# Pushfit soil pipe as dust extraction



## sumo2001

Hi
I want to use a mix of 110mm pushfit underground pipe and 110mm pushfit soil pipework as dust extraction with my SIP 3hp twin extractor what are peoples thoughts please?
I've got some soil pipe already just wanted to use underground fittings as half the price of solvent weld and can be taken apart easily if gets blocked.


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## Selwyn

Crack on. Avoid 90's


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## sumo2001

Excellent can start getting bits together


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## Rorschach

Go for it. I would do some basic earthing if it were me though, partly for safety, partly to stop me getting shocks.


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## Myfordman

+1
For a 90 translation use two 45 degree bends or a so called "slow bend" from the underground range. Glue in 100mm plastic blast gates into pipe ends with foaming pu glue and the other side fits 100mm flexi to the machine perfectly.
Ignore anyone who tells you there is a static problem.


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## Rorschach

Myfordman":tojxhbt7 said:


> Ignore anyone who tells you there is a static problem.



You have never experienced a static shock from an unearthed system then? I have, from a PVC pipe setup, from my shop vac and from my sandblaster. Not pleasant at all, almost broke my leg on the sand blaster one.


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## Myfordman

Rorschach":3ir32g1j said:


> Myfordman":3ir32g1j said:
> 
> 
> 
> Ignore anyone who tells you there is a static problem.
> 
> 
> 
> 
> You have never experienced a static shock from an unearthed system then? I have, from a PVC pipe setup, from my shop vac and from my sandblaster. Not pleasant at all, almost broke my leg on the sand blaster one.
Click to expand...


No I have not had any shocks from a system with 20 odd metres of horizontal runs 8 vertical drops and an unearthed metal cylone and steel collection bin that has been installed for 15 years or so.
furthermore there is nothing to earth in a plastic system.
maybe you should earth the machine that gave you the shocks


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## Rorschach

Myfordman":1h31flne said:


> No I have not had any shocks from a system with 20 odd metres of horizontal runs 8 vertical drops and an unearthed metal cylone and steel collection bin that that been installed for 15 years or so.
> furthermore there is nothing to earth in a plastic system.
> maybe you should earth the machine that gave you the shocks



No of course, you are right, I must have imagined it. It impossible that someone could have a different experience and offer an alternative viewpoint.


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## Trevanion

Not to contradict you Myfordman as you know more about electrical pixies than I ever will, but I've had a couple of shocks from a PVC pipe extraction that was hooked up to a 12" thicknesser before, nothing seriously major but enough to give you a jolt to wake you up. If you were planing full width you could feel the static about three inches away from the pipe and it would make your arm hair stand on end, once replaced with a steel spiral duct there wasn't an issue anymore. That was the only pipe in the system that was PVC too, the rest was already spiral duct and this was a temporary fix with a 6ft length of duct.

You do see people wrap copper wire around PVC pipes in a spiral as a way of earthing the system or somehow stopping the static escaping, again, no idea whether it works or not.

Whether the stuff about dust explosions due to the static is quite true I don't really know.


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## Myfordman

Having seen a few posts over the years about shocks I've even tried to get shocks off mine to no avail.
All I can say is the outside of the pipe runs do get a bit dusty as do the walls near the pipes but i can hold onto both pipes and the metal cyclone and not get a the slightest tickle.


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## sumo2001

Cheers for advice


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## Rorschach

Myfordman":3tzoypes said:


> Having seen a few posts over the years about shocks I've even tried to get shocks off mine to no avail.
> All I can say is the outside of the pipe runs do get a bit dusty as do the walls near the pipes but i can hold onto both pipes and the metal cyclone and not get a the slightest tickle.



So you have seen others mention it but because you have not experienced it yourself you dismiss them all and advise the OP that it is all nonsense. Very irresponsible.


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## SkinnyB

Trevanion":h37yx8dw said:


> Not to contradict you Myfordman as you know more about electrical pixies than I ever will, but I've had a couple of shocks from a PVC pipe extraction that was hooked up to a 12" thicknesser before, nothing seriously major but enough to give you a jolt to wake you up. If you were planing full width you could feel the static about three inches away from the pipe and it would make your arm hair stand on end, once replaced with a steel spiral duct there wasn't an issue anymore. That was the only pipe in the system that was PVC too, the rest was already spiral duct and this was a temporary fix with a 6ft length of duct.
> 
> You do see people wrap copper wire around PVC pipes in a spiral as a way of earthing the system or somehow stopping the static escaping, again, no idea whether it works or not.
> 
> Whether the stuff about dust explosions due to the static is quite true I don't really know.




Had a similar thing with my drum sander not too long ago. I was sanding across the grain full 500mm width probs 80grit (not something I usually do) and the static build up on the extract hose was intense. On the extract hose just above the sander you could feel it around the pipe long before you touched it. Bit of a shock when I first touched it.


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## Lons

Myfordman":19k9bjlp said:


> Having seen a few posts over the years about shocks I've even tried to get shocks off mine to no avail.
> All I can say is the outside of the pipe runs do get a bit dusty as do the walls near the pipes but i can hold onto both pipes and the metal cyclone and not get a the slightest tickle.



I've had several systems over the years mostly based on u/g 110mm pvc as I could get them through my business at no personal cost and never in 40 years have had even a suggestion of static charge, that doesn't mean it can't happen to others, my wife for instance got static shocks getting in and out of some cars while I didn't so maybe some people are more susceptible than others.

Ignore karen, he's just starting up another argument because some of the others have died down, any one who says _" almost broke my leg on the sand blaster one "_ is talking out of an orifice that isn't his mouth, you can't almost break a leg, you either do or you don't. I could say I almost  got hit by a car this morning, at least I would have if I'd stepped out in front of it. :lol: :roll:


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## Mike Jordan

Use the purpose made metal ducting, the blast gates, hanging brackets,and other things will fit together easily, it's fire resistant and won't generate static. It also avoids giving giving an insurance man an ideal excuse to blame you if the worst happens.
It won't cost very much more and it's a proper job rather than a slightly cheaper bodge.


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## MikeK

Mike Jordan":2icuysmx said:


> Use the purpose made metal ducting, the blast gates, hanging brackets,and other things will fit together easily, it's fire resistant and won't generate static. It also avoids giving giving an insurance man an ideal excuse to blame you if the worst happens.
> It won't cost very much more and it's a proper job rather than a slightly cheaper bodge.



I want to shop where you shop, or have some of what you're smoking. I outfitted my basement shop with 120mm purpose made metal ducting, blast gates, hanging brackets, and other things that fit together easily for the modest sum of €2,900. I transported and installed it, but a turn-key installation would have added another €1K to the price.

I am replacing my current system this year with 150mm pushfit drain pipe to take advantage of the 3HP blower, correct design mistakes I made, and improve the extraction. My cost to replace it with 150mm pushfit drain pipe, inlcuding the custom blast gates made for the pipe, is €525. The most expensive parts of the new ducting are the five blast gates I ordered from the States made to work with the drain pipe.

I decided on the new design after visiting a larger production shop near Heidelberg that has been using this type of pipe for over 20 years without any static buildup or fires. Since I asked specifically about any static buildup (none noticed), I'm sure the owner of the shop would have mentioned if he had nearly broken any limbs.


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## Rorschach

Well it seems some have had static problems and some have not, it's not a simple equation it seems.

The measures to avoid the static for me were so easy and cheap it seems silly not to do it just on the offchance, the sandblaster being the simplest of all. I still have not manged to sort the shop vac problem though, when cleaning large amounts of fine shavings I still get the odd shock and can definitely feel the pipe taking a charge as the hairs on my arms are attracted to it.


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## Mike Jordan

MikeK. I think you must be shopping at the wrong suppliers or someone saw you coming. The difference is not that big.


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## Distinterior

Mike J is right.....The metal spiral ducting is a bit more money, but not that much more!

Take a look at this link....

https://www.i-sells.co.uk/metal-ducting ... 155=Spiral


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## Mike Jordan

Galzanized ducting in 125mm is approx £5.00 and a blast gate the same size is £20 
Have a look at Dustspares site.


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## sunnybob

If I can inject a teeny bit of science in here?

The static comes from the wood chips scraping along the inside of the plastic pipe. Exactly the same effect as stroking a balloon across a woollen jumper and then sticking the balloon to a wall.
NONE of the pipes create static by themselves. The greater the flow speed, the more static produced.

Now, how are the pipes connected to the wall? if they are fixed with pipe clips, and you have left the rubber bumper pads on the clips, then the pipe is insulated.
If you have metal clips touching the pipe and then fixed to the wall in such a way that the metal clip stud is NOT insulated by a plastic wall plug you have earthed the pipe.
If the pipe goes into a metal container with a motor attached, its earthed through the mains lead.
So, most systems are earthed somewhere and will never produce shocks.
But if you have a powerful extraction system, into plastic hoses and plastic pipes and plastic cyclones, and the securing clips arent physically touching brick walls, guess what? you have static!
easy peasy innit?

On large installations I have heard of bare copper wire being threaded through the entire run and earthed through the pipe at each end.


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## MikeK

Mike Jordan":38dqwtsd said:


> MikeK. I think you must be shopping at the wrong suppliers or someone saw you coming. The difference is not that big.



Your definition of purpose built is different than mine. The spiral duct in the link you provided is for low-pressure HVAC systems, not dust extraction systems, and is similar to spiral ducting available here at similar prices. The largest diameter available when I was shopping was 110mm, so this was already too small for my dust collection system. If you have a link to purpose built dust collection ducting that is similar in price to S&D pipe, I would like to see it.

Here is a link to the Schuko website that makes purpose built components for dust extraction systems that I installed. If you have a link to purpose built dust collection ducting that is similar in price to S&D pipe, I would like to see it.

https://www.schuko.de/en/products-syste ... components

The ducting I bought and installed is purpose built for dust extraction systems, with smooth interior surface and flange connections. Most importantly, it is not prone to collapsing like the thin wall HVAC spiral duct. According to the Bill Pentz website, the standard (for the U.S.) 30-gauge ducting can collapse if the blower is turned on with the blast gates closed. Since no one at any of the big box stores here could tell me how thick the metal was, and it would flex if squeezed, I passed on it.


