Thread: Earthing pvc pipework

Originally Posted by ian

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.
Ian

The 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.

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
<OWe use static straps on everything
<Ono man made fibre
<Ostuff like that
<O</O
<O</O
<Oand as for phones ........ myth busters can get stuffed </O
<Oit the rubbing of the man made fibre clothes that cause the problems </O
<Oor if you drop the phone and the battery comes away </O
<O</O
<OAsk the young guy i work with how easy it is to catch fire
<Ohe's done it twice
<O</O
<Overy 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

Originally Posted by Lucas

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

I 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...



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Originally Posted by Ashore

...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.

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 .




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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

Originally Posted by Harry72

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.


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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"

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.

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.

Originally Posted by Harry72

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.



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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.

Originally Posted by 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.

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

Originally Posted by Harry72

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....