Pressure Head loss w/out a given diameter
Pressure Head loss w/out a given diameter
(OP)
Hi
How can i get the Diameter of a duct or pipe if I only have Flow Rate?
And where did the 0.1inch/100ft of friction head loss comes from? Is it from experience? I can't find it in ASHRAE Handbook.
Thanks in advance.
How can i get the Diameter of a duct or pipe if I only have Flow Rate?
And where did the 0.1inch/100ft of friction head loss comes from? Is it from experience? I can't find it in ASHRAE Handbook.
Thanks in advance.





RE: Pressure Head loss w/out a given diameter
B. Accepted in the Engineering community.
RE: Pressure Head loss w/out a given diameter
Other parameters maybe added by other members.
RE: Pressure Head loss w/out a given diameter
If you have determined to use either 0.1 IWC or 0.08 IWC and know the flow, then use the SMACNA HVAC System Duct Design Manual, Duct Friction Loss Chart, to get the equivalent round duct size. If not using round, then go to the rectangular conversion table.
RE: Pressure Head loss w/out a given diameter
Please correct me if I'm wrong because I am just a newbie in HVAC design.
@willard3: Sir, you are right that I can't get the diameter if I only have flow rate that is why I am looking for the basis of 0.1 inch WC/100ft (supply) & 0.08 inch WC/100ft (return). The example in ASHRAE Handbook Fundamentals 2009, the diameter is given & that is why they were able to get the friction head loss through friction chart or Darcy Weisbach equation maybe. I was able to read some blogs & they say that the most commonly used, (maybe rule of thumb?), is 0.1 inch WC/100ft. So, I am thinking if they got it from their own experience.
@dynamo78: Sir, from your own point of view, which is better in designing Ductworks, Velocity Method or Equal Friction Method?
@urgross: Sir, I was able to read a blog & it says that 0.08 inch/100ft is for the Return Duct & the 0.1 inch/100ft is for the Supply. Is it correct?
Thanks in advance.
RE: Pressure Head loss w/out a given diameter
You might want to look at static regain, as long as you are beginning in HVAC.
RE: Pressure Head loss w/out a given diameter
HTH Kuya.but I maybe older than you.LOL
RE: Pressure Head loss w/out a given diameter
@dynamo78: Are you also using the 0.1 inch/ 100ft Rule of Thumb for Equal Friction Method?
RE: Pressure Head loss w/out a given diameter
RE: Pressure Head loss w/out a given diameter