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## sumo2001

If I run wire to my metal base extractor will that earth it ?


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## sunnybob

If you connect a copper wire direct to a bare metal area on the can and then to the earth connector on the appliance, then yes, its earthed.
Note BARE metal, paint will not conduct current.


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## Trevanion

MikeK":nneps4eq said:


> the standard (for the U.S.) 30-gauge ducting can collapse if the blower is turned on with the blast gates closed.



Your usual spiral ducting here is twice as thick as that and it's still less than £5 a meter for 125mm, Mike Jordan is honestly saying the truth when he says there's barely anything in it between PVC and Spiral Duct.

Someone I know has just upgraded their dust collection set-up from a cowboy affair to spiral ducting and proper gates and such and buying everything new it cost him around £2000 and a few days to put it all up, and this was in a 4000sqft building with several machines to hook up to.


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## Roland

The problem with static isn’t getting a shock. There is a risk that a spark can ignite a dust/air mix, causing an explosion. Not common, but not a risk I’d like to take.


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## MikeK

Trevanion":41em56b0 said:


> Your usual spiral ducting here is twice as thick as that and it's still less than £5 a meter for 125mm, Mike Jordan is honestly saying the truth when he says there's barely anything in it between PVC and Spiral Duct.
> 
> Someone I know has just upgraded their dust collection set-up from a cowboy affair to spiral ducting and proper gates and such and buying everything new it cost him around £2000 and a few days to put it all up, and this was in a 4000sqft building with several machines to hook up to.



You are truly fortunate to have resources like that! The spiral ducting available at the big box stores here is useful for nothing more than low pressure ventilation. It would almost be cost effective to drive to the UK and load up my truck with your thicker ducting.


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## Inspector

Roland":1ikerb1b said:


> The problem with static isn’t getting a shock. There is a risk that a spark can ignite a dust/air mix, causing an explosion. Not common, but not a risk I’d like to take.



Actually you can't get a big enough spark from a home DC until you use 12"+ diameter PVC (read that somewhere) and the DC big enough to move the air though it to build up the charge. Also you have to have the perfect concentration of dust which using home shop including drum sanders we can't reach. A big wide belt sander might get there but how many of us have 1 meter wide belt sanders in the shop? 

The most common cause of DC fires is wood getting hot from friction with the wood pinching the saw blade or some other tool. The ember sits for some time in the bottom of the machine or in the DC and smoulders away until it starts to burn. The other reason is sucking up some metal and it hitting the impeller with that spark causing a fire.

The only reasons to try bleeding off the static is in some installations you can get an annoying zap and with the advent of CNC routers there is a possibility of the static discharging through the computer, frying some of the boards. 

http://cliffsgarage.tv/articles/dustExplosion.html
http://www.woodcentral.com/articles/sho ... _221.shtml

Pete


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## gregmcateer

Gents, 
I'm a little nervous of entering the ducting fray, which might head into a sharpening- style fracas before long, but here goes:

On the dustspares website, (thanks for the link- very useful), there are blast gates for 16 odd quid and also butterfly gates at just over 9 quid - is there a worthwhile advantage to the former?

Thanks in advance

Greg


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## Inspector

Blast gate when open is unobstructed so nothing for the shavings to hang up on. A butterfly valve always has the disc in the duct where shavings can hang up, eventually blocking the duct. Use blast gates.

Pete


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## gregmcateer

Cheers Pete, 
I suspected as much - bit like proper water shut off and ball o fix style limiting flow. 
Thanks
Greg


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## Lons

I'm a lot more concerned about my belt / disk sander causing a fire that my DC system as I've experienced it.
OK my own fault as I didn't clean it thoroughly enough, thought I had and I disconnected the DC outlet and connected a shop vac because I sanded some metal however there was a build up of sawdust in a corner which ignited due to metal sparks, it was a solid lump not fine dust, luckily saw it quickly but won't be doing that again in a hurry. #-o Pure laziness as I have several other means of grinding metal.


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## Rorschach

I am not really worried about fire from static (fire from sparks does worry me of course), I am only worried about the nasty shocks I was getting. Earthing solved this problem entirely (aside from shop vac) the potential fire prevention is an added bonus.


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## gregmcateer

Rorschach":1e1ijuf6 said:


> I am not really worried about fire from static (fire from sparks does worry me of course), I am only worried about the nasty shocks I was getting. Earthing solved this problem entirely (aside from shop vac) the potential fire prevention is an added bonus.



Did you just run a bare copper wire down the inside and connect it at both ends to metallic parts?


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## Rorschach

gregmcateer":1a3uxuad said:


> Rorschach":1a3uxuad said:
> 
> 
> 
> I am not really worried about fire from static (fire from sparks does worry me of course), I am only worried about the nasty shocks I was getting. Earthing solved this problem entirely (aside from shop vac) the potential fire prevention is an added bonus.
> 
> 
> 
> 
> Did you just run a bare copper wire down the inside and connect it at both ends to metallic parts?
Click to expand...


No I used aluminium tape (the kind used for sealing ducts etc) and ran a strip down the length of the outside of the pipe and then connected to earth at the extractor end, it worked well. 
My sandblaster has a copper wire clipped to the house earthing point and then I also wear an earthing strap on my wrist when using it, again it works perfectly, no shocks since. 
I have not had any good ideas for the shop vac though as the hose is plastic as is the cyclone so earthing is tricky.


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## gregmcateer

That's helpful, thank you


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## gregmcateer

Gents, continuing this thread seems as good a place as any:

Blast Gates - 2 questions:

1. To avoid any jamming up with debris, should they be installed in the vertical pipe run, so they are horizontal, or in the horizontal runs so they are vertical?

Or doesn't it matter a hoot?

2. As close as poss to the extractor or as close as poss to the machine making the mess? (I assume the extractor, to minimise unnecessary 'pull'

Thank you in advance.

Greg


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## Doug B

If your blast gate is vertical it stands a chance of either dropping shut or falling open if it doesn’t have some sort of open/close fixing.
Usually gates are placed near the machine for ease of access especially if the extractor is the other end of the shop.


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## gregmcateer

Hi Doug, thanks for that.
I'll give it a go


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## mindthatwhatouch

Rorschach. Re: shop vac.
Try wrapping aluminium tape around the perimeter of the shop vac and have a little trailing bare conductive lead draped to touch the floor.


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## DBT85

IIRC Mike Jordan once referred to anyone doing it with plastic ducting and home made blast gates as "penny pinching clowns".


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## Spectric

Hi

Don't forget that brown underground soil pipe is not UV resistant, it will fade and degrade in sunlight wheras the Black and Grey are designed for exposure to sunlight above ground.


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## Mike Jordan

My only motive for such abuse is to concentrate the minds of fellow woodworkers. The few pounds saved will be easily offset by the fact that your insurance will be negated by the increased fire risk from static and the total lack of fire resistance.
Using incorrect materials will provide your insurers with a great excuse to point out the elevated risk you created. It's quicker and easier to do it right!


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## Rorschach

Mike Jordan said:


> My only motive for such abuse is to concentrate the minds of fellow woodworkers. The few pounds saved will be easily offset by the fact that your insurance will be negated by the increased fire risk from static and the total lack of fire resistance.
> Using incorrect materials will provide your insurers with a great excuse to point out the elevated risk you created. It's quicker and easier to do it right!



Maybe just avoid the abuse, in my experience it doesn't concentrate the mind, it makes people more likely to rebel and makes people think less of the person doing the abusing.


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## Mike Jordan

You can't deny the truth of my statement can you.


A


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## Rorschach

Mike Jordan said:


> You can't deny the truth of my statement can you.
> 
> 
> A



Eh?


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## SammyQ

Popcorn?


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## MikeK

Gents, please keep the discussion civil.


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## clogs

as for MikeK's over expensive metal ducting....it could be a country specific price prob......
I just bought enough guttering for an average 3 bed detached house and it cost over €850 euros....just materials in plastic......
full body showers in a fiber glass screen assy is very cheap in France [about a 1/3 of the UK price] 
but nuts n bolts are 5 times more expensive than the UK.....
brass plumbing fittings here are about 30-50%cheaper than the UK dont ask about France.....
it all in the geography I'm afraid.......
I like ur style MikeK more photos of the shop and ur fancy add on's please.....good for ideas.....


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## RichardG

For info this is worth a read on the subject, it’s very thorough.

Grounding PVC and Other Dust Collection Myths


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## Spectric

I would not get too hung up about static electric generation in your extraction systems, lifes to short and it will not shorten it any more unless you waste time thinking about the what if's. If it was carrying natural gas or flour then I would take it seriously but it is going to take some spark to ignite your wood dust in a home workshop, it has not got the power of the Haddron collider. Personally I do my best to minimise dust but always end up having to give the place a good hoover regularly as I prefer to make dust and not worry about controlling it to much.


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## DBT85

Mike Jordan said:


> My only motive for such abuse is to concentrate the minds of fellow woodworkers. The few pounds saved will be easily offset by the fact that your insurance will be negated by the increased fire risk from static and the total lack of fire resistance.
> Using incorrect materials will provide your insurers with a great excuse to point out the elevated risk you created. It's quicker and easier to do it right!


Any actual evidence of your claims? or just the usual PVC causes explosions myth?


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## MikeK

clogs said:


> as for MikeK's over expensive metal ducting....it could be a country specific price prob......
> I just bought enough guttering for an average 3 bed detached house and it cost over €850 euros....just materials in plastic......
> full body showers in a fiber glass screen assy is very cheap in France [about a 1/3 of the UK price]
> but nuts n bolts are 5 times more expensive than the UK.....
> brass plumbing fittings here are about 30-50%cheaper than the UK dont ask about France.....
> it all in the geography I'm afraid.......
> I like ur style MikeK more photos of the shop and ur fancy add on's please.....good for ideas.....



