I have settled on grounded PVC for my dust collection system and have a quick question. I am using flexible hose from my machines to the PVC; will duct tape be work for this connection? It appears that it is not a very snug fit from 4″ PVC to 4″ flexible hose and tape is the only answer.
Is there a better way to connect PVC to flexible hose?
I am using the quick disconnect fittings from the flexible hose to the machines.
Any suggestions are appreciated.
As I remember, the 4" PVC Pipe is a little larger than the flexible hose. I made adapters from PVC Pipe by cutting off about 6" and taking a piece of it out length wise. Then compress the sides together to fit inside the standard 4" PVC fittings and glue with PVC glue. use standard hose clamps to attach the flexible hose.
Which PVC are you using?
Sched. 40 supply line (probably not)?
Or the thin-wall PVC drain pipe (I'm guessing it's this type).
For Sched. 40, an aluminum blast gate fits kinda snug inside the pipe, so I just glued it in place with Titebond, and connected the flex hose to the other side.
For thin-walled PVC drain pipe, Woodcraft has an adapter (#142028) to connect to flex hose.
Rockler Woodworking and Hardware also sales a 4" quick disconnect fitting that you might want to check out.
I went to HD and I am going to install the thin walled grounded PVC. I will order the quick disconnect hose connectors to see if they work, if not I will try to use the suggestion of splicing a 6" piece of PVC that has some of the side removed.
Thanks everyone for your suggestions.
You are actually thinking of using DUCT tape for DUCTS-- What a novel idea!
Seriously, when my hose and fittings were exactly the same diamer. I made a 8 " internal sleve by splicing an 8" piece of pvc (more or less as described above) and then just duct taping the hose and fitting together and to the sleve. Works fine and is cheap.
I noticed this discussion of using PVC as conduit for dust collection. I've always heard that PVC is very high in generating static electricity increasing the risk of fire, a very real problem. Why not just use metal which is cheaper, easier to work with and easy to (electrical) ground?
I used metal ductwork once. The stuff you would use for your heating and air conditioning in your house...maybe I should have capitalized ONCE. To make a long story short, it collapsed because I was a little to anal-retentive about leakage. Since there was no leakage, the vacuum built up and it collapsed like a tin can being run over by a mack truck. Luckily, I only had one run to a single machine. If this is the metal being referred to, then yes, it is cheaper. However, I was using a 6" main run and was PLANNING on tapping off of it .
I now used the thin-wall PVC. I drilled one very small hole at each end of each peice for a ground wire on the inside of the pipe. At first, I was concerned that this would contribute to clogging, but it hasn't in 4 years. On long runs, I would drill two holes about 3/4" apart every three feet or so and simply brought the wire to the outside with the first hol and right back in through the next hole. Yes, it was a little bit of a pain to feed the wire out the first hole when it was in the center of the pipe, but the cleanliness of the installation was worth the extra couple hour of headache. About half way through the installation, I started installing the pipes with the wire at the top most part of the pipe so it couldn't be seen. Every time I look at the pipes where I installed the wire on the bottm, I cringe and wish I had thought ahead. But hey, oh well, right?
The first month after installation, I was worried that I should have at least TRIED to get clear pipes, but now I realized that it really doesn't matter.
Another problem I had with the thin wall was that my local supplier carried 4" as their largest diameter. I had to re-plan my piping network to accomodate the difference.
4" metal duct may have survived since it would not have collapsed as easily. I guess you could alway just drill some holes here and there to create leakage, but that just not the way I am.
I've read all sorts of ideas about grounding, including using foil tape which, I would think would work just as well. Since PVC is not a conductor, the static charge builds up in the air? or the pipe itself? I don't know which. In either case, I would think foil tape attached to a metal probe (like a screw) to inside the pipe at regular intervals would do the trick, making sure the blower and the machine are electrically bonded together in the grounding circuit
Any thoughts on this point?
I think it sounds like a pretty good idea. The only things I can think of are as follows:
1) I assume you are using the adhesive backed, aluminum foil tape that is used in the HVAC industry (The REAL duct tape). As far as I know, the adhesive is not conductive, so making sure that each segment of the tape conducts properly to the next may present a problem.
2) If you use screws as "grounding electrodes", I would pay attention to two things. Firstly, I would put the through the top of the pipe to prevent any heavier chunks of debris from catching on them. Secondly, all the foil tape that I have used is pretty thin, so I would be extra careful when installing the screws, I would probably use a round head screw and use a washer so the foil didn't get torn to badly.
3)I am certain that this is not what you had in mind, but don't use the foil tape as a mean of providing the ground reference for your machine as this would be quite dangerous. It should be sourced from the load center from which the power is sourced.
4) What if we combined your technique of using screws as the electrodes with my technique of using wire? It may be easier to simply run a piece of bare, solid copper wire (I would use at least 16 gauge) from screw to screw. If you put a solderless ring terminal (the crimp type) under the head of each screw then I would think that would provide very close to the same results. The difference should be negligible. Sorry, it's been 12 years since I took Grounding and Shielding in college. In the future, when you add a run to your piping system, I would think this method would allow an easier modification by removing the screw and adding another ring terminal for your additional piping segment. Just a thought...
How far inside the piping do you plan on the screws extending? I would think that 1" would suffice, but I would put a screw every 24" or so. That may seem like over-kill, but not every piece of sawdust is going to touch every screw, so the more screws you have, the more grounded the sawdust would be.
Hope this helps...
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