This review presents my comparison of methods for calculating the pressure loss a straight section of pipe with the help of these software:
Autodesk Revit, MagiCAD, Valtec and other.
Before this "test" I had no idea about two things : how and for what the exact formula settles pressure loss MagiCAD and Revit, and how these estimates are close to the Russian standards. I knew one thing for sure: all calculations which at the time I performed using MagiCAD and Valtec was fine, all objects are finished and work perfectly.
This led me to investigate the most common case: notice how colleague was making selection of diameter pipeline using Autodesk Revit for the heating system. Heating load on one floor — 15 kW.
And then I look at the section of the pipeline, which brings together all the radiators in a heap: Autodesk Revit automatically selects 20 mm diameter. But in my experience their previous calculations could say that the diameter of the pipe must be at least 25 mm, which was subsequently confirmed in the program MagiCAD. So the question has arisen about — who is right?
Want to mention once that I am not in any way claim to completeness and the accuracy of the data listed below, but the fact of differences in the calculations you may notice themselves, and all the data on them are presented "as is". Same I do not belong to the same organization, one way or another connected with the producers this software.
The main results of the calculation:
the water flow rate 644.7 kg/hr, the diameter of tube 20 mm, roughness 0.007, flow rate 0.583 m/s, temperature in/out — 80/60 C:
Autodesk Revit — 128.2 Pa/m
MagiCAD — 209.9 Pa/m
Calculation based on official Autodesk Revit Help
Pressure loss calculation for 15 kW load (procedure like Autodesk Revit Help do)
Those 2 last link above are to files in PTC Mathcad Prime format. You can use them to check all the data, or to modify them to fit your needs.
And this is two files in PDF format for quick view of files content:
Тo one answer? Amazing! Nobody deals with the calculation of systems? Only drafting?
No one answer? Amazing! Nobody deals with the calculation of systems? Only drafting?
I know that a lot of user do, in fact, ignore Revit's calculations. I suggest that you try asking this question over at the forums on AUGI.com, as there are more experienced and knowledgeable mechanical users, there.
Purchasing program, I paid including the fact that the program is able to calculate the hydraulics. And every year by paying a subscription I'm counting on to get an answer from the expert to my question: are my assumptions true or not. And following your logic, I should not pay attention to the obvious errors in the program? Then why and what I was paying and each year pay a lot of money? In this case, I wish I bought a specialized software, such as magicad.
And I have kept silent for calculations in the field of heat loss. There is also a grave error. For example, in the formulas for the calculation of heat loss is no accounting of two coefficients : resist heat absorption and resistance to heat transfer. But that's a topic for another conversation.
I understand that, and you should indeed get what you paid for. However, these forums are peer supported and almost entirely comprised of end users freely helping other end users, with the periodic visit from Autodesk support personnel. You could take advantage of your Subscription and open a Support Case; this can be done done from the Subscription Center on Autodesk's main website.
Personally, my knowledge lies more with the electrical discipline and with general platform-based issues, which is why I haven't been much help here. Though, I do want you to find any assistance that is needed, hence my suggestion to ask on AUGI where there is a higher chance (I believe) of getting an answer to this question from an expert in this field.
Additionally, I would never suggest that you ignore the problems, flaws, and errors with this (or any other) Autodesk software. Voice your issues! I guarantee that you're not alone. Also, below is a feedback link which I encourage the use of in addition to opening a Support Case.
Autodesk Product Support
The following link is setup for you to submit feature requests, or feedback, directly to our Development group:
http://usa.autodesk.com/adsk/servlet/index?siteID=123112&id=1109794
Hello Vitaliy5151--
There are many methods by which one can compute the friction factor, which affects the pressure drop calculation… depending on which is used will affect how similar the result is to another product that may use a different method. There are 16 methods documented in a 2011 FME Transactions article, which, amongst other customer feedback, led us to enhancing Revit 2014 to enable customers and 3rd parties to add additional methods to Revit. Jeremy' Tammik's blog provides insight into how you might do this. So, if so inclined, you could change how 2014 works to suit your needs to get results aligned with your expectations.
Revit 2015 provides two additional methods 'out of the box', for both duct and pipe, based on the Colebrook Method and the Haaland Method….these two methods were the top cited from customers and 3rd parties.
Please see this video demonstrating the results of these two methods in 2015 using the sample file you had provided to Product Support. The results on the right appear to be nearly the same, while the results on the left vary from 2.5 to 4%... without knowing more about MagiCAD's method, if they are rounding in the result, or if you rounded in the Revit model, or if there was some other variation in inputs, it is hard to guess where the difference is from.
Sorry for the delay in responding to your inquiry, but we could not report this new functionality until our new product line was officially announced late last week.
Does this appear to address your need in an acceptable way?
Respectfully,
«Does this appear to address your need in an acceptable way?»
Yes, it is.
About video: I got this video from support 4 march 2014. Thank you for your answer!
looks great martin..hopefully you have managed to fix the heatload calculation issues as well;)