Now, before we begin, I absolutely do not recommend doing this, and take no responsibility for what you do with this guide, but if you're like me and don't listen, at least do it outside and wear a respirator. You'll thank me later.
Also, this doesn't work for "coffee can" type filters, they're built differently. If I open one of mine, I might make a post on how to disassemble it, but they are far more dangerous than the green civil filters. It's best to keep them sealed up for display only. Actually that goes for all filters, display only. I did this so I could have a safe filter for airsoft games/cosplay.
Dremel tool/metal file
Container that a filter will fit in
someting that you can hit with a hammer that fits into the top hole of the filter and isn't pointy, I recomend a dowel rod
Sharp utility knife
And obviously the filter.
Is going to be disassembled into these parts:
From left to right: canister body, upper particle filter and charcoal grid, container filled with charcoal granules, lower charcoal grid, lower particle filter (the dangerous piece), and the canister bottom.
Part 1: Preparing the canister
Notice the edge of the canister? How it has the rim, then that inner lip? The goal is to cut the rim of the canister, and leave that lip alone. I've seen several videos where the inner lip of the canister is thought to be what holds it on, and people wind up utterly destroying the canister. That inner lip holds the particulate stage secure inside the canister.
On to dissassembly, then!Take the dremel tool or file, and carefully go along the rim of the canister, until a small crack can be seen in the metal. It should look similar to the below image when finished.
Part 2: Removing the bottom
If the bottom of the canister has been filed down properly, when pulling the sealing plug out of the bottom, the entire bottom of the filter, with particle stage attached, will come off. The particle stage is dangerous, take the bottom of the filter/particle stage and put it into a plastic bag, its needed in Part 4.
Part 3: Removing meshes/grids and charcoal
Take the threaded cap and rubber seal off the top of the canister, and find a metal pipe or wooden stick, something that fits into the hole. I used a wooden dowel rod, to avoid puncturing the metal meshes. Put the canister into a shallow bucket or container where it can sit upright. This part is important to keep the charcoal from going everywhere.
Now, place the stick/screwdriver into the top of the canister and lightly tap it with a hammer, I stress LIGHTLY, until the meshes holding the charcoal come loose. If its hit too hard, the top mesh will be punctured and it'll never come out of the canister body. If its been done correctly, there will be a small popping sound, and charcoal will spill out of the bottom, along with the upper mesh/particle barrier and lower metal grid.
Bag up the charcoal and meshes, and discard or keep them if you wish to make a display. Take the now hollow canister and wash the inside of it well. No charcoal pellets or dust should remain.
Part 4: Removing the particle stage from the bottom of the canister
The bottom of the canister, which was removed in Part 2, should look something like this. Note the metal part is connected to the particle stage.
Take a knife, and very carefully cut the particle stage, using the attached metal piece as a guide. Try to cut as close to the metal as you can, and avoid damaging the corrugated area of the particle stage. Once cut, the particle stage and the metal bottom of the canister will probably still be attached with a glue or epoxy type material. It should pull free easily without damage if the paper has been cut properly. Bag up the particle filter immediately upon completing this step, it is the asbestos containing part. Wash the metal canister base piece thoroughly with water.
The canister base should have a small portion of the particle paper still crimped into it, and probably looks like this.
Cover it with tape, but be careful not to block the air holes, or the sloped edges along the outside, otherwise you won't be able to breathe through it or fit the base back into the canister body. After the leftover paper piece has been covered, push the filter base back into the empty canister housing. If desired, glue could be applied to permanently hold the canister together.