Dear Dynamo Experts,
Is it possible do understand which duct is main duct and which one is branch duct by using dynamo. I have a one input (it is duct fitting -Tee). And there are 3 duct connected to this fitting and I want to know which of these ducts is connected to this Tee fitting is main which is branch by using dynamo.
Just FYI : branch duct is perpendicular to main ducts.
Thanks for helps in advance.
Size perhaps?
Any solution possible using Dynamo? 
No clear idea here, there may be a way to utilize flow rate or a similar parameter which is simple. I’m not an expert on the MEP side. Perhaps @T_Pover has an idea?
One other possibility: utilize shortest walk.
Idea would be to get the location line of all duct systems in a view, build a connected network via some fancy polyline operations, find ‘endpoints’ where the network only extends in one direction, and then do a shortest walk from each endpoint member to the origin point. Search the walk networks for common items - those are your mains - and revert back to the duct elements. The drawback with this is the method may tax your system a good bit, the extent of which I am not sure of. I’m also not sure of how to find the start point beyond size (pretty sure the largest of the singlely connected ducts would work, but again, no expert here).
Hi,
if your branches are always perpendicular, the strategy could be to group the pipes connected to a fitting and then remove the 2 pipes of 3 that are parallel.
You can use nodes from MEPover package (thanks @T_Pover! ) to select collectors and pipes connected to collectors. The rest of the job is to filter out the parallel vectors.
If you have fitting with more or less than 3 pipes, than it has to be adjusted.
Hope it helps!
Many Thanks Lucamonzoni! 
