Author Topic: Piped extraction  (Read 5602 times)

Offline The Bowler Hatted Turner

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Piped extraction
« on: July 29, 2018, 09:24:52 PM »
I am considering putting in piped extraction in the workshop. I am thinking of using the brown soil pipe that you can get from builders merchants.I realise I will have to install blast gates etc.but my question is this. To prevent static electricity building up could I just earth the pipe?Pr do I need to do a bit more than that? I am just fed up moving my flexy pipe all around the workshop all the time and just thought to plumb it in once and for all and just open whichever gate I need for extraction.

Offline GBF

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Re: Piped extraction
« Reply #1 on: July 29, 2018, 10:18:28 PM »
Why would you earth plastic pipe.

Regards George
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Offline Bryan Milham

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Re: Piped extraction
« Reply #2 on: July 29, 2018, 10:22:13 PM »
John,

I'll have a look through my old records, but somewhere I read or possibly still have an article that said the Static build up in dust extraction was not needed.

Not saying it was right, but the facts and figures behind the article seemed to make sense and agree with my electrical knowledge (I'm an Electronics Eng though).
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Offline The Bowler Hatted Turner

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Re: Piped extraction
« Reply #3 on: July 29, 2018, 11:06:37 PM »
Why would you earth plastic pipe.

Regards George
George not sure if you have to but I always thought(perhaps mistakenly) that there is an explosion danger from sparks caused by static electricity. I hope to be proved wrong as not having to worry about earthing it would certainly make life easier.
Thanks Bryan, I wait for your reply.

Offline Bryan Milham

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Re: Piped extraction
« Reply #4 on: July 29, 2018, 11:57:41 PM »
John,

I can't find the article I remember, hoever I've attached an article of Earthing Extraction piping, if it's any help, and something I always thought was a brilliant idea.
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Offline The Bowler Hatted Turner

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Re: Piped extraction
« Reply #5 on: July 30, 2018, 08:19:00 AM »
Bryan thank you very much for that, exactly what I needed.

Offline Paul Hannaby

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Re: Piped extraction
« Reply #6 on: July 30, 2018, 12:43:10 PM »
Earthing a non conductive plastic pipe is about as effective as nailing jelly to the ceiling!

Offline bodrighywood

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Re: Piped extraction
« Reply #7 on: July 30, 2018, 01:10:08 PM »
Earthing a non conductive plastic pipe is about as effective as nailing jelly to the ceiling!

Whether this is true or not I can't comment but have to applaud the phrase. LOL ;D ;D ;D

Pete
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Offline The Bowler Hatted Turner

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Re: Piped extraction
« Reply #8 on: August 10, 2018, 12:50:32 PM »
I missed this reply from Paul.You are obviously using the wrong nails Paul, you need the ones with larger heads as the ovals certainly will not hold jelly on the ceiling. But I usuallly use velcro as that works so much better and it is easier to remove the jelly once you have finished with it.

Offline Les Symonds

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Re: Piped extraction
« Reply #9 on: August 10, 2018, 12:57:01 PM »
Being a non-technically-minded sort of guy, I'm failing to grasp the issues here. I recall, as a child, rubbing a balloon against my hair to induce static. My hair stood on end and the balloon would stick to the wall, so clearly, static can build up on plastic surfaces (the balloon, that is, not my hair) and therefore can be present in/on the extraction pipes. Are we saying that this presence of static does not pose a hazard, whereas static on electrically conductive materials does pose a hazard?

Help me out, please, somebody!

Les
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Offline Bryan Milham

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Re: Piped extraction
« Reply #10 on: August 10, 2018, 01:23:29 PM »
Les,

Basically this issue stemmed from Dust explosions in grain storage silos. Dust + static electricity spark = big bang.

For us, it's the movement of dust through the piping that causes static, a problem in woodwork sawmills etc where lots of dust is continuously being extracted. But there is a question over whether there is a case to answer at our level of extraction and dust making.
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Offline Les Symonds

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Re: Piped extraction
« Reply #11 on: August 10, 2018, 01:35:43 PM »
Hi Bryan....I understand how the static is generated, what I don't understand is whether or not a spark can be generated within plastic pipes, and therefore, is earthing useful. There seems to be some level of disagreement in this thread.
Les
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Offline Bryan Milham

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Re: Piped extraction
« Reply #12 on: August 10, 2018, 01:48:58 PM »
Yes, he said, shaking his head!
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Offline fuzzyturns

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Re: Piped extraction
« Reply #13 on: August 10, 2018, 03:25:27 PM »
Les, firstly you cannot generate static electricity in electrically conducive materials, since they conduct the electric charge to the closest point of discharge. Secondly, in order to create a bang you'd need some way of converting the static electricity into a spark. That's in theory possible, e.g. by bringing a grounded piece of metal close to the pipe.  However, it would have to happen on the inside of the pipe, since that is where the dust is. So this is actually now getting quite tricky.
I have read an article from a retired fireman on this subject, and he said that in his entire professional career of around 35 years he had never ever seen or heard of a dust explosion in an amateur wood working workshop. And most pro workshops use 6" metal pipes anyway (which are essentially grounded by connecting them to machines that are grounded).

Offline Paul Hannaby

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Re: Piped extraction
« Reply #14 on: August 10, 2018, 09:41:23 PM »
You can generate a static charge in a conductor as long as it is insulated from any discharge path. Have you ever got out of a car and got a shock when your foot touched the ground? That's a perfect example of a conductor (the car body) holding a static charge because it is insulated from earth by the wheels.
I'm not sure where this fits in to plastic pipes but never mind ;)