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This website has claims falsely that oxygen tanks need co2 scrubbers and candles don’t. That is not true and can get people hurt! You need co2 scrubbers for an

This website has claims falsely that oxygen tanks need co2 scrubbers and candles don’t. That is not true and can get people hurt! You need co2 scrubbers for any oxygen producing solution, since co2 kills faster than o2 scarcity. Having a candle, and just a candle alone in a hermetically sealed room will result in suffocation as fast as without it. I reported the post as it contains false and dangerous info.

xenadu02 4y ago
> in a hermetically sealed room I thought these chambers have pressure-triggered relief valves and rely on elevated pressure in the chamber to force air out? Basically dumping some of the existing air/gas in the chamber which carries away some CO2 with it.
- FieryTransition 4y ago
  Yeah, unless you need to stay silent for detection reasons or warfare, my guess would be that in a fixed facility, it would be way cheaper and reliable to have a positive pressure or flow of air going outward. I've seen windows and buildings do this completely passive, so a modern design would only have this as an absolute emergency, as they are dangerous and doesn't solve the Co2 problem. Don't see how this is relevant for civil use though, but hey, maybe some paranoia can sell some candles.
- aaron695 4y ago
bryanrasmussen 4y ago
Is there such a thing as a portable c02 scrubber - other than a plant?
- rdl 4y ago
  Yeah -- soda lime, etc. e.g. https://minearc.com/remove-co-co2-in-refuge-chamber-chemical-scrubber/ https://minearc.com/remove-co-co2-in-refuge-chamber-chemical...
  - JoshTriplett 4y ago
    Are there solutions for CO2 scrubbing that use electricity and can run indefinitely, rather than chemical substrates that get used up and require replenishing?
    - rdl 4y ago
      Yes, but the context of this post was emergency systems which are purely chemical. For routine operations on e.g. a submarine, https://www.naval-technology.com/contractors/materials/atmosphere-control-international/ https://www.naval-technology.com/contractors/materials/atmos... As other people have mentioned, this is a great introduction to the topic: https://www.youtube.com/watch?v=g3Ud6mHdhlQ https://www.youtube.com/watch?v=g3Ud6mHdhlQ
    - atrus 4y ago
      While probably not as applicable on Earth, the ISS CO2 scrubbers use a chemical substrate that is then exposed to space where the CO2 is sent off. https://www.eni.com/en-IT/scientific-research/space-free-co2.html https://www.eni.com/en-IT/scientific-research/space-free-co2...
    - frederikvs 4y ago
      It looks like Monoethanolamine (MEA) can be reused after a regeneration cycle. Of course, you will need somewhere to dump the CO2. https://en.wikipedia.org/wiki/Ethanolamine#Gas_stream_scrubbing https://en.wikipedia.org/wiki/Ethanolamine#Gas_stream_scrubb...
      - adrianN 4y ago
        Soda lime can also be used after a regeneration cycle. If you heat it sufficiently it releases the CO2 again.
    - krisoft 4y ago
      Sure. The trick is that there are regenerative chemical substrates. The material absorbes co2, gets saturated, cycled to a different part where it is heated and releases the co2 and can be used to capture again. If you use electricity to do the heating and cycling you have exactly what you asked for. On the other hand these units are usually not small or portable. Here is a press release from a manufacturer: https://www.naval-technology.com/contractors/materials/atmosphere-control-international/ https://www.naval-technology.com/contractors/materials/atmos...
- swiftcoder 4y ago
  And plants are not viable as CO2 scrubbers on small scales. It takes a lot of plants to scrub the CO2 exhaled by a single human - somewhere on the order of 10 full-size trees!
  - TaylorAlexander 4y ago
    This would make for a lovely mine if you had 10 full size trees inside it.
    - ryanmercer 4y ago
