About HVAC Parts

When working with HVAC you can decide to work with catalog that contains

• Case1 : "Full parametric" parts (no predefined configuration)
  • At each placement system creates a new reference
  • the part adjust to the element on which it is placed 
  • Part Definition : instanciation rule = "New Reference"
• Case2 : or fully resolved individual standard part
  • At each placement the Part is placed as a new Instance
  • the part reference will be filtered to found the one in catalog with compatible size with the selected element
  • Part Definition : instanciation rule = "Reuse or New Reference" or "Reuse Reference"

in most of the case in HVAC, 

• Circular part are standard (Case2)
• Rectangular part are non-standard (Case1)
  • note : it could be good to standardized the duct rectangular section size to minimize the number of possible configuration and then to optimize the procurment

About HVAC Attributes

Equivalent diameter

Because it is easier to do the calculation for Circular duct section , the result of the sizing calculation is a Diameter but we call it Equivalent Diameter.

In case that selected duct reference that will be used later will be not circular. then we need to found the values of HeighxWidth that give the same pressure loss or resistance that the calculated Circular/equivalent diameter. This is done through empiric formulasas an equivalent  the equivalent diameter is the diameter of a circular duct or pipe that gives  rectangular duct or pipe.

In CATIA HVAC the criteria tha tis used for compatibility check between component is the Equivalent Diameter. which is the unique attribute that allows to ensure the same flowrate allong the line even if the section shape is changing

Wall Thickness

References

see dedicated page about HVAC Part creation in SETUP section