Duct Fittings

[smoothscale]

Hello everyone, can anybody help me please. I am new in estimating ducts. My question is how do you estimate/quantity take-off duct fittings? For example you have a 750x500 Supply Air Duct, then at the end it splits to three, (one to the right, one to the left and the other just go straight. So you have 2 elbows and a reducer. And where should I include the quantities of the fittings, should I include it to the quantities of my SAD? I attached a sample picture. Thanks

 

[dbill74]

First thing, you need to clarify what you are estimating, cost, pressure drop, size.
I am guessing pressure drop from what you've given us. In which case, and based on the diagram you provided, you would need to do at least 2 calculations.
1) From the unit to the split.
2) From the split out to one side including drop through the elbow and volume of air in this branch.
3) From the split through the central branch.

Then to find the loss to a side branch you simply add the losses from 1) and 2) above. For the center run add the losses from 1) and 3) above.

 

[smoothscale]

hello sir, thank you very much for this answers, I thought I have to measure the fittings separately. Now I know what to do. Thanks again, I really appreciate it. Blessings!