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MEP 2013: Duct Flow = Multiple Values l/s

40 REPLIES 40
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Message 1 of 41
Schmit01
3670 Views, 40 Replies

MEP 2013: Duct Flow = Multiple Values l/s

Ok so the new air flow breakdown of a single duct is a nice update when when checking my Flow and velocities. But besides having to place a damper and measure its flow at a point, how am I suppose to tag a duct now indicating its flow without getting "Multiple Valuel/s"?

 

Ryan 

South Africa

MEP 2013

40 REPLIES 40
Message 2 of 41
Martin__Schmid
in reply to: Schmit01

Hello Ryan-

 

Do you use flow tags on ducts for internal use only, or are you required to show the flow on the ducts for construction document deliverables?



Martin Schmid
Product Line Manager
Mechanical Detailing and Electrical Design
Architecture, Engineering, and Construction
Autodesk, Inc.

Message 3 of 41
Schmit01
in reply to: Schmit01

Hey Martin 

 

Generally no, I dont directly tag the duct for the flow and use a damper instead. However we are working on a rather large complicated jigsaw of a project shaired with other consultants and their requirement is for the properties to be shown on the risers such as flow, size & system name which I would do with a single tag.

 

The annoying part is it worked perfectly fine in 2012. Yes I can do a work around and create a flow meter for those points but now its a lot of work that has to be done again. And ufortuantely we dont work on the same standard of using "Tees" but rather "Take offs". 

 

 

Message 4 of 41
al.armiger
in reply to: Martin__Schmid

Martin,

 

The data for the maximum flow for a section of duct is obviously there as it is reported in the pressure loss reports. Although we do not specificially tag the flow on a view we do use it for conditional formatting in schedules which no longer works. Can we access this value from with revit without writing code?

 

Regards,

 

Al

Message 5 of 41
Martin__Schmid
in reply to: al.armiger

Yes, the flow data exists, and is computed/updated with every change to the system.  The data is stored on Connectors.  The pressure loss reports extract the data from Connectors, and generates the output.  Connectors are not schedulable using 'normal' Revit schedules since they are not 'normal' Revit elements... futher, their data is not accessible from Duct schedules or tags.  The only way that you could populate a 'maximum flow' parameter on a duct element would be to use code (via the API) to dynamically (or manually) update such a parameter by extracting the values from each connector, and finding the largest.



Martin Schmid
Product Line Manager
Mechanical Detailing and Electrical Design
Architecture, Engineering, and Construction
Autodesk, Inc.

Message 6 of 41
al.armiger
in reply to: Martin__Schmid

Martin,

 

Although the ability to view the flow at any point along a duct/pipe is a step forward, the inability to view this simply in the properties is a backward move IMO.

 

Suggestion for future release would be to make this propogate and viewable and schedualable (sic) at the duct level.

 

regards,

 

Al

Message 7 of 41
Martin__Schmid
in reply to: Schmit01

Hi Al- how did you use the Flow value for conditional scheduling? What were you looking for by way of the schedule?



Martin Schmid
Product Line Manager
Mechanical Detailing and Electrical Design
Architecture, Engineering, and Construction
Autodesk, Inc.

Message 8 of 41
al.armiger
in reply to: Martin__Schmid

Martin,

 

See the attached screen shot, basic conditional format in that if the velocity is "4.0 m/s > Velocity or Velocity > 7.5 m/s" cells turn red. In the project this can be used for verification that velocities are within standard design parameters from one schedule rather than multiple colourised floor plans. Data was also able to be exported to excel for other calculations as necessary.

 

This won't work in ducts that have "Multiple Value" for Velocity (same for Friction and Flow).

 

Regards,

Al

Message 9 of 41
Martin__Schmid
in reply to: al.armiger

Hi Al-- that is a very helpful example.  Thanks for taking the time to reply.  You can find this info in the Pressure Loss Report (PLR)... but I understand that the conditional highlighting is additionally beneficial, which isn't provided in a PLR.



Martin Schmid
Product Line Manager
Mechanical Detailing and Electrical Design
Architecture, Engineering, and Construction
Autodesk, Inc.

Message 10 of 41
al.armiger
in reply to: Martin__Schmid

No worries Martin. At least one Mechancial Contractor that I know off is not upgrading to 2013 as they use the schedules for a simillar task. So I'm not the lone voice in this space.

 

Regard,

 

Al

Message 11 of 41
Martin__Schmid
in reply to: al.armiger

If the PLR provided conditional formatting, would this solve the problem (for you and the contractor?)



Martin Schmid
Product Line Manager
Mechanical Detailing and Electrical Design
Architecture, Engineering, and Construction
Autodesk, Inc.

Message 12 of 41
al.armiger
in reply to: Martin__Schmid

Martin,

 

The PLR can be exported to CSV and conditional reporting applied in excel.

 

If the conditonal reporting could be applied on generation to HTML or CSV it would be a work around but still requires the generation of a report whenever you want to check the data. I can give to someone without revit to verify, although I could do this with a schedule in 2012. There would need to be more functionality with fully editable report templates which we could build in the revit template. Simple fields only available currently.

 

A lot more work then I would like to commit to particularly as the 2012 solution just worked.

