Washing a Carbon Filter

[tequila_sunrise]

I was gifted a fat 4" carbon filter from a buddy who had used it sparingly. I have used it for no more than 2 weeks and already it is giving out. I went to my local hydro shop's website and found a cheap one that looks almost identical to the one I have (no branding). It says on the description that it can be washed once.


My question is, should I even bother to wash the filter or should I just buy a new one ($45)

I reckon that i will have to wash it and let it dry for a good 24 hours.

So has anyone tried this?

 

[justanotherbozo]

censorship sucks!

 

[tequila_sunrise]

It looks like the short fat one 4th from the right. However there are no markings on the cotton batting.

Also I doubt that I will be able to open it up without a hacksaw. I want to say its welded shut.

 

[justanotherbozo]

censorship sucks!

 

[confedrate69]

if i remember correctly in the instructions on my can 33 and 118 lb eco filter they say do not get wet

 

[tequila_sunrise]

http://www.discount-hydro.com/productdisp.php?pid=590&navid=23

Mine looks identical to the one with the black straps. Now that I think about it, It is riveted shut... I will go grab it from the room and check.


edit:

I took the prefilter off of it and you can clearly see a 6" cap and a 6" -> 4" reducer... both riveted on


The wire mesh (outer) is held on... looks like it was soldered.


fuck it im going for it. IF this doesnt work, I will get a new one friday.

 

[1969]

You can cook your carbon in the oven to sort of reactivate it again. We cook ours once a year here and have never had a problem.

 

[justanotherbozo]

censorship sucks!

 

[FarmerTed]

You can cook your carbon in the oven to sort of reactivate it again. We cook ours once a year here and have never had a problem.

Can you tell me at what temp you cook it and for how long?
Thanks.

 

[messn'n'gommin']

I copied this from a home distillers forum. Since my carbon isn't used up, I haven't done this yet. But, mark my words, when it does, I will! Still, it is my understanding that while drying in the oven...it is gonna stink! Maybe drying it out late at night will sidestep that problem, but, something to consider if you decide to do this a couple of hours before company comes over.

Mike writes of his technique for cleaning carbon for reuse ..

I think you will find that the extreme heat procedures you read about concerning commercial reactivation of carbon are not necessary in a hobby situation. I regularly treat my carbon after use, and find that it serves me very well. Rather than calling it "reactivation", it is perhaps better to describe the process as "cleaning", as "activation" really means treating raw carbon so that it has a suitable internal structure with a very large surface.
Try this:
o Wash used carbon in plenty of running water to get rid of all external rubbish. I do this simply by rinsing under a tap with the carbon in a sieve.
o Then boil it in an open pan of water for around quarter of an hour. This will get rid of the bulk of the volatiles. If you want to do a really thorough wash, carry on by boiling it up in an ordinary pressure cooker for 10 minutes. This will get rid of even more than open air boiling.
o Finally, strain off all the carbon and rinse under a tap for a minute, then spread it all out on a wide baking tray covered in ordinary baking foil (saves rusting the tray!).
o Shove that in the kitchen oven to dry slowly at around 160C/320F, making sure that you periodically open the oven door to vent the smelly steam that comes off.
It takes time to drive all the water off, but organic molecules still held inside the carbon will come off with the steam quite readily at this low temperature. Don't try heating at the highest temperature your oven is capable of .. not only is it unnecessary, you will also run the risk of ending up with a pile of gray ash! Try it. I think you will find that it's more than adequate.

(The following was a response to someone's suggestion about using a microwave to dry the carbon instead of an oven.)

Mike warns about using a microwave :

Carbon is a good conductor of electricity, so microwave radiation is readily absorbed. However, high voltages are generated across the gaps between the granules. Sparks result when the voltage jumps across these gaps. Air is a good insulator, so this sparking will readily occur when the carbon is dry, for the voltages can be very high indeed. Strong eddy currents in the carbon heat the granules as it does have some resistance, so plenty of heat is generated, usually ending up with the carbon igniting.

It's slightly different when the carbon is wet. Water is generally considered to be a good conductor, but that is only because it can readily dissolve salts that disassociate in solution into electrically charged ions, and these carry the current. Water that has been through the distilling process has no salt content, and any salts present in the carbon/water mix will generally be those lingering on after the manufacturing process. The water separating the carbon granules is therefore a fairly good insulator and sparking will also be experienced, usually with generation of a bit of hydrogen and oxygen as the water is broken down by electrolysis. The heat generated will initially go towards heating and vaporizing the water, so keeping the carbon below its ignition point. However, when all that water has boiled off, the dry carbon will then heat up - as before - and ignite. One "interesting" side effect you might notice if treating damp carbon in a microwave is that you can end up with an explosion, for that dampness may well contain a goodly proportion of alcohol if you haven't first washed the carbon thoroughly. The atmosphere in the microwave can quickly reached critical proportions with the oxygen in the air, and a spark is a tried and true way of igniting that mix! You can even get the same effect in an ordinary oven from a red-hot heating element if the carbon still has a lot of alcohol left in it ... ending up with a muffled thump and the oven door blowing open!! (Been there, done that, and would be wearing the T-shirt if it hadn't been scorched!)

Moral? Do NOT dry carbon in a microwave oven as the risks of fire or even explosion are too great, and wash carbon thoroughly in lots of clean water before drying in an ordinary oven ... keeping the oven door slightly open to vent any flammable gases that will almost certainly be given off, as no amount of ordinary sluicing in water will get rid of all the alcohols deep inside the carbon granules. Proof that they are indeed still there will become more than evident to your nose as they are vaporized ... so keep the kitchen windows wide open if you don't want the whole house to reek of congeners!


Hope this helps and please let us know how it works out if you do. Good luck!

Namaste, mess

 

[tequila_sunrise]

good info on cooking it.

I just washed it off in the tub under hot water, I am going to let it dry in the sun all day today.

I am going to make one per the instructions this weekend.


Thanks guys!

 

[1969]

Can you tell me at what temp you cook it and for how long?
Thanks.

We put it in at 300 degrees for about an hour. I've read people doing only 150 for a half hour to some saying it has to be at least 500. Our scrubber is at least 5 years old and works like a champ for how we do it.