Activated Carbon Filter X Deep Acrylic engraving

Hey people :slight_smile:

I got my BOFA Oracle Air Filtration x Exhaust system a week ago and was very pleased with it however it started to smell really bad anyone has so experiences with Acrylic engraving and cutting using an activated Carbon Filter ? I cant find any relatable information about this. The guys from BOFA just told me that Acrylic can saturate Carbon Filters very quickly but I have used it for like 3-4 days now . Please share some experiences :slight_smile:
Information :
Deep Acrylic engraving 2mm and cutting 4mm.
The Filtration system has a pre Filter 95% and a combined HEPA + 15kg Activated Carbon Filter.
Cheers and greetings from Germany

Because of the relatively high price and because I have the options, I built my own filter. I use 2 pre-filters and an approx. 5 cm thick activated carbon filter. My experiences coincide with yours, after a week it starts to smell familiar of acrylic. I’m lucky enough to be able to vent out in the open without bothering anyone. But of course it is rather disappointing that the filters do not work as expected. Do you have a plan B?

I just got a dm from someone who told me he is literally using 200kg of activated carbon for his similar usage and change that every 6-8 weeks. I think im pretty f…d :smiley: my plan B is also to vent outside from a shaft. Invested 3k€ in nothing thats for sure

oh man, you have to buy an entire coal mine for just 1 year of laser operation….
Fortunately, I have only lost a little money on my homemade filter.

I am not a chemist here, but these are my thoughts…

Since plain activated charcoal is just a carbon source baked in an oxygen free or low oxygen environment, I would think you could just burn it off to regenerate it. If you do it in open air at not too high a temp it should be fine, but if you want to go with higher temps you would want to keep the air away so it doesn’t burn off. A nearly sealed container with a vent would allow the heat to drive out the contaminants and avoid letting oxygen in to convert the carbon to CO/CO2… I think for 200kg of charcoal, I would consider insulating a large steel BBQ smoker and heat it with electricity or natural gas and drive off the contaminants. Looks like in bulk it is $.50 - $3.00 US per kg… Maybe cheaper if you have a local source…

Kind of like drying out silica gel pellets, just at a higher temperature.

Some activated charcoal coated things I have used had you set it in the open sunshine for several hours or up to a couple of days and let the sunlight and UV rays remove some of the contaminants. That was for open air charcoal covered filters where the charcoal coating was thin and they used a plastic mesh of some sort to act as the web for the charcoal. It helped some of them, but not really as good as new. Still worth doing for most of them…

Also, ozone is very effective at removing odors like you are describing and an ozone treatment running through the filter regularly might solve the problem. Those are pretty common now since the pandemic make ozone treatments a more popular thing. My car was done a few weeks ago since it developed an odor after a week or two at the dealer…

An HVAC UV-C emitter might also break down the contaminants like the sunshine and refresh the activated charcoal… Those are not hard to set up, but I do not know how effective they would be since they might work on a filter material, but not so well on chunks of charcoal…

I would think the heat treatment or ozone is better at getting inside the pores of the activated charcoal.

I was thinking for someone in his situation, acrylic vapors are mostly boiled plastic so I would also expect it to condense and coat the surface of the charcoal… Just like leaded gasoline did to catalytic converters.

However , just like automobiles, he could run the exhaust through a heated catalytic converter to ~400C-600C and it would act to destroy much of the partially burned HC things in the exhaust… Once you get the catalyst hot enough to ignite, the acrylic smoke particles it is oxidizing would supply some portion of the energy required to keep the catalyst hot. It would be pretty simple to use an automotive O2 sensor and temp sensor to monitor the thing running inside a small insulated fire box like an insulated 20lb propane tank.

I would think that there is not really any significant fuel value in that much smoke, but I do not know the size of his laser exhaust and I do not know how much vapor he is generating, but I would doubt it would be a significant source of heat. If it is, he could use at least some of the waste heat for hot water boost or winter heat in cold climates or something…

Seems like 200kg ~8 times per year @ maybe $250 US per fill is a lot of $… If a fill is only $50 then it is just the cost of business…

Cooking it seems a little easier though the catalyst might mean never changing filters…

The whole coal mine thing was meant ironically :wink:
In industry, exhaust is “washed” in large cylinders. A lot of energy and water is used and there are residual products that must be disposed of.

There is only one A/C regeneration method that is really practical for the hobbyist… steam. You probably don’t have the resources to use chemical regeneration, and good thermal regeneration requires really high temperatures (something like 800C !!!) that you won’t achieve in your kitchen.

Steam regeneration effectiveness depends on what has been adsorbed onto the carbon, but it might work to extend the life of your carbon bed.

You can try baking the carbon in your oven, and you will get some limited regeneration, but it won’t be like fresh A/C afterwards.

Whether you bake it or steam it, do it in a WELL ventilated area. Lots of nasty things come off of that carbon.

I would think if you put the A/C in mostly sealed metal box on a gas fired grill it would hit 800-900F and bake off most things. If the box is not mostly sealed though I think it will burn the charcoal and just make CO2…