Dust collection / Control - Page 2

Dust collection / Control · 06-11-2009, 09:08 PM

Far too many months ago when I built my shop I constructed a closet to eventually house my compressor and DC. Today I finally finished the DC piping installation.

The closet has an exterior metal foam core door with the weatherstripped side facing the closet interior for sound control.

Where the original window was I have installed double sheets of fiberboard with a small air gap in between for sound control. On the interior side the bottom half has been cut away to allow air pressure generated by the DC to escape by flowing between the sheets of fiberboard. This allows for relief but also absorbs sound.

On the exterior of the door, the top half of the fiberboard has been cut away and I constructed a filter box with melamine coated pegboard air baffle to house an air filter so that any dust escaping from the 1 micron DC filter bag is not returned to the main shop.

The filter is a 16x20 Merv 12 rated 4" pleated paper high efficiency filter made by Honeywell. It is housed behind a sliding BB panel.

Delta 50-760 housed in the closet with a short length of flex hose connecting it to my 4" PVC shop piping. The DC is controlled by an RF remote.

Start of the pipe run exiting the closet.

East - West main trunk with the hose to my tablesaw connected. The yellow end cap is temporary until I obtain another blast gate and another drop will be installed at this terminus. The wide turn wye to the North - South line is visible.

This is the North- South line running across the shop. This line has another drop installed in the center portion of the shop, one for the RAS, and one angled for use with the drillpress. Also visible is my Jet air cleaner which does a fantastic job of keeping stray dust under control. Barely visible just in front of the Jet and just below the light is a 4" pipe in the wall which terminates outside in a louvered vent. Eventually this will be piped to a ceiling mounted exhaust fan box similar to a bathroom exhaust fan to suck out particularly nasty fumes from finishing etc.

I am pleased with my installation and it seems to be doing everything I expected from it.

Glennbear · 06-12-2009, 01:42 PM

Originally Posted by RSM

Glenn, great looking set-up. I'm quite envious, I'm trying to set up dust collection but it isn't near that nice.

As far as static electricity on PVC, I found an interesting "study" about PVC static discharge from a guy who works at MIT and was able to reference numerous lab tests in extreme conditions. (Link below). Its very long but very thorough, but it all boils down to it being a myth. Static can in fact build up on the outside of the pipe, and the inside as everyone knows. The reason it builds up is because PVC is an insulator and the charge can't travel. Therefore, the charge only accumulates in the immediate local area, and can't build to a larger charge (again b/c PVC is an insulator and doesn't conduct electricity). Therefore it is not possible for the charge to accumulate enough to cause a discharge that could start a fire. However, the bigger risk is the dust traveling in the pipe, since this too is an insulator and is traveling very fast (therefore lots of friction, therefore charge). However the accumulation of charge in the dust cloud is the same issue with PVC, and the charge buildup is the same in metal duct or PVC pipe, grounded or not. However it has been shown not to be a discharge risk (even though this is all beside the point of whether PVC is ok or not).

So, the gist of the article is that PVC pipe will not cause a fire if used as ducting. Grounding the inside provides no benefit as far as risk of dust explosion. Grounding the outside doesn't do anything either, since the inside is what you are concerned about, and since PVC is an insulator the charge can't move from the inside to the outside. Finally, the one benefit of grounding the outside is that it can help remove some of the charge (in the vicinity of the conductor) that will reduce the static discharge the user experiences when grabbing the pipe by hand. However it only removes the charge in the conductor's immediate vicinity. The outside of the pipe would need to be completely encased in a conductive material (and grounded) to remove all of the charge.

Article: http://home.comcast.net/~rodec/woodw.../DC_myths.html

Sorry for the long post and hope I'm not hijacking the thread too badly. The shop pics do look great. The sound baffle on the door looks like it will work quite well!

Ryan

Thanks Ryan, the sound control works quite well but one must keep in mind that the smallest unbaffled opening can allow noise to travel. I discovered this when I was sheathing the closet walls and a 1/4" gap at the top had to be covered with molding to prevent noise migration.I am aware of that study on static and others which validate the lack of hazard.

RSM · 06-12-2009, 02:07 PM

I'll probably have to just use hearing protectors into the foreseeable, since I definitely don't have room to separate a DC from my workspace. But I'll keep your method in mind for someday when I have my dream shop...

Hope posting about that study wasn't a rehash of old posts, but I have had quite a bit of trouble wading through superstition vs. confirmed data about the static dishcharge, so since it was brought up, I thought I should post it if it could help save some folks from the trouble of running wire all through their piping.

BTW - how are you connecting the 4" flex hose to your S&D pipe? Are you using the commercially available adapters (Rockler, Woodcraft) or did you make your own - and if so, any tips?

Thanks,

Ryan

Glennbear · 06-12-2009, 03:44 PM

Originally Posted by RSM

I'll probably have to just use hearing protectors into the foreseeable, since I definitely don't have room to separate a DC from my workspace. But I'll keep your method in mind for someday when I have my dream shop...

Hope posting about that study wasn't a rehash of old posts, but I have had quite a bit of trouble wading through superstition vs. confirmed data about the static dishcharge, so since it was brought up, I thought I should post it if it could help save some folks from the trouble of running wire all through their piping.

BTW - how are you connecting the 4" flex hose to your S&D pipe? Are you using the commercially available adapters (Rockler, Woodcraft) or did you make your own - and if so, any tips?

Thanks,

Ryan

I used Sch 40 PVC pipe since there was a greater variety of fittings available locally. A lot of folks use thin wall S&D so what worked for me will probably not if you use that material. I took a piece of flex hose to the local BORG and found a PVC fitting with the same ID as the Sch 40 pipe and the same OD as the ID of the flex. This fitting is used where I connect flex directly to the pipe. In most cases the connection is done via a metal blast gate which fits tightly enough into Sch 40 pipe that a sheet metal screw or some silicone caulk will secure it. To connect the hoses to the other side of the blast gates I used the commercial adaptors from the woodworking supply houses (quick connect) which fit inside the flex on one side and over the blast gate flange on the other. The commercial adaptors are a friction fit onto the blastgate flange but since some of my gates point straight down I drilled a hole through the adaptor and gate flange to insert a removable pin to hold them in place. With the exception of the RAS, none of my blast gates have a permanently assigned hose and I just run a hose from the nearest gate to whatever machine I am using.

Jeff Mills · 06-12-2009, 10:49 PM

Nice

I use a snow shovel and a push broom