Eric. Posted April 16, 2014 Report Share Posted April 16, 2014 That is the question. Obviously it's just static grounding itself to its nearest opportunity. I'm not one who really buys the whole "spark ignites dust" theory. And I suppose the amount of electricity released here is so minute that it couldn't possibly harm the machine, right? Just wanted to confirm that... I'm assuming I'll get a bunch of conflicting opinions. Sorry that most of this is out of focus...but I think you'll get the point... Quote Link to comment Share on other sites More sharing options...
Llama Posted April 16, 2014 Report Share Posted April 16, 2014 Nice K9! Quote Link to comment Share on other sites More sharing options...
G S Haydon Posted April 16, 2014 Report Share Posted April 16, 2014 Our LEV units have explosion panels not joking! Reminds me of C6H12O6(s)+6O2(g) --> 6CO2(g)+6H2O(g). Not sure how dangerous it would be at this level. Quote Link to comment Share on other sites More sharing options...
Eric. Posted April 16, 2014 Author Report Share Posted April 16, 2014 Our LEV units have explosion panels not joking! Reminds me of C6H12O6(s)+6O2(g) --> 6CO2(g)+6H2O(g). Not sure how dangerous it would be at this level. I don't know what the hell any of that means except the last ten words. 1 Quote Link to comment Share on other sites More sharing options...
DaveT Posted April 16, 2014 Report Share Posted April 16, 2014 I don't know what the hell any of that means except the last ten words. I'll second that! Quote Link to comment Share on other sites More sharing options...
G S Haydon Posted April 16, 2014 Report Share Posted April 16, 2014 :-). LEV = Dust Extraction Letters & Numbers = Explosion in a custard factory (dust spark etc) Quote Link to comment Share on other sites More sharing options...
Llama Posted April 16, 2014 Report Share Posted April 16, 2014 Graham, your words need subtitles! 2 Quote Link to comment Share on other sites More sharing options...
Beechwood Chip Posted April 16, 2014 Report Share Posted April 16, 2014 I don't think it's a big deal, but if it was me I'd loop a bare wire around the flex duct and connect it to the body of the sander, or any convenient ground. Quote Link to comment Share on other sites More sharing options...
G S Haydon Posted April 16, 2014 Report Share Posted April 16, 2014 Graham, your words need subtitles! Nowt wrong with my words Mel 1 Quote Link to comment Share on other sites More sharing options...
Llama Posted April 16, 2014 Report Share Posted April 16, 2014 Nowt wrong with my words Mel That is my favorite word now. 1 Quote Link to comment Share on other sites More sharing options...
pghmyn Posted April 16, 2014 Report Share Posted April 16, 2014 As much chemistry as I remember from this semester, which is minimal, that is glucose and enough oxygen to ignite and combust to form carbon dioxide and water. Quote Link to comment Share on other sites More sharing options...
Eric. Posted April 16, 2014 Author Report Share Posted April 16, 2014 As much chemistry as I remember from this semester, which is minimal, that is glucose and enough oxygen to ignite and combust to form carbon dioxide and water. You're a doomsdayer type ain't ya? I bet you got a whole basement full of canned goods, bottled water and gas masks. I have NEVER seen or heard a confirmed case of a static spark igniting dust and the world exploding. I might do that, Chip, or just snip that little piece of bare wire off so it can't arc there, and the static can build up to heartstopping voltage until I brush against a pipe...as is usual. Or maybe I'll use some aluminum tape to hold it down to the DC port so it just disperses the static as it's created instead of building and arcing. Quote Link to comment Share on other sites More sharing options...
..Kev Posted April 17, 2014 Report Share Posted April 17, 2014 Take a look at Granaries Eric, it happens there more frequently than you might think. This is, however, a far cry from the dust in your shop. We had a local one go up just a few years ago. I think I'd go with Chip's suggestion Quote Link to comment Share on other sites More sharing options...
Trip Posted April 17, 2014 Report Share Posted April 17, 2014 ==>I have NEVER seen or heard a confirmed case of a static spark igniting dust and the world exploding. Well, the world doesn't explode --- but a grain silo or two goes every once in a while... But, not small wood shops... Best practice is to verify conductivity between the tool and DC to control static build-up and prevent sparking... If you have a simple Ohm meter, you can unplug your tool and DC (eliminates path to ground via branch circuit/ground bar bonding) and test for conductivity across the flex hose... Obviously, if you read conductivity, then you're AOK. If no conductivity, then you don't have a solid metal-to-metal connection and need to make one... Depending on your flex hose, you can just expose the bare metal wire rib on both sides of the hose, tuck the wire back under the hose and use the clamps to get a solid connection. If you have hose with a plastic rib, then run a 24g un-shielded braided copper wire from the metal duct through the flex hose and screwed-in at the tool. If the DC inlet port is plastic, then jump it and bond to the tool frame. Quote Link to comment Share on other sites More sharing options...
