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Author Oxygen levels
ChrisJC

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Oxygen levels
Posted: 30/09/2020 10:15:26
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I was thinking about oxygen levels in Iron Mines. I saw a video the other day of somebody with an oxygen meter around 14% and they appeared quite breathless.

Then I considered my recent experience of hiking at altitude (Inca Trail at over 4000m), and wondered what the oxygen levels were there.

This page:
https://hypoxico.com/altitude-to-oxygen-chart/
suggests that oxygen levels were 12.3%, at which I had no problem.

Can the two be equated?, or are they different?

Chris.
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Down and beyond

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Oxygen levels
Posted: 30/09/2020 10:42:52
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I am unsure of the honest answer to that so I am not going to answer that but what I will say is , it’s possibly the high level of carbon dioxide inside the mine that’s causing the o2 depletion, this I don’t believe can be picked up on a 4x not sure if you can get a sensor changed to this instead , I no it’s obviously a very dangerous gas on it’s own , can this gas kill you before the o2 goes to a low level so the 4x doesn’t show it ? I have always believed low o2 shows this gas so if some one can answer these also I would be most grateful


Have been at 14.1 and it was a serious SurrenderThumb Down

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IP: 82.132.229.40 Edited: 30/09/2020 10:51:26 by Down and beyond
sinker

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Oxygen levels
Posted: 30/09/2020 11:13:21
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ChrisJC wrote:

I was thinking about oxygen levels in Iron Mines. I saw a video the other day of somebody with an oxygen meter around 14% and they appeared quite breathless.

Then I considered my recent experience of hiking at altitude (Inca Trail at over 4000m), and wondered what the oxygen levels were there.

This page:
https://hypoxico.com/altitude-to-oxygen-chart/
suggests that oxygen levels were 12.3%, at which I had no problem.

Can the two be equated?, or are they different?

Chris.


I'm no expert but I'm sure that air pressure has a bearing on O2 saturation etc. Temperature also.
All my industrial and CasCare training takes into account effects of temperature but assumes "normal" air pressure; 'summit of Snowdon' effectively.



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Oxygen levels
Posted: 30/09/2020 11:19:24
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Hi Chris,
Acclimatization is important too.
The low Oxygen partial pressure at altitude is noticeable at the beginning of an alpine climbing trip but a few days later your body has adapted. No time to acclimatize when you walk into a mine...
James
IP: 77.44.49.149 Edited: 30/09/2020 11:20:30 by Expelunker
pwhole

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Oxygen levels
Posted: 30/09/2020 11:28:37
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DCA's research in caves and mines into this issue shows that in most cases underground (in Derbyshire at least), O2 depletion is usually exactly replaced by CO2. So a 2% drop in O2 will mean there's 2% CO2 present. That's quite high for most people, and if SRT is involved, that's very high - I write from personal experience of just how horrible that is. The bottom of Nettle Pot is not a good place to be in that situation.

Just mooching about is tolerable though - Water Icicle Cavern in Monyash is regularly hovering around the 2% CO2 mark, but as it's virtually all horizontal walking in large passage, most people don't have much of a problem. Knotlow and Hillocks mines, not far away, are also usually high, but they do involve SRT inside, so could pose more of a problem.

Long soughs going through shale could introduce other fun gases though, all of which will also deplete O2 percentages without necessarily increasing CO2 levels. Stoke Sough and Hillcarr Sough both get pretty nasty after about 500m, and nobody really goes any further - in Hillcarr you can't anyway due to a shale blockage. I guess in ye olden days most shafts on a big sough system would be open - or at least not blocked, so even on soughs as long as those, some fresh air would usually be available.

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Down and beyond

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Oxygen levels
Posted: 30/09/2020 11:47:00
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I see very interesting Thankyou . So would you agree personally that high co2 is picked through low o2 on a 4x or is this not a truthful fact ?

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ChrisJC

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Oxygen levels
Posted: 30/09/2020 13:31:32
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Interesting. The idea that O2 is replaced by CO2 in approximately equal proportions should be testable with a suitable gas monitor. That does surprise me a bit - I would have thought that the biggest change would be the apparent increase in nitrogen as that is the largest component of air. I think I need a bit more convincing that this is what happens when the O2 has been consumed by oxidising iron (i.e. in an iron mone).

The acclimatisation thing had occurred to me - I had spent a few days acclimatising to the altitude in Peru. Although we did drive in a few hours from Nazca (about 1500m) to a mountain pass at 4600m where we got out for a walk about - and that wasn't a big issue (although you could tell!)

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pwhole

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Oxygen levels
Posted: 30/09/2020 14:10:28
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All I can say is that in Derbyshire limestone at least, you can make a reasonable assumption that whatever the reading is, if it's lower than outdoors it will have been replaced by CO2 to the same amount.

