# Is this 6" sewer pipe "long 90º" fitting enough of a sweep?



## roverson (Aug 29, 2017)

Hi everyone. Working out my shop dust collection and planning on buying everything from McMaster-Carr. I'm wondering if I can substitute some of my 90º turns (composed of two 45º fittings) with some of these "long 90 degree elbows" from McMaster Carr? Or will these cause significantly more resistance than two 45º fittings?


McMaster-Carr long 90 degree elbow: https://www.mcmaster.com/9102k116


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## ducbsa (Jul 6, 2014)

I played with this http://www.freecalc.com/fricfram.htm

and tried 2 45's, got 1.07 in pressure drop. then with a 90, got 1.05. Yes, it was water, but air won't be much different.

Bottom line, not worth modifying an existing system, but might as well do it for new work - fewer fittings to buy and install.


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## HoytC (Dec 30, 2019)

That fitting will be better than two 45s. The 45s are a sharp bend, R/D = 0.5 while that fitting looks like 0.75, so no sharp edge internally like the 45 has.
This site http://www.freecalc.com/ductloss.htm shows a loss coefficient of 0.33 for a 0.75R/D ninety and 0.355 for EACH of the two forty fives at 0.5R/D, so almost twice the pressure loss for the two forty fives compared to the sweep ninety.


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## woodnthings (Jan 24, 2009)

*Not easy to find in 6" long sweep ...*

However I did find these:
https://www.amazon.com/Charlotte-Pipe-PVC-00304-1400/dp/B004TSTDBQ


https://flexpvc.com/cart/agora.cgi?...gSweepElbows&p_id=P304-060&xm=on&ppinc=detail


https://www.pvcfittingsonline.com/6...g5BjZgtbwT54LdQiOVJy70-2lozFKPPBoCOgsQAvD_BwE


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## HoytC (Dec 30, 2019)

woodnthings said:


> However I did find these:
> https://www.amazon.com/Charlotte-Pipe-PVC-00304-1400/dp/B004TSTDBQ
> 
> 
> ...



Those are all DWV/Sch40 size. It looks like OP is using Sewer & Drain. The two sizes are not compatible.


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## woodnthings (Jan 24, 2009)

*I knew that but ......*

The SDR 35 elbows are all but impossible to find in a long sweep:
https://www.completeplumbingsource....0PYmfwhtRPT11KECBf8LoqdvuIPQoXpxoCFZwQAvD_BwE


You could use the more readily available and cheaper PVC schedule 40 and heat shrink or expand the ends to fit the SDR 35 as shown in these You Tube videos:
https://www.youtube.com/results?search_query=heat+bending+PVC+pipe


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## HoytC (Dec 30, 2019)

woodnthings said:


> The SDR 35 elbows are all but impossible to find in a long sweep:
> https://www.completeplumbingsource....0PYmfwhtRPT11KECBf8LoqdvuIPQoXpxoCFZwQAvD_BwE



Good find!


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## roverson (Aug 29, 2017)

oh man thanks everyone! this is great! I am doing a completely new install so I will save a lot by not using all the double 45's! I think I'll just go with woodnthings link to the Complete Plumbing Source site—that is a good find! Not that expensive when you price out two 45's from MacMaster-Carr comparatively.


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## Rency (May 26, 2017)

woodnthings said:


> The SDR 35 elbows are all but impossible to find in a long sweep:
> https://www.completeplumbingsource....0PYmfwhtRPT11KECBf8LoqdvuIPQoXpxoCFZwQAvD_BwE


Good find indeed.
Thanks a bunch.


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## roverson (Aug 29, 2017)

Just to report back, I purchased the long sweep 90ºs from Complete Plumbing Source and received them today and they fit the ASTM D2729 thin wall 6" pipe I found from a local supplier perfectly.


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## Rency (May 26, 2017)

roverson said:


> Just to report back, I purchased the long sweep 90ºs today from Complete Plumbing Source and received them today and they fit the ASTM D2729 thin wall 6" pipe I found from a local supplier perfectly.


Great news. 
Thanks for reporting back.


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