Measuring ventilation ducts area

[Puzon]

Hello

 

As a hvac calculation engineer i often need to measure quickly pipes length and ventilation ducts area.

Measuring pipes lenght is quite easy with qselect + tlen.lsp, but, so far, i've no idea how to measure ducts area quickly.

 

I'd like to add that ducts surface seen in 2D would satisfy me and i only talk about 2D drawings.

Do You have any idea how to do this measure? Maybe there are lisp routines that could help?

[RobDraw]

I can't think of a quick way of doing this. A lot depends on how the ducts were drawn, ie 1-line, 2-line, lines and arcs, polylines, etc. I've seen and done a lot of HVAC drafting and some of the techniques I've seen would make this exercise frustrating. That being said. I think I would draw polylines right over the ducts and add up the areas. How big an area you use for each polyline is going to depend a lot on how you like to do it. If you give me more information about what you got to work from, I may be able to help some more.

 

By the way, why do you need the area? I can't think of a reason for it.

Edited August 12, 2011 by RobDraw
typo

[ReMark]

There have to be any number of lisp routines that measure and report back the area of a polygon. I think Lee Mac wrote one didn't he? Could probably find a couple at the Cadalyst magazine website (Cad Tips & Tricks) or at "The Swamp" or at the "CADforum".

[SLW210]

You could hatch and retrieve the area of the hatch. A closed polyline, a region and a boundary will all give area. It can be retrieved with List or properties. As mentioned there are plenty of LISP around for this. Cadalyst and The Swamp as well as CADTutor should have the necessary LISP.

 

How are you needing to use the information?

[ReMark]

Lee's area label lisp may be overkill but it's worth a look.

 

See this...http://lee-mac.com/arealabel.html

[Puzon]

Thanks for your responses. I'll try to work with them.

 

When i have an area of ducts seen on 2D draft i can extrapolate it and receive approximate amount of ducts surface. It is needed in my work for 2 purposes:

 

1. To check if quantities received by me from investor are true.

2. To quickly estimate quantities if i didnt get them from investor.

 

I know i can draw polylines on existing ducts and then count their area, but that requires some time. I'm looking for a quicker way to do it.

 

I attach exemplary draft that i was working with some time ago.

 

If you have any idea how to count those ducts quickly, i'll be gratefull.

 

For example I tried to explode blocks, convert all lines to polylines, and count polylines area, but that gave me some unreal numbers.

 

I also wonder if there is a script that could:

count closed polyline area,

then check what is duct's dimension inside that closed polyline (f.e. 500x300),

and then count real surface of duct.

R1.dwg

[ReMark]

Your request for a "script" seems to be quite specific. I think a custom lisp routine would be required. Scripts are generally used to batch process a number of files. Do you have multiple drawings you would have to generate this information for?

[Puzon]

Sorry, I expressed myself imprecisely. I was thinking of lisp routine. We are only talking about 1 drawing.

[tzframpton]

Maybe try this one. It's a little limited but I you might get use out of it in other ways. I don't think it actually calculates distance, but does have a distance option.

DUCTCAL.zip

[Tyke]

You could hatch and retrieve the area of the hatch. A closed polyline, a region and a boundary will all give area. It can be retrieved with List or properties.

 

As SLW said you can hatch the ducting. If you ensure that in the hatch properties you don't have a tick in the box to create separate hatches and then select a point in each section of a run of ducting it will give a single hatched area from which you get the area from properties.

 

You will have to do some selecting on screen whatever you do and if you place the hatch on a separate layer it can be later frozen, so you can always refer back to it if you want, or delete it when you're done.

 

I did approximately half of your drawing in less than two minutes!

[tzframpton]

As SLW said you can hatch the ducting. If you ensure that in the hatch properties you don't have a tick in the box to create separate hatches and then select a point in each section of a run of ducting it will give a single hatched area from which you get the area from properties.

 

You will have to do some selecting on screen whatever you do and if you place the hatch on a separate layer it can be later frozen, so you can always refer back to it if you want, or delete it when you're done.

 

I did approximately half of your drawing in less than two minutes!

Calculating duct sheet metal surface area isn't quite that simple. You have to think that it's a volumetric space, not a flat 2D area. So the formula is (pi)r²h for round duct and (lw)h for rectangular to calculate what Puzon is trying to do, I'm assuming anyways. And that's not even accounting for your transitional fittings.

 

Puzon, have you looked into maybe trying AutoCAD MEP out for a test run? You can make custom schedules that create a BOM (Bill Of Material) with all the ductwork drawn. It might be too much for your needs though.

 

On a side note, after looking at your drawing I think you might be able to benefit from this program from a programmer who has now left the community here: http://www.cadtutor.net/forum/showthread.php?30545-*FREE*-HVAC-or-Piping-program-for-AutoCAD

I see that you might still be using standard CAD practices in your duct designing when doing two line duct, drawing it line by line, creating the fittings manually, etc. Hope this helps.

[Tyke]

Calculating duct sheet metal surface area isn't quite that simple. You have to think that it's a volumetric space, not a flat 2D area. So the formula is (pi)r²h for round duct and (lw)h for rectangular to calculate what Puzon is trying to do, I'm assuming anyways. And that's not even accounting for your transitional fittings.

 

I appreciate what you are saying Tannar and I totally agree with it too. But the OP said

I'd like to add that ducts surface seen in 2D would satisfy me and i only talk about 2D drawings.

and hence my suggestion.

[tzframpton]

I was under the impression that the original poster meant he draws in 2D so he wanted a solution for 2D duct drawings.

[Tyke]

Either way Puzon has both alternatives and he can choose which one he wants to use. I hope we have helped to over come his problem.