resistance coefficient - T fitting
resistance coefficient - T fitting
(OP)
in a duct system of ours, we had a T fitting to allow for gas flow in perpendicular direction to the main flow direction. Then we decided not to allow that flow and hence we blanked the opening off using a wooden plank. But since it is not 100% air-tight, there is some resistance coeff. associated with this section. Can someone please point me to the correct source to look up to calculate the resistance coefficient for this section. I was looking in ASHRAE 1992, but could not find anything relevant.





RE: resistance coefficient - T fitting
RE: resistance coefficient - T fitting
I believe from your explanation that the flow you now have cotinues straight through the tee and the sideways branch is the one blanked off. The resistance for a tee in that flow configuration has an equivalent pipe length (L/D) of 20. If the flow has to make a 90 degree turn and flow out the branch, the L/D increases to about 60.
RE: resistance coefficient - T fitting
I think your tip is helpful.
I was looking into "Hand book of Hydraulic Resistance" by Idelchik. I have not found any mention of such case there. May be I am not looking carefullly.
Can you please tell me the book source where I can get the info that you provided? I will like to quote that source in my report.
Thank you very much.
RE: resistance coefficient - T fitting
When calculating the pressure drop, I understand that I need to take L/D as 20, but what value of f should I use ? --- Is that the same as used for the pipe ? -- The one that was calculated from Moody chart ?
RE: resistance coefficient - T fitting
I recommend you consider posting this same question in the Mechanical/HVAC forum. As you are probably dealing with fractional inches of water pressure drop where velocity head is a significant component, there could be additional considerations for your system beyond the general chemical engineering experience with piping systems. Just a thought, SShep
RE: resistance coefficient - T fitting
Friar Tuck