Earthing pvc pipework

[keith53]

Hello,

Seeing the post of Soren's workshop has prompted a question. I believe I'm seeing pvc ductwork for his dust extractor system. I've heard/read somewhere that pvc should be earthed because of the possibility of static electricity and thus the potential for fire. I've been toying with the possibility of using pvc for a routing system for dust extraction when I finally get my workshop sorted out properly (somewhere between now and 2014).

I've used a 5 metre length of pvc between my Triton sawbench and dust collector for some years now without any problem.

Is this idea of fire a realistic possibility or is it just an excuse to sell yet another product?

Cheers,
Keith

[bitingmidge]

Keith,

There's HEAPS written on the subject, in summary a domestic system has little chance (read none) of a static induced fire happening, and is almost impossible to satisfactorily earth in any case.

Have you checked the "best of the best" forum links?
http://www.woodworkforums.ubeaut.com.au/showthread.php?t=16776

Check these links for starters, there are a number of others which I haven't searched, try searching "machinery connections" "PVC ducting" if you need more:
http://www.woodworkforums.ubeaut.com.au/showthread.php?t=6702&highlight=earthing+PVC
http://www.woodworkforums.ubeaut.com.au/showthread.php?t=16230&highlight=earthing+PVC
http://www.woodworkforums.ubeaut.com.au/showthread.php?t=9096&highlight=earthing+PVC
http://www.woodworkforums.ubeaut.com.au/showthread.php?t=14723&highlight=earthing+PVC

If you want some practice you can drop over to my place next weekend when I'm hopefully finishing mine off!! :rolleyes: :rolleyes:

Cheers,

P

[keith53]

Fantastic... All questions answered.


Search, then post... Search, then post.

Keith

[bitingmidge]

Fantastic... All questions answered.

Just part of the service!
Cheers,

P :D

[Iain]

If you really want more info do a google search and see how many US forums are getting heated over this.
It seems to be a continual hot topic with no conclusive outcomes apart from some 'cyberscraps' :D

[Cliff Rogers]

I saw an interesting episode of 'Myth Busters' on the plane last week.

The 'myth' that they were trying to bust was that a construction worker was killed by a static discharge from a lenght of PVC pipe that he had been sand blasting to get paint off it.

The outcome was that they could not get a static charge big/strong enough to generate a lethal discharge because it kept leaking away too quickly to build up to a lethal potential.


PS. I know that 'Lethal Discharge' and 'Static enduced fire/explosion' are different but they are sort of the same. :confused:

[gazaly]

I saw an interesting episode of 'Myth Busters' on the plane last week.I know this isn't the topic (sorry Keith), but 'Myth Busters' has to be the best show on TV, ever.

I love how they prove/disprove the theory, then set about destroying everything by the most dramatic method possible.

Brilliant!

[soundman]

I hate myth busters. :mad:

What right have they got to have such a funn job.

I want to be paid lots of money to build weird stuff & blow it up too. :D

[Iain]

Soundman, sit down and shut up, it's on soon :D :D :D
NB. Your avatar, you know he was gay???

[numbat]

Even my soon to be 9 year old son loves Mythbusters - I think he would love to have a job like that - after he retires a the Formula 1 world champ http://www.woodworkforums.com/images/smilies/biggrin.gif

Cheers

[Soren]

I have not bothered specifically earthing my PVC ducting, mainly because it is fixed with metal brackets into the brickwork all along, and I surmised that this would be 'earth' enough. :o (crossing fingers)

Bitingmidge
Look forward to see the pics on Monday :D :D

[gazaly]

For goodness sake Soren, stay on the the topic!
..............
Oh.......sorry............that is the topic.

[bitingmidge]

Bitingmidge
Look forward to see the pics on Monday :D :D

You really are a cruel heartless bastard aren't you Soren? :D

I thought I'd see how long I've been "nearly finished":

Dust Collection - Machinery Connections
I thought I'd start a new thread specifically regarding ducting and connections. In May I posted on another thread that I had almost completed running 6" ducting (PVC), and now I have almost nearly completed!

I am astounded at how many bends and metres of pipe my simple little system has consumed! It is now time to make the connections and I would love to hear what others have done and how it works.
:eek: :eek:
I have a Jet DC1200, and have almost installed 6" ducting to all equipment, when finished I will have about a metre of 4" flex to each machine. :eek: :eek: :eek:

Cutting Holes In MDF
I am about to embark on the next great blast gate adventure which of course will mean cutting a lot of holes in 6-18mm MDF with diameters mostly 150 or thereabouts but going down to 75mm. :eek: :eek: :eek: :eek:
From all of that, I now conclude that each year about this time I get the urge to work on PVC. Therfore there is a chance that I will be finished soon, failing that, it will be at least another year!

help, I think I'm drowning in woodchips

P
:D :D :D

[Cliff Rogers]

..... mainly because it is fixed with metal brackets into the brickwork all along.....
Ummm.... no. :D

[keith53]

After reading one or two articles whose links were included in bitingmidge's post, I'm convinced its all a bit of a furphy.

