# CETRAL VACUUM SYSTEMS



## Madman (Jan 5, 2008)

We are installing a central vacuum system in our shop. It has the standard high velocity bag over bag







main vacuum, which we set up behind the shop. Instead of buying the corrugated plastic hose and fittings, we used PVC pipe







. 
It seems to me that some of these systems may need some sort of static electricity arrestor. I would imagine wrapping the pipe with bare copper wire, and connecting that wire to a ground would work. However, not being an electrical engineer, nor an electrician, I'm not sure if that's the correct method, or that the system even needs a ground.


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## John J (Dec 29, 2007)

I am not positive but that may work....you nay have to put some hose clamps every so often to bind the copper to the plastic. 

Also will any sparks inside the pipe cause sawdust to ignite as in Catch Fire. 

The other thing to watch out for as I have made this mistake. Either use pre bent PVD electrical 90 degree bends or use 2 as in two each 45 degrees to make a 90. The standard straight 90 degree water type elbow will clog up. Been there done that. 

Let us know how you make out with the static problem. This will be a interesting thread.


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## hawkeye2 (Jan 6, 2008)

I don't know if they are avaliable in the sizes you need but you might look into sanitary elbows and fittings. They are made for septic systems and feature large radius bends and a cleanout fitting straght off the end so that you can get to the clogs.


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## Greg Elmassian (Jan 3, 2008)

put a few sections of metal conduit in line every so often and ground them... wires on the outside of pvc pipe will do nothing, it is not a conductor. 

I have a central vac, they really suck! 

Greg


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## Semper Vaporo (Jan 2, 2008)

Posted By John J on 23 Dec 2009 07:16 PM 
I am not positive but that may work....you nay have to put some hose clamps every so often to bind the copper to the plastic. 

Also will any sparks inside the pipe cause sawdust to ignite as in Catch Fire. 

The other thing to watch out for as I have made this mistake. Either use pre bent PVD electrical 90 degree bends or use 2 as in two each 45 degrees to make a 90. The standard straight 90 degree water type elbow will clog up. Been there done that. 

Let us know how you make out with the static problem. This will be a interesting thread. 


I remembered some DIY TV show that mentioned using a wire inside the pipe to dissipate static charges... but... I just Googled VACUUM PVC PIPE STATIC and found the following link... not that it is to be believed any more than any other web site, but it is some info... there were lots of other "hits" in Google, you might try your own search.

http://www.centralvacuumstores.com/cvs/truth.php


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## Semper Vaporo (Jan 2, 2008)

Posted By Semper Vaporo on 23 Dec 2009 07:42 PM 
Posted By John J on 23 Dec 2009 07:16 PM 
I am not positive but that may work....you nay have to put some hose clamps every so often to bind the copper to the plastic. 

Also will any sparks inside the pipe cause sawdust to ignite as in Catch Fire. 

The other thing to watch out for as I have made this mistake. Either use pre bent PVD electrical 90 degree bends or use 2 as in two each 45 degrees to make a 90. The standard straight 90 degree water type elbow will clog up. Been there done that. 

Let us know how you make out with the static problem. This will be a interesting thread. 


I remembered some DIY TV show that mentioned using a wire inside the pipe to dissipate static charges... but... I just Googled VACUUM PVC PIPE STATIC and found the following link... not that it is to be believed any more than any other web site, but it is some info... there were lots of other "hits" in Google, you might try your own search.

http://www.centralvacuumstores.com/cvs/truth.php



And then there is the other end of the spectrum...

http://www.woodweb.com/knowledge_ba...ction.html


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## Madman (Jan 5, 2008)

The simplest solution seems to be the guy who inserted stainless steel screws at certain intervals along his PVC vacuum pipe. Then he wired them all together, and connected the wire to a ground.


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## dieseldude (Apr 21, 2009)

Follow this link: http://home.comcast.net/~rodec/woodworking/articles/DC_myths.html and don't worry about the "grounding" issue. I haven't blown up the shop yet and neither will you!


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## Spule 4 (Jan 2, 2008)

Yes, and we did not have a fatality here in TN with a wood shop with a dust explosion just this past Summer....


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## John J (Dec 29, 2007)

Posted By Greg Elmassian on 23 Dec 2009 07:41 PM 
put a few sections of metal conduit in line every so often and ground them... wires on the outside of pvc pipe will do nothing, it is not a conductor. 

I have a central vac, they really suck! 

Greg "They Really suck" Do you mean as in poor performance or good quility vacume and work well?


