Is there a possibility to define pressure drops over Hvac related components in Ifc (eg. like in IfcDuctSegment, IfcPipeSegment, IfcFan, IfcPump etc.)?
Every child class of IfcDistributionElement might have multiple IfcPort or preferably his child class IfcDistributionPort which have a Pset for specific domains eg. for ducts : Pset_DistributionPortTypeDuct which contain a pressure propertie. Pressure drop or gain (for a fan) is difference between inlet and outlet pressure value.
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Thank you for the information, but I need to export the information about pressure drops/gains from Revit. However in Revit it is for a far as I know only possible to add properties to families and not to the ports. So this is not really a solution? Do you know also an workaround for this?
Another strange thing: for an IfcFan properties like pressure rise and mass flow are accessible in Pset_FanTypeCommon and for a IfcPump, which also realises a pressure rise, pressure and mass flow are not accesible.
However there exist als the property PHistory for entities, but this is neither accessible
As you might have guessed. Revit is not the best to read and write IFC. I recommend you to read :
To the best of my knowledge Revit is not able to export this info correctly. I recommend you to use a custom Pset.
However you cannot always define pressure drop correctly e.g. for a tap. Internally Revit has a connector logic with similar informations you see in IfcDistributionPort Pset but you cannot manage it :
I see that you already opened an issue related to MEP on revit-ifc tracker 
Yes, I did already read the links you mentioned and came also to the conclusion that Revit is not the ideally IFC tool. Therefor I asked here my question, to see if someone more experienced with Revit-Ifc could maybe help me. But I will do the workaround with custom Pset.
Thanks for the help!
Maybe you could try a dwg based workflow. BricsCAD ultimate has mechnical and BIM functions included. This might give you ifc export the way you like them.
Is it possible to store in IFC4 density and kinematic viscosity of the fluid transported in a duct system?
We would like to store in IFC4 all parameters required for pressure drop calculation, but we haven’t found any property or attribute to store these two parameters.