Plastic Vs. Metal Dust Collection

[Steve Kohn]

So as to not hijack other threads I wish to ask a question. Everyone seems to believe that plastic is cheaper to install than metal. However I don't believe I have ever seen anyone post the actual numbers. Has anyone really run the calculation?

Here would be my assumptions for a garage shop system. Trying to keep it simple so it isn't a major effort to calculate. If you have already run the numbers for your system post these instead.

40 feet of straight pipe either snap-lock 6" metal 26 guage from the BORG or 6" green plastic pipe.
Fittings to make 8 90 degree turns in the 6 inch pipe, either long radius metal or using 2 45 degree plastic and a small piece of straight.
3 Wye fittings
Hangers as needed say 10.
Primer/Glue for plastic, or metal tape for metal.
I am going to ignore the cost of adapters from 6 to 4 inch pipe, blast gates, etc. since this could be interchangeable.

[David Hostetler]

I have my listing of price differences, but I worked in 4" and not 6", and the price difference is pretty big...

A 10' joint of 4" S&D PVC runs $7.69 locally.
A 4' piece (the longest I could find) of 4" spiral duct is $10.99, (x 2.5 = $27.48 for 10').
Y fittings, elbows, etc... Were similarly higher in cost. When I ran the total number, I would have been $279.00 & change into the full plumbing including blast gates, hose, etc... for PVC, or $629.00 & change for metal... I was having a hard enough time justifying the cost of plumbing the system to LOML...

I do NOT have my system glued though. It is taped for service reasons...

[Tom Wassack]

Greetings from NC!


So as to not hijack other threads I wish to ask a question. Everyone seems to believe that plastic is cheaper to install than metal. However I don't believe I have ever seen anyone post the actual numbers. Has anyone really run the calculation?

Here would be my assumptions for a garage shop system. Trying to keep it simple so it isn't a major effort to calculate. If you have already run the numbers for your system post these instead.

40 feet of straight pipe either snap-lock 6" metal 26 guage from the BORG or 6" green plastic pipe.
Fittings to make 8 90 degree turns in the 6 inch pipe, either long radius metal or using 2 45 degree plastic and a small piece of straight.
3 Wye fittings
Hangers as needed say 10.
Primer/Glue for plastic, or metal tape for metal.
I am going to ignore the cost of adapters from 6 to 4 inch pipe, blast gates, etc. since this could be interchangeable.

A quick call to Spiral Manufacturing http://www.spiralmfg.com/ yielded the following...
40 feet - 6" 24 gauge spiral pipe - $11.36 / 5' section = $90.88
8 - 6" dia long radius die stamped elbows - $17.92 / ea = $143.36
3 - 6"x6"x5" tapered reducing lateral (wye) - $35.71 / ea = $107.13
4 - 6" male couplings for connecting pipe sections - $1.86 / ea = $7.44
Hanger strap and duct sealant not figured.

Total cost - $348.81 + shipping to your corner of paradise.

Respectfully,
Tom Wassack
Asheboro, NC

[george wilson]

Dare you ask your home owner's insurance about even having a dust collection system?Be careful about this. My work mate was refused insurance because he had a SMALL forge 200' AWAY from his house. Makes no sense,I know,but......

[David G Baker]

Time to switch insurance companies. You may have to pay a higher premium on your insurance if you have something they can nail you on but you should find a carrier that will insure you.
In my area several insurance companies will not insure you if you have a wood burning appliance in any of your buildings except for a detached outdoor furnace. My insurance company will insure me but add a couple hundred dollars a year to my bill. It charges $175 for a corn burner and the corn burners are probably safer than natural gas and propane appliances.
I had not heard about being denied insurance due to a dust collection system.

