missing anything am I?

He claims that the 1,200 ft2 OH1 mechanical room in addition to 600 ft2 of adjacent light hazard will push this project over the limit.. I haven't run the numbers yet to check.

TIA

 

[TravisMack]

Under UFC criteria, I have never been able to do what is being attempted as you described. Does the mech room have a 10' ceiling? If it is higher, his design area will have to be greater than 1800 sq ft. I have always had to extend the remote area out into the LH areas to get the full 1800 sq ft since, as you state, the room design method is not allowed under UFC criteria.

If it runs over the limit of the pump, it does. How much does it run over. Can he modify the pipe sizes to get it under - choke down sizes to the light hazard areas and increase in the OH area? I have had to do this on occasion in order to stay within certain limits of water supply.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[NewSprinklerGuy]

Gentlemen,

Pls forgive how late I am to this thread, but I am new to this forum and the issue you previously discussed is very similar to a dilemna I have. Here is my situation:

We are designing a fire station for Creech AFB, NV. We also have to follow requirements of UFC 3-600-01, which states the design area must be at least 3,000 ft2. Since the remote area is a vehicle bay (2,978.88 ft2/ordinary group 1/ceiling 25 ft at the peak) and the roof is sloped more than 2 in 12 (add 30%), my minimum design area is 3,900 ft2, which goes well beyond the boundaries of the vehicle bay. On the other side of the fire-rated wall is the admin area, common areas, and sleep rooms, etc. (all light hazard).

Question #1: Since the remote area falls short of the 3,900 ft2 total I need, am I correct if I extend the design area into the light hazard area, even though the vehicle bay is separated from the light hazard areas by a 2-hour wall? I believe I am correct, but want to be sure.

I realize that the vehicle bay is 900+ ft2 short of the 3,900 ft2 requirement, but I think my dilemna comes from my belief that if a fire were to develop in the vehicle bay area, the sprinklers should be able to control the fire before it gets through the wall into the light hazard area. Designing the system for a 3,900 ft2 area at 0.15 gpm per ft2 will require what I call a significant water supply. And although the UFC doesn't allow the room design method, this seems to be a perfect situation for an approved deviation/exemption from the UFC requirement. My opinion, of course. I freely admit I may be waaaaaay off.

Question #2: should I recommend to my project engineer that we install a horizontal gypsum roof in the vehicle bay area? That would take the design area back to the 3,000 ft2 range and allow me to calculate just 1 extra sprinkler from the light hazard area, keeping the water supply requirements down. This is not my favorite option because of access to sprinklers for maintenance, but it is an option...maybe...if we put in access portals, which may open up a whole new can of worms that I won't go into on this post.

I've already calculated the vehicle bay (30 SSU sprinklers) and including the 250 gpm inside/outside hose requirement, I am looking at approx. 761 gpm so far. My fear is that if I have to add approx. another 11 sprinklers from the light hazard area, even at 0.1 gpm per ft2, that may push the water supply requirements "too high."

Sorry this was long winded. I am going to finish up the rest of the 3,900 ft2 design area to see where that takes me. I just wanted some guidance to sanity check any assumptions I may have made. Thanx in advance for any help you can provide.

Shawn Lee

 

[Oremus]

Is this strictly a UFC thing? According to 13 you wouldn't take a light hazard office building and calculate it to ordinary group II because you have 10 ft storage in a couple of closets. Why would you do it in this case?

 

[NewSprinklerGuy]

Oremus, I finished up the calcs last night. Here's what I did:

I did the hydraulic calcs for the 30 sprinklers in the vehicle bay (2,978 ft2) at 0.15 gpm.

The other 900+ ft2 came from 11 sprinklers in the light hazard area and was calculated at 0.10 gpm.

I balanced out all the flows and eventually came up with a water supply requirement we could live with (so far).

That gave me the 3,900 ft2 I needed. I took a look at some plans submitted by a FPE for another project on our base and that's how it was done on those plans--about 1,540 ft2 in one area and another 1,500 ft2 in a separate area of the bldg.

Does that sound right to you? I could see no other logical/acceptable way to get the 3,900 ft2. What do you think?

Shawn Lee

 

[pipesnpumps]

Shawn,
Sounds like you answered #1 yourself, mostly.

For Question #2, Gypsum ceiling=potential freezing issues.

Oops, if your hosestream gpm is 250 gpm as you stated, that should have been 500 gpm for OH1 (Table 4-1).

Some additional thoughts/warnings to keep in mind:
-remember that EC heads are not allowed per UFC
-you need to be designing to NFPA 13-2010.
-Don't forget forward flow test header downstream of the BFP, 1/2" safety valve, exterior accessible shutoff valve (PIV 40' from bldg preferred), hydrant within 150' of FDC, and complete hydrant flow test data.. I need rubber stamps that have standard review comments for all of those..

If I think of it, I will post my standard UFC wet pipe review checklist from work Friday.

You can get approval for what is called an "exemption" to UFC requirements, but your logic would need to be very sound and provide equivalent protection.. An exemption is a somewhat formal process and can be alot of fuss when it comes to DoD. The base fire chief cannot technically approve it, has to go to Tyndall AFCESA's Chief FPE. (see exemption process in front of the UFC). I wouldn't recommend going this route. You pull out the exemption request card for impossible or ludicrous circumstances only, and this is neither.

 

[pipesnpumps]

Here is the review checklist. This is for ENGINEERED plan submittals for WET PIPE sprinkler systems in facilities where UFC 3-600-01 Fire Protection Engineering for Facilities applies.

You can all thank me later... Anything I can do to help get better designs submitted is worth the effort!

 

[NewSprinklerGuy]

pipesnpumps,

Thanks very much for the info/advice. I caught the 250 gpm hose stream "ooops" day before yesterday.

Big thanks for the checklist. It will definitely help out.

Shawn Lee