Ashrae Duct Fitting Database Software Free 90
Tilo Chopin
When we design duct and pipe fitting, we will need to use the fittings loss efficient to be ASHRAE or CIBSE. Once in a blue moon, ASHRAE will update their duct fitting loss efficient. Since Revit have ASHRAE in its system, what is the ASHRAE duct fitting database version Autodesk is supporting now? v6.0.0.5?
Hi Mariah, there is a lot of fittings that have issues with the Co-efficient calculation from the ASHRAE TABLE on the ducts and Pipe fittings. I have traced it back a couple of years now if you look at the forum.
Hello @mariah.ferranti this is also an issue for me. I have a lot of issues with the co-efficient calculations from the ASHRAE table on the ducts and pipe fittings. Is there any plan to fix this, or is this a low priority issue? Unfortunately, these issues make the system pressure portion of the software next to useless, because I am having to do calculations by hand again.
@Anton_Welgemoed Did you find a post on the ideas forum that supports this issue?
Trying to move into something more efficient than spreadsheets. Hopefully software where you can draw the duct system in single line, select fittings from the ASHRAE duct fitting database, and calculate a total system pressure drop.
I recently received a somewhat anxious call from a friend in the sheet metal industry. He won a nice duct order, but his submittals were being rejected because he needed to provide published performance data for his duct fittings.
There was a time, 40 or 50 years ago, when only a small group of companies manufactured spiral and flat-oval ducts. Each company developed its own duct fittings catalog, and standard dimensions varied between them. Those duct systems operated at higher pressures and velocities than we use now so small differences in pressure drops could be a big deal.
Meantime, we all started buying plasma tables that came pre-loaded with patterns for common fittings. As a result, we no longer made our own hand patterns for duct fittings, and we all pretty much make duct the same way for dynamic performance (pressure drops and loss coefficients).
The ASHRAE Duct Fitting Database (current version 6.00.05), initially offered in 1994, is an online database with flow resistance data for over 200 spiral duct, rectangular and flat oval fittings. Rather than a collection of graphs, it is a calculation tool for determining precise pressure drops given sizes and flow conditions. It also includes industry research going back 80 years. When a particular fitting is on screen, the database references the published research that provided the data. Plug in size and flow conditions, and it will determine pressure drop.
**Although the ASHRAE Duct Fitting Database has performance on a wide range of duct fittings, the resource is intended to be an ongoing project. Any ducts or fittings not in the database can be added by contacting Bob Reid at bobthe...@gmail.com. This story originally appeared in the February 2020 issue of SNIPS magazine.
As you can see, a poor fitting that was of little consequence in a small duct could have a
significant loss in the large duct. This is because small ducts take a lot more perimeter to surround the volume they contain.
Lower velocities imply lower velocity pressures, so the impact of a poor fitting in a small duct will be much less significant than if that same fitting were installed in a larger duct operating at the same friction rate.
Plus, with computers and software, there are some neat tools to help you make a very informed decision in a timely fashion. The numbers I used for most of the tables in the preceding post were generated using the ASHRAE duct fitting database software in a matter of a few key strokes; I spent more time writing about and printing the results than I did doing the math.
So, when I ran the numbers in the fitting database, here is what I came up with. The loss coefficients pretty much tell the story and interestingly enough, the mitered elbow is about the same as the fitting you are dealing with. The smooth radiused elbow is nearly an order of magnitued better
I personally tend to use the ASHRAE duct fitting loss coefficients. When I first started doing it, they were in the form of tables that you could reference in the back of the fundamentals handbook. I think the last handbook where they were included was the 2009 Fundamentals edition.
Since the fitting loss is a function of the loss coefficient and the square of the velocity pressure, the significance of an improved loss coefficient will go up non-linearly with the velocity in the duct.
Input the flow rate and fitting information to calculate pressure loss and obtain loss coefficient data for hundreds of ASHRAE duct fittings in both I-P and SI units. Browse and search for information on round, rectangular, and flat oval duct fittings with pictorial outlines.
This database, available on CD, includes loss coefficient tables for more than 200 round, rectangular, and flat oval duct fittings. Featuring pictorial outlines of each fitting, this CD is useful to design engineers dealing with a variety of duct fittings. For any given fitting, the user may enter the flow rate and fitting information and obtain loss coefficient data and associated pressure loss.
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