Standpipe demand

[NewFPeng]

Hello

I have a building with a class III standpipe system that is also fully covered with an autotmic sprinkler system (combined system). I'm hydraulically calculating the system and the HMD floor has 5 standpipes. How many of those am I supposed to supply?

The Code says:
5-9.1.2* Hydraulic Calculation Procedure.
Hydraulic calculations and pipe sizes for each standpipe shall be based on providing 250 gpm (946 L/min) at the two hydraulically most remote hose connections on the standpipe and at the topmost outlet of each of the other standpipes at the minimum residual pressure required by Section 5-7. Common supply piping shall be calculated and sized to provide the required flow rate for all standpipes connected to such supply piping, with the total not to exceed 1250 gpm (4731 L/min).


I would greatly appreciate it if someone helped interpret this clause, especially "and at the topmost outlet of each of the other standpipes".

Thanks

 

[TravisMack]

flow (2) outlets at 250 gpm at the remote standpipe. At 250 gpm at the top outlet of the additional standpipes for up to 2 more standpipes for a total demand of 1000 gpm. (only 1 more standpipe if your building footprint is >80k sq ft) Because you have a sprinklered building, your demand is capped at 1000 gpm.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[NewFPeng]

Thanks for the reply.
What if:

My building is fully sprinklered, and has only one standpipe that feeds 4 outlets all on the HMD floor. Do I have to flow all 4 at 250gpm?

My building is fully sprinklered, and has only one standpipe that feeds 4 hose outlets, one at each floor. Do I have to flow all 4 at 250 gpm?

Another thing is;
I'm trying to get a grip on this. Correct me if I'm wrong, I have to flow (250x2) gpm at the HMD standpipe, then I have to flow 250 gpm at each additional standpipe up to 1250 (1000 if sprinklered)? This I understand but,
What if the HMD standpipe has more than 2 hose outlets? Is the priority for the extra flow given to the additional hose outlets on the HMD standpipe? or the other standpipes?

 

[stookeyfpe]

For the title of NewFP Eng your neither are an engineer or an Engineer with a degree in Fire Protection Engineering. Q equals 1,000 GPM for your design. The NFPA standards are clear on that.

 

[NewFPeng]

Thank you . I clearly understood that Q=1000 gmp for the building I asked about in my first post. The follow up questions are not related to it. I meant to say, "What if I had a building and..."
I'm trying to understand how the code applies in different scenarios.

 

[TravisMack]

If you have a horizontal standpipe, you are going to have more than one connection per floor. If you have a vertical standpipe, it would be rare to have more than (2) connections per floor. You typically have one at each floor and (2) at the top to facilitate testing. Just because you have a standpipe that serves 30 floors, it does not mean you would flow 4 outlets on that standpipe.

The calculation procedure is pretty straightforward in NFPA 14. Just follow it as outlined and you should be good to go.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[NewFPeng]

Thank you very much.