[Patrick Laflamme]

Be careful using plastic, a lot of insurance companies won't insure you if your system is PVC. PVC will build up a charge much more quickly than stove pipe will and discharge the shock very easily with no provocation. Not only does that prove a distraction hazard if you're operating your table saw lets say and all of sudden you jerk your head up reflexively at the loud pop and flash in your shop; but it will cause a fire or even a small explosion if the mix of air dust in the pipe is just right. (and it will be at some point) Even wrapping a coil of bare copper run to ground doesn't help as much as people think. If you do use PVC and DON'T tell your insurance they won't pay when something happens.

Most fire codes actually demand metal stove pipe or duct work (which is why an insurance company can drop you without a hassle) and most insurance companies will cover a system done out with metal because it can be grounded safely and completely. If you annoy the wrong neighbor you could end up without insurance and fines from the fire marshal by using PVC.

Also if you look in your local phone book or one of those free papers every community has; you'll find listings in the back for small HVAC companies, dryer and/or stove repair, other businesses in that vein. I got in touch with an appliance repair guy that lives a few streets over and after explaining what I needed when setting my brothers garage up for dust control and we picked up all the ductwork we needed for a about third less than the BORG was offering it at; with better advice to boot. Of course as a small possible backfire for others in the nieghborhood the guy has added installing metal ductwork for dust control systems to his list of services.

[Rob Russell]

Be careful using plastic, a lot of insurance companies won't insure you if your system is PVC. PVC will build up a charge much more quickly than stove pipe will and discharge the shock very easily with no provocation. Not only does that prove a distraction hazard if you're operating your table saw lets say and all of sudden you jerk your head up reflexively at the loud pop and flash in your shop; but it will cause a fire or even a small explosion if the mix of air dust in the pipe is just right. (and it will be at some point) Even wrapping a coil of bare copper run to ground doesn't help as much as people think. If you do use PVC and DON'T tell your insurance they won't pay when something happens.

Most fire codes actually demand metal stove pipe or duct work (which is why an insurance company can drop you without a hassle) and most insurance companies will cover a system done out with metal because it can be grounded safely and completely. If you annoy the wrong neighbor you could end up without insurance and fines from the fire marshal by using PVC.


I work for a property / casualty insurance company. I'm not aware of anything in our rating for homeowners that precludes someone using PVC for DC piping.

I would politely suggest that you back up your statements with something factual like "I talked with my insurance company 'ABC Insurer' and this is what they told me".

There is also no exclusion in most homeowners policies for stupidity. Some of the causes of claims that we pay out would make you shake your head and suggest that the claimant was a candidate for the Darwin Awards.

[Chris Padilla]

Be careful using plastic, a lot of insurance companies won't insure you if your system is PVC. PVC will build up a charge much more quickly than stove pipe will and discharge the shock very easily with no provocation. Not only does that prove a distraction hazard if you're operating your table saw lets say and all of sudden you jerk your head up reflexively at the loud pop and flash in your shop; but it will cause a fire or even a small explosion if the mix of air dust in the pipe is just right. (and it will be at some point)

In a pro shop, MAYBE the mix of air and dust will explode but for us hobbiests...I SERIOUSLY doubt it. Dust explosions are not that easy to generate and the static discharge is quite weak.

[glenn bradley]

From my local irrigation supply:

10' of 6" ASTM 2729 - about $14
6x6x6 PVC wye - about $16
6x6x4 PVC wye - about $12
6x6 45* - about $10

I have notice price swings of up to 25% up AND down on the PVC; what's that all about?

[glenn bradley]

In a pro shop, MAYBE the mix of air and dust will explode but for us hobbiests...I SERIOUSLY doubt it. Dust explosions are not that easy to generate and the static discharge is quite weak.

A guy at M.I.T. was actually able to create the environment required for a spark to ignite wood dust in the lab. This was a density of about 50 grams per cubic meter (start chewing) and a flash of about 500 degrees F. Anything that breathes air would have been unconscious well before he was able to reach the density required for an ignition point. But, it can be done; just probably not in your garage ;-)

In industrial environments were dust is routed to rooms or bag farms away from people it would be wise to have a healthy respect for standard safety procedures. I couldn't find any events where the ignition occurred in a room where people work. There are plenty of examples of dust explosions in unmanned concentration areas where the proper procedures should have prevented them.

