Multiple fire risers and multiple FDC's

[moondoggy]

We recently installed two separate risers covering several different areas of the building. Each is covered by its own FDC located on the same side of the building.

The fire marshal recently commented that the two fire systems have to be connected together, With one FDC. Is this an NFPA code requirement or other national code requirement?

 

[stookeyfpe]

Is the building a highrise? If so, NFPA 14 would require the FDCs to be interconnected because it requires two remote but connected FDCs on a highrise building.

If not, I would say that it is not required. See NFPA 13, section 8.16.2.4.5. You are required to provide a sign indicating the portions of the building served by the individual FDCs.

 

[jgailla]

The last civil design we did the fire marshal made us use only one FDC. I don't believe this was a code requirement, just the personal preference of the fire marshal. Their rationale was that they didn't want the firefighters looking around for different FDC's or worrying about whether they were hooked up to the right FDC. This was for a 100,000 square foot one story building.

 

[sprinklerdesigner]

While not an NFPA issue many fire codes, BOCA for one, require if a building has multiple FDC's then all FDC's be interconnected so if you pump into one you charge all the systems in the building.

 

[stookeyfpe]

But not in the International Fire or Building Code ...

 

[moondoggy]

Hi Sprinkler Designer,

We thought we had a solution. We have a water pit at curbside from which we thought we could tie into the fire water line at that point and charge the system from the street. Only problem is that this fire water line, in addition to being the source for the two FDC's at the building, also charge the Hydrant loop around the building. The fire marshal did not like it and his only reason for not accepting this solution is because it is not done elsewhere in his township.

Is there a code (any) that would prohibit doing it this way, i.e., charging both the FDC's and hydrants?

 

[TravisMack]

Moondoggy:

I have done something similar on many large warehouse projects. There is a supply from the city main to the pump room. From there, we exit the pump and install the underground fire loop around the building. This puts all of the hydrants on the loop at pump pressure. We then installed 2-way hydrants, instead of the 3-way with pumper connections. The AHJ ws just concerned that some one would try to connect from the pumper outlet on the hydrant to the pump on the truck. Since the hydrants only had 2.5" outlets, that was not a problem.

The only thing that would caution me in your scenario is if the hydrants are not on a dedicated fire line. You don't want to charge the water loop if there are domestic devices coming off of it. In the situation I described above, we always had a dedicated fire loop around the building.

 

[moondoggy]

Hi TravisMack,

Could you give me alittle better understanding of your first paragraph. I am having a little trouble understanding what you described.

Again, I have a fire loop around the building, 8" piping to which five hydrants are installed around the building. Off this line I tapped into it at two separate points and brought water into the building to feed two independent backflow preventers feeding separate sprinkler riser systems within the building. A FDC is feed into each fire riser header.

 

[TravisMack]

OK..let's see if I can describe this better.

Let's say you have a large warehouse, with a pump room located in the NW corner of the building. We would make a tap from the city main and run it directly to the pump at the NW corner. Off of this line would be a "suction" 3-way hydrant. From the pump discharge, we would go back underground and feed a fire line loop around the building. Off of this loop would be fire hydrants and lead-ins to the various system risers.

There would be one FDC located at the pump room. The FDC would charge the entire site fire line, thereby charging all of the hydrants and risers/systems. The 3-way suction line hydrant is located adjacent to the FDC and upstream of the pump. This allows the FD to connect to a pumper connection on the hydrant and then go to the pump on the truck. From there, they can charge the ENTIRE SYSTEM via the FDC.

Doing this provides a single point of connection for the entire facility. Most of the AHJs I have dealt with prefer this arrangement for these large facilities.

 

[moondoggy]

Hi TravisMask,

Thanks for the clarification. Now if I understand you, charging the entire hydrant exterior loop as well as the interior riser pipes from a single FDC is acceptable?

We had an inspection from the local code fire inspector today. He was sent to review our approved fire sprinkler system drawing and the actual installation. We put the system in in accordance with the Fire Code Inspector Approved Fire System Drawing which approved the individual FDC connections not interconnected. It did not matter that they previously approved this installation. Today they said we had to interconnect the two separate riser installations and run a line to the front of the building to a single FDC. This involves installation of an additional 700 feet of piping through a food facility already in operation.