Had I known about the substantial price difference in metal ducting between Germany and the UK, I would have made a trip across the channel with my truck for a shopping spree. My upcoming dust collection change will replace the existing 120mm metal ducting with 150mm S&D pipe.

I prefer to think of my shop add-ons as functional upgrades that happen to look nice.


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## Doug B

Spectric said:


> I would not get too hung up about static electric generation in your extraction systems, lifes to short and it will not shorten it any more unless you waste time thinking about the what if's. If it was carrying natural gas or flour then I would take it seriously but it is going to take some spark to ignite your wood dust in a home workshop, it has not got the power of the Haddron collider. Personally I do my best to minimise dust but always end up having to give the place a good hoover regularly as I prefer to make dust and not worry about controlling it to much.


It’s not the risk of fire, I tend to agree with you on that Roy it’s the bloody big static shocks you can get off it if it isn’t earth that’s the real pipper.


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## Sandyn

If you blow dry sawdust, even just air at high velocity along a plastic pipe there is a risk of static build up. The effect is a very real demonstrable physical phenomenon. BUT it may not happen with every set up, it depends on so many things like materials, humidity. Some plastic tubes are made from a conductive material, carbon is added to the plastic to make it conductive enough to stop static build up. Conductive plastics. 

Some people may be plagued with it, others may never have problems. All of you must have done the static electricity tests at school? rubbing a balloon then holding it above your head, hair standing on end. Sticking a balloon on your chest, even stoking a cat can generate static charges and sparks ( a source of huge amusement for me).

When the sawdust passes along the tube, it causes charge to move to or from the plastic pipe, so the pipe may end up with a huge positive or negative charge. It depends on the material. The end result can be a static shock and possibly a spark. It's not the same as electricity flowing, it's the build up of charge, so it happens with insulators and of course electricity will not flow in an insulator, which allows it to build up charge, then dissipate that charge to a passing ground point, like your hand.

If I ever had the problem, I would try an experiment with conductive paint, I would have an open end of the pipe vented to the outside, then blow air along the tube, while spraying Conductive paint in where the air is being blowing in. You would then need to bring a connection from the paint out to ground. I would just use copper tape. I have never tried this, but it's a way of getting the inside of a tube conductive and hopefully static free. It might wear off very quickly, but not certain how robust it would be. An alternative is to stick copper tape as far as you can along the inside of the pipe and ground.


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## Inspector

RichardG said:


> For info this is worth a read on the subject, it’s very thorough.
> 
> Grounding PVC and Other Dust Collection Myths



I linked the same in post 28 but it is something worth repeating.

Pete


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## MikeK

Inspector said:


> I linked the same in post 28 but it is something worth repeating.
> 
> Pete



It was like déjà vu all over again.


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## Keith 66

I just fitted extraction for a laser cutter, all stuff bought from ductstoreuk.co.uk, 150mm spiral duct was £18.04 a 3m length, 100mm £11.25. Screwfix price for grey pvc 110mm pvc soil pipe is £15.89.
So its actually cheaper to use the proper stuff!
As for static that can be proper fun, i was once trimming a new 18ft GRP boat hull & once i had finished got the shop vac going & started sucking up all the dust, vac was metal cased, after about 5 minutes i went to turn it off & as my index finger approached the switch at a distance of about 3/4" a great fat spark jumped the gap to my finger with a sharp crack! 
While polishing moulds static shocks were a regular occurence.


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## RichardG

Inspector said:


> I linked the same in post 28 but it is something worth repeating.
> 
> Pete


Sorry, my mistake, didn’t read the full thread thoroughly....


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## Arnold9801

sunnybob said:


> If I can inject a teeny bit of science in here?
> 
> The static comes from the wood chips scraping along the inside of the plastic pipe. Exactly the same effect as stroking a balloon across a woollen jumper and then sticking the balloon to a wall.
> NONE of the pipes create static by themselves. The greater the flow speed, the more static produced.
> 
> Now, how are the pipes connected to the wall? if they are fixed with pipe clips, and you have left the rubber bumper pads on the clips, then the pipe is insulated.
> If you have metal clips touching the pipe and then fixed to the wall in such a way that the metal clip stud is NOT insulated by a plastic wall plug you have earthed the pipe.
> If the pipe goes into a metal container with a motor attached, its earthed through the mains lead.
> So, most systems are earthed somewhere and will never produce shocks.
> But if you have a powerful extraction system, into plastic hoses and plastic pipes and plastic cyclones, and the securing clips arent physically touching brick walls, guess what? you have static!
> easy peasy innit?
> 
> On large installations I have heard of bare copper wire being threaded through the entire run and earthed through the pipe at each end.




I think as there isn’t doubt both ways regarding static on extraction pipes, there isn’t any harm in playing safe as the consequences if it does go wrong are only to obvious. So... to play safe is it just alright to wrap copper wire around the outside of the plastic ducting or is it a MUST that it has to go on the inside?


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## OldWood

I'm slightly reticent to entering this conversation (!) coming from a desire to fit such a system but no practical knowledge. Locic sasys to me plastic drain pipe as all fittings are immediately available at the local plumbers outlet, and how ever carefully you design something an immediate back up of parts is worth quite a lot of money.

I can understand the bare copper wire down the plastic pipe conducting away the electrostatic charge, but how do you get the wire out to earth it? Having just written that I realise a small hole at some point and silicone to seal it, or a 4mm bolt with earth tags inside and out.

But then I have difficulty with the option of placing of aluminium tape on the outside of the pipe - could I ask if Sunnybob could continue his discourse on static electricity to explain how the charge generated inside a plastic pipe gets to the outside, and further, referencing this tape, how it works when it will have an adhesive layer and possibly a plastic layer before you get to the conductive film on the surface.
Rob

Editted to say this is now an out of date request as I'm reading the article from Wood Central!!


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## Chris70

MikeK said:


> It was like déjà vu all over again.


Is that tautology?


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## gregmcateer

RichardG said:


> For info this is worth a read on the subject, it’s very thorough.
> 
> Grounding PVC and Other Dust Collection Myths



Thanks for sharing this - way over my little head scientifically, but reassuring to read.


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## Sandyn

Very interesting article. For me, the interesting line is " * However, if you choose to use PVC ducting in your home shop, the risk of an electrostatic explosion due to the ducts is, at worst, extraordinarily small. From the research papers I have read, this risk is essentially zero* "
so the risk is 'essentially zero'......but not zero


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## MikeK

Chris70 said:


> Is that tautology?



Yes, but it's a quote attributed to Yogi Berra, and American baseball player for the Yankees. He was famous for nonsense quotes, such as "The future ain't what it used to be."


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## Trextr7monkey

Interesting thread I had a workshop with a commercially fitted extraction system which was mostly wood working machinery with about 14 points fitted. It was all installed using various diameters of spiral tube with flexible hoses to each applicance. 
Couple of points 
1) Over time equipment was moved around andthe system was modified in places with lengths of 110mm drain pipe as long lengths of flexible pipe get expensive and collect dust. The annual HSE inspection did not raise this as an issue.
2) Blast gates were fitted to all points and never got blocked there was one rotating butterfly valve attached to a sweep up hood for the cleaner and that occasionally caused problems.
3) The metal duct system replaced a plastic tube diy installation that had operated for many years the tubes appeared to function well it was the old plastic bags on the cyclones that made the system useless.
4) With all tubes shut off there was suitable suction to clear any minor blockages that could occasionally be heard bouncing up and down the dropper tubes. We were advised to just use one port at a time but in practice this didn’t always happen


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## Inspector

RichardG said:


> Sorry, my mistake, didn’t read the full thread thoroughly....



No sweat Richard. Everyone skims long threads at some point along the way and even when you do follow one over a period of time you forget some of what has been said and restate it again. 

Plastic is an insulator and when it sparks only a small area near the contact point discharges. Trying to bleed all of it off so it doesn't build up is nearly impossible. Maybe wrapping the whole pipe with wire screen (chicken wire for instance) like a Faraday Cage might work but if going to that extreme one might as well get metal ducting.

I've said it before, maybe even in this thread , the only reason to try grounding is to reduce nuisance shocks and for dust collection to CNC machines to protect their circuit boards where a stray shock can fry them.

Everyone is free to make their own choices. Best if done after research rather than fear but we wouldn't be human if we did that all the time. 

Pete


----------



## Lard

I replaced my flexible pipework with 110mm drainage pipe a few years back and, although screwfix is handy/local for immediate purchases, I bought the vast majority of pipe and fittings from an online company.

Cant remember the exact company but here’s a suitable web example to illustrate.....

Example price is *~£9 for 3m length* of 110mm pipe (incl vat).....they charge a one-off delivery of ~£9 for orders below £90



110mm Underground Drainage Pipe x 3m PE



Out of interest I‘ve also just completed a project for my cousins where the gf bathroom was a replaced with a brand new ff room which, obviously, involved some above ground drainage. I got them to buy online. Worked perfectly and saved a fair amount.


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## DBT85

Sandyn said:


> Very interesting article. For me, the interesting line is " * However, if you choose to use PVC ducting in your home shop, the risk of an electrostatic explosion due to the ducts is, at worst, extraordinarily small. From the research papers I have read, this risk is essentially zero* "
> so the risk is 'essentially zero'......but not zero


The risk of getting struck on the bonce by a meteor also isn't zero. Yet you don't walk the street wearing a Challenger 2 as a hat.


----------



## gregmcateer

DBT85 said:


> The risk of getting struck on the bonce by a meteor also isn't zero. Yet you don't walk the street wearing a Challenger 2 as a hat.



Don't you????


----------



## Sandyn

DBT85 said:


> The risk of getting struck on the bonce by a meteor also isn't zero. Yet you don't walk the street wearing a Challenger 2 as a hat.



Absolutely not. I just found the article slightly odd in some areas. It is a very good article. I'm taking a slightly tongue in cheek view of it and the poor wee soul spent ages in the library, but it's a bit dismissive of the problem,then goes into great detail how to counteract it.

The 'Myths'

1 " I do not know the explosive power of this volume of dust, but I do not think this is going to level your shop."
:-I read as ---he hasn't a clue, but has guessed it's not a problem. If you are going to produce 'the definitive guide to static in PVC'. one thing you can't do is guess, but we all do it...