 

The data is obviously there as it is available in the PLR just not visible to the average Revit user.

 

Simple solution IMO is to display the data in the properties/schdules as  a readonly MaxFlow (MinFlow, Min/MaxFriction, Min/Max Velocity would be nice too.)

 

I'm sure there are plenty of other things we could do with the data in calculated fields if it was available to us.

 

Frustrated as always,

 

Al

Message 13 of 41
asommer
in reply to: Martin__Schmid

Whoa... I just started my first Revit 2013 job, I didn't notice the "Multiple Values" for the flow in the duct... In 2012, you select a duct and then read the flow.  I don't need to tag it, I just need to select it and read the info on it.  What flow other than the connected flow is it reading?  There is really only one flow value that should be there.

 

Exporting a PLR doesn't quite go with the workflow we utilize.  Our engineers want to utilize the schedule and conditional formating as others did before,  Find the one that is highlited (by hitting "Show"), and fix it without having to look through an exported file broken into sections or inspecting a whole system for issues.

 

We had a great way to check our duct system.  What gives?  Can I get it back?

Message 14 of 41
Martin__Schmid
in reply to: asommer

>> What flow other than the connected flow is it reading?  There is really only one flow value that should be there.

If there are taps, there are likely multiple flow values along the length of the duct... refer to the attached image.. what is the 'flow' in this case?

 

>>Find the one that is highlited (by hitting "Show"), and fix it without having to look through an exported file broken into sections or inspecting a whole system for issues.

Fix what?  



Martin Schmid
Product Line Manager
Mechanical Detailing and Electrical Design
Architecture, Engineering, and Construction
Autodesk, Inc.

Message 15 of 41
asommer
in reply to: Martin__Schmid

1.  We would "Tee" that main instead of "Tap".

2.  Where you show your "Flow Tag", it should say 500 CFM.

3.  It is not giving me a flow at all, it is saying "Multiple Values".

4.  In Conditional Formating in a "Duct Schedule", you can make it highlight if the Friction value is above what you require.  Same for Velocity.  From the schedule, I Right-Click the value that is highlighted, hit "Show", it takes me directly to the duct that has too much Friction or Velocity.  I would typically just make the duct larger.  I can normally read these same values in the properties dialog.  For some reason, our Engineers and Designers like this better than the "System Inspector".

 

Please see attached image.  I get a value for the individual runouts to diffusers (Top Tag), but not upstream.  The second from the top should have a flow of 200.  3rd should say 400, bottom should say 200.  Why would there be "Multiple Flow Values?

Message 16 of 41
Martin__Schmid
in reply to: asommer

The reason your case says multiple values can be discovered using a system color scheme... or, refer to the attached image. 

 

If I understand correctly, you are trying to find and fix is cases where the velocity or friction exceede some value. 

 

What do you think of the mechanism for finding Flex Ducts exceed the specified length?  I.e., in Mechanical Settings > Duct Settings > Conversion > Branch > Maximum Flex Duct Length... when you have flex duct that are too long, you can use the Warnings window to find them.



Martin Schmid
Product Line Manager
Mechanical Detailing and Electrical Design
Architecture, Engineering, and Construction
Autodesk, Inc.

Message 17 of 41
asommer
in reply to: Martin__Schmid

I see........................  We will have to find a different way.  What was the Reason for this change?  Did it improve something else?

 

If there was a "Warning" about over-pressure or over-velocity, that might be OK, however some systems are different than others.  In this case, the system Upstream of the Fan Terminal Units is a High Velocity, High Pressure System.  Downstream, the Pressure and Velocity are designed to be lower.  We also Size Return and Exhaust systems with different Friction And Velocity values than Supply.

Message 18 of 41
Martin__Schmid
in reply to: asommer

The reason for the change is that in 2012 the scenario in the attached image would have the pressure drop computed based on the entire duct length having a flow of 1500 CFM.  In 2013, the pressure drop is properly computed based on the allocation of 500 CFM and 1000 CFM in the sections as indicated.

 

This was a general problem from all duct/pipes with taps.



Martin Schmid
Product Line Manager
Mechanical Detailing and Electrical Design
Architecture, Engineering, and Construction
Autodesk, Inc.

Message 19 of 41
asommer
in reply to: Martin__Schmid

Ok, That makes sense.  Thanks for your replies, Martin.

Message 20 of 41
al.armiger
in reply to: asommer

Ahh we love a good robust discussion.

 

I may be repeating myself but....

 

I understand the reason for the change but still feel that the parameters for MaxFlow should be available to the user as well. It is this figure that is used to calculate the duct size not the flow in a particular portion of a duct length. Think of exporting out to a separate sizing package or similar, this would now be defunct, the cynics would say deliberately but I am not so mean spirited.

 

A warning will still negate the use of schedules to verify the ductwork sizing.

 

As the parameter still exists againsts the connectors (it is used internally for the sizing calcs) it should be still possible for Autodesk to open this figure up to the user.

 

I think you will find that a number of groups will come out of the woodwork once this is realised, I can now personally count four.

 

I'm all for more robust software but Autodesk have to mindful that removing access to parameters/tools/etc. will break customisation out on the floor which has always been one of Revits strengths.

 

Regards,

 

Al

 

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