Yes, in the most extreme circumstance, if everything falls into place and enough voltage is present, it is possible to have a problem. Not very likely though...

You could also be walking along the street and have a solid gold jumbo jet fall on you. Possible, but not very likely...

[Ashore]

IF you want to cross the "Ts" and dot the "eyes"run a thin copper wire through all your pipes and earth at one end. Something along the lines of winding wire
you can often get this from your son in law if his in the game.

Its like wearing braces and a belt
Can't hurt but if your in a hurry can be a pain



The trouble with life is there's no background music.

[Cliff Rogers]

....run a thin copper wire through all your pipes and earth at one end.....
Yes but... :rolleyes:
there are those who will argue that this just gives the 'built up charge' something to arc to, therefore creating an ignition source for the fire/explosion...:cool:

[Ashore]

Infact if the copper wire runs through the entire pipe of 8" diam then the size of the particle that could build up a charge that could generate a static charge that would cause a positive particle to create an arc would be larger than the pipe size by a factor of 3000 or more(taking a length of 1 meter and a diameter of 20 mm
But this is only going on my experiance as a Marine engineer where we studied the size of particles in clouds formed in large oil tanks that could cause static discharge
A constant earthing inside a pipe duct / cable tray / tank or vessel with an insulated outer coat reduces the chances of static discharge within said vessel

Personally I don't think 4 or 6 inch ducting would cause a problem as the particles are not big enough to build a charge of sufficent size to cause an arc to form and to what

My statement stands "Its like wearing braces and a belt"

Or another way "better safe than sorry"

Personally as my own choice I ran a wire through my pipes , only because I had the wire and the time.

I don't knock anyone who advocates earthing or non earthing
The arguements for and against can be convincing

Go with what feels right if you have the spare uninsulated wire run it down the pipe can't hurt
But dont get to sitting up worring all night if you don't.





The trouble with life is there's no background music.

[keith53]

One point I got from this article

http://mywebpages.comcast.net/rodec/woodworking/articles/DC_myths.html

was that usually the volumes are unsufficient to create the density of dust and therefore the potential for a static discharge of sufficient size to actually ignite anything. He's pretty definite about not being able to earth pvc but what I'm gathering is that earthing of an end-point (machine or dust collector) should be undertaken because of the possibility of a static discharge thru the operators hand or other body part.

He says that points of change of direction (tees/reducers etc) are points for static buildup. I know in my case, with the possible exception of the thicknesser (check out the post from the guy suggesting we were mis-pronouncing the names of these things - the gall) or perhaps the lathe when I'm on a roll, I don't generate a lot of dust/shavings or not enough where I'd have vivid mental images of the particles all jostling for space and exchanging static charge as they move along the pvc path to the dust collector bag...

[bitingmidge]

Look forward to see the pics on Monday :D :D

Well Keith53 came, saw and doesnt' reckon I've got a snowflake's chance in Brisbane of finishing the system next weekend!!!
:eek: :eek: :eek: :eek: :eek:

Some may see that sort of comment as a challenge, and to them I say:

Oh well, there's always next year!

Cheers,

P
:D

[Soren]

............

Oh well, there's always next year!

Cheers,

P
:D

Seeing it is your birthday, and have a great one, at that, you should be spending time with your family, instead of sitting here in front of the computer, dreaming up excuses for not finishing the ducting :D :D :D :D

[Cliff Rogers]

..... you should be spending time with your family, instead of sitting here in front of the computer, .....

What????? I thought we were his family..... :confused:

[Soren]

What????? I thought we were his family..... :confused:

OK I suppose that is true, but I expect that there may be others, who are geographically closer, that Midge can share a bottle with on the auspicious occasion

:D :D :D

[outback]

Why not use EARTHenware pipe for ducting? :D

[Cliff Rogers]

Outback!!!

[outback]

Welcome back Cliff. :D

[ozwinner]

Outback!!!
Or Outfront too.

Al ;)

[Ashore]

Or Outfront too.

Al ;)Pehhaps outrigger if the pipes up high





I don’t mind growing old, it sure beats the alternative.