      minecraft intensifies
  - elmolino89 4y ago
    Single human produces around 1kg of CO2 per day: https://www.sciencefocus.com/planet-earth/how-much-does-human-breathing-contribute-to-climate-change/ https://www.sciencefocus.com/planet-earth/how-much-does-huma... Seems that algae are up to 400x more efficient at CO2 scrubbing than terrestrial plants. See: https://newatlas.com/environment/algae-fueled-bioreactor-carbon-sequestration/ https://newatlas.com/environment/algae-fueled-bioreactor-car... No idea though if such bio-tanks are a viable solution in a rather devoid of solar light shelters.
  - malfist 4y ago
    Plants are generally net neutral in CO2 consumption. They consume CO2 during the day, but when not producing energy through photosynthesis, they consume O2 and produce CO2 for their cellular respiration. The net effect is generally, plants release similar amounts of CO2 at night as they consume during the day. The exception here would be plants that use Crassulacean acid metabolism for photosynthesis, which would be a lot of your arid native plants.
    - jandrese 4y ago
      I would expect plants to be CO2 negative while growing since they're using the carbon to add to their dry mass. Once fully grown I'd expect the plants to be roughly neutral.
- frederikvs 4y ago
  Yes, e.g. if you look at "rebreather" diving equipment, it's essentially a backpack life support system, including CO2 scrubber.
- rootusrootus 4y ago
  Wasn't that one of the things Apollo 13 had to figure out how to rig up in order to survive?
rdl 4y ago
I don't see where it claims that. They point out that piped air is one option (which is basically continuous open circuit in these settings; exhausting to outside.). The alternative is oxygen cylinders mounted on the chamber (or inside the chamber), which (generally) require scrubbers. Oxygen candles are then mentioned; they are essentially a nearly direct replacement for oxygen cylinders, but with somewhat better storability. It is silent on whether co2 scrubbing is needed, but obviously would in the same settings oxygen cylinders would.
- SapporoChris 4y ago
  "A candle is an entirely independent source of oxygen from within the refuge chamber. In this way, it’s isolated from common faults found in the other sources: Compressed Air: The feed can often be compromised during an emergency due to damage to the circuit or carbon monoxide contamination requiring the chamber to be isolated." The candle is not isolated from the common fault of carbon monoxide contamination. Both Oxygen candles and oxygen cylinders will generally require scrubbers.
  - lultimouomo 4y ago
    I think you are mixing up carbon monoxide contamination and carbon dioxide build up. They mean that with oxygen candles you don't risk having your very oxygen reserve introduce carbon monoxide in the air you breathe, as it could happen of you have a contamination at the source of compressed air.
    - SapporoChris 4y ago
      Okay, ignoring carbon monoxide contamination. The site also states: "Oxygen cylinders are used in the event compressed air fails and generally require the support of a scrubbing system to remove carbon dioxide and carbon monoxide from the air." If Oxygen cylinders generally require a scrubber I think it's safe to assume that a Oxygen candle will also need a scrubber. They list issues with other systems but don't acknowledge the same problems that exist with their own.
swixmix 4y ago
Oxygen candles smell bad. I would never want to use one except in an emergency situation. No scrubber necessary if I’m just evacuation.
deleted 4y ago
[deleted]
bell-cot 4y ago
I disagree, for contextual reasons. Oxygen candles are an emergency safety supplies item for people who get serious training in industry- and facility-specific safety procedures. Notice the slant to the headings, language, photos, etc. on the page. This is very clearly not a consumer product, and phrases such as "Used as the last means of breathable air within a refuge chamber..." really don't suggest "try this at home, kids!".
