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July 19, 2013

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Jeremy, using this method, could you theoretically calculate the friction loss of sprinkler piping systems?

To do so, in addition to what you show, it would need to be able to know pipe/fitting elevations (pressure loss due to elevation), take into account pressure increases due to fire pumps, take out flows due to open hydrants, and only flow sprinklers (with a given k-factor) which are set to "flowing" (in the sprinkler family), at a specified minimum pressure.

You would also need a script that adds node tags to every junction/equipment like inlet/outlet of fire pumps.

If you could do all that, sprinkler layout technicians like me (and our companies) would be paying you around $1000-5000 for each license of your add-on... There are only two other companies that have Revit "solutions" for fire sprinkler hydraulics right now, and both rely on external programs or import/export functionality, both are buggy and no good, and probably will never utilize this feature because they want to keep the hefty $5000-12000 pricetag for their external software.

Can you provide instructions on how to build and install the add-in?

Dear Gary,

The procedure is identical for all Revit add-ins. It is described in full detail in the DevTV and interactive tutorials provided by the Revit developer centre and getting started materials:

http://thebuildingcoder.typepad.com/blog/about-the-author.html#2

Cheers, Jeremy.

Jeremey,

I have a comment and question about this addin.
Under:
static public void getSectionsFromSystem(MEPSystem system, List sections)

I had to change this line:
MEPSection section = system.GetSectionByNumber(ii);
to
MEPSection section = system.GetSectionByIndex(ii);

Because the sections weren't necessarily in numerical order, and also didn't always start at one. Maybe I misunderstood what you were doing there, but I was having a rough time getting all the sections until I changed this to index.

My question is, when I use section.TotalPressureLoss, I get a double of 9.27246709... The API documentation under "MEPSection.TotalPressureLoss Property" states that the default value for this is Kgf per square feet, which converts to almost 4 inches of water, way beyond what's actually in my 2 diffuser system. Is KgF per square feet correct? Pascals, inhg, KgF per square meter, stones, slugs, furlongs, yards and atmospheres, don't seem to correspond with the Revit reported value (using the system inspector) of 0.1222531 inwg either.

As always thank you for this blog and the examples you provide.

Jeremey,

Have you seen in the API a way to turn off system calculations for all piping and duct work instead of individually as currently required?

Dear Arif (or Arief :-),

No, I am not aware of any such switch.

However, in the far distant past, I sometimes ran an MEP-specific add-in that only manipulated generic Revit element parameters in Revit Architecture, with no Revit MEP machinery available.

That enabled me to make changes to the parameters and thus change the MEP model without any recalculations being triggered.

Cheers, Jeremy.

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Jeremy Tammik

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