Another way is to calc both separately, but make sure you have a node that acts as the connection point between the two systems (easiest way is to include the base of system riser node for each system in each calc). You can create a k-factor for each system at this node ( k = Q / sqrt(p), although the calc program may already show you the k-factor at each node). Open the calc of the more demanding system (higher pressure required), input the k-factor of the other system at the balance point and run it. The more demanding system will cause the less demanding system to overflow (Q is higher than when you calculate the system on its own), but that’s OK as long as it still works with the flow and pressure you have available. If not, make modifications to the more demanding system to decrease the pressure required at the balance point, thus decreasing the overflow.
It’s definitely simpler (less thinking required and less iterations) if you can do it all in one calc. But that sometimes creates a calc that looks very complicated (lots of nodes). -Kyle M at Aero From: Ben Young <[email protected]> Sent: Tuesday, September 23, 2025 3:33 AM To: Discussion list on issues relating to automatic fire sprinklers <[email protected]> Subject: [External][Sprinklerforum] Re: Calculating in-rack sprinklers along with ceiling sprinklers Calc them as one calc. Sprinkcad has a designator for in racks. It's the easiest way to balance the two systems Benjamin Young On Mon, Sep 22, 2025 at 10:11 PM Lawrence Dirks <[email protected]<mailto:[email protected]>> wrote: Dear Sprinkler Forum Representative, The question I have today is pertaining to “balancing” in-rack sprinkler output with that of the ceiling output in a high-risk commodity application. I am using SprinkCAD within AutoCAD for this project, and I believe that the only way for me to run the calculation is with two separate calcs; however, I understand that the fire scenario would be such that the in-racks would need to operate simultaneously with the ceiling sprinklers. I assume that to represent this within calcs, I would need to modify the input criteria for the two separate calcs such that the outputs are adjusted as representative of simultaneous discharge. Towards this end, what strategy should one use for generating this balance across the two separate design areas? I look forward to your reply. Kindly, Lawrence _________________________________________________________ SprinklerForum mailing list: https://lists.firesprinkler.org/list/sprinklerforum.lists.firesprinkler.org To unsubscribe send an email to [email protected]<mailto:[email protected]>
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