Eric. Posted April 17, 2014 Author Report Share Posted April 17, 2014 ==>I have NEVER seen or heard a confirmed case of a static spark igniting dust and the world exploding. Well, the world doesn't explode --- but a grain silo or two goes every once in a while... But, you don't here about wood shops... Yeah, the wood shops are what I was talking about. Can't I just ground the thing right where it's sparking so that it's constantly dispersed instead of building up and arcing? That would be problem solved, no? Quote Link to comment Share on other sites More sharing options...
Trip Posted April 17, 2014 Report Share Posted April 17, 2014 ==>Can't I just ground the thing right where it's sparking so that it's constantly dispersed instead of building up and arcing? The short answer is yes and no... Best practice is zero potential between the tool and DC via the ductwork, not via a separate path to ground (which is why you test with the tools unplugged)... Does this really matter? Well, for a small shop, not really... An industrial shop is a different story... A separate path to ground will work, just [maybe] not as well. Static would [probably] continue to build-up in the hose... But if bond the tool to the DC via the ductwork, you won't have static buildup anywhere in the system --- and you won't get shocks from (or dust sticking to) the hose... If your flex hose has a wire support (better grades of flex hose do), what you're supposed to do is expose an inch or two of the wire on each side of the hose and loop the exposed wire back through the clamp and under the hose at the connection for good metal-to-metal contact... However, these days, most tools have plastic DC ports so you need to run a short lead to bridge across the plastic. From your video, it looks like your hose has wire ribbing -- however, cheap hose has plastic and you need to run a copper wire through the hose... If I remember, i'll shoot a photo or two this weekend... Quote Link to comment Share on other sites More sharing options...
estesbubba Posted April 17, 2014 Report Share Posted April 17, 2014 Your dog seems concerned! Quote Link to comment Share on other sites More sharing options...
Eric. Posted April 17, 2014 Author Report Share Posted April 17, 2014 All of my hoses have wire ribbing, but none of them are grounded. Honestly I was exaggerating a bit when I acted like I get hardcore shocks all the time...truth is, I rarely get shocked, and when I do it's not that bad. But I DO get a ton of dust sticking to the duct (PVC) so it would be nice to eliminate that. Guess I need to work on it since it's "the right thing to do." Quote Link to comment Share on other sites More sharing options...
Trip Posted April 17, 2014 Report Share Posted April 17, 2014 Yea, it's a bit OCD to worry about grounding flex hose, but after getting a wide-belt (and some rather wicked shocks), I decided it was time to revisit my setup. It took all of one hour, a VOM and a spool of braided copper wire to get everything up to snuff. Haven't had a shock in years. While I was at it, I ran a smoke test and sealed a couple of leaks that had crept into my ductwork over the years... Quote Link to comment Share on other sites More sharing options...
TerryMcK Posted April 17, 2014 Report Share Posted April 17, 2014 I used to work in the engineering department for a photographic film manufacturer and they kept the humidity high inside the machine (in reality a massive 7 storey 2000 foot long temperature and humidity controlled building) to minimise static. When the humidity drops it's like sheet lighting and makes your hair stand on end (assuming you have any hair - I don't ). You don't want to touch it. Mind you the base material was polyester and around 6 feet wide and running at around 450 feet a second! You wouldn't be able to raise the humidity levels high enough in your shop (or want to) to get rid of it entirely. The photographic machine used to run at around 98% humidity at 68 degrees F when doing film. The guys used to walk around in shorts under lightweight overalls as it felt so hot. I don't think you will have any issues at all with such small sparks Eric. If the hose is reinforced with steel or other metal you could always find the end and ground it to the metal of one of your machines if you were worried. It would simply and safely dissipate to ground. The static will only be very low energy but will make you jump. The electronics of the controller will not be at risk at all. I don't think I would be bothered trying to ground it - much rather work wood Great machine BTW. You must be really pleased with that one. 1 Quote Link to comment Share on other sites More sharing options...