- modec 4y ago
  But there is also an oxygen candle above every seat in passenger airplanes, right? Then it would be a consumer product ...
  - deleted 4y ago
    [deleted]
  - dividedbyzero 4y ago
    I think that's stretching the definition of consumer product to the point of losing its usefulness. A lot of (semi-)automated emergency tech contains seriously dangerous stuff, like explosives or highly toxic materials, and these devices are usually very carefully engineered to keep the risks from using that tech acceptable even under emergency circumstances, and risk tolerance tends to be a lot higher for a device meant to be used in a decompressing plane in the first place. You can't use that oxygen candle outside such a situation, and you can only use it through the extremely constrained user interfaces provided by the yank switch and mask.
    - modec 4y ago
      Ok fair. I just thought that it proved that they could be made safe. I now realize that emergency situations have very different tolerances for safety.
    - bell-cot 4y ago
      This. Similar - a residential electrical service panel. It's generally okay for even a little kid to flip a wall-mounted light switch. Touching the circuit breaker handles on the service panel is a "competent adults, paying close attention, only at need" activity. And digging inside that service panel should only be done by professionals.
foxyv 4y ago
This is correct. A person in a hermetically sealed suit will die of CO2 poisoning a long time before Oxygen deprivation. However in most mines, they will engineer gas permeability so that CO2 and other poisonous gasses can seep to areas with lower concentrations and out of the mine. Coal mines seem to be particularly bad with regards to permeability. In this case, an Oxygen candle _MAY_ be enough to keep people alive. However, why O2 tanks would need scrubbers and candles wouldn't doesn't make any sense. https://www.hindawi.com/journals/ace/2018/3976505/ https://www.hindawi.com/journals/ace/2018/3976505/ https://www.cdc.gov/niosh/mining/works/coversheet1621.html https://www.cdc.gov/niosh/mining/works/coversheet1621.html
samatman 4y ago
Just so we're all perfectly clear, this one poster got upset about this website and reported it for misleading information and this is now the top comment. The company sells an air scrubber: https://minearc.com/products/air-quality-management/life-support-systems/ https://minearc.com/products/air-quality-management/life-sup... I love this place.
throwawayboise 4y ago
False and dangerous to whom? Anyone in a position to be using oxygen candles or bottled oxygen in a survival shelter setting is likely to have had safety training in how to use them, and if it is a situation where CO2 concentration is likely, that should have been accommodated in the construction of the refuge or shelter.
HWR_14 4y ago
> You need co2 scrubbers for any oxygen producing solution, since co2 kills faster than o2 scarcity. Given their uses are the space station, planes and submarines, cant you just vent some of the atmosphere out since you're in a pressurized tube of some kind to lower the CO2?
- rtkwe 4y ago
  It's far too expensive to launch new material up to do that. It's much better to scrub out the CO2 specifically than to throw out mixed gases. If you're just removing CO2 you only need to replace it with new oxygen which can be electrolicized from water stores but if you're tossing out cabin air in bulk there's stuff like nitrogen that's harder to replace. The ISS is basically sea level air with 21% O2 and the rest nitrogen plus trace CO2 and other gasses, that nitrogen would be much harder to replace. With hydrolysis you just have waste Hydrogen to toss which could in the future be combined with CO2 from the scrubbers to create methane fuel (probably not in significant quantities but it closes the cycle on O2 as the Sabatier reaction also creates H2O which could feed back into electrolysis or drinking.