[outback]

Outhouse?

[Ashore]

Outhouse?A little outdated most are inside now



The trouble with life is there's no background music.

[ian]

A constant earthing inside a pipe duct / cable tray / tank or vessel with an insulated outer coat reduces the chances of static discharge within said vessel
I don't knock anyone who advocates earthing or non earthing
The arguements for and against can be convincing
I think what you really want to earth is not the duct but the AIR inside the duct. Moving air and wood dust can build up a charge that might be sufficient to arc when it goes through a grounded metal blast gate or the dust collector. Because PVC is an insulator the charge can't disipate through the walls of the pipe. Rather than run a wire through the pipe it's probably sufficient to drive a screw attached to earth through the PVC duct evey couple of metres.

Ian

[Ashore]

I think what you really want to earth is not the duct but the AIR inside the duct.
Rather than run a wire through the pipe it's probably sufficient to drive a screw attached to earth through the PVC duct evey couple of metres.
IanThe air does not store a charge , the particles in the air carry the charge
However your idea of a screw every meter or so grounded on a single wire is a great way to retrofit a grounding system. The best i've heard yet.

Cliff
if the earth wire runs the length of the pipe then a static charge will earth before it reaches the size capable of causing an arc.
Run a car with an earth strap and you don't get those zaps as you get out
the charge can't build up as its constantly earthing out.



The trouble with life is there's no background music.

[Lucas]

Just a quick reply

there are those who will argue that this just gives the 'built up charge' something to arc to, therefore creating an ignition source for the fire/explosion
I work in the petroleum industry and work around fuel everyday
As you could imagine static is a big problem for us
<O:pWe use static straps on everything
<O:pno man made fibre
<O:pstuff like that
<O:p</O:p
<O:p</O:p
<O:pand as for phones ........ myth busters can get stuffed </O:p
<O:pit the rubbing of the man made fibre clothes that cause the problems </O:p
<O:por if you drop the phone and the battery comes away </O:p
<O:p</O:p
<O:pAsk the young guy i work with how easy it is to catch fire
<O:phe's done it twice
<O:p</O:p
<O:pvery lucky once ..... some burns still .......... oh thats right static doesnt cause fires ..... trust me it does so does stupidity

So next time your getting petrol and the guy in the Hi Vis Vest comes up and asks you to get off the phone, put out the smoke, or just to hold the nozzle(Nozzles have an eatrh from the tip of the spout to the pump that runs to an earth stake)

He's not doing it for you ....... He's doing it so he can work tomorrow with the skin on his body

<O:p

[Ashore]

Just a quick reply
I work in the petroleum industry and work around fuel everyday
As you could imagine static is a big problem for us
<O:pI was on an oil tanker carrying crude and products, in that field you can't stop static. They gave up and now & make all the tanks inert all the time.
They take away the oxygen the air space in tanks must be less than 4% oxygen this is below the lower explosive limit.
In your industry lucas you can't take away the oxygen anymore than you can in pvc ducting and static can become a problem. Some times people don't realise that a charge of 22 milli amps is enough to create an arc and phone batteries if shorted create an arc of far greater power.
Or that petrol starts to give off vapor at -10* c
Have never seen footage of cameras from inside fuel tanks showing lightning striking from clouds formed within these tanks from water vapor.
Static is a problem, granted the volume within a normal shed ducting system
is proberly not enough to cause a problem but why take the risk.
Its finally up to you but for a few dollars more...



The trouble with life is there's no background music.

[Cliff Rogers]

...Run a car with an earth strap and you don't get those zaps as you get out the charge can't build up as its constantly earthing out.

...
True but not the same thing in this case.
The car is all metal & contuctive & is insulated from the ground by the tyres.

The plastic ducts are insulators in their own right.
They can not conduct electricity but they can build up a static charge.
It is not possible to discharge the static charge on one part of the plastic duct by touching it with metal in another part of the duct.
Humidity in the air helps, that's why static builds up faster in the dryer air during winter time.

[Ashore]

Cliff
I am not trying to say that by running an earth wire you will stop the static build up,you can't stop the particles from building a charge. But you are giving the static charge a better chance to earth out before it builds up to the point where it can form an arc that is dangerous.
The first grounding point on some ducting systems may be the fan housing itself and by the time a dust particle reaches it the charge will be higher than if it had been able to discgharge along the way.
The idea behind the bare wire within the pipe was only to allow the matter being transported througt the pipe to earth out when its charge is small rather at the end of its run where the charge may be higher.
Ian's idea with a wire outside the pipe and screws at regular intervals may be better than a wire inside the pipe.
I dont think any home setup would create a big enough charge to cause a problem but as I said before It Can't hurt It all comes down to a personal choice
There is no by-law etc forcing you to do it . I do because static electricity causes me concern .




