Sorry, my bad about the bad explanation.
Each fitting has a loss method (ASHRAE coefficient, specific coefficient, specific loss, or not defined). Whatever method you use, it will create a static pressure loss value from that (ex. 0.25 inches water column (in. wc.)). The total static pressure loss of the system is the sum of all static pressure loss values of all the fittings, duct runs, and pieces of equipment.
When I do a calculation, if I do it without Dynamo in Revit, I have to select each individual fitting (ex. all elbows) click on the “Loss Method Settings” edit and change what type of fitting its using in the ASHRAE Table (Table in first picture).
I’ve looked at this post, MEP - How to set dialog box values, which shows how to set the Loss Method dropdown (Warnings_NoLossDefined (1).dyn (6.9 KB)
).
And with this script, (Change-Coeff.-loss-fitting-duct.dyn (7.5 KB)
) they changed the “Specified Coefficient” to a number.
What I’m looking to do is reuse the python script to change the fitting from the ASHRAE table. I think the biggest part would be finding how to they relate each fitting in the table to a value or string.
I’m recognizing that this reply could just make it even more confusing.