90' Elbows

[jrv331]

Is there a formula to figure out the resistance difference of a 90 degree street elbow vs a sweeping elbow? Its my thought that a sweeping elbow will have less resistance and have a better water flow. The only sweeping elbows my HD carries are the DWV and Im guessing that I should not be using them for my lines.
Thanks
John

 

[spishex]

You're right about the DWV. Here are the equivalent pipe lengths.

For 1.5":
-Standard 90 = 4'
-Street 90 = 6.7'
-Sweeping 90 = 2.7'

For 2":
-Standard 90 = 5.5'
-Street 90 = 8.6'
-Sweep 90 = 4.3'

Friction loss in ft. will depend on your water flow, but about 10% would give you a good idea. For example, 100' of 1.5" pipe adds 10' TDH at 40 GPM. So a standard 90 at 40 GPM will add .4' TDH.