2 " You simply can't ground an insulator."
:-Of course not, but if you have a charged insulator and put a ground near it, it will tend to reduce the charge. That's what lightning conductors can do. Charge will leak from earth via the conductor to cancel the charge on nearby clouds and can stop a discharge. The terminology 'grounding' is wrong, but it's literally what you do. You bring a ground to the insulator, just as a lightning conductor 'brings the ground to the sky'. He has to chill out about terminology.

3 " As seen above, the collected dust pile and the collection bag are greater hazards than the ducts. Fortunately, in practice home shop sized dust bags have shown themselves to pose little explosion hazard."
:-Totally irrelevant to PVC pipes and static.

4 "There is little or no static on the outside of the PVC unless you are rubbing the outside for some reason; the static is on the inside. The electric field due to the static charge in the pipe can cause a discharge on the outside"
:-It doesn't matter what the physics behind it is. People see effin big sparks from plastic tubes . He is being technically correct, but needs to chill out about terminology.


For me, static and dust explosions are not a concern, but I respect the concerns of other people who are worried about it. As for wearing protection against a meteor . NASA spends a fortune looking for meteors, so I don't need to wear Challenger 2 as a hat.  ....and there are many people who do have disaster shelters for when the meteor strikes. I bought an extra toilet roll, so I'm OK!

When you start to quantify a problem like static in a tube, you are on to a looser, because there are so many variables but it is a non zero risk.
When it comes to health and safety, the risk has to be assessed see here, in particular the ducting requirement. I would say a better description is that the risk is 'not known'. not 'essentially zero' The risk in PVC pipe is apparently real if the HSE require conductive ducting.
I think that anyone who feels they need to do something about plastic pipe, are doing the correct thing for them. It seems there is no guaranteed way to completely prevent the possibility of discharge. Whether that causes a dust explosion is a completely separate problem and even more complex.

If anyone is really concerned, my advice now would be they should just follow the HSE advice and fit conductive ducting.


----------



## Heluvaname

Apologies if I've missed it, but does anyone use, or have a source for, clear rigid pipe for dust extraction?
Sure I've seen a systems somewhere, which seemed to make sense for easily spotting issues, and it looked cool to see the dust whizzing along!


----------



## Inspector

There are 2 1/2” size packages here at Lee Valley but nothing bigger that I know of. You can get clear PVC in larger sizes that have astronomical prices that make it too expensive to even consider.
Pete


----------



## Sandyn

Heluvaname said:


> Apologies if I've missed it, but does anyone use, or have a source for, clear rigid pipe for dust extraction?
> Sure I've seen a systems somewhere, which seemed to make sense for easily spotting issues, and it looked cool to see the dust whizzing along!


 There is some HERE, but a bit expensive. I would light it with blue LEDs


----------



## Heluvaname

Thanks, but at c£50/m I think I may give clear a miss!


----------



## Heluvaname

Would look great edge-lit with blue LED though


----------



## Davey44

I have a couple of new lengths of LARGE soil pipe (110mm I believe). Will check tomorrow if anyone's interested. It makes a relatively inexpensive means of installing a large extraction system, especially if you're using a high volume/ large power motor extractor. Spurring off a large primary with smaller secondaries gives one of the best options for an effective and efficient system.


----------



## mikej460

MikeK said:


> Yes, but it's a quote attributed to Yogi Berra, and American baseball player for the Yankees. He was famous for nonsense quotes, such as "The future ain't what it used to be."


Yes but then again he was smarter than the average Berra..


----------



## Keith 66

Just saw this on fb Oxford fire service called to a fire in an extraction system, I guess this is why metal ducting is a better choice.
,Facebook,


----------



## Sandyn

According to the report it was a spark from a saw that caused the fire in the metal ducting. I think it must have been clogged with sawdust. I think the metal ducting may have prevented the spread as it seems to have been limited to the extraction system


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## Terrytpot

to be honest I was quite surprised at how cheap the galv spiral ducting is .. screwfix sell 110.. soil @ £15.89 3m whereas Dustspares sell 125 spiral @ £15.96 3m. or 100mm @ £13.20 3m. I'm not quite ready to install ducting myself but think when I am I know which way I'll be leaning


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## Mike Jordan

Terrytpot* you have it sorted ! I am amazed that fellow woodworkers will invent excuses and go to lots of trouble to convince themselves that materials designed for drainage are safe and better than the proper ducting. It all joins up easily and has no static problems or need for suspect earthing methods
It's fire resistant and matches industry standards. It will be interesting to see if your sensible approach leads to you being accused of smoking wacky bacy as I was a few posts back.*


----------



## dzj

PVC works well, but at those prices, you might as well do it properly.
Most important thing is to keep your shop clean. Spark or no spark, you can't have a fire if there's nothing to ignite.


----------



## Mike Jordan

Axi sell plastic fittings for use with drainpipe systems. From what little I've seen they are more expensive than the metal versions.


----------



## DBT85

Mike Jordan said:


> Terrytpot* you have it sorted ! I am amazed that fellow woodworkers will invent excuses and go to lots of trouble to convince themselves that materials designed for drainage are safe and better than the proper ducting. It all joins up easily and has no static problems or need for suspect earthing methods
> It's fire resistant and matches industry standards. It will be interesting to see if your sensible approach leads to you being accused of smoking wacky bacy as I was a few posts back.*


Which posts were these?


----------



## Mike Jordan

It was MikeK in an early post. In fairness I did Imply that he was a little gullible. It turns out that his shop is in an area where metal ducting is grossly overpriced.


----------



## Retired

Hi,

I was trained down a deep coal mine; if you want to mix combustible dust with static then expect the worst; it's too late when there's an explosion. Why kick this dangerous subject around on a forum in front of the world; a phone call to your local fire service should be the first point of contact. I was in charge of the timber department at work and would never use plastic for woodworking machinery extraction.

Check with your home insurance company who would most likely reject an insurance claim.

Kind regards, Colin.


----------



## TRITON

Myfordman said:


> +1
> For a 90 translation use two 45 degree bends or a so called "slow bend" from the underground range. Glue in 100mm plastic blast gates into pipe ends with foaming pu glue and the other side fits 100mm flexi to the machine perfectly.
> Ignore anyone who tells you there is a static problem.


I'd use gaffa or duct tape rather than glue as its easier to reconfigure shold he wish to.


----------



## Mike Jordan

Retired, you are right and have the knowledge! The phone call you suggest would have been ringing out on my desk a couple of decades back.
I've tackled fires in dusts and actually caused them In controlled circumstances. The insurance problem has also been mentioned before.
It seems that nothing will convince the plastic pipe champions!
I have a friend who's system runs underground from his workshop ( where the pipes are metal) to discharge in a shed in the back garden, that's the only piece of safe plastic ducting I know of.


----------



## gregmcateer

I have no axe to grind either way, just an interest in learning more. 
So - if plastic pipe is that dangerous, 
a) why is it permitted by HSE?
And
b) why do pretty much all wood cutting and shaping machinery manufacturers and DE machines supply them with at least some length of plastic pipe?

Genuine question, btw


----------



## Mike Jordan

As you say, most systems, including mine,have short lengths of flexible plastic pipe connecting machines to the metal ducting. This is kept to a minimum and is of course earthed through the machine and the metal pipes. It does however generate some static, this can be seen in the fact that small chippings tend o stick to the outside of the pipe when the system is new.
The effect seems to stop when the pipes get a bit grubby. 
The flexi pipe is usually made with a wire spiral bonded into it. 
Let's be clear, the chances of a dust explosion in a small system must be very small, but it's one that is largely eliminated by the use of the proper ducting which is the same price, or even cheaper, than plastic.
Explosions in dust can be very violent and destructive, as Retired mentioned coal mines take great care to avoid /suppress any occurrence since many lives are at risk. If you want to see evidence of problems try googling fires in paper or pulp mills.


----------



## Retired

Hi,

I agree with you entirely Mike Jordan. 

Spark Arrestor Manufacturers | Spark Arrestor Suppliers

Before retiring I was registered with the HSE because of my responsibilities being in charge of the timber department at work. Having been safety trained down a deep coal mine I know only too well the risk of explosion; yes the risk is small in say a home workshop but what if the explosion should happen in your own workshop; it would then bring the risk home to you but then of course it always happens to someone else.

I used to receive up to date information from the HSE 

HSE Woodnig Newsletters

I and a colleague used to visit a large demonstration once each year of all modern woodworking equipment; one demonstration showed spark arrestors these really demonstrating how easy it was to cause a fire/explosion this in steel ducting so nothing is 100% safe.

TIMCON - The Timber Packaging and Pallet Confederation

There's so much legislation around these days it's surprising anything gets done here in the UK. I thought it was complicated enough over 20 years ago keeping up to date but now it's an whole lot worse. I was also in charge of two more departments and the responsibility weighed heavily on me as well as the huge amount of stress of the normal job keeping everything running smoothly. 

It's no longer being accountable of your own mistakes or actions but anyone in management right up to the very top could well end up in court in serious trouble should an employee be involved in an accident even though management weren't present at the time. 

I'm very careful as to replies I post on open forums because should I encourage anyone to adopt an unsafe practice it could come back to me as in this thread; if I said it's fine to use plastic ducting in extraction and a member took me at my word then suffering an explosion quoting me saying I'd encouraged the use of plastic ducting I'd be very exposed indeed because I know I'm completely unqualified to offer such advice.

What does surprise me is that so many would think nothing of spending a lot of money on the latest must have electronic gadget which would be out of date in a month or pay to watch someone kick a ball around a field but would begrudge paying for personal safety? 

I DON'T RECOMMEND THE USE OF PLASTIC DUCTING AS BEING DESCRIBED IN THIS THREAD.

Kind regards, Colin.


