DC duct- two 45's or one LR 90 elbow

[David Giles]

Is there a significant pressure drop difference in 6" PVC between two 45 elbows compared to one 90 degree long radius elbow? The total price is about the same and either one fits the duct layout.

[John Gregory]

Is there a significant pressure drop difference in 6" PVC between two 45 elbows compared to one 90 degree long radius elbow? The total price is about the same and either one fits the duct layout.
I am not an expert, but that what I did where I could. Seems to make sense to me for a smoother flow.

[Jim Becker]

Depends on the effective radius of both methods...I would think that from an air flow perspective, a true LONG radius continuous curve would be better in performance, but when you are working with available components, two 45º elbows with a short connection in-between get you a higher effective radius than available one-piece alternatives.

[Chris Padilla]

The long-radius is usually big bucks but if comparable to two 45s, go with the long radius. For 6" S&D fittings, the long-radius fitting is A LOT more than two 45s so that is why I went the way I did.

[David Giles]

I was quoted $22 for a 6" long radius where the radius is 1.5x the diameter, I'm sure. The 45 fittings were $13 each. The 45's give a bigger diameter sweep, but it's not as smooth of a curve. Probably a wash. Thanks for back checking me.