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## Greg Elmassian (Jan 3, 2008)

Kinda both JJ, a lame joke, and the fact that they ofter work better... 

Merry Christmas, 

Greg 

p.s. the screw idea is ok if you only have sawdust, if you have curls of wood, they can hang up on the screws and help clock your pipe, just like a wire inside the pipe.


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## denray (Jan 5, 2008)

I have installed several medium to large central systems, of course we use steel piping, static is not an issue with metal. I have helped several friends do small systems for thereselves, and they chose plastic, We always run a bare wire on the inside. Bring out the wire through a hole drilled through the plastic and secure it to a source of metal to create a ground. I have been hit with a 480 volt shock, BUT the most painful shock I have ever experience was from a plastic dust collector pipe. The static shock jumped over 4 ft down a pipe, sounded like a 22 rifle being shot, burnt a small hole in the side of my hand the diameter of a pencil eraser, and hurt like the dickens, that hurt for a couple days, looked like a deep cigerate burn. That pipe did not have any bare wire in the pipe. Plastic pipe without a ground will have dust sticking to the outside, with a inside wire the pipe will stay pretty well dust free. Static becomes a clinging source.
Speaking of fire, yes it can happen, and the people that it has not happen to, needs to include the phrase, NOT YET. A fire in a dust collector can be an extrmely fast spreading fire, because you have fuel being feed by an extreme amount of air. Not to scare anyone but a bare wire in the pipe takes a few minutes to install as you are installing the system, with a very little expence. I love my central system, and would not be without one. Grizzley is a good source for plastic fittings, and blast gates. Good luck Dennis


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## Madman (Jan 5, 2008)

Posted By denray on 24 Dec 2009 02:15 PM 

I have installed several medium to large central systems, of course we use steel piping, static is not an issue with metal. I have helped several friends do small systems for thereselves, and they chose plastic, We always run a bare wire on the inside. Bring out the wire through a hole drilled through the plastic and secure it to a source of metal to create a ground. I have been hit with a 480 volt shock, BUT the most painful shock I have ever experience was from a plastic dust collector pipe. The static shock jumped over 4 ft down a pipe, sounded like a 22 rifle being shot, burnt a small hole in the side of my hand the diameter of a pencil eraser, and hurt like the dickens, that hurt for a couple days, looked like a deep cigerate burn. That pipe did not have any bare wire in the pipe. Plastic pipe without a ground will have dust sticking to the outside, with a inside wire the pipe will stay pretty well dust free. Static becomes a clinging source.
Speaking of fire, yes it can happen, and the people that it has not happen to, needs to include the phrase, NOT YET. A fire in a dust collector can be an extrmely fast spreading fire, because you have fuel being feed by an extreme amount of air. Not to scare anyone but a bare wire in the pipe takes a few minutes to install as you are installing the system, with a very little expence. I love my central system, and would not be without one. Grizzley is a good source for plastic fittings, and blast gates. Good luck 
Dennis 



Dennis,
Can the gound source be the same gound wire that comes from the panel box? In other words, can I run the wire to a junction box nearby, that is grounded?


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## Spule 4 (Jan 2, 2008)

I am having a total brain lapse due to a migraine right now, but I think NFPA 77 specifies a separate ground than just using the elctrical one? If memory serves, NFPA 30 (flammalbe liquids) states to use either the plumbing or a rod driven into the ground....but again, going by memory. 

Also remember grounding (to ground) and bonding (interconnection to a grounded item). There should be little to no resistance drop, this could cause static build up.


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## denray (Jan 5, 2008)

Do not use the same ground as electrical, just think if you had a motor that shorted out, it would put a ground wire partially hot inside a pipe with dust in it. either ground to a ground rod, or a piece of equipment that is bolted to the floor. Dennis


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## dawgnabbit (Jan 2, 2008)

Hi, All

FWIW, I ran a bare copper grounding wire down the INSIDE of each PVC pipe in my system, and grounded the ends of the wire to the collector motor's frame. At the other end, the wire is grounded to the metal frames of the stationary tools. I see no sign of dust clinging to the exterior of the pipes and have never had any kind of shock.


I read in a woodworking magazine--either ShopNotes or Wood--that with PVC pipe of 4" diameter or less, the air-fuel mix is never right for a spark-ignited explosion. ABOVE 4" diameter, the situation changes, and it's best to use metal pipe.

Like I say, FWIW.

Dawg.


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## Spule 4 (Jan 2, 2008)

Another tip: Periodically check with a VOM your grounds and bonds. We have had a few surprises come up at work....


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