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dust collection

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Blog entry by Rob200 posted 01-19-2021 01:55 PM 710 reads 0 times favorited 6 comments Add to Favorites Watch

I am working on my mew shop and getting ready to put in dust collection and looking at the two ty of pipe to use .what i am finding is you need a good grounded system. one thing i like to find out has any one know of a home shop burning down do to dust collection. not that you heard it from a story but know for fact it happened

-- Robert Laddusaw and no I am not smarter then a fifth grader ( and no I canot spell so if it is a problem don't read it ))



6 comments so far

View ibewjon's profile

ibewjon

2267 posts in 3801 days


#1 posted 01-19-2021 02:12 PM

I do not. From what I have read, there is little chance of a fire in a home shop dust system. The shock hazzard however is very real. That is why I used 26 guage 5” steel duct. The steel cost about the same as pvc. There is no way to ground pvc pipe because it is an insulator. There is an article in wood magazine issue 245, March 2017 about choosing the correct type and size of duct. It also lists an article about grounding pvc at wood magazine .com.

View ibewjon's profile

ibewjon

2267 posts in 3801 days


#2 posted 01-19-2021 02:26 PM

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View TEK73's profile

TEK73

330 posts in 716 days


#3 posted 01-19-2021 08:09 PM

I have not heard about one burning down, but I have carried out my burning vaacum cleaner.
Had a badly positioned router bit that caused the wood to start glowing, getting suvked in and it started to burn inside the vaacum dust bag.

I belive the static and explition risk is a bit hyped. But it is unplesant to handle/beeing around (know that from the vaacum I use).
So due to that, metal pipes or grounding may be a good idea.

I belive that both 100mm and 125mm ducting works good. Most machines have 100mm (4”) connectors.
Table saws and router table often has a Y split, so you get suction both on top and below. For those, having 125mm until the Y would be ideal – but not sure how mucj real differenxe it makes.
Main point is having a fan with enough power (ideally 3hp or above).

-- It’s good to have an end to journey toward; but it is the journey that matters, in the end. - Ursula K. LeGuin

View TheSnekkerShow's profile

TheSnekkerShow

21 posts in 393 days


#4 posted 01-19-2021 10:02 PM

I’ve never heard of it happening, and I’ve previously (maybe foolishly) used alcohol to soften complicated grain on pieces of wood before putting them in a thickness planer connected to a dust collection system. The flex hose I’m using for dust collection has the steel coil built in and it’s going to a metal trash can, so I think the system is pretty well grounded. I’d echo that too much PVC increases risk so you’d want to check for and deal with any static.

-- Ben -- https://www.youtube.com/TheSnekkerShow

View Madmark2's profile

Madmark2

2300 posts in 1597 days


#5 posted 01-19-2021 10:35 PM

Dust Collector fires/explosions are myth, urban legend. If they were true don’t you think DCs would come with giant foot high red letter signs screaming ”DANGER! EXPLOSION HAZARD!”? They don’t because they don’t.

Volume of 4” (or 6”) piping is too small to sustain a flame front. Especially at 800+ cfm air flow. To be big enough the volume needs to be measured in feet, not inches. This has been tested by UL.

Even if theoretically possible (which it isn’t) safety overpressure valve is a simple dryer vent. Suction (negative pressure) pulls it closed, positive pressure pushes vent open dissipating any threat. Put a piece of tissue paper across the opening to reduce static loss but still have an easily burstable vent.

Problem with static is that it zaps you while you’re working. Ground at the tool to back past where you hold it and call it good.

Sawdust piles will generally slump and smother small fires.

-- The hump with the stump and the pump!

View bbasiaga's profile

bbasiaga

1259 posts in 3003 days


#6 posted 01-20-2021 12:49 PM

I had to manage NFPA compliance for dust conveying systems at work for a few years. A true dust explosion is very unlikely. The dust has to be very dry, and it has to be fully airborn at such a density that you couldn’t see your arm at the end of your hand through it. Go watch a youtube video of a clearvue cyclone working – you generally can hardly even see the dust. Someone commented that a 4” pipe can’t convey an explosion anyway. I think NFPA set the cut off at 3”, but its close.

The more real risk is that you suck up something that sparks and start a fire. If you do any metal work, don’t do it in the same place as your woodwork! My highschool almost burned down one day when they had an electrical problem in the metal shop, so that class went over to use the woodshop room for a day. It was cool watching all the firefighters from the lawn of the school. They got it out in about an hour, and then we had to go back to class. We were super ticked off – the place was literally on fire and we couldn’t even get a day off!

Static will will be a personnel hazard more than anything. I use the anti static hose on my HF DC, But for some reason I still get a shock off my planer sometimes. It’ll wake you up!

_Brian

-- Part of engineering is to know when to put your calculator down and pick up your tools.

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