Thread: dust extraction

There are conflicting views on this issue.

Some say its completely unnecessary.

Originally Posted by rsser

Some say its completely unnecessary.

I'd have said that most consider it completely unnecessary.

Here's my take on it:

PVC is a damned good insulator... even if/when it builds up a high static charge it only discharges for an area of about 1" radius from the point of earthing. Whether it be your finger, an earth-strap or whatever, and not enough to cause damage. (Mythbusters demonstrated this quite clearly when they "busted the myth" but I've held this point of view for a lot longer than that show has been running. )

Some people suggest adding screws every foot or so along the duct, connected by wire to an earth... but if you do the maths that is only about 4sq" out of every 150sq" actually earthed... or a mere 1/36 of the total area. Which is a totally pointless effort in my books.

Others run a length of wire down the inside of the duct, but IMHO that's just asking for trouble with future jams in the duct.

With metal ductwork it's a different story and an earth is needed. But thats easily done.

I'm with skew, I've read a lot of the theory in local and US magazines, researched on the web, watched mythbusters but, at the end of the day, I've had my 100mm PVC plumbing set up operating for about 3 years, no earth, no static charges and no hair raising episodes.
Fletty

We used 6 inch PVC pipe in an industrial factory with around 6 cubic metres os sawdust going through it a day for over 5 years and never had a problem. Yes you sometimes got 'zapped' if you touched the pipe and it definately made your hairs stand up when you walked underneath it, but never any problems.

Originally Posted by bentley

I have recently moved and have connected my machiery and dust extractor, using pvc plumbing pipe. Someone tells me that it needs to have an earth, because static electricity can cause fires if it not earthed properly.Anyone know how to do it.

Yes it is a small risk but there are much greater risks in people sheds than this one. IMHO the risk of starting a fire by a spark from the PVC is much less than not collecting the sawdust so overall you are reducing fire risk.

Cheers

Originally Posted by Skew ChiDAMN!!

PVC is a damned good insulator... even if/when it builds up a high static charge it only discharges for an area of about 1" radius from the point of earthing. Whether it be your finger, an earth-strap or whatever, and not enough to cause damage. (Mythbusters demonstrated this quite clearly when they "busted the myth" but I've held this point of view for a lot longer than that show has been running. )

Some people suggest adding screws every foot or so along the duct, connected by wire to an earth... but if you do the maths that is only about 4sq" out of every 150sq" actually earthed... or a mere 1/36 of the total area. Which is a totally pointless effort in my books.

Others run a length of wire down the inside of the duct, but IMHO that's just asking for trouble with future jams in the duct.

With metal ductwork it's a different story and an earth is needed. But thats easily done.

That seems to be the exact opposite information that the salesman trying to sell me a dusty gave me.

My plans were to use PVC ducting, with a grounding kit, and his advice was use metal, don't need to ground it, and I wont get static from it.

Though I must say, my preference is still PVC, and going by what a lot of Forum members have said, I don't think it will be a huge problem. I can also put together a PVC system myself, wont glue the joints and it can be removed whenever it needs to be, metal presents a whole raft of problems, including not being able to manufacture some parts of it.