riser sizing 1

[yazguli]

Sorry for asking such a basic question!
In a 6 floor car parking the design area consists of 12 sprinklers in 6th floor.Suppose the flow rate to be 240 g.p.m and the feed main pipe size to be 3".What will the flow rate for which the riser size will be calculated at lower floors?The same 240 g.p.m or more? Not a combined system,wet sprinkler ,similar floors.

 

[TravisMack]

You can just calc the worst case area (assumed as the 6th floor in your case) and size the others based on that. So, whatever pipe sizing you have for the 6th floor, that would be replicated on the 1-5 as well.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[yazguli]

Thank you TravisMack for your reply . By "riser" I mean the vertical pipe feeding floor main pipes.So my question is : What is the size of this vertical pipe between floors ? Will the size be increased in lower floors or not and if it will,how much; proportional to number of design area sprinklers in every floor or any other way?
best regards

 

[TravisMack]

I understand the vertical pipe between floors is what you are talking about. You will size it based on calculations on your worst case area.

You can have a 4" riser feeding a 10 story office without issue, if you have enough pressure. I assume you are not sizing per pipe schedule and are sizing per hydraulic calculations. If the latter, then the calcs drive the size. If you need bigger pipe closer to the bottom to help with friction loss, then so be it, but it is soley determined by calculations.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[yazguli]

Travis Mack
It is the latter.Thank you very much.You are very helpful .