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Ok, everyone, I've gotten myself really mixed up today. This is like one of those times where you're asking yourself "is this really how 'the' is spelled?"
This is for design intent calculations only. When you do your friction loss calcs on an extra hazard group 2, a 0.40 gpm/2,500 sqft, are you using the total flow demand minus hose connection? As an example, if I need to run 375 ft of pipe and I know that my most remote sprinkler requires 40 gpm (remember, this is only for design intent!) I am typically multiplying my distance by 1000 gpm for worst case scenario. The sprinkler contractors will do the detailed steps back to the nodes and mains. Hopefully I can right myself back up. Just one of those weird times. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
8 Comments
Dan Wilder
9/1/2023 07:37:04 am
In most cases, no hose allowance until you get back to the supply. So the last design intent calculation I saw went like this (modified for your numbers):
Anthony
9/1/2023 08:07:32 am
This is how I do my "napkin" calculations as well.
Jesse
9/1/2023 10:29:17 am
What Dan said
Dan Wilder
9/1/2023 08:31:52 am
Also - plug for the Toolkit...it has many of these calculators to help out the process
Jesse
9/1/2023 10:30:20 am
I emphatically second Dan's plug for the ToolKit. If you're not using it, you're cheating yourself. Thanks for creating this Joe!
Joe Meyer
9/1/2023 10:32:58 am
Wow - that means a lot, especially coming from you both - thank you for the endorsement!
Casey Milhorn
9/1/2023 08:53:28 am
Dan nailed it. It's amazing how many younger/newer designers can't do this. It's very important that estimators and designers are able to do a quick and dirty analysis like this. it can mean the difference of getting a RFI out day one of a signed contract, or 3 or 4 months into a contract when it gets a lot messier to tell someone they need a pump and/or tank. If I'm doing design intent for someone and it's close, that's when I take the time to pull a full calc together. On the delta flow (overage), I'll use anywhere from 5% for a gridded warehouse, to 50% or more for a dry attic. You have to account for the inefficiency of the system due to layout, weird elevation changes in your remote area, mixed K factors, etc.... that's where some people get in trouble with their design intent calcs.
Glenn Berger
9/1/2023 09:48:51 am
Way to go Dan! Leave a Reply. |
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