Ozone thru Activated Carbon Scrubber

[GP73LPC]

first off, in all of my links replace hxxp with http.

second, i apologize for the length of this post, but i couldn't help it.

DISCLAIMER: if you decide to configure your odor control this way, please test as Carbon Monoxide is tasteless, odorless and deadly. the tests and detectors are cheap and worth the peace of mind.


this discussion is about ozone, it's safety/danger and whether a carbon scrubber should be used to help clean up the ozone smell. you can smell ozone after a rain or on a sunny summer day. once you know what it smells like you can easily recognize it. i have heard some say it smells like chlorine and i suppose that is not too far off the mark, although to me it also has a clean smell to it, if i can use the word clean to describe a smell, lol.

i have used a small ozone generator in a living area and it ran continuously. if you can exhaust your ozone outdoors that is preferrable, but if not i had mine in front of my carbon scrubber and that eliminated most, if not all of the ozone smell.



safety:
per OSHA, safe allowable limits for 8 hour exposure, 5 days a week (workplace) are 0.10 ppm (parts per million) or 200 µg/m3 (micrograms per cubic meter). for full time 24 hour exposure safe limits are 0.01-0.03 ppm or 60 µg/m3.

test kits/strips are available for $10-$20 online. i do recommend testing if you are going to be exposed at all, as ozone can cause health issues.

here are two examples:
hxxp://www.amazon.com/gp/product/B00AMPIQHM/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1
and
hxxp://www.amazon.com/Ozone-Test-Paper-Pack-12/dp/B006BCPFSS/ref=sr_1_1?s=industrial&ie=UTF8&qid=1361949850&sr=1-1



my history:
i started growing initally back in 2002. i was a member at CW and did a ton of reading, planning and designing before build my SUPER STEALTH FISHTANK CABINET (link in my sig, it was slick, check it out). needing to be completly smell free in an apartment and then in a rental house i decided on a carbon scrubber and an ozone generator. after some research, i decided on a small portable unit called an OZONE30 (hxxp://www.amazing1.com/ozone.htm). it produces 30-100 mg of ozone per hour.

i designed my cabinet to have a negative pressurized growing chamber and a positive pressurized air cleaning chamber (baffle box). i used a passive intake and a passive exhaust with a couple of PC fans between the two chambers driving the air in the cabinet. my passive exhaust was really just a hole cut in the bottom of the baffle box approximately 12" x 16" or so. the cabinet was elevated on 2x4's (open on the back for about 10") so the air could exhaust out the back side. over the passive exhaust i placed an A/C filter and taped it down. on top of the filter i added a layer of activated carbon about 1-2 inches thick. thus i had created my carbon scrubber, which was just a horizontal layer of carbon over the filter.

inside the baffle box which was approximately 18"x12"x36", i placed my ozone generator. none of this is really important, just a summary so you can understand how it was designed. it you want to see it's location check my FISHTANK CAB link in the sig.

so essentially the baffle box mixed my grow chamber exhaust with O3 (ozone) before the positive air pressure forced the air across the activated carbon, through the A/C filter and out the back of the cabinet. Nirvana's Afghan was the only strain i ever grew that i could smell and it was just around the cabinet and not the rest of the apartment. i had family, friends and maintenance workers in and around the cabinet with no issues. in fact the maintenance guys would come and go while i was at work, so my odor control had to be on top of it. btw, with this setup i used the above mentioned test strips and all was good.




ozone thru activated carbon:
so once i joined this site back in 2010 and posted in the 'ozone machine thread' https://www.icmag.com/ic/showthread.php?t=220371 , where on page 2 after describing my setup icmag member bakelite informed me that there could be dangers with my design.

Ozone reacts with activated carbon and forms carbon dioxide (CO2) and carbon monoxide (CO). It would be an excellent way to scrub ozone from your exhaust but I wouldn't want to vent it indoors.

bakelite went on to say:

GP,

Absorption and Reaction with GAC
Activated carbon adsorption is extensively used for small applications where air is the ozonator feed gas. This is an adsorption process whereby the reaction consumes the carbon media. The material used is elemental carbon which has been steam activated to provide a large internal surface area. “Carbon is a strong reducing agent, therefore upon contact with ozone gas, the carbon is oxidised to carbon monoxide and carbon dioxide, resulting in destruction of the ozone molecule,” Philip explains.
This reaction degrades or powderises the granular activated carbon, therefore it has a finite life. To this end, the ozone consumes the carbon by slow-rate combustion. Due to this consumption of carbon, the media must be replaced regularly. When the carbon is saturated with water and washed with sprays, the reaction becomes partially catalytic, requiring a larger volume of GAC to be used.
“For ozone installations where oxygen is used as the feed gas, carbon adsorption destructors must not be used, due to the dangers of combustion,” Philip warns.

Here is the link:

http://hydroponics.com.au/free-articles/issue-36-introduction-to-ozone-generation

There is other information out there regarding O3 and Activated carbon but most are technical publications. FWIW laser printers have a small activated carbon filter to get rid of O3 generated by them.

