# 6" HVAC duct mating to 6" PVC ASTM3034



## Holbs (Nov 4, 2012)

I pulled a 6 foot piece of 6" PVC Sewer ASTM D-3034 (I believe this is aka SDR 30) out of a dumpster as I was curious how it mates up with standard 6" HVAC metal ducting and fittings. Male ends do not fit in (maybe 1/8" too large) but the female ends of the HVAC fittings and duct fit in snugly with no slop. It got me thinking about a couple things. For standard HVAC parts, is it REALLY that horrid to mate male & female together even though the flow of direction is backwards? The lip of the female HVAC feels about 1/16" raised off the wall of the male.which is alot worse than when I have to crimp ends manually.
Basically, everyone has said HVAC ducting has to be modified for dust collection as the air flow is reversed. Modified by cutting off female ends and crimping your own on parts. But does the 1/16" crimped end pointing into the air flow doesn't sound that earth shattering CFM or air flow disturbance effect, whether mated to this PVC or HVAC?


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## FancyShoes (Aug 31, 2014)

I doesnt really effect it, the best way to test this completly is to measure your cfm or static pressure, then reverse the airflow, and retest, I dont think you will see mucj difference, I truly believe adding one 90 degree angle into a system will effect it more than the question you asked.


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## wapakfred (Jul 29, 2011)

I've had some HVAC mated to PVC for many years. I'm sure there is an effect, but it's so small you'd have to measure it with laboratory instruments. One thing I did was put some foil duct tape over the joint on inside the of the pipe, just to smooth it out a little. The foil really sticks, and is very thin…so it works out fairly well. The other thing is, it's not too hard to change the flow direction. The crimps can be hammered out (on the 6" pipe) with a little effort, and the female end can be crimped with crimping pliers.


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## Holbs (Nov 4, 2012)

Fred..that's what I am in the middle of right now. Re-doing my dust collection system from waist high (or even from bottom corners) to overhead with drops. I was considering PVC but then thought of the $$$ invested in my current 26gauge HVAC material (snap duct, 6×6x6 wyes, 45's, etc) and thought it best to stay HVAC. But this time, hammering out excessive crimps, duct taping (with approved HVAC tape… kinda like duct tape), sealing every seam (which was not done originally), and now using 3 pop rivets for every joint. When complete, I'll take pix and start a new forum topic of it


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