Fire flow for sprinkler systems 1

[DPAJR]

I am working on a short plat with a private fire system. I need to size fire pumps for fire department connections as well as sprinklers. The house sizes and locations are undecided at this point. Is there some rule of thumb for gpm per thousand square feet of building just to get a ball park figure?

Thanks,
DPAJR

 

[TravisMack]

If you are doing houses, it is typically governed by NFPA 13D. In that standard, you are only required to calculate 2 heads flowing. The largest demand with 2 heads flowing 20 gpm each is 40 gpm + a few gpm for over discharge. Most homes can typically be done at about 60-70 psi with moderate pipe sizing. You will need to bring in a minimum of 1¼" piping for the supply, with a 1" meter.


If by Fire Dept Connections, you mean hydrants, then your pump capacity will be affected by that significantly more than the sprinkler systems.

 

[DPAJR]

Hi Travis,

Thanks for the quick response. Your answer is really helpful. I will be posting a star for you. If there are three houses should the flow be tripled? This is a fairly remote location but there is no brush or forest for miles just sand.

The reason I was looking for a quick ball park is that I just ordered NFPA 24 and then I find I need two more NFPA documents. My local university book store stocks some NFPAs but doesn't have 13 or 20. It's not just the expense it's the delays. I can't wait to see what additional documents I will need once I get my hands on NFPA 13 and 20.

Thanks again,
DPAJR

 

[TravisMack]

From a fire sprinkler standpoint, we only design for a single event at one time. If all 3 houses go at once, you have much bigger issues to worry about

24 is going to cover the underground installation. 13 will cover you more commercial type buildings. You will want 13D for one and two family dwellings. 20 will cover your pump requirements.

You may also require the IFC (International Fire Code) to determine what your site fire flow requirements are going to be. Commonly, you have requirements of 1500 gpm @ 20 psi at any hydrant. So, for your area of 3 houses, you have the flow without a problem...it is pressure that will be an issue. So, you may need to provide a pump with 1500 gpm @ 50 psi or something along those lines. That pump should provide around 60 psi at the flows for a house.