Conduit with and without fittings - when to use which?

[HVAC-Novice]

for an HVAC project I ran some existing conduit to show how much clearance I need. I figured out how to add fittings/crosses etc. Basically they work like a pipe. So far so good. 

There also is a "conduit without fittings". Why would I ever need that? And if I needed it, I could just use the conduit with fittings, and just not use fittings. To top it off, the " conduit without fittings"  also can be assigned with fittings and seems to be able to create runs with all the fittings as far as I can tell. One difference is, an elbow can't be converted into a cross (in " conduit with fitting" I can select an elbow and select a "+" to make it a junction box)

I read some threads that made it sound like the difference is if conduit gets bent in the field. But to me as modeler/designer it doesn't seem to matter how a fitting is created (field-bent vs. pre-made).

There doesn't seem to be a flex conduit option.

Am I missing something? Can someone explain why we have 2 types and when we would use one over the other? 

[timlove]

They do function slightly different in Revit.  I hate Conduit with Fittings, as Conduit Runs are only the straight sections, once you hit a fitting it becomes a different run, and fittings are not included, mostly because they are intended to be a fitting added to straight conduit.  For that reason, we use Conduit without Fittings, even for PVC.  At high level modeling, the fitting sizes can be an issue for modelers, as is creating schedules.  Bend radius and angles are also restricted when setting up conduit with fittings.

Flex conduit has been a request for over a decade, we have large flex conduit so I don't know why it is not a thing in Revit since pipe and duct both have flex.  Have created conduit to pipe fittings so I could use pipe flex for 4" conduits before.

So if you are just doing it for graphics or to demonstrate an idea of how conduits could be ran, either one works just as well. 

[HVAC-Novice]

Thanks for the explanation. I'm not scheduling conduit. and if I would do some electrical design, I only would model some main runs to indicate space required etc. I wouldn't model all the small conduits to each equipment (unless they are major clearance issue). fittings would be left to installer, I suppose. So, for me, it seems using the "conduit with fittings"  works just fine. FWIW, most projects we get from consultants never show any conduit or any indication where to run them. I always found it odd since you at least want to ensure the main runs have space in the field. 

I don't understand what you mean by "once you hit a fitting it becomes a different run". I initially though conduits serve a function in electrical systems (like pipes in hydronic systems) . I looked into the E-panels and those connectors can be tied to voltage etc. parameters. but it seems there aren't parameters that would actually use the connected load (to the panel). but if it would, I assume the conduit can be used to "connect"  panels and other electrical equipment and create the system (like hydronic pipes do). I'm just not sure if this is actually functioning. If it does, i see your concern what " becoming a different run"  means. 

[fabiosato]

Hello,

Conduit without Fittings can be used to represent flexible conduits since they create conduit runs to calculate the total length.

The use of flexible pipes is not very efficient in 3D environment and it is not possible to restrict the minimum bend radius as well. The use of Parallel Pipes is not available for Flex Pipes, which can be very time-consuming depending on the design you need to create.