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ABD SS6 - Hydraulic calculations

Tomasz Magiera
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Hello,

I have an issue with hydraulic calculation which are made for ventilation installation. 

What I need is to calculate a pressure loss on a ductwork to fit a correct fan or ahu. For those who are not a sanitary engineers i explain that for that calculation I have to total linear loss which depands on duct's roughness and lenght and local losses which are couses by changing duct direcion, dimensions etc.

ABD has a tool called Duct System Sizing Dialogs but what I find is that it calculate only a linear losses and not even for duct's size which I drawn in a model but for duct's size which is set on settings>limit duct velocity. And here my question:

- can ABD callculate also local losses causes by elbows, transitions etc?

- can I set Duct System Sizing tool to make a calculation for a duct's size which I drawn on a model?

- can I export that calculation to an exel file?

It seems that without program's abilty to make that simple calculations I will have to find out another program to make it. Does anyone know a program which is working with aecosim and can make those calculations?

  • 0 Offline in reply to stan.white

    Hi Stan, I was researching a problem I was facing similar to this when I stumbled on your explanation. Could explain further on how Netsys can be used to address this. I am most interested presently in addressing an existing duct system and trying to improve system performance.

  • 0 Offline in reply to stan.white
    My main intention at this moment is not balancing but as U mention "blow air throught existing geometry and spit out the numbers". All is need to know after finishing a ductwork model is a pressure loss at the worst path to be able to get a proper fan or ahu. A duct sizing utility tool is showing only a linear losses, not a local losses (on a elbows, transitions etc) so I U also see a calculations are not accurate.
    To sum up this this discusion does anyone know is there a program for aecosim like magicad for revit to calculate a whole pressure losses on a ductwork?
  • 0 Offline in reply to Tomasz Magiera
    Is it your intention to achieve balance via your calculations? Or are you just trying to blow air and pressure through existing geometry, and spit out the numbers?

    Our sizing utility is “equal friction method” to attempt to balance flow.
    So... if existing geometry (think exaggerated) were to be loaded into the Duct Sizing Utility, AND... All the ducts were then locked in Sizes to the existing geometry... You would get calculated losses per component...BUT… you are making all the assumptions of actual flow at the ends, when in fact, all the air could be blowing out of the nearest hole, if that is true, So the answer is “no”. A sizing utility attempts to achieve desired flow at the outlets. Only then, can pressure losses be predicted.

    This is an applied science called Computational Fluid Dynamics, which attempts to predict flow and pressure losses on existing geometry. So the short answers is, if you are not “balancing” to predict flow, your pressure losses are not accurate. That’s not a limitation of the software, it’s a scientific statement of the method employed.

       

  • 0 Offline in reply to stan.white

    Hello
    Thanks for U help but I am looking for program which is calculating a pressure loss on a whole ductwork after I drawn it. ABD's duct sizer is a tool which is setting a duct's size according to a parameter which U define for example velocity or linear pressure loss. But as U know creating a ductwork many times requires duct's velocity changes in a place where there is not enought space. After drawing huge and complicated ductwork it is necessary to choose a correct fan/ahu where we have to include linear and local pressure loss. As I spoke with colleagues from different officess they are using for example magicad for revit files.
    Does anyone know such program which is working with ABD?

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