xenadu02 4y ago

> in a hermetically sealed room I thought these chambers have pressure-triggered relief valves and rely on elevated pressure in the chamber to force air out? Basically dumping some of the existing air/gas in the chamber which carries away some CO2 with it.

FieryTransition 4y ago
Yeah, unless you need to stay silent for detection reasons or warfare, my guess would be that in a fixed facility, it would be way cheaper and reliable to have a positive pressure or flow of air going outward. I've seen windows and buildings do this completely passive, so a modern design would only have this as an absolute emergency, as they are dangerous and doesn't solve the Co2 problem. Don't see how this is relevant for civil use though, but hey, maybe some paranoia can sell some candles.
aaron695 4y ago

bryanrasmussen 4y ago

Is there such a thing as a portable c02 scrubber - other than a plant?

rdl 4y ago
Yeah -- soda lime, etc. e.g. https://minearc.com/remove-co-co2-in-refuge-chamber-chemical-scrubber/ https://minearc.com/remove-co-co2-in-refuge-chamber-chemical...
- JoshTriplett 4y ago
  Are there solutions for CO2 scrubbing that use electricity and can run indefinitely, rather than chemical substrates that get used up and require replenishing?
  - rdl 4y ago
    Yes, but the context of this post was emergency systems which are purely chemical. For routine operations on e.g. a submarine, https://www.naval-technology.com/contractors/materials/atmosphere-control-international/ https://www.naval-technology.com/contractors/materials/atmos... As other people have mentioned, this is a great introduction to the topic: https://www.youtube.com/watch?v=g3Ud6mHdhlQ https://www.youtube.com/watch?v=g3Ud6mHdhlQ
  - atrus 4y ago
    While probably not as applicable on Earth, the ISS CO2 scrubbers use a chemical substrate that is then exposed to space where the CO2 is sent off. https://www.eni.com/en-IT/scientific-research/space-free-co2.html https://www.eni.com/en-IT/scientific-research/space-free-co2...
  - frederikvs 4y ago
    It looks like Monoethanolamine (MEA) can be reused after a regeneration cycle. Of course, you will need somewhere to dump the CO2. https://en.wikipedia.org/wiki/Ethanolamine#Gas_stream_scrubbing https://en.wikipedia.org/wiki/Ethanolamine#Gas_stream_scrubb...
    - adrianN 4y ago
      Soda lime can also be used after a regeneration cycle. If you heat it sufficiently it releases the CO2 again.
  - krisoft 4y ago
    Sure. The trick is that there are regenerative chemical substrates. The material absorbes co2, gets saturated, cycled to a different part where it is heated and releases the co2 and can be used to capture again. If you use electricity to do the heating and cycling you have exactly what you asked for. On the other hand these units are usually not small or portable. Here is a press release from a manufacturer: https://www.naval-technology.com/contractors/materials/atmosphere-control-international/ https://www.naval-technology.com/contractors/materials/atmos...
swiftcoder 4y ago
And plants are not viable as CO2 scrubbers on small scales. It takes a lot of plants to scrub the CO2 exhaled by a single human - somewhere on the order of 10 full-size trees!
- TaylorAlexander 4y ago
  This would make for a lovely mine if you had 10 full size trees inside it.
  - ryanmercer 4y ago
    minecraft intensifies
- elmolino89 4y ago
  Single human produces around 1kg of CO2 per day: https://www.sciencefocus.com/planet-earth/how-much-does-human-breathing-contribute-to-climate-change/ https://www.sciencefocus.com/planet-earth/how-much-does-huma... Seems that algae are up to 400x more efficient at CO2 scrubbing than terrestrial plants. See: https://newatlas.com/environment/algae-fueled-bioreactor-carbon-sequestration/ https://newatlas.com/environment/algae-fueled-bioreactor-car... No idea though if such bio-tanks are a viable solution in a rather devoid of solar light shelters.
- malfist 4y ago
  Plants are generally net neutral in CO2 consumption. They consume CO2 during the day, but when not producing energy through photosynthesis, they consume O2 and produce CO2 for their cellular respiration. The net effect is generally, plants release similar amounts of CO2 at night as they consume during the day. The exception here would be plants that use Crassulacean acid metabolism for photosynthesis, which would be a lot of your arid native plants.
  - jandrese 4y ago
    I would expect plants to be CO2 negative while growing since they're using the carbon to add to their dry mass. Once fully grown I'd expect the plants to be roughly neutral.
frederikvs 4y ago
Yes, e.g. if you look at "rebreather" diving equipment, it's essentially a backpack life support system, including CO2 scrubber.
rootusrootus 4y ago
Wasn't that one of the things Apollo 13 had to figure out how to rig up in order to survive?

rdl 4y ago

I don't see where it claims that. They point out that piped air is one option (which is basically continuous open circuit in these settings; exhausting to outside.). The alternative is oxygen cylinders mounted on the chamber (or inside the chamber), which (generally) require scrubbers. Oxygen candles are then mentioned; they are essentially a nearly direct replacement for oxygen cylinders, but with somewhat better storability. It is silent on whether co2 scrubbing is needed, but obviously would in the same settings oxygen cylinders would.

SapporoChris 4y ago
"A candle is an entirely independent source of oxygen from within the refuge chamber. In this way, it’s isolated from common faults found in the other sources: Compressed Air: The feed can often be compromised during an emergency due to damage to the circuit or carbon monoxide contamination requiring the chamber to be isolated." The candle is not isolated from the common fault of carbon monoxide contamination. Both Oxygen candles and oxygen cylinders will generally require scrubbers.
- lultimouomo 4y ago
  I think you are mixing up carbon monoxide contamination and carbon dioxide build up. They mean that with oxygen candles you don't risk having your very oxygen reserve introduce carbon monoxide in the air you breathe, as it could happen of you have a contamination at the source of compressed air.
  - SapporoChris 4y ago
    Okay, ignoring carbon monoxide contamination. The site also states: "Oxygen cylinders are used in the event compressed air fails and generally require the support of a scrubbing system to remove carbon dioxide and carbon monoxide from the air." If Oxygen cylinders generally require a scrubber I think it's safe to assume that a Oxygen candle will also need a scrubber. They list issues with other systems but don't acknowledge the same problems that exist with their own.