Hope this helps.

-bakelite

this also from the hydroponics.com.au page

Ozone Off-Gas Destruction
Ozone is an oxidative and reactive gas which is harmful to humans above certain concentrations. Ozone gas is heavier than air, therefore any undissolved ozone must be removed from the system and disposed of correctly. Several methods are available for ozone destruction, but the simplest one used for hydroponic applications is by ozone adsorbtion and reaction with Granulated Activated Carbon (GAC)

and then bakelite added this:

GP, I would think that the level of CO2 and CO being generated would depend on the mount of voc's (in our case terpenes etc.) that are present in the air at the time of oxidation.

What would be optimal is to run the ozone scrubbed air through this stuff:
http://www.caruscorporation.com/content.cfm/carulite-200

It is a catalyst that converts O3 into O2.

I agree. The negative effects of ozone have been exaggerated in recent years, especially by the EPA. Hence all the hysteria over air cleaners that produce it. IMO if you limit the time that an ozone machine is on in a room, then you can minimize any deleterious effects that it may have on you.
-bakelite

so much to my surprise i had been putting C02 and Carbon Monoxide into my living are by running O3 through GAC. well i decided that my design was flawed and decided not to do it again. i do not feel i suffered any health issues because of this and to this day i am healthy as i can be.



well so fast forward to 2013 and i am growing once again after a long layoff. i created a very ghetto carbon scrubber but still believe in NO SMELL AT ALL so i hook up my OZONE30. the place i currently rent is kinda small and the ozone seems a bit over powering to me. i just have it set in the room i am growing hooked to a timer. running 15 mins every hour. well the smell is stronger than i feel comfortable with so i ordered the above B1-C test card. awaiting the arrival now to see what kind of concentration i am getting.

in the meantime i remembered the conversation with bakelite, but could not remember the specifics. i finally found the thread and re-read it. i also did a little further google research and found this page and this quote:

hxxp://ozonelaundry.wordpress.com/category/ozone-science/

Activated Carbon Method
Activated Carbon is also an excellent way to eliminate excess ozone. The most important point to remember when it comes to using activated carbon to destroy ozone is to always use a metal container (preferably stainless steel) to hold your carbon media. The reason for this is because the process of passing ozone gas through carbon causes the carbon to heat up and reach extreme temperatures. If you use a plastic container to house your media, you greatly increase your risk of it melting and causing an ozone leak, or worse yet, starting a fire. So, when using activated carbon, keep in mind, use a metal container.

whoa, so now i see the carbon heats to point of potential fire. i am sure that is exagerated but obviously this mix does create heat and this was also news to me.

well being the a-hole i am and not wanting to take no for an answer (wanting to go back to filtering my O3 through GAC) i decided to look into some Carbon Dioxide and Carbon Monoxide tests to see if this can be done safely. apparently it is done and even recommended so even though you can't believe everything you read on the web, i feel that these dangers are some what exagerated.

so needless to say, i am going to order me a couple test kits/strips/monitor, re-arrange/re-build my current setup so that i am pushing O3 through GAC.

if you are interested, here are a couple of links to some tests. again around $10-$20...

Carbon Dioxide
hxxp://www.amazon.com/Active-Air-Co2-Tester-Kit/dp/B003X0R228/ref=sr_1_4?ie=UTF8&qid=1361954409&sr=8-4

Carbon Monoxide
hxxp://www.amazon.com/Pro-Lab-CA101-Carbon-Monoxide-Test/dp/B000MIN9PS/ref=sr_1_7?ie=UTF8&qid=1361954351&sr=8-7

Carbon Monoxide monitors can also be had for around $20-$25...





so this is a project in progess. to summarize, this may or may not be dangerous, GAC degrades much, much faster when O3 is filtered through it and i am determined to find out if this is viable option in a human inhabited environment. as mentioned above by bakelite, this application is used in some printers...


if anyone has more information on this subject, please speak up and let me know whatcha got.

again, i apologize for the length of this post

thanks for you time

 

[GP73LPC]

so i got my B1-C ozone detector card today and these are the results i got with my OZONE30 running on the lowest setting fr 15 mins. the test requires 20 mins, but my unit is set on a timer to run 15 mins every hour. here is a pic of the compare chart and descriptions.



i actually have two OZONE30's. one in my grow room and one in my living area.

test 1 - i ran the ozone30 in my living area with my test card in the living area for 20 mins. as you can see, it fell into the 3 range. potentially unhealthy, especially for children, asthmatics or those with respiratory issues. and definitely not for 24 hours a day.




test 2 - i ran my upstairs grow room unit for 15 mins with my test card in my living area for 20 mins and it fell into range 2. normal ozone on sunny day. okay, but not acceptable for 24 hour exposure by osha standards.