We proposed giving them a new FDC connection at the valve pit located at the curb. It would charge the exterior hydrant loop as well as charging the two separate, currently installe FDC's and thereby their associated riser sprinkler systems to which they supply. From your description, this approach seems acceptable. We just need to convince the Fire Prevention people.

 

[TravisMack]

Moondoggy:

That is exactly what I was saying. I can understand them not wanting 2 FDCs. It can be confusing.

What you are proposing with the single FDC to charge the entire system is not a problem. I would ask the inspector to show you where in the standards that it says you can't do that. He may try to hang up on the fact that you can't have a shutoff valve in the FDC piping. However, if you read further into NFPA 13, you can have shut off valves for multiple riser systems.

I think you have a winning argument all around. The only thing you may have to look at is your backflow prevention. If you put the FDC on the incoming line, you will likely need to have a backflow preventer between the city supply and the FDC. If you just have check valves in your area, it should not be a real issue.

 

[LCREP]

Take a look at NFPA 13, 2002 page 235 and figure A8.15.1.1.4. It shows a pit with an FDC. This is very common way to feed the system. I perfer this set up then running 700' of 4 inch pipe, not good when you have high sprinkler demands.

 

[LCREP]

Also take a look at the Fire Protection Handbook, 19th edition, Chapter 20, page 10-393,Fire Department connections, will help with your case to the FD. Check out Automatic Sprinkler System Handbook, 2002 edition, page 333, exhibit 8.41, and the comments in blue at the top of the page. All info to make your case with, good luck, let us know how it turns out.

 

[cdafd]

If you already have a fdc feed inside the building a way to go is tee off of that feed inside the building and hot the same size feed main on the other system at the nearest point and you are interconnected. All you need is an addtional check valve.

I would say the problem wit trying to pressurize both the fire hydrants and sprinkler system is you may never get any pressure to the system with the amount of pipe laid and if you have two or three fire trucks sucking from the same lines.
Also, if you have a fire pump being feed by the same main, you cannot have the fdc before the intake it has to be connected on the discharge side

 

[ChrisConley]

Bah, I hate stupid questions... but how else can you learn?

What does the acronym FDC stand for?

 

[moondoggy]

FDC: Fire Department Connection

 

[TravisMack]

maybe I didn't explain properly, but the FDC is installed on the discharge side of the pump in the scenario presented above.

As far as not getting pressures, we have calculated the system and allowed for a fire hose allowance at the loop to account for the Fire Dept use of the line.

 

[moondoggy]

Can anyone provide me with a copy of the NFPA 13, 2002 page 235, figure A8.15.1.1.4. If not can you paraphrase or describe what it says.

Same for the Fire Protection Handbook, 19th edition, Chapter 20, page 10-393,Fire Department connections and the Automatic Sprinkler System Handbook, 2002 edition, page 333, exhibit 8.41, and the comments in blue at the top of the page. My sprinkler contractor does not have these versions.

 

[cdafd]

moondoggy

sorry I throw a fire pump into your set up.

I still do not like the set up wher you pressuirze the sprinklers and fire hydrants. There is the potential to rob the sprinkler system.

Once again you can connect from one fdc inside the building to the nearest largest main in the other system and supply a check valve. this may cut down on the amount of pipe that needs to be run.

 

[TravisMack]

Cdafd:
What is the difference if you pressurize the entire loop and take water from the discharge hydrants, or if you take water from the suction hydrants.

I can do a K14 50 PSI ESFR (1200 gpm system demand) system with a 1000 GPM pump and not pressurize the loop, or I can use a 1500 GPM (1200 gpm system demand + 250 hose allowance) pump and pressurize the loop. How is it really any different? If I don't pressurize the loop, I size my pump for the sprinkler system only. If I do pressurize the loop, the pump is sized for the system demand plus hose allowances.

On very large projects, it can be a considerable cost savings to pressurize the loop and install multiple pressurized lead-ins to the buildings to serve a riser manifold. The project I am thinking of was 1.3 million sq ft under roof. There were 33 overhead systems and 3 in-rack systems. It was determined that the cost savings to do the pressurized loop was significant on the project.

I am curious as to the objections, and not trying to argue. I am trying to learn from others. Do you feel that the hose allowances required by NFPA are inadequate to and cause you to rob from the system?

Stookey - If you are following this thread, what are your thoughts on this scenario?