Dry pipe sprinkler system design without flow test 2

[jrk7490]

I have a new 12,106 sq.ft. building materials warehouse. Occupancy =S-1 - Commodity classification III (lumber) Building height is 27'. Racks include 4 high-2 deep pushback racks, bay racks, single sided and double sided pallet racks-all 18'h (top of storage is 22'), A-frame racks w/4 arm levels 14'h and cantilever racks. aisles are (2) 92"w and (1) 108"w.
Question 1. using LD (large drop heads di i need in-rack sprinklers?
Question 2. How can I safely create bid documents (size of service, compressor size, etc) without knowing what pressure/flow is available?

 

[SprinklerDesigner2]

Question 2. How can I safely create bid documents (size of service, compressor size, etc) without knowing what pressure/flow is available?

You can't.

I couldn't bid this project without a flow test.

Maybe a 6" feed might do, perhaps an 8" or 10" or 12"? Who knows without a flow test? Answer=Nobody. Perhaps (more likely than you might think) the city supply isn't adequate so maybe a tank and fire pump is required or perhaps a pond with vertical turbine pump? If you got a tank figure $1.00/gallon so a 100,000 to 200,000 gallon tank will blow the budget for this building.

Based on the information given I would estimate the budget for fire protection to be somewhere between $20,000 and $300,000 but it could be higher.

You can't begin to do anything until someone conducts a reliable flow test. How can you come up with a compressor size without knowing the capacity of the system which you can't do until it is laid out which can't be done without knowledge of the water supply which requires a flow test?

 

[jrk7490]

SprinklerDesigner2, Thank you very much. You would not believe the hassle it is to explain to my client that a flow test is a must. It took approx. 2 weeks to have them understand that this is not a basic sprinkler layout. I can't even have them realize that a 8'x8' spk room will not even come close of being large enough to fit all the equipment. However, I do know that they will realize later when it will be probably too late. ANything to save a buck but in the end they spend more. ?????
Thank you very much again for your input

 

[b1ueshift]

In answer to your second question, you created bid documents assuming a certain level of pressure and flow is available. You then inform the owner that there is a risk that if the required pressure and flow is not available, the contractor will be entitiled to a varation to increase the pipe sizes above what you have nominated.

If the owner can live with that risk, then there is no problem. If they cannot, then someone will have to do a flow test before you issue tender documents.

 

[jrk7490]

Thanks. My concern at the moment is that I told to lay all equipment out in an 8'-0" x 8'-0" sprinkler room which must contain the DCDA, dry pipe valve and accessories, duplex air compressor and accessories, etc which is not going to fit regardless of the compressor size. But it would help to prove this issue if I can give a compressor size and DCDA size which a 6" is approx. 62" in length and must have a 3'-0" open are in front of the device. Is there any options?

 

[SprinklerDesigner2]

I make mistakes every single day; I run into beams I didn't see on the drawings, sometimes hit lights, hit HVAC ducts often enough but big deal, that's why fitters carry cutters, threaders and groovers. I try to keep my mistakes to a minimum but try as hard as I can I still make them. So what?

But the one mistake I do not make is the flow test. I started laying out sprinkler systems 35 years ago next month and the only time a job has scared me is when there was a difference between the flow test figured for the job and the actual flow test conducted after we got the job.

Running into a duct might cost $300 in labor and material but having not having enough water could cost enough to retire.

Before I did anything on this project I would conduct a flow test. I would invest $500 in a flow test kit (have your gauges certified), get the local fire official to help/witness and carefully document it with dates, times and get signatures of everyone there. I insist on conducting my own flow test using my certified gauges unless the AHJ will give it to me in writing on their letterhead.

You are laying out a 6" DCA which is going to be the smallest size but this thing is going to be 8" or even larger.

It isn't impossible but I will be surprised if this building doesn't require a fire pump.

We're talking about compressors so this is a dry pipe system, right? My first thought was ESFR K25 but the dry system knocks that out.

It does appear you need one level of in rack sprinklers using large drop but IMO that is the least of your problems. Based on Table 12.3.2.2.1(a) (2002) you are going to need a theoretical minimum supply of (25+(25^.5*11.2)+500=1,900 gpm not counting the in rack sprinkler or the additional water required to balance the system. Using large drop this job is going to end up needing 2,500 gpm and that is a lot of water. I will be surprised if the city can deliver this, you should think in terms of a 10" feed and DCA and, most likely, if you are lucky, a 1,500 or 2,000 gpm fire pump. Most likely (95% chance) the city doesn't have the water to supply the pump @150% so you are looking at a 150,000 to 200,000 gallon tank @ $1.00/gallon. Then the pump room (larger than 8'x8' I can guarantee you) and don't forget the boiler to keep the tank from freezing and tell the owner to enjoy his $15,000 per season heating bill that goes on forever.

Given the small size of this building the owner will have more tied up in the fire protection than they will the building.

And someone is pushing you for a "guess" on this?

 

[jrk7490]

SprinklerDesigner2,

Thanks again.
As the title of this post states, this is a dry pipe system.
I totally agree with your reply. I also considered the ESFR K25 at first. The 6" main was based on the slim possibility that in-rack sprinklers can be eliminated but all roads seem to be applying to wet systems.
The best scenario I have came across thus far is from a TYCO Interoffice Memorandum-Design Alternatives to Large Drop Sprinklers which the sprinkler recommendation for Single, Double,
Multiple-Row Racks without Solid Shelves (which they never confirmed type of shelves),
Max, Stor. Hgt. = 25', max. Clg. Hgt. = 35'
0.356/2600 (density/area) w/ 1 Level In-Rack Sprks
system demand = 926 GPM +132 GPM (Rack Sprks) = 1058 GPM as per NFPA13 (2002) Table 12.3.2.1.4
Recommended Sprinkler = ELO-231 (TYCO)
In addition, shouldn't I use Table 12.3.2.2.1(c) (2002) and not Table 12.3.2.2.1(a) (2002)? Table (a) is for storage up to 20' and these racks are 18' + storage at 42" high.

Thanks again for your reply. They were very informative.

 

[SprinklerDesigner2]

jrk7490,

Remember the 1058 gpm is the theoretical minimum which is is never achieved and depending on what you got in terms of roof slope etc I can see the actual demand being 1100 to 1300 to which you have to add the 500 hose too.

The one thing I am not sure about is the racks. These aren't normal racks but cantilever A-Frame holding bunks of lumber? Since they don't have typical flu spaces I am not sure what the correct design would be. I can guess but all it would be is a guess.

Unless specifications were specific, if it was a normal design build job, I would stipulate my design in my proposal but after I got the job I'd pay for a knowledgeable professional engineer advice. It's cheap insurance.

 

[chicopee]

Question #1- You may need in-rack sprinklers if you have solid shelves; check the NFPA.