----------



## Sandyn

gregmcateer said:


> I have no axe to grind either way, just an interest in learning more.
> So - if plastic pipe is that dangerous,
> a) why is it permitted by HSE?
> And
> b) why do pretty much all wood cutting and shaping machinery manufacturers and DE machines supply them with at least some length of plastic pipe?
> 
> Genuine question, btw



When trying to get to the bottom of this question, I did find this It seems to suggest that HSE recognise the risk of plastic ducting, and recommend the following. 

"""Make ductwork as short as possible with a minimum number of bends. The design should specify a minimum transport (or conveying) velocity3 of 20 m/s to minimise dust deposits.* Use only conductive materials for ductwork so that any static electricity generated can be discharged to earth. """*

EDIT:- I don't follow HSE advice at home (on just about everything) , but if it was work related, it would be a different matter.


----------



## Mike Jordan

That's a clear and sensible statement Colin.
I've wondered throughout this thread if axi and other suppliers of plastic parts which are intended for use with drainpipe would find themselves in the firing line if the worse happened.
I have some concern about those who advocate the use of pallet wood for use in woodworking. My knowledge is limited but I believe that a lot of it is treated with chemicals which means that it shouldn't even be burnt let alone inhaled as dust.


----------



## gregmcateer

Colin, Mike, Sandyn,
Thank you for your input and clear, helpful explanations. 
Cheers
Greg


----------



## Retired

Hi,

Thanks Mike Jordan; yes it pays to be very careful using any second hand timber;

"Why are blue pallets illegal?
This stands for Methyl Bromide which is a harmful chemical used to prevent wood eating insects consuming the *pallets*. It was *banned* in the *UK* 5 years ago so they are much rarer to come by now.1 Jul 2015

We made thousands of pallets and packing crates etc. we also bought in loads of 300 at a time second hand Euro pallets. Occasionally blue pallets would turn up and I was aware of the problems associated with reusing "Chep" pallets so these were not reused by us. I'm out of touch with all modern safety laws having retired 20 years ago. Yes lots of timber is harmful to an unsuspecting user; treated timber for exterior use gives off toxic fumes when burned but few will be aware of this; I'm unsure if this is still the case. Exotic timbers used by woodturners can cause serious health problems.

We never used treated timber for making pallets just buying 3 cube loads at a time of sawn softwood.

Broken pallets were always a problem for me to dispose of at work; one of my team members lived on a council estate in Barnsley and he had a neighbour who was retired and kindly cut up firewood for other neighbours; he wasn't a driver but to get rid of broken pallets I often authorized a team member who could drive to borrow the works pick up truck hence everyone was happy. One day the team member asked for more pallets so I asked him how many his neighbour could cope with "as many as you have" I despatched a 40' curtain sided trailer; the load of broken pallets filled three front gardens; I did at the time knowing where he lived asked if his neighbours were using the pallets as double glazing?

Obviously in the timber department we had lots of saw dust and shavings; one of the team had hamsters and I refused to let him take sawdust; I just didn't have the time to stand and explain so he left in a huff; later in the day I asked him if he wanted to kill his hamsters; we'd been running a lot of hardwood through the saws.

Sorry to divert this thread off topic but whomever pays the money has the choice as to type of ducting they use for dust extraction; it's easy to knock H&S guidelines but they are there for everyone's safety.

Kind regards, Colin.


----------



## TRITON

> The flexi pipe is usually made with a wire spiral bonded into it.



Yeah but its not connected to anything. And certainly not to earth. The wire is encaptulated totally so even at each connected side- which is plastic incidentally, the wire doesn't touch any metal part of machine or extractor.


----------



## NetBlindPaul

The wire is intended to be exposed at the end where it mates to the metallic duct and be connected to said metallic duct.
BS 7671 requires that the metallic duct in most cases is connected to the orotectice conductor network of the electrical installation and is thus connected to earth via this path.
Building regulations require compliance with Part P of the building regulations, which require compliance with BS 7671.
Plastic pipe work such as 110mm soil pipe etc. is not safe, nor suitable for use for extraction.
Whilst your home insurer will probably not be interested in any harm you bring on yourself whilst undertaking yiur hobby.
The small print of your policy may well require compliance with BS7671, and mat well consider the use of plastc ductwork for the conveyance of dust, which is a well known and documented explosion and fire risk, would also invalidate qny claim you may make.
In any business undertaking, compliance with the law is required, and realistically, this would preclude the use of plastic duct.


----------



## Inspector

Paul I don't doubt for a second your qualifications. You said "_is a well known and documented explosion and fire risk_". I've seen that written many times over the years but have never seen any actual reports from home shops. Factories and sawmills for sure but never a home shop static explosion/fire. I'll happily sit corrected if there are any.

Pete


----------



## MikeK

Inspector said:


> Paul I don't doubt for a second your qualifications. You said "_is a well known and documented explosion and fire risk_". I've seen that written many times over the years but have never seen any actual reports from home shops. Factories and sawmills for sure but never a home shop static explosion/fire. I'll happily sit corrected if there are any.
> 
> Pete


Pete,

I'm with you on this. I searched for years to find just one documented case where a hobbyist woodshop experienced an explosion or fire directly attributed to static buildup in the PVC ducting. Given the widespread use of non-metallic ducting throughout Austraila, North America, and Europe in basement, shed, and garage shops, I would expect at least one report of a static-induced explosion to support the claims; however, I have never found any.


----------



## Retired

Hi,

https://www.hse.gov.uk/pubns/wis32.pdf

Page 2 Please look under ductwork.

This morning I intended to email our local fire department sending them a link to this thread requesting their expert recommendation and guidelines but looking at the mixed replies it appears a number of members are saying it's safe to use plastic ducting for wood chip/dust extraction. Home workshop fires/explosions simply don't feature on mainline news but are generally in local news as are household gas explosions. HSE clearly state "USE ONLY CONDUCTIVE MATERIALS FOR DUCTWORK" If you disagree and go ahead to use plastic ducting and suffer a fire/explosion then at least I and others like Mike Jordan have taken the time to post the dangers. 

I wonder how many members have actually witnessed the power of an explosion in a confined space; I have during my time working down a deep coal mine whilst a deputy was shot blasting.

Many years ago my younger brother at the time living in a flat in Wakefield awoke to find the front of the old Victorian building missing; huge calor gas cylinders were stored in the basement these for cooking purposes. Fortunately there were no casualties; this explosion made it as far as local TV but not national TV.

Four dead in UK wood mill explosion

Kind regards, Colin.


----------



## NetBlindPaul

Just because there are no incidents that can be found for DIY setups causing explosions or fires, this does not mean this can be ignored.
The hazard is real.
The risk is real.
You might even fine that in time insurers will clamp down on home workshops.

I really hope this does not happen, as likely I will have to give up my commercial workshop soon and move my machinery home, I have a mix of wood working, very basic, a tidy Harrison lathe and a Bridgeport, plus various welding equipment.
Unfortunately, I’m writing this from a hospital bed having been paralysed from the navel down by cancer, in the last few weeks. So I don’t think I will be in a position to continue renting the workshop without income.


----------



## Doug B

I personally don’t use plastic ducting other than flexible hose & whilst not denying static charge can cause explosions it’s interesting that companies like Camvac produce a ducting made from plastic tubing & they aren’t the only ones.

Surely these companies aren’t taking the suggested risk without any thought of possible liability, I fully understand that flour can & does easily ignite but surely as woodworkers we aren’t producing such fine dust in relevant quantities to cause an explosion as linked to by Retired?


----------



## NetBlindPaul

In a business ”undertaking” the law requires that the LEV system is CE/UKCA marked in its installed condition, that means it must comply with the EHSR’s of the MD/SMSR.
This is not an option, failing to do this is illegal.
Obviously in DIY this does not apply.
However in the event of a domestic failing, the insurance company loss adjusters would be looking for a way to avoid paying out.
Being an expert witness myself, I would simply be looking to the ducting being plastic and I would then look into the guidance around that and the previous commercial incidents nd the science behind the ignition energies to illustrate that the plastic duct was unsuitable and that the user choosing this obviously did not understand the hazards.
Then I would illustrate that LEV must meet the. MD/SMSR to be legal to be placed on the market, which includes own use.
After that it would be up to the insurance company or court to decide, if this was applicable to a DIY scenario.
After all the machinery you buy must comply to be legal.

The suppliers at the moment can sell what they like, you. only need to look on the various online auction sites and similar even those with .co.uk domains, those based in China are even more of a risk.
It is the designer and manufacturer of the LEV system who is responsible for compliance.

One last point, if one were to purchase something from one of the Chinese auction or sales site, or come to that, any site selling outside the UK/EU, then even as a private individual you then become the importer with all of the legal obligations of that role. Basically you take on the responsibility as the manufacturer, and become legally liable for the compliance of the product in the UK/EU.

The fine details of this moving forward are subject to the BREXIT agreement, however, SMSR is UK law and the EHSR’s are identical to the MD, as is the rest of the legislation I have quoted, and changes will. depend on the “agreement”


----------



## Retired

Hi,

I'm sorry to learn of your serious health problem Paul and wish you a full and speedy recovery also a very happy New Year. 

Downsizing your workshop can be good as in my case. We have our garage directly beneath our detached bungalow but now it's a fully kitted workshop with the car outside on the driveway. Over the years I collected lots of big heavy machines including Dominion woodturning lathe; Colchester Triumph engineering lathe; Startrite combination woodworker and Startrite industrial Volant 24" bandsaw; I reached the point I had so much machinery I struggled to work bumping into them all the time so I downsized; I can still carry out any woodworking or metalworking I'll ever need to do in a home workshop; the machines I had were way over the top so now I've got smaller machines and even added to them; some are on wheels/casters but I can now work in reasonable comfort; one real hazard is if I'm kneeling down under the radial arm saw I forget the arm is above me; OUCH.

I was brought up with huge industrial machinery and still think bigger is best but I really didn't need so much power; my current machinery and tooling are all excellent quality and I enjoy owning and using them; my sawbench is home made at 4hp and my bigger machines were bought mostly as scrap and rebuilt by me to suit my needs with modifications carried out. I'm not a fan of modern tinny machinery covered in self adhesive safety labels or fitted with guards that actually make the machine feel unsafe; one very important thing seems to be missing these days its called common sense; we now need safety labels stating not to poke a finger into a moving cutter; still we also need road signs stating "No road markings".