The trouble with life is there's no background music.

[Harry72]

What we need is some smartyass industrial chemist should come up with conductive thin walled PVC, be a real winner IMHO.
Ashore, I thought petrol's boiling point was -40°c

[Ashore]

Ashore, I thought petrol's boiling point was -40°c
Harry72 you may well be correct however petrol is a mixture of many (even hundreds) of different hydrocarbons. Each component has its own boiling point which means that a fuel boils over a range of temperatures.
The temperature I quoted is the IMO accepted temp for that at which petrol will give off a vapor capable of substaining combustion.


The trouble with life is there's no background music.

[Harry72]

Im am going by what the fire course instructor at work is saying.
Im sure that cars will run in below -10°c, so long as the cooling water has anti-freeze, on SBS a while ago they had a show where a guy stayed in the most inhospitable places on earth one was -40°c and they drove there, in a small truck unsure weather it was petrol or diesel and get this... they were heating the diff and gearbox with small fires under them before driving!

Hey if you wana do the "°" symbol, hold the alt key and type "0176"

[Iain]

That inhospitable place was near Siberia for memory, and the problem with Diesel is that it turns to a gel in freezing conditions, there is of course what we call Alpine Diesel which has an additive to prevent this but I still don't know what temps it will work at.
Speaking of fires under the diffs, I have had my tyres frozen to the road at Falls Creek, always carry hessian bags now if I'm heading up there in snow season, park on the hessian, no probs when moving off.

[outback]

Dunno about adding stuff to alpine diesel, stuff I get from May - Sept is called winter diesel, by me anyway, it has supposed to have had moreof the wax taken out.



To overcome the PVC static thing, why not fill the void inside the pipe with a steel rod, plenty of earthing then.

[Ashore]

Im sure that cars will run in below -10°c, so long as the cooling water has anti-freeze, on SBS a while ago they had a show where a guy stayed in the most inhospitable places on earth one was -40°c and they drove there, in a small truck unsure weather it was petrol or diesel and get this... they were heating the diff and gearbox with small fires under them before driving!

Hey if you wana do the "°" symbol, hold the alt key and type "0176"Yes cars run at lower than -10 "0176" c
They have spark plugs that ignite the fuel which is injected in an atomised form into the combustion chamber
Diesel starts to give off a vapor at 100 "0176" c

I think I saw somewhere that trucks in alaska had a pan fitted under the engine that ether was burnt in prior to starting to get the oil in the sump liquid enough to run the engine.



The trouble with life is there's no background music.

[Iain]

Mr Ashore, I have a friend who is teaches the Army mechanics and he showed me a European diesel engine that ran spark plugs to assist with ignition, I think it was for a military application.
I can't get in touch with him and I forget who made it, just wonder if you had seen this in your travels, I suspect it may have been Puch but not sure.

[Ashore]

Mr Ashore, I have a friend who is teaches the Army mechanics and he showed me a European diesel engine that ran spark plugs to assist with ignition, I think it was for a military application.
I can't get in touch with him and I forget who made it, just wonder if you had seen this in your travels, I suspect it may have been Puch but not sure.Iain have not seen any diesel engines with Spark plugs ,perhaps you are refering to glow plugs
These are shaped like spark plugs but are used to perheat the air in a preignition chamber prior to starting
Rgds Russell



The trouble with life is there's no background music

[Cliff Rogers]

Hey if you wana do the "°" symbol, hold the alt key and type "0176"
Cool, I new there was a way 'cos I read it in a geek book about last century sometime.... :D

[Cliff Rogers]

... why not fill the void inside the pipe with a steel rod, ....
DOH!!!!

[journeyman Mick]

Hey if you wana do the "°" symbol, hold the alt key and type "0176"

If you're like me, by the time you remember that you could've typed "degrees", or even quicker, "deg."

Mick the lazy and forgetful :p

[bitingmidge]

Did Mythbusters kill off this thread tonight?

P
:cool:

[craigb]

Did Mythbusters kill off this thread tonight?

P
:cool:

Yep. I think so :)

[RETIRED]

Yep! Busted! :D

Was considering busting this thread too.

[Ashore]

Was considering busting this thread too.
Ah you have power that us lesser mortals only dream about
And I even left the " busting this thread " bit alone
Rgds Russell




Procrastinate Now! Or think about it and do it later