swixmix 4y ago

Oxygen candles smell bad. I would never want to use one except in an emergency situation. No scrubber necessary if I’m just evacuation.

deleted 4y ago

[deleted]

bell-cot 4y ago

I disagree, for contextual reasons. Oxygen candles are an emergency safety supplies item for people who get serious training in industry- and facility-specific safety procedures. Notice the slant to the headings, language, photos, etc. on the page. This is very clearly not a consumer product, and phrases such as "Used as the last means of breathable air within a refuge chamber..." really don't suggest "try this at home, kids!".

modec 4y ago
But there is also an oxygen candle above every seat in passenger airplanes, right? Then it would be a consumer product ...
- deleted 4y ago
  [deleted]
- dividedbyzero 4y ago
  I think that's stretching the definition of consumer product to the point of losing its usefulness. A lot of (semi-)automated emergency tech contains seriously dangerous stuff, like explosives or highly toxic materials, and these devices are usually very carefully engineered to keep the risks from using that tech acceptable even under emergency circumstances, and risk tolerance tends to be a lot higher for a device meant to be used in a decompressing plane in the first place. You can't use that oxygen candle outside such a situation, and you can only use it through the extremely constrained user interfaces provided by the yank switch and mask.
  - modec 4y ago
    Ok fair. I just thought that it proved that they could be made safe. I now realize that emergency situations have very different tolerances for safety.
  - bell-cot 4y ago
    This. Similar - a residential electrical service panel. It's generally okay for even a little kid to flip a wall-mounted light switch. Touching the circuit breaker handles on the service panel is a "competent adults, paying close attention, only at need" activity. And digging inside that service panel should only be done by professionals.

foxyv 4y ago

This is correct. A person in a hermetically sealed suit will die of CO2 poisoning a long time before Oxygen deprivation. However in most mines, they will engineer gas permeability so that CO2 and other poisonous gasses can seep to areas with lower concentrations and out of the mine. Coal mines seem to be particularly bad with regards to permeability. In this case, an Oxygen candle _MAY_ be enough to keep people alive. However, why O2 tanks would need scrubbers and candles wouldn't doesn't make any sense. https://www.hindawi.com/journals/ace/2018/3976505/ https://www.hindawi.com/journals/ace/2018/3976505/ https://www.cdc.gov/niosh/mining/works/coversheet1621.html https://www.cdc.gov/niosh/mining/works/coversheet1621.html

samatman 4y ago

Just so we're all perfectly clear, this one poster got upset about this website and reported it for misleading information and this is now the top comment. The company sells an air scrubber: https://minearc.com/products/air-quality-management/life-support-systems/ https://minearc.com/products/air-quality-management/life-sup... I love this place.

throwawayboise 4y ago

False and dangerous to whom? Anyone in a position to be using oxygen candles or bottled oxygen in a survival shelter setting is likely to have had safety training in how to use them, and if it is a situation where CO2 concentration is likely, that should have been accommodated in the construction of the refuge or shelter.

HWR_14 4y ago

> You need co2 scrubbers for any oxygen producing solution, since co2 kills faster than o2 scarcity. Given their uses are the space station, planes and submarines, cant you just vent some of the atmosphere out since you're in a pressurized tube of some kind to lower the CO2?

rtkwe 4y ago
It's far too expensive to launch new material up to do that. It's much better to scrub out the CO2 specifically than to throw out mixed gases. If you're just removing CO2 you only need to replace it with new oxygen which can be electrolicized from water stores but if you're tossing out cabin air in bulk there's stuff like nitrogen that's harder to replace. The ISS is basically sea level air with 21% O2 and the rest nitrogen plus trace CO2 and other gasses, that nitrogen would be much harder to replace. With hydrolysis you just have waste Hydrogen to toss which could in the future be combined with CO2 from the scrubbers to create methane fuel (probably not in significant quantities but it closes the cycle on O2 as the Sabatier reaction also creates H2O which could feed back into electrolysis or drinking.