Blower Inlet Transition Sizing
Blower Inlet Transition Sizing
(OP)
I am retrofitting a replacement blower to an existing ring dryer to accommodate some increased airflow requirements. I have calculated the system static and flow requirements and have selected a blower that matches. (38" WC at 18,000 CFM) The question I have is regarding the inlet flange (suction side) on the blower which is 30" ID, vs the existing duct size which is 20". I wasn't sure if there were any issues with fabricating a transition piece to match these dimensions. The manufacture has recommended a 10X diameter length of the transition to minimize any system effects, and otherwise says would not be an issue with airflow or otherwise.
Other fans I considered met the same requirements but had the fan inlet ranging at 21" - 23" ID, but these were significantly more costly, so I would like to use the other unit with the larger inlet.
Just thought I would get a sanity check from anyone with more experience than I on this. Thanks.
Other fans I considered met the same requirements but had the fan inlet ranging at 21" - 23" ID, but these were significantly more costly, so I would like to use the other unit with the larger inlet.
Just thought I would get a sanity check from anyone with more experience than I on this. Thanks.





RE: Blower Inlet Transition Sizing
I do not doubt that there are 20 x 30 transition pieces -> Those are only sheet metal/flange elements. But I don't see how you have addressed air flow area through that small a suction. It will screw up your efficiency in the fan at minimum.
RE: Blower Inlet Transition Sizing
Kc will vary; for angles between 3.5 and 17.5 degrees, Kc= .011*angle^1.22; for angles between 2.5 and 3.5, Kc=.13; any angle less than 2.5 degrees consider straight run.