# Pressure drop in Ifc **URL:** \ **Category:** IFC\ **Created:** [April 6, 2020, 11:14am UTC](https://forums.buildingsmart.org/t/pressure-drop-in-ifc/2565 "2020-04-06T11:14:51Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![ArnoMarechal](https://avatars.discourse-cdn.com/v4/letter/a/77aa72/32.png) [@ArnoMarechal](https://forums.buildingsmart.org/u/ArnoMarechal)\ **Post date:** [April 6, 2020, 11:14am UTC](https://forums.buildingsmart.org/t/pressure-drop-in-ifc/2565/1 "2020-04-06T11:14:51Z")
Is there a possibility to define pressure drops over Hvac related components in Ifc (eg. like in IfcDuctSegment, IfcPipeSegment, IfcFan, IfcPump etc.)? ---
**Author:** ![Cyril](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.buildingsmart.org/cyril/32/353_2.png) [@Cyril](https://forums.buildingsmart.org/u/Cyril)\ **Post date:** [April 10, 2020, 10:19am UTC](https://forums.buildingsmart.org/t/pressure-drop-in-ifc/2565/2 "2020-04-10T10:19:42Z")
Every child class of [IfcDistributionElement](https://standards.buildingsmart.org/IFC/DEV/IFC4_2/FINAL/HTML/link/ifcdistributionelement.htm) might have multiple [IfcPort](https://standards.buildingsmart.org/IFC/DEV/IFC4_2/FINAL/HTML/link/ifcport.htm) or preferably his child class [IfcDistributionPort](https://standards.buildingsmart.org/IFC/DEV/IFC4_2/FINAL/HTML/link/ifcdistributionport.htm) which have a Pset for specific domains eg. for ducts : [Pset\_DistributionPortTypeDuct](https://standards.buildingsmart.org/IFC/DEV/IFC4_2/FINAL/HTML/link/pset_distributionporttypeduct.htm) which contain a pressure propertie. Pressure drop or gain (for a fan) is difference between inlet and outlet pressure value. ---
**Author:** ![ArnoMarechal](https://avatars.discourse-cdn.com/v4/letter/a/77aa72/32.png) [@ArnoMarechal](https://forums.buildingsmart.org/u/ArnoMarechal)\ **Post date:** [April 10, 2020, 12:41pm UTC](https://forums.buildingsmart.org/t/pressure-drop-in-ifc/2565/3 "2020-04-10T12:41:23Z")
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](https://standards.buildingsmart.org/IFC/DEV/IFC4_2/FINAL/HTML/link/ifcfan.htm) properties like pressure rise and mass flow are accessible in [Pset\_FanTypeCommon](https://standards.buildingsmart.org/IFC/DEV/IFC4_2/FINAL/HTML/link/pset_fantypecommon.htm) and for a [IfcPump](https://standards.buildingsmart.org/IFC/DEV/IFC4_2/FINAL/HTML/link/ifcpump.htm), 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 ---
**Author:** ![Cyril](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.buildingsmart.org/cyril/32/353_2.png) [@Cyril](https://forums.buildingsmart.org/u/Cyril)\ **Post date:** [April 12, 2020, 8:41pm UTC](https://forums.buildingsmart.org/t/pressure-drop-in-ifc/2565/4 "2020-04-12T20:41:55Z")
As you might have guessed. Revit is not the best to read and write IFC. I recommend you to read : - [How to create better IFC files with Revit](https://thinkmoult.com/how-to-create-better-ifc-files-with-revit.html) - [IFC from Revit - Part 1](https://www.bim42.com/2018/03/ifc-for-revit-1/) - [IFC from Revit - Part 2](https://www.bim42.com/2018/03/ifc-for-revit-2/) 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 : ![2020-04-12 22_24_01-Snoop Objects](https://us1.discourse-cdn.com/flex016/uploads/buildingsmart1/original/2X/b/b4490be895f3a5b5ca33a6cee0299775d70a15c5.png) I see that you already opened [an issue related to MEP on revit-ifc tracker](https://github.com/Autodesk/revit-ifc/issues/162) đź‘Ť ---
**Author:** ![ArnoMarechal](https://avatars.discourse-cdn.com/v4/letter/a/77aa72/32.png) [@ArnoMarechal](https://forums.buildingsmart.org/u/ArnoMarechal)\ **Post date:** [April 13, 2020, 6:54am UTC](https://forums.buildingsmart.org/t/pressure-drop-in-ifc/2565/5 "2020-04-13T06:54:46Z")
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! ---
**Author:** ![Hans\_Lammerts](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.buildingsmart.org/hans_lammerts/32/835_2.png) [@Hans\_Lammerts](https://forums.buildingsmart.org/u/Hans_Lammerts)\ **Post date:** [April 13, 2020, 9:13am UTC](https://forums.buildingsmart.org/t/pressure-drop-in-ifc/2565/6 "2020-04-13T09:13:56Z")
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. [https://www.bricsys.com/en-eu/mechanical/features/](https://www.bricsys.com/en-eu/mechanical/features/) ---
**Author:** ![JiriK](https://avatars.discourse-cdn.com/v4/letter/j/f1d935/32.png) [@JiriK](https://forums.buildingsmart.org/u/JiriK)\ **Post date:** [August 17, 2020, 2:16pm UTC](https://forums.buildingsmart.org/t/pressure-drop-in-ifc/2565/7 "2020-08-17T14:16:17Z")
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.