test 3 - i ran the grow room unit for 15 mins with the test card in the grow room. this also fell into range 2 (which kinda tells me this unit is a little weaker than my living area unit or more than likely the extra 5 mins downstairs was too much). again, this is acceptable, but not for 24 hours a day.



so in conclusion, running on a 15 min timer every hour seems like it will be safe, 20 mins every hour is too much.


next, i will rebuild my grow chamber exhaust system so i am treating that exhaust with ozone first and then running through some activated carbon.

i am ordering my carbon monoxide test tonight or tomorrow and will report those results back to everyone as soon as i am able. will probably test the carbon dioxide to, but i don't expect any issues there. i really don't expect any issues with the carbon monoxide testing either, but i want to be safe, that's just my nature.

thanks again for your time

 

[GP73LPC]

ok, update time.

the carbon monoxide danger has been debunked (at least for 30mg of ozone per hour, which is very low by ozone generator standards). i have my ozone30 running on low inside the baffle box and being pushed out across a vertical layer (1 inch thick) of activated carbon.

normal air quality in regards to carbon monoxide according to the test.





and with the ozone30 running constantly, the ozone test now shows it fell into range 2. normal ozone on sunny day. okay, but not acceptable for 24 hour exposure by osha standards. an improvement by running through the carbon.





next i will run a test with the ozone30 back on a timer and in front of the carbon. i suspect this will be acceptable and a viable solution for anyone wanting to run ozone in a living area as added protection over just a carbon scrubber. if successful, that would be exposure at 15 mins per hour in range 2 (6 hours total over 24 hours) which would be acceptable by osha standards. <-- this is my goal.





just before posting i found some leaks in my baffle box. now that those are sealed i am going to run my test again with the ozone30 running constantly. this is my final test on this card so if it still falls within range 2, i will have to order another test card to continue testing.

 

[GP73LPC]

ran my final test, but i think this last test was a bit ineffective as the dot that changes color was not even white to start with. it was about the same exact color as it was after 20 mins




bottom line is, i can smell no more ozone since i fixed the leaks on the baffle box. retested the carbon monoxide and ALL IS GOOD !!!

no ozone smell, no weed smell, no carbon monoxide.

what i will say is the air coming across the activated carbon is warmer than what is coming out of my grow chamber, but nothing close to being hot or starting a fire.

i will take a temp reading and report back.

so to summarize...





running minimal amounts of ozone thru activated carbon is not a problem.

i can now live in a safe environment and have company over without worries.

hope this has beneficial to someone.

 

[GP73LPC]

ok, just set up a thermometer in the exhaust of the carbon scrubber and the difference is only a couple of degrees warmer than in the grow chamber itself.

the new setup is perfect for my situation...

 

[Harry Gypsna]

Don't fuck with Carbon Monoxide.
Lot's of people die every year due to malfunctioning or badly fitted gas boilers and fires. It will kill you in your sleep.
The brother of a chick I know died from Carbon Monoxide poisoning. It was 2 weeks before they found him. His dogs had eaten him when the huge bag of food in the kitchen ran out..

 

[GP73LPC]

Don't fuck with Carbon Monoxide.
Lot's of people die every year due to malfunctioning or badly fitted gas boilers and fires. It will kill you in your sleep.
The brother of a chick I know died from Carbon Monoxide poisoning. It was 2 weeks before they found him. His dogs had eaten him when the huge bag of food in the kitchen ran out..

did you read the thread?

i am very aware of the dangers of CO, thus the testing.

not to mention, if you read the thread you would realize i ran my old cabinet exactly like this in my bedroom where i slept for years.

back in the day i was not aware of the creation of CO by running ozone thru activated carbon. of course, i am alive and well.

this time however, i wanted to actually check by getting a CO test. so i did and it detected NO CARBON MONOXIDE.

now i appreciate your concern and higher doses of ozone might create problems.

i am not advocating anyone do this without testing, but i personally think the warnings are way over blown. and if you read the thread you would have seen that some large printers actually are configured this way (with ozone running thru activated carbon to reduce the dangers of the ozone).

my unit was on low and was producing no more than 30mg per hour, so others will want to test if they configure this way.

thanks again for your concern, but i got this...

 

[JKD]

A company called trackfresh sells a filter that converts Carbon Monoxide to Carbon Dioxide if you want to reduce the risk even further - as long as you can feed it to your plants or exhaust it outside as obviously if it displaces enough O2 you'll still die...

 

[ChaosCatalunya]

I saw posts on IC that said O3 screwed up Activated Carbon, so always believed O3 generators should be run in a baffle room downstream of a carbon filter. It is also a very handy backup system in case of power cuts, use with a UPS battery backup ... read up about "Redundancy" in critical Engineering systems.

 

[GP73LPC]

JKD, thanks. not too worried as i have tested and there is no Carbon Monoxide being exhausted.

CC,
worked in the IT business in data centers for years. i understand redundancy just fine. With that said O3 does ruin Activated Carbon more quickly. more frequent washings of the carbon are required is my understanding.

thanks for the reminder