I agree with all members who are against the use of plastic for woodworking extraction.

ComDust victim awarded $39.7 million

Just a final word from me regarding using plastic ducting; it's your choice.

Kind regards, Colin.


----------



## Sandyn

NetBlindPaul said:


> Unfortunately, I’m writing this from a hospital bed having been paralysed from the navel down by cancer


Hi Paul. There but for the grace of a god, go I. I am very sorry to hear of your illness. I hope you have a full and speedy recovery and get back into your workshop soon!!


----------



## Sandyn

Health and Safety is also a guise for transferring responsibility. Companies have to follow HSE guidelines to remain legal (so they can't be blamed), but the problem with something like static sparks in plastic ducting is that the real risk to domestic users is extremely low, Just taking a common sense approach, the internet isn't full of accounts of people having burnt their house down because of a spark in their dust extraction, but in industry, because it's a recognised risk, the HSE have to legislate. We end up in many cases legislating for the tiny probability of something happening, the the whole population have to change their habits because of an almost zero risk. For commercial ventures, they just have to abide by the law. 
For home users, they have the ability to review all the information and make an informed decision, which suits what they do and their system. In my particular case, I don't think there is a risk, so I will continue to use the plastic ducting I have, but I have taken note of everything said here by people with huge experience in this area and respect that experience. Also I now know that spiral metal conduit can be purchases as cheaply as plastic, so if I eventually upgrade from my use of cheap plastic stuff, It would be stupid not to take note of what people on here have said. I would chose metal ducting, similar cost, so why not.


----------



## dzj

An interesting read from a US forum:


Grounding PVC and Other Dust Collection Myths


----------



## Inspector

Paul I wish you a speedy recovery.

Pete


----------



## gregmcateer

Paul,
Sincere best wishes and I too hope you a full and speedy recovery.
Greg


----------



## OldWood

I've followed this discussion with considerable interest. I am not a tub-thumper as I feel one or two here are, though I would like to take the general advice which seems to be to go metal.

But I won't - certainly initially - as I don't have a system yet installed and I really don't know how I am going to install it nor the best runs. The logic therefore from that perspective is to go plastic as I can go along to the local builders merchant and buy all the bits off the shelf as I need it. Go metal and I would be collecting carriage costs, the design would need to be right from day 1 which would mean the task may never actually get started.
Rob


----------



## mpcpba

dzj said:


> An interesting read from a US forum:
> 
> 
> Grounding PVC and Other Dust Collection Myths


An excellent well researched article which lays out the real risks clearly. Many thanks for finding it.


----------



## NetBlindPaul

dzj said:


> An interesting read from a US forum:
> 
> 
> Grounding PVC and Other Dust Collection Myths



I have no issues with the science and principles of article.

I do have an issue that the “codes“ quoted which are not applicable in the UK/EU.
The requirements in the UK/EU are not for explosion venting.
The UK/EU requirements are that the potential for fire or explosion must be engineered out, such that they cannot happen.
Explosion vents may be fitted, but, are superfluous, if the equipment meets the EHSR’s.
If the explosion vents are required then the equipment is not legal for placing on the market.

One must consider that in making your LEV system in your home workshop,you are designing and manufacturing a piece of equipment that falls into the requirements of the MD/SMSR.It also falls under Annexe V of the legislation and is accompanied there by devices to control electrostatic discharge, which also must be controlled and limited by the legislation such that it cannot pose a hazard.

This is a typical difference in legislation between the USA and the UK/EU and many other areas which directly adopt ISO and IEC standards.
The USA allow catastrophic events, then try to mitigate the consequences, the rest of the world tends to require that the potential for catastrophic events is engineered out.

One only need look at the use of PPE, comparing the UK & the USA, in the UK PPE is a last resort after all other engineering measures have been applied to minimise the risk. In the USA, it is almost the first choice.

US machinery built to US standards and imported into the UK that I have inspected for compliance with the MD & the relevant harmonised standards was no where near compliant, nor even safe. The electrical safety was 30 years behind what would be expected in the EU.

Now I realise that these comments are centred around the legislation as applied to a business undertaking.
However, the law does not draw a distinction as to whether the machinery is manufactured as part of a business undertaking or not, it could probably be argued either way, and an insurer would likely push for legal compliance in the event of an issue.

The Directive states as follows:

Article 2
(i) ‘manufacurer’ means any natural or legal person who designs and/or manufactures machinery or partly completed machinery covered by this directive and is responsible for the conformity of the machinery or the partly completed machinery with this Directive with a view to its being placed on the market, under his own name or trade mark or for his own use. In the absence of a manufacturer as defined above, any legal or natural person who places on the market or puts into service machinery or partly completed machinery covered by this Directive shall be considered a manufacturer;
...
(k) ‘putting into service’ means the first use, for its intended purpose, in the community, of machinery covered by this directive;

The directive also contains a list of safety devices in Annexe V which includes LEV and devices to control electrostatic discharge. Which require special consideration under the directive.

I realise that this is potentially subject to change by the “BREXIT” agreement, however, until this is deciphered we will not know and the last advice we had from BEIS was that initially nothing would change as it is mirrored as UK legislation.

However the point still remains whether this legislation would be extended to a DIY scenario. I think that will require a serious event, which I am sure we can all agree that we do not want to happen.
If it did then the subsequent court case would create the relevant case law and legal precedent.
The one thing I am unsure about is if a legal case has taken place with regard to other DIY machinery which could have already set a precedent.


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## Misterdog

It's much easier to use metal ducting than push fit plastic, unless you remove the rubber sealing ring. Chamfering the cut end of the plastic and lubricating aids initial insertion, but try taking it apart a few months/years later. It sets like glue.
Metal ducting from a dedicated ducting supplier costs around the same, though you need an angle grinder to cut and tape to seal.

I have used plastic 'soil pipe' extraction for around 20 years, in one of my shops and have metal in another.

I think there are far easier ways to cause sparks in ducting systems than static.
Metal fragments in chipboard, and bullets in solid timber spring to mind.
If cutting very hard wood which traps the blade enough heat can be generated to ignite the chippings.

How many static explosions crop up in a Google search ?

This video seems well balanced on the subject, though the explosion believers will not like it.


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## Walcote

Is there much consideration for 4" vent pipe? I recently made a system with 1 10m run and 3 drops and the 4" vent pipe was at least 50% cheaper than any other solution I looked at such as Soil Pipe and Galv. I was worried about static so have a bare copper wire running internally the length of the duct to ground and I have had no shock personally and no indication of static build up so far. It took a little more invention as there are not so many off the shelf dust extraction parts for it so I 3D printed and Laser cut gates and various fittings but they could easily have been done with basic woodworking skills. If anyone is interested, let me know and I'll post the 3D files online. I will be replacing the remaining 90 degree turn with 2 45s when I get a chance. The only downside was I couldn't find an unequal Y joint so it has T joints for the drops. Not ideal but it works brilliantly with whatever drop in efficiency not causing a problem. I'm interested to hear what others think of the solution and hope no one is going to tell me the big reason it was all a bad idea!!





Please excuse the mess! I am sorting through a bunch of stuff.


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## Heluvaname

Misterdog said:


> It's much easier to use metal ducting than push fit plastic, unless you remove the rubber sealing ring. Chamfering the cut end of the plastic and lubricating aids initial insertion, but try taking it apart a few months/years later. It sets like glue.
> Metal ducting from a dedicated ducting supplier costs around the same, though you need an angle grinder to cut and tape to seal.
> 
> I have used plastic 'soil pipe' extraction for around 20 years, in one of my shops and have metal in another.
> 
> I think there are far easier ways to cause sparks in ducting systems than static.
> Metal fragments in chipboard, and bullets in solid timber spring to mind.
> If cutting very hard wood which traps the blade enough heat can be generated to ignite the chippings.
> 
> How many static explosions crop up in a Google search ?
> 
> This video seems well balanced on the subject, though the explosion believers will not like it.




I was thinking that using the solvent weld soil pipe socket fittings, and just pushing together without glue would seem to provide a pretty good seal/fit rather than the rubber gasketed "push-fit" system.
I guess you could also PTFE tape around the joints if necessary, allowing them to be easily taken apart for blockage et later if needed.


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## Heluvaname

Walcote said:


> Is there much consideration for 4" vent pipe? I recently made a system with 1 10m run and 3 drops and the 4" vent pipe was at least 50% cheaper than any other solution I looked at such as Soil Pipe and Galv. I was worried about static so have a bare copper wire running internally the length of the duct to ground and I have had no shock personally and no indication of static build up so far. It took a little more invention as there are not so many off the shelf dust extraction parts for it so I 3D printed and Laser cut gates and various fittings but they could easily have been done with basic woodworking skills. If anyone is interested, let me know and I'll post the 3D files online. I will be replacing the remaining 90 degree turn with 2 45s when I get a chance. The only downside was I couldn't find an unequal Y joint so it has T joints for the drops. Not ideal but it works brilliantly with whatever drop in efficiency not causing a problem. I'm interested to hear what others think of the solution and hope no one is going to tell me the big reason it was all a bad idea!!View attachment 99627
> 
> 
> Please excuse the mess! I am sorting through a bunch of stuff.



Forgive my ignorance, but what is the difference in diameter between this and the PVC soil pipe "solvent weld" system, and the off-the-shelf extract accessories such as blast gates?


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## Walcote

Heluvaname said:


> Forgive my ignorance, but what is the difference in diameter between this and the PVC soil pipe "solvent weld" system, and the off-the-shelf extract accessories such as blast gates?



I'm not totally sure. I think it is marginal but it is a little smaller and the Vent Duct is thinner wall so I don't think it is compatible without some kind of home made converter. I bought it all here:

TLC Direct 4" Vent Duct

It all came in at under £100. Including buying a load of extra connectors and angles for spare and some of which I butchered to reuse in the blast gates.


