Woodworking Talk banner

1 - 7 of 7 Posts

·
Registered
Joined
·
28 Posts
Discussion Starter #1 (Edited)
OK. I have my 1 1/2 delta 1200cf/m dust collector. I am using it tool to tool now with a 4" reinforced clear plastic hose on my shop floor. I eventually want to put in a permanet "hose" system on the ceiling of my shop with separate drop downs to my TS Mitre SAw, Router table, etc.. What are the advantages/disadvantges of using PVC or the reinforced clear flex hose?

Thanks in advance for any help
 

·
Senior Member from MN
Joined
·
219 Posts
I have what you have currently. But I'm guessing the clear tube would allow you to see clogs? Does the clear tubing include a ground wire?
 

·
Registered
Joined
·
28 Posts
Discussion Starter #3
DC piping

I am not sure whether or not to put the ground wire in my eventual ceiling piping which I mught use the clear reinforced plactic or PCP overhead and clear plastic drops to the machines. I see posts that are contridictory: don't need to ground it in home shop; if you ground, foolish to wrap ground around outside; if you ground, you should wrap outside and run one inside

I don't know what is the best to do.
 

·
Senior Member from MN
Joined
·
219 Posts
Please note that I am not a dust control or ESD expert. Someone else can chime in. But I do know electricity.

A ground wire on the inside of the pipe will help to ground the dust on the inside of the pipe and help reduce the chance of an electrostatic discharge within the pipe that could ignite the dust. But you should make sure to ground one end of the wire to the frame of the collector, which should be grounded to your home electrical ground through the motor and cord. Alternatively, I suppose you could attach it directly to some other ground in your shop. Also, the wire should be bare (no insulating sheath).

I can't see that an internal ground (inside the pipe) would hurt, other than increasing the chances of a clog.

As to the external ground (wrapped around the pipe), without having done this myself, I can only guess that this is intended to discharge static electricity that builds on the outer surface of the pipe so that when you touch it, there is no spark outside the pipe. I would think this spark would not ignite anything inside the pipe (but again someone else might chime in here). I do not know whether an external wire would ground dust on the inside of a plastic pipe (but I do not think it would).
 

·
Registered
Joined
·
28 Posts
Discussion Starter #6
dc piping

OK if I used metal pipe for the overhead main section of the system, what type of metal pipe? Do I use the Sprial type that say Rockler sells or do I go to LOWES/HOME DEPOT and get "flue" pipe like on my water heater or furnace? Will "flue" pipe work well enough with a 1200 cf/m collector in a small one-car garage shop running one tool at a time? Also, would I be able to get all the sized fittings I would need to connect the overhead main section of the system metal "flue" pipe to the flex hose that will then connect up to my machines?
Lots of questions I know. Would like to hear from anyone who has done what i am thinking about?
Thanks:blink:
 

·
Registered
Joined
·
19 Posts
From WOODWEB
WOODWEB DISCLAIMS any and all RESPONSIBILITY and LIABILITY for the accuracy and application of the information below. Readers agree to evaluate the significance and limitations of the information provided, and accept full responsibility for the application of this information. Read More ...
?

PVC piping -- OK for dust collection?

Why PVC piping is not safe for your dust collection system. March 19, 2001


Question
I hear you're not supposed to use plastic pipe for dust collection. Why?
Forum Responses
The main reason why PVC pipe is not recommended is the buildup of static electricity and the high risk of explosion.

Plastic pipe systems are not designed for dust collection use. A necessary diversity of fittings to meet design requirement does not exist. Also, plastic pipe elbows have a very short radius and plastic tee fittings are improper for dust removal. It is these types of problems that lead to an inefficient dust collection system.
With a metal dust collection piping system, static electrically won't develop. Elbows and other various fittings are properly designed for conveying dust. The diversity of fittings and accessories will enable you to meet design requirements.

I have found no problems using schedule 40 PVC. You do need to run a ground wire to each machine. As far as elbows are concerned, you can use electrical sweeps, which ease the bends. Also, don't use tees, use Y fittings.

I used plastic in my first shop. The static electric buildup was amazing. I tried to control it with ground wires, but still had problems. Don't take a chance on a dust explosion--use metal. Commercial heating contractors often stock the spiral duct and fittings since they are used in big buildings for air handling.

The National Fire Protection Agency recommends non-combustible ducting when conveying combustible material. As we know, wood dust is combustible, as well as PVC pipe, never mind the static buildup, which is a source of ignition.
When we create a duct system, the interior should be as obstruction-free as possible. A copper wire will snag chips and curls. In addition, many extraction systems are abrasive, such as the conveying of hardwood chips. This material will wear the copper wire.

When we had a PVC system in our shop, I had a chance to discuss the plastic pipe/static situation with an electrical engineer well-versed in industrial issues. According to him, there is virtually no way to protect a plastic based system. The static builds on the surfaces (inside or out) of the pipe and nothing but a continuous metallic ground (more like a coating than a wire) inside the pipe would mitigate the static buildup. He convinced me to get rid of the plastic and redo our system with metal pipe and fittings.
While removing the plastic (prior to a metal install) on a Monday after a non-working weekend, I noticed that the pipe still held a charge from the previous Friday's work. As a precaution I put on light duty rubber gloves. I got zapped right through the gloves by the static discharge from a length of pipe connected to the planer, which had been working hard the previous week. A few minutes later I picked up a piece of pipe that had also been connected to the planer and watched as a large spark arced from the pipe to my chest. These shocks were not life-threatening, as the discharge was mostly voltage with little amperage. That said, they made me painfully aware of the potential for static build-up. You may get away with a plastic system for years, but some day when you are collecting large quantities of fine dust through your new wide-belt sander, disaster may strike. I'd never consider using anything but metal pipe for dust collection.
 
1 - 7 of 7 Posts
Top