Its bad..but HOW MUCH bad it is?
Its bad..but HOW MUCH bad it is?
(OP)
I have attached an image of a square throat elbow whose aspect ratio is around 1:8. (Width 32in, height 4in). Contractor has used 2 of these elbows to cross a beam. and there is some length of straight duct section of these dimensions too (around 6-7ft). i want to know HOW MUCH bad it is? As per my rough calculations the duct friction loss came out to be 1.53, equivalent dia 13in and equivalent length 39ft. However, i need someone more expert in design to vet these parameters as standard charts and tables are not telling much beyond aspect ratio of 1:4. After that, I am a bit confused on how to interpret these parameters to convert these into simple pressure drop loss, cfm loss, AHU energy consumption increase or any other parameter which I dont know. Can somebody help me through this in order to quantify the damage this elbow will bring?
Thanks in advance!
Thanks in advance!





RE: Its bad..but HOW MUCH bad it is?
RE: Its bad..but HOW MUCH bad it is?
RE: Its bad..but HOW MUCH bad it is?
RE: Its bad..but HOW MUCH bad it is?
"If you are checking the design, did you take ½ the flow and run math based upon a 4:1? You will need to advise more info to evaluate the system. Is this a transfer duct between to spaces at 600fpm or an exhaust duct running at 1800 fpm? If this is lined with 1”, your ratio will now be 15."
Yes that is what I want to have a grip on. I am not much into design. Could you please elaborate more on this? or could you please point me to some good resource where I can learn this design process from start to end? I know how to calculate cooling load tonnage and CFM required zone-wise. Once I get those things, what are the next steps involved? How to size ducts? How to select equipment? What is the ordering?
RE: Its bad..but HOW MUCH bad it is?
RE: Its bad..but HOW MUCH bad it is?