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## Walcote

Walcote said:


> I'm not totally sure. I think it is marginal but it is a little smaller and the Vent Duct is thinner wall so I don't think it is compatible without some kind of home made converter. I bought it all here:
> 
> TLC Direct 4" Vent Duct
> 
> It all came in at under £100. Including buying a load of extra connectors and angles for spare and some of which I butchered to reuse in the blast gates.



For reference, the actual ID of the 4" Duct I bought is approx. 98mm. I don't know what the Solvent Weld Soil Pipe is but I believe stated diameter is usually 110mm. They also sell a 5" and a 6" if you were to go for a bigger capacity system.


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## Inspector

Walcote said:


> Is there much consideration for 4" vent pipe? I recently made a system with 1 10m run and 3 drops and the 4" vent pipe was at least 50% cheaper than any other solution I looked at such as Soil Pipe and Galv. I was worried about static so have a bare copper wire running internally the length of the duct to ground and I have had no shock personally and no indication of static build up so far. It took a little more invention as there are not so many off the shelf dust extraction parts for it so I 3D printed and Laser cut gates and various fittings but they could easily have been done with basic woodworking skills. If anyone is interested, let me know and I'll post the 3D files online. I will be replacing the remaining 90 degree turn with 2 45s when I get a chance. The only downside was I couldn't find an unequal Y joint so it has T joints for the drops. Not ideal but it works brilliantly with whatever drop in efficiency not causing a problem. I'm interested to hear what others think of the solution and hope no one is going to tell me the big reason it was all a bad idea!!View attachment 99627
> 
> 
> Please excuse the mess! I am sorting through a bunch of stuff.



I won't tell you you did wrong but going forward I will tell you your plan to change from the 90º to a pair of 45º fittings won't improve anything. As a 90º with what looks to be a 0.75R or smaller, you have an equivalent drag of 37'/11.28M of straight pipe. A 45 elbow has an equivalent of 20'/6.1M so making the turn with two is 40'/12.52M plus whatever straight piece between. Want to call it 41'/12.5M? That improvement is going backward. Now if you can find an elbow with a radius of 1.5R (maybe from one of the other types of pipe you can get even if it means a little cutting/grinding to make it fit) you will have a 17'/5.18M equivalent of straight pipe. Those numbers come from page 54 of http://www.lorencook.com/PDFs/Catalogs/Cookbook_Catalog.pdf

Taking the T fitting out and replacing with a couple 45º fitting will make a big improvement because the T has a straight duct equivalent of 125'/38.1M. That coming from 6A on page 61 on the link above. If you want a template calculator for cutting the pieces to make a 45º branch fitting. Pipe Joint Template Software

My metric equivalents are rounded up/down a bit. 
Pete


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## Misterdog

'Swept' elbows create less drag.






110mm 87.5° S/S Underground Drainage Bend (swept)







www.plastics-express.co.uk


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## Sandyn

NetBlindPaul said:


> However the point still remains whether this legislation would be extended to a DIY scenario. I think that will require a serious event, which I am sure we can all agree that we do not want to happen.


In a DIY scenario, you aren't bringing anything on to the market i.e. you are not selling the system, I don't see it how any of the directives could be made to apply in law. 
What do you think? 

I was in IT equipment manufacturing certification, so different ways of injuring and killing people, I produced many bespoke systems which were sold.
There is scope within the directives to sell a product without approvals, if it is a prototype and if you don't produce many. The customer must obviously understand what they are buying. This wouldn't waive your requirement to make sure it's safe, so whilst you can, it exposes you to risk if something goes wrong. You could do a self certification, but that generally isn't worth the paper it's printed on, just box ticking, 
I could see a few apparent ways round the legislation, but all of them expose the company to risk. 

If all that fails, you just sell it on the internet from the far east!!


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## NetBlindPaul

Sandyn said:


> In a DIY scenario, you aren't bringing anything on to the market i.e. you are not selling the system, I don't see it how any of the directives could be made to apply in law.
> What do you think?
> 
> I was in IT equipment manufacturing certification, so different ways of injuring and killing people, I produced many bespoke systems which were sold.
> There is scope within the directives to sell a product without approvals, if it is a prototype and if you don't produce many. The customer must obviously understand what they are buying. This wouldn't waive your requirement to make sure it's safe, so whilst you can, it exposes you to risk if something goes wrong. You could do a self certification, but that generally isn't worth the paper it's printed on, just box ticking,
> I could see a few apparent ways round the legislation, but all of them expose the company to risk.
> 
> If all that fails, you just sell it on the internet from the far east!!



With respect to the MD, it specifically includes equipment designed and built for one's own use.
Now yes these pieces of legislation are aimed at businesses, but this is not defined in the legislation.

In the MD & LVD, there is no legitimate means for placing a device on the market if it is not compliant.
However, both of these are self-certification apart from certain safety devices, and LEV is borderline.
One could ignore the legislation and EHSR's and just put the CE mark on and sell it, the chances of getting caught are slim, and this would expose the company to risk.
However, any conscientious engineer or professional should never consider such if they have any sort of moral compass.

I don't believe that your last comment is serious surely?


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## NetBlindPaul

Misterdog said:


> 'Swept' elbows create less drag.
> 
> 
> 
> 
> 
> 
> 110mm 87.5° S/S Underground Drainage Bend (swept)
> 
> 
> 
> 
> 
> 
> 
> www.plastics-express.co.uk


Absolutely!
The larger the bend radius the better, also, a 45 deg leg T is much better than a 90 deg T.
Straight seamed metal duct is better than spiral.
Solid duct is better than flexy.


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## Misterdog

Should we all fit our extractors within explosion proof cubicles, and also have spark arrestor systems?

To be fully compliant.


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## gregmcateer

Walcote,
Please don't apologise for the 'mess' - that is operating theatre clean and tidy !!


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## Walcote

gregmcateer said:


> Walcote,
> Please don't apologise for the 'mess' - that is operating theatre clean and tidy !!


Haha. Thanks, It looks so much better and is nicer to use when tidy but it's definitely hard to keep it that way!


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## BruceK

Walcote said:


> Is there much consideration for 4" vent pipe? I recently made a system with 1 10m run and 3 drops and the 4" vent pipe was at least 50% cheaper than any other solution I looked at such as Soil Pipe and Galv. I was worried about static so have a bare copper wire running internally the length of the duct to ground and I have had no shock personally and no indication of static build up so far. It took a little more invention as there are not so many off the shelf dust extraction parts for it so I 3D printed and Laser cut gates and various fittings but they could easily have been done with basic woodworking skills. If anyone is interested, let me know and I'll post the 3D files online. I will be replacing the remaining 90 degree turn with 2 45s when I get a chance. The only downside was I couldn't find an unequal Y joint so it has T joints for the drops. Not ideal but it works brilliantly with whatever drop in efficiency not causing a problem. I'm interested to hear what others think of the solution and hope no one is going to tell me the big reason it was all a bad idea!!View attachment 99627
> 
> 
> Please excuse the mess! I am sorting through a bunch of stuff.


Great looking workshop. Hopefully mine will look like that soon. I'm currently making blast gates for a 110mm underground pvc system and plan to earth the pipes as you have yours. How are you heating your workshop?


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## NetBlindPaul

I do have a different view on LEV having done the BOHS LEV courses, and been involved in the aftermath of two LEV fires, one where I was called upon to remove the burned out system and check the machine over for damage. Luckily the fire was limited to the LEV filter assembly, but that was a full evacuation of the premises and two fire appliances. Yes it was commercial, but a very small joinery, admittedly with big machines.
The other I was called upon as an expert witness to review an LEV fire on a smll Record bandsaw with a dedicated LEV in a school, so very similar to a DIY setup. It was not possible to ascertain the root cause of the fire, and it did not destroy the LEV. Again this was a full evacuation of over 1000 pupils and a call to the local fire brigade, I think though it was 4 appliances as it was a school.
I can’t say too much as to the exact locations nor findings due to client and commercial confidentiality, but, I think this covers enough to get the gist.


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## Walcote

BruceK said:


> Great looking workshop. Hopefully mine will look like that soon. I'm currently making blast gates for a 110mm underground pvc system and plan to earth the pipes as you have yours. How are you heating your workshop?



Thanks it has taken quite a few years to get it that way but it's almost there... kind of! I was lucky to have bought a house with an annex with Air Conditioning already built in. There are two Mitsubishi Electric split AC systems in there. It is perfect for the workshop. Cool in summer, warm in winter and keeps the humidity in check. I'm not sure I would have splashed out in the first place had it not been there but if it is available to you I highly recommend it.

As for the blast gates, from making them, the thing I was most pleased with was fitting microswitches to each one. I ran them into a relay to switch the extraction on. This way it means the system is switched on at the tool and is on till the gate is shut. This makes me shut the gates each time which I forget a lot so there are not extra gates open unnecessarily.


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## OldWood

Having seen that Paul is of the opinion that insurance companies could well apply commercial legislation requirements to DIY extraction systems, where does that place the amateur using machinery from a bygone era. We all take care of ourselves as far as possible with guards and the likes but I am thinking of the bandsaw as an example where modern machines in the industrial world will have a brake to stop the blade quickly. The same will apply with many other machines where i understand dc injection into a 3 ph motor will stop it pretty quickly.


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## NetBlindPaul

OldWood said:


> Having seen that Paul is of the opinion that insurance companies could well apply commercial legislation requirements to DIY extraction systems, where does that place the amateur using machinery from a bygone era. We all take care of ourselves as far as possible with guards and the likes but I am thinking of the bandsaw as an example where modern machines in the industrial world will have a brake to stop the blade quickly. The same will apply with many other machines where i understand dc injection into a 3 ph motor will stop it pretty quickly.



I'm not "of the opinion" per se.
I am just highlighting the potential that should there be a claim on your house insurance policy the insurer would potentially be looking to appoint loss adjusters and expert witnesses to limit their financial exposure.
They might look to expect a similar level of safety for protection of their insured asset as would be expected in the legislation covering that product if it were procured from a supplier.
A DIY built system would not offer that level, especially if it used plastic pipework.

