Laser Exhaust Scrubber

[Randy Digby]

Does anyone use a scrubber on their laser exhaust to address the odor problem associated with cutting plastic? If so, I would be interested in a source point for one.

[Dmitriy Kumets]

We have a TEKA unit which does a sort of decent enough job for being in an office but the real cost of it is in consumables. The charcoal cartridges are very expensive and IMHO don't last very long. If you can, vent outside.

-Dima
ps- while you don't get crazy fumes with the indoor venting filter, it doesn't exactly smell like roses. It's a "good enough" solution but not it you are using the machine heavily

[Randy Digby]

Well, I decided to build a scrubber just to see if I can. I finished the container today and the activated charcoal should arrive tomorrow. I'll still vent outside because I don't have a HEPA filter for the solids, I just need to make the odor go away. If that dosen't work then its $2,000.00 to $4,000.00 for a store bought model.

[George Brown]

Well, I decided to build a scrubber just to see if I can. I finished the container today and the activated charcoal should arrive tomorrow. I'll still vent outside because I don't have a HEPA filter for the solids, I just need to make the odor go away. If that dosen't work then its $2,000.00 to $4,000.00 for a store bought model.

I built my own and it works perfectly. I don't vent outdoors at all.

[Marc Myer]

Some time ago a plan was posted for a scrubber that used water instead of charcoal filters. It was ingenious. Has anyone tried it? I'm venting outdoors now, but always looking to improve.

[Randy Digby]

Good deal George. Would love to get the details on your scrubber. Mine is 14" x 14" inside (MDF construction) with the inlet in bottom side and outlet on the side near the top. All joints are caulked inside and the top will have weather stripping at the sealing point. The unit is 30" high. I put a piece of closet shelving (wire grid type) just above the inlet to support the first of two 14" x 14" filters. I caulked around the lower filter so no fumes can bypass it. I'll top load the filters with 25 pounds of activated charcoal when it arrives this afternoon. Do you have any suggestions before my final assembly?

[George Brown]

Good deal George. Would love to get the details on your scrubber. Mine is 14" x 14" inside (MDF construction) with the inlet in bottom side and outlet on the side near the top. All joints are caulked inside and the top will have weather stripping at the sealing point. The unit is 30" high. I put a piece of closet shelving (wire grid type) just above the inlet to support the first of two 14" x 14" filters. I caulked around the lower filter so no fumes can bypass it. I'll top load the filters with 25 pounds of activated charcoal when it arrives this afternoon. Do you have any suggestions before my final assembly?

I built mine at 20x20 horizontally. Inexpensive 2" thick furnace prefilter. HEPA filter, then lastly charcoal filter. Used 25 lbs carbon. I do mostly wood, but do acrylic also. Any smell I have comes off the cut wood itself and not from the exhaust not removing the smoke. The consumables are a fraction of the cost of the commercial units. After the carbon filter is the fan the pulls air through the whole stack.

[Randy Digby]

Thanks George. Sounds close to mine. I was going to push air through mine, but your reasoning is better because it eliminates any odor leakage on the "dirty" side of the scrubber due to air leaks. I think I have all the fittings needed to make it a "pull" sustem instead of a "push" system. On second thought, that is at least a double thank you.

How long of a run do you get before you have to change out the filters and charcoal?

[George Brown]

Thanks George. Sounds close to mine. I was going to push air through mine, but your reasoning is better because it eliminates any odor leakage on the "dirty" side of the scrubber due to air leaks. I think I have all the fittings needed to make it a "pull" sustem instead of a "push" system. On second thought, that is at least a double thank you.

How long of a run do you get before you have to change out the filters and charcoal?

Have not changed the charcoal or the hepa filter yet (about 8 months). The prefilter I have change about ever 4 months. But of course it depends on how much cutting you do. I think I get as much life out of it as a commercial unit, but the refill cost is MUCH less.

[Randy Digby]

Just made first (and second) run. First run resulted in no noticable odor outside near the vent but I had too much back pressure (blower too small ??) and had considerable smoke build-up in the laser. I removed some charcoal, still no odor and smoke removal is better but not where it should be. Guess its time to order a new blower. I'm pushing through about 5 inches of charcoal now (14" x 14" area) ..that may still be more than is needed. Thoughts?

[George Brown]

Just made first (and second) run. First run resulted in no noticable odor outside near the vent but I had too much back pressure (blower too small ??) and had considerable smoke build-up in the laser. I removed some charcoal, still no odor and smoke removal is better but not where it should be. Guess its time to order a new blower. I'm pushing through about 5 inches of charcoal now (14" x 14" area) ..that may still be more than is needed. Thoughts?

5 inches is way too thick, mine is about half of that. Too thick and you'll have a lot of resistance to air flow. I also use a 1.5 hp blower to get enough flow. The hepa filter also helps since it traps particles before they get to the charcoal, so the charcoal only has to deal with gas removal.

[Randy Digby]

Thanks George, that's good info. I'm close, just got to fine tune a little now. I had to get something in place in a hurry, so my rig is not maintenance friendly. I've got time now to redesign one and make access to the filters, etc. a little easier. Thanks for the information from your unit - certainly does help.

[Frank Defert]

Hi Everyone,

I too am in the planning and building stages of an exhast scrubber. However I draw a blank look where ever I ask about activated charcoal.

The prefilters are simple furnace filters for particulates and it was suggested to use activated charcoal hood range filters for odour. But you guys are talking about ordering charcoal and installing it into the chamber box by thickness and or weight. Could someone please elaborate on the " charcoal "

I do quantities of plastic and would like to reduce /eliminate the smell component of my exhaust as it vents outside.

Thanks in advance .... Frank

[Jerry Hewett]

We are also working on building a scrubber. The blower we are using is from Harbor Freight ITEM 94029-3VGA. The price is listed @ $99.

Thanks for the info from this group!

Jerry Hewett

[Randy Digby]

Frank, you can go to the McMaster Carr web site and search for activated charcoal. You may find it a little cheaper elsewhere but these guys deliver supper fast. I've been using them for at least twenty years (maybe 30) for industrial components.

[George Brown]

Hi Everyone,

I too am in the planning and building stages of an exhast scrubber. However I draw a blank look where ever I ask about activated charcoal.

The prefilters are simple furnace filters for particulates and it was suggested to use activated charcoal hood range filters for odour. But you guys are talking about ordering charcoal and installing it into the chamber box by thickness and or weight. Could someone please elaborate on the " charcoal "

I do quantities of plastic and would like to reduce /eliminate the smell component of my exhaust as it vents outside.

Thanks in advance .... Frank

General Carbon
973-523-2223
c-30 Activated Carbon
55#, $120 with shipping

[Lisa Higginbotham]

I'll top load the filters with 25 pounds of activated charcoal when it arrives this afternoon.

Where did you get the charcoal? I have a Trotec Speedy 2 and the filters need replaced. Trotec wants approx $450 for each. I was thinking I could just replace the charcoal without buying it from Trotec. It has a thin sheet of filter material on top of the charcoal under the grid and I wasn't sure what to use to replace that.

The big filter I will have to get from Trotec. I have airhosed it to extend its life but it needs replaced now.

[Frank Defert]

Randy / George,

Thanks for your replies and the great thread!

Frank

[Randy Digby]

I got my charcoal from McMaster Carr. George got a better price from General Carbon and he has the contact info in his post.