Determining Combined Supply Pipe Size

[Haldorson]

Hello,

I have a project - 6,000 square foot industrial building - where I have been asked to confirm the required incoming combined supply pipe size. I have completed the sprinkler design and calculations and I can make it work adequately with a 4" incoming.

The domestic system requires a 3" pipe size.

Am I okay specifying a 4" incoming or should it be 6"?

Is there a rule-of-thumb that would be useful for me?

 

[cdafd]

yes seperate taps/ lines for domestic and fire sprinkler main

is this in the US??????

 

[Haldorson]

The incoming is combined domestic and fire.

This project is in Canada.

 

[chicopee]

What do the Canadian building and the insurance inspector have to say about that?

 

[sspeare]

Don't look for "Rules of Thumb."

What are your flow requirements? Sprinkler = _?___ GPM. Domestic = __?__ GPM? If you're combining Spkr & Domestic in the same lateral (check with your AHJ), then:

Total Flow = Spkr + Domestic. Select a lateral pipe size that gives a reasonable velocity at your peak flow. Then, see if you can live with the resulting pressure drop in the lateral. Repeat the process until you achieve an optimum. It's called: Hydraulic Calculations.