As far as injuries go, it would not involve the premises insurer, the treatment would be by the NHS and as it is DIY it is not RIDDOR reportable and thus would be looked upon as a folly more than likely.
Therefore no interest from HSE, nor the LA.

Two completely different sets of legislation and requirements for the LEV and injuring yourselves with old machinery, because you are building bespoke LEV after the SMSR has come into force.

As far as the machinery goes, the offence would be supplying a machine which does not comply, PUWER requires that all machinery must meet minimum safety standards. Any dealer is legally bound to ensure that any machinery they sell is compliant with PUWER, pending installation.
Even if this is to an individual (i.e. DIY buyer).
However, PUWER is definitely a workplace piece of legislation. It does not apply to home DIY use, so the buyer/user as long as they are not operating for remuneration would be in the clear.


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## Walcote

Inspector said:


> I won't tell you you did wrong but going forward I will tell you your plan to change from the 90º to a pair of 45º fittings won't improve anything. As a 90º with what looks to be a 0.75R or smaller, you have an equivalent drag of 37'/11.28M of straight pipe. A 45 elbow has an equivalent of 20'/6.1M so making the turn with two is 40'/12.52M plus whatever straight piece between. Want to call it 41'/12.5M? That improvement is going backward. Now if you can find an elbow with a radius of 1.5R (maybe from one of the other types of pipe you can get even if it means a little cutting/grinding to make it fit) you will have a 17'/5.18M equivalent of straight pipe. Those numbers come from page 54 of http://www.lorencook.com/PDFs/Catalogs/Cookbook_Catalog.pdf
> 
> Taking the T fitting out and replacing with a couple 45º fitting will make a big improvement because the T has a straight duct equivalent of 125'/38.1M. That coming from 6A on page 61 on the link above. If you want a template calculator for cutting the pieces to make a 45º branch fitting. Pipe Joint Template Software
> 
> My metric equivalents are rounded up/down a bit.
> Pete



Thanks Pete. That is a great bit of information. The conventional wisdom seems to be 2x45º elbows are better than one 90º so this is useful to know with the added confirmation of source material. I will print some large radius bends and smooth Y shaped junctions when I next get a moment. The system appears to work well as it is but it is always good to add some extra oomph without resorting to increasing power! Comparing it to runs of straight pipe is a very easy way to relate to the information as well as a method to calculate the numbers. Cheers!


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## NetBlindPaul

Leaks in the runs are another way to loose lots of efficiency too, so make sure your joints are air tight.
Mind, you need to ensure also that you have enough air to hit the transport velocity to carry the waste all the way to the filter. Not such a problem if your duct is all the same size and you only use one machine, so only one gate open at a time, as long as you have the velocity at the most extreme point you should be fine.


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## Walcote

NetBlindPaul said:


> Leaks in the runs are another way to loose lots of efficiency too, so make sure your joints are air tight.
> Mind, you need to ensure also that you have enough air to hit the transport velocity to carry the waste all the way to the filter. Not such a problem if your duct is all the same size and you only use one machine, so only one gate open at a time, as long as you have the velocity at the most extreme point you should be fine.




More good points. I learned the hard way with the velocity issue. I bought a load of flexible hose for cleanup but had to replace it all with a wider diameter to keep the air flowing. Same with the run into the belt sander.


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## NetBlindPaul

Try to keep flexy to a minimum. The losses are immense. I can’t recall the figures but it is something like 1m of flexy is the equivalent of 30m of longitudinally seamed steel. I am more than happy to be corrected if someone else has the exact figures.

I have limited resources stuck in my hospital bed!


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## Sandyn

NetBlindPaul said:


> With respect to the MD, it specifically includes equipment designed and built for one's own use.
> Now yes these pieces of legislation are aimed at businesses, but this is not defined in the legislation.
> 
> In the MD & LVD, there is no legitimate means for placing a device on the market if it is not compliant.
> However, both of these are self-certification apart from certain safety devices, and LEV is borderline.
> One could ignore the legislation and EHSR's and just put the CE mark on and sell it, the chances of getting caught are slim, and this would expose the company to risk.
> However, any conscientious engineer or professional should never consider such if they have any sort of moral compass.
> 
> I don't believe that your last comment is serious surely?



I'm not familiar with the MD, perhaps there is a similar clause for IT equipment, but I missed it. They are such convoluted documents. That is quite significant to include home built equipment. 
When it comes to making money, there seems to be no moral compass in some cases. I have been in a company and discovered a plastic part had been moulded with the wrong material. I informed management, but was completely overruled about informing customers who had already purchased the product. I wanted to do a recall/replacement of the bad part. It led to huge arguments and me being classed as a troublemaker. In the end I was cut off all communication/meetings, My conscience was clear, so left them to it. Just a rubbish company.

No, my last statement was not serious, I was being sarcastic,   A lot of the stuff I have received from a big online retailer has come from the Far East. It either has no CE marking, or it's illegally CE marked, or had what I call a Far East 'certification'. The online retailers refuse to take responsibility and you have absolutely no chance of finding the manufacturer should something go wrong, so that's the way to sell non certified products.

In your experience....do you think far eastern supplied (unbadged) machinery has had the proper certification done on it? 

Hope you are doing well


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## NetBlindPaul

Some of the Far Eastern machinery is done correctly but not a lot of it.
We do work with some Japanese companies that are trying to get it right, but they simply don’t understand the requirements.
I have worked with one Chinese company who really wanted to get things right again they didn’t understand the requirements and I struggled to get them to. In the end it fell down because they were unwilling to allow any technical information to leave the company. Thus they could not have the technical file held in Europe.


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## Inspector

NetBlindPaul said:


> Try to keep flexy to a minimum. The losses are immense. I can’t recall the figures but it is something like 1m of flexy is the equivalent of 30m of longitudinally seamed steel. I am more than happy to be corrected if someone else has the exact figures.
> 
> I have limited resources stuck in my hospital bed!



Happy New Year Paul.
The losses approach to 3 to 1 as a rule of thumb. The closest to exact figures that come to mind at the moment is this online duct friction loss calculator. On-Line Duct Friction Loss You can play with different sizes and lengths of ducts and materials to get the static pressure loss in inches of water. It doesn't have the metric option you would be more likely to have worked with but I'm pretty sure you can figure it out.  Once you get a result you can go back and change it to a different duct material to see how much of a change there is. I suppose in a mixed material system one would figure out the different areas and add the results together for a total.

When one realizes a small DC only has 5 or 6 inches of static pressure with no flow and only a couple when wide open it shows why many small shops have so much dust everywhere.
Pete


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## NetBlindPaul

Inspector said:


> Happy New Year Paul.
> The losses approach to 3 to 1 as a rule of thumb. The closest to exact figures that come to mind at the moment is this online duct friction loss calculator. On-Line Duct Friction Loss You can play with different sizes and lengths of ducts and materials to get the static pressure loss in inches of water. It doesn't have the metric option you would be more likely to have worked with but I'm pretty sure you can figure it out.  Once you get a result you can go back and change it to a different duct material to see how much of a change there is. I suppose in a mixed material system one would figure out the different areas and add the results together for a total.
> 
> When one realizes a small DC only has 5 or 6 inches of static pressure with no flow and only a couple when wide open it shows why many small shops have so much dust everywhere.
> Pete


Yes the procedure is to calculate the individual losses for the linear sections by material and the individual bends and fittings and any flexy, then add them to get the total lossess.


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## Doodahdebs

I fitted my ducting about 20 years ago and couldn’t afford metal at the time so used plastic soil pipe. I was aware of the static issue so I ran a copper wire along the outside of the pipe fixed at intervals with a self tapping screw that went just through to the inside of the pipe. I took the wire insulation off where it wrapped around the screw. Then I took the wire outside fixed it to a short length of copper pipe and stuck it in the ground. It was easier than trying to run a wire inside the pipe. I‘ve never had any static build up so it seems to work.
Best wishes to Paul, I hope you get better soon.


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## Chippymint

Myfordman said:


> Having seen a few posts over the years about shocks I've even tried to get shocks off mine to no avail.
> All I can say is the outside of the pipe runs do get a bit dusty as do the walls near the pipes but i can hold onto both pipes and the metal cyclone and not get a the slightest tickle.


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## Chippymint

Whatever opinion one has, it's a fact that you can get static build-up in plastic pipe work. Not only can it give you a shock it can also cause a fire. Yes it might depend on a set of circumstances but it's possible and it's known of around the world's woodworking fraternity. 

Taking reasonable safety steps is a good thing and let's be honest the cable and connectors are not going to cost a lot in the grand scheme if things. Also, be mindful that your house or business or life insurance policy may not cover you if you have ignored their or best practice safety advise - they will do anything to get out of paying. 

Another way is to fit spiral ducting avoiding the issues mentioned.


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## beech1948

Some 12 years ago I looked at my plastic waste pipe ducting which was 110mm and thought I would try to move to a larger size. I was buying a new DC as well which could be adapted to take 200mm pipe.

The issues became apparent early on. Either metal or plastic 200mm pipe was not just very expensive but ruinously so. eg 110 mm plastic was about £16 per 6m whilst 200mm plastic was £49.89 for 3m. Metal was similar.

After many nights trying to reconfigure the costs I decided I had to try to redesign the size and shape of the DC. I ran it down the middle LHS of the workshop in a 10m run and attached 8 offshoots still at 200mm to get to various machines. Most machines need to have a reducer to 110mm close to the actual termination point. My table saw and planer were adapted to 200mm and that has worked well.

Most people should be able to cope with 110mm waste pipe, with aluminium taped joints, a copper wire run down the outside and terminated on the DC.

The warnings about Fire and Shocks are real but overdone. The combustible mix of dust to air to get an explosion is 99.9% not achievable in a home workshop. If you have had such an explosion please speak up but if you have a commercial shop please don't as different characteristics to the dust/air mix apply. Similarly with shocks. If you have "earthed" your static from plastic have you still had a shock.? Let me know. After over 30 yrs of plastic waste pipe operation with copper wires to take the static and aluminium tape to bind the joints I have NEVER had a shock.


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## matkinitice

This video just came into my feed.

Worth a watch.


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