Like blade guards and respirators; in the discussions of plastic vs. metal, we all make our own choices.

[Chris Padilla]

From my local irrigation supply:

10' of 6" ASTM 2729 - about $14
6x6x6 PVC wye - about $16
6x6x4 PVC wye - about $12
6x6 45* - about $10

I have notice price swings of up to 25% up AND down on the PVC; what's that all about?

Pretty good prices. PVC = oil...maybe that accounts for it??

10' of 6" ASTM 2779 (all white) - about $24 for me from an irrigation warehouse

All fittings I purchased were from McMaster-Carr

[Jimmy Coull]

A guy at M.I.T. was actually able to create the environment required for a spark to ignite wood dust in the lab. This was a density of about 50 grams per cubic meter (start chewing) and a flash of about 500 degrees F. Anything that breathes air would have been unconscious well before he was able to reach the density required for an ignition point. But, it can be done; just probably not in your garage ;-)

In industrial environments were dust is routed to rooms or bag farms away from people it would be wise to have a healthy respect for standard safety procedures. I couldn't find any events where the ignition occurred in a room where people work. There are plenty of examples of dust explosions in unmanned concentration areas where the proper procedures should have prevented them.


Like blade guards and respirators; in the discussions of plastic vs. metal, we all make our own choices.

MIT also stated that there was pretty much no chance of this environment happening in a dust collection/cyclone system of less than 3 hp., which is what most home systems are. sometimes it is best to read the whole article.:rolleyes:

[glenn bradley]

10' of 6" ASTM 2779 (all white) - about $24 for me from an irrigation warehouse

Sorry, I should have mentioned that the first few places I found were $20 - $25 for a 10 foot stick. Someone, here I believe, steered me onto Horizon online. There just happened to be a distribution center a few miles from my work and the prices were great.

[Jim O'Dell]

My first 2 sticks of 6" 2729 were 18.40 plus tax. The last three sticks, same place, were 10.35 each. The guy remembered me and my stereo system in the van.:cool: Gave me wholesale pricing. I still need to check the Horizon place here next time I need parts, and I'm going to have to change things when I'm able to purchase the cab saw. Good to see their prices on fittings are good! Jim.

[Bill Blackburn]

Boy oh boy oh boy --- I'm reading so much stuff that is either the biggest bunch of poppycock on earth or you are dealing with carriers that have a single lightbulb burning in some 2nd store office that I never heard of. Run. don't walk, and get a real insurance carrier if that's the case

We were just down this road and I thought maybe .... :(

http://sawmillcreek.org/showthread.php?t=110620

guess not:rolleyes:

Read reply #25 okay!

[Dan Friedrichs]

+1 for Horizon.

10' stick of 6" ASTM2729 was $16
6" wyes were about $12
6"->4" adapters about $10

I grumbled a little about the price of the fittings at first (he wanted to charge me something like $23/ea), and somehow, the prices all came down by about half. I think that was the "you don't have an account" markup being removed :)

[Chris Padilla]

Sorry, I should have mentioned that the first few places I found were $20 - $25 for a 10 foot stick. Someone, here I believe, steered me onto Horizon online. There just happened to be a distribution center a few miles from my work and the prices were great.

Horizon! Yes, that is the place I used. I bought my stuff a couple years ago so I don't know if they are cheaper or more expensive now.

[Thom Sturgill]

If you are worried about static here's an idea - get some of that aluminium tape and run that INSIDE the PVC leaving enough at the ends to wrap around to the outside about 4". Do the same to the fittings such that the tapes make good contact. Run screws through the fittings at the tape if you wish, but definitely ground the end to the DC frame.