G S Haydon Posted April 17, 2014 Report Share Posted April 17, 2014 http://www.pjdust.co.uk/faq21_whatarethecausesoffireinlev.htm Quote Link to comment Share on other sites More sharing options...
Popular Post Eric. Posted April 17, 2014 Author Popular Post Report Share Posted April 17, 2014 I used to work in the engineering department for a photographic film manufacturer and they kept the humidity high inside the machine (in reality a massive 7 storey 2000 foot long temperature and humidity controlled building) to minimise static. When the humidity drops it's like sheet lighting and makes your hair stand on end (assuming you have any hair - I don't ). You don't want to touch it. Mind you the base material was polyester and around 6 feet wide and running at around 450 feet a second! You wouldn't be able to raise the humidity levels high enough in your shop (or want to) to get rid of it entirely. The photographic machine used to run at around 98% humidity at 68 degrees F when doing film. The guys used to walk around in shorts under lightweight overalls as it felt so hot. I don't think you will have any issues at all with such small sparks Eric. If the hose is reinforced with steel or other metal you could always find the end and ground it to the metal of one of your machines if you were worried. It would simply and safely dissipate to ground. The static will only be very low energy but will make you jump. The electronics of the controller will not be at risk at all. I don't think I would be bothered trying to ground it - much rather work wood Great machine BTW. You must be really pleased with that one. Thanks Terry. Your post makes sense. I think I'm not really worried about the explosion theories but I might go ahead and ground everything anyway just to get rid of the annoyance of the static. I've been under the assumption that I'd have to run bare copper wire through all the pipe and ground it to a single location, but Trip's advice to ground at each machine sounds easy and makes sense. Haven't had much time with the Supermax yet, but so far I'm loving it. I still need to order more paper so I can use it the way I need to use it....the 80 grit that comes with the machine hogs material but frankly it leaves the surface rougher than the planer does. http://www.pjdust.co.uk/faq21_whatarethecausesoffireinlev.htm Shut up dude! We had this resolved...why you gotta get all scientific on me?!? In Amurica we don't care about science...the truth is only a matter of what you "believe." There's no such thing as right or wrong. 3 Quote Link to comment Share on other sites More sharing options...
CessnaPilotBarry Posted April 17, 2014 Report Share Posted April 17, 2014 Food for thought here... I've always found the best antidote for static shocks from plastic is increased humidity. Computer and data transport rooms are humidified, because even shocks that are too small to feel can damage electronics. Quote Link to comment Share on other sites More sharing options...
G S Haydon Posted April 17, 2014 Report Share Posted April 17, 2014 Love it! Quote Link to comment Share on other sites More sharing options...
Trip Posted April 17, 2014 Report Share Posted April 17, 2014 ==> I've been under the assumption that I'd have to run bare copper wire through all the pipe and ground it to a single location That's another way to go and more applicable for setups not using metal ductwork. It's also more applicable for 'hybrid' installs -- metal ductwork, but wooden 'shop-made' blast gates and/or PVC fittings, reducers, etc... But again, there's no need to go wild --- we're not talking fire/explosion/etc risk -- we're talking about avoiding shocks, reducing dust build-up, etc -- we're talking managing an 'annoyance'... Folks are also correct, higher-humidity helps and is used in industrial applications (we keep our labs at 55%). But that's not really applicable in a home-based garage shop... For me, it was about the occasional shock (which in the winter and coming-off a wide-belt sander can be rather painful) and not having dust sticking on the flex hose connections. I use metal ductwork, fittings, blast gates, etc... so, for me, it was a quick/simple effort. I only had to jump one plastic inlet, so it wasn't a big deal... Now, if you've got an all-PVC setup, then it's more of an effort -- but still, a 500' spool of braided 24g copper ground wire is maybe $10... http://www.mcmaster.com/#catalog/120/3782/=rktc4r On a side note, one area that should always get done -- earth the DC's filter stack to the cyclone housing (the foam-rubber sealing gasket in the filter stack is an insulator)... Unfortunately, most folks don't know about bonding the filter (and few ever RTFM) to the cyclone, but it improves lifespan/performance. For my setup, I took a 4' 16g braided copper wire and attached one end to a mounting bolt on the cyclone housing and used an alligator clip to earth the wire mesh on the filter... For plastic cyclones, it's more involved. Quote Link to comment Share on other sites More sharing options...
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