The only reason I'm being slightly cagey is that there have been a few anomalous carbon monoxide readings over the last few years (I was present at one) that just didn't make sense and still don't, but most folks probably wouldn't be expecting that to be present. I guess if a 4X4 has that sensor on it then at least you'd know and scarper quickly.

But the measurement I saw was in a shaft, and it got pretty high pretty quickly, so you'd have to do a changeover on the rope and begin prussicking out immediately in that instance - we were on the surface lowering it down so we were fine, but we had planned to drop it if the reading was OK. As it turned out it was pretty much lethal. And that was in limestone, miles from any quarries, so I'm still baffled by that one.

Edit: there's an info page on the DCA website about the issue - we do have records available to show sampling done over various time periods:

https://thedca.org.uk/conservation-access/carbon-dioxide-in-caves-and-mines
IP: 81.174.241.13 Edited: 30/09/2020 14:13:12 by pwhole
Down and beyond

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Oxygen levels
Posted: 30/09/2020 14:23:37
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Yes that statement reads correct to my knowledge I agree . That’s the hardest thing how regularly it changes with atmospheric pressure but luckily have had lots of clear advise on here about all of that so understand it much better now , I think the best option is to find a 4x that has changeable
Sensors remove 1 that you don’t need which I am unsure of what’s the weakest link to remove and add a co2 sensor in its place .

Other option carry a standard Altair 4x and buy a recommended co2 sensor so you have a 5x for a budget of the price ? But this seems to good to be true this option i am sure it would have faults ,are these co2 sensors designed for underground use ie mines drains ? When I worked on highways was always a 4x ? On my 4x course they did tell me co2 is notable by o2 reduction but this was nothing to do with mines just a monitor course but I guess it still stands


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pwhole

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Oxygen levels
Posted: 30/09/2020 15:13:21
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My colleague at the DCA who actually runs the testing program assures me that if you're only concerned with CO2 levels (in Derbyshire limestone - the endless caveat), then a cheap single-gas O2 meter will suffice, as all you need is he subtraction from outdoors to give you the CO2 level. So if it's 19%, it's 2%.

I'm not very knowledgeable about iron mines, but rust is heavier than iron from all the oxygen it's absorbed, so in those cases a low O2 reading may not necessarily be purely to CO2 replacement.
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staffordshirechina

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Oxygen levels
Posted: 30/09/2020 18:34:06
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Iron mines tend to produce more co2 than many other mines owing to the geology. We used a 5 gas version of the common BW technologies monitor. The fifth gas was co2. This is an expensive monitor at around £1500, the extra cost being for that gas alone. The ordinary 4 gas version is around £400.
The presence of co2 does affect the o2 level directly but it also upsets the o2/n2 balance and so when you consider "blackdamp" it means that that is actually a mixture of co2 and surplus n2 from the inbalance. Thus the o2 level in iron mines (and coal mines) is knocked back a bit more than just by the co2 percentage.
I can remember doing clever calculations at college to work it out exactly but in real life it doesn't matter. If the o2 is low then leave, or in our case re-arrange the ventilation to clear it.
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Morlock

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Oxygen levels
Posted: 30/09/2020 22:04:01
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Not sure if this clarifies the issue/



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ChrisJC

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Oxygen levels
Posted: 01/10/2020 07:01:21
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Morlock wrote:

Not sure if this clarifies the issue/

I'm not sure either! Big Grin

I'm going to have to think about what that actually tells us (if anything).

Chris.
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Down and beyond

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Oxygen levels
Posted: 01/10/2020 07:10:54
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It looks to me like a breakdown of the components of the air around you if you was in a black damp area 20.93 is a high reading well bit higher than usual you would probably have this level in a nice clean countryside with no cars .

The 0.03% carbon is very low unless I have made a major f**k up looking at it as when we breath out that’s normally around 4% if I remember It correctly which isn’t harmful in a open environment.

So my conclusion is that’s the components on black damp which it says am even more confused on how that works ! Haha Laugh

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IP: 82.132.229.103 Edited: 01/10/2020 07:54:01 by Down and beyond
Down and beyond

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Oxygen levels
Posted: 01/10/2020 08:40:04
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staffordshirechina wrote:

Iron mines tend to produce more co2 than many other mines owing to the geology. We used a 5 gas version of the common BW technologies monitor. The fifth gas was co2. This is an expensive monitor at around £1500, the extra cost being for that gas alone. The ordinary 4 gas version is around £400.
The presence of co2 does affect the o2 level directly but it also upsets the o2/n2 balance and so when you consider "blackdamp" it means that that is actually a mixture of co2 and surplus n2 from the inbalance. Thus the o2 level in iron mines (and coal mines) is knocked back a bit more than just by the co2 percentage.
I can remember doing clever calculations at college to work it out exactly but in real life it doesn't matter. If the o2 is low then leave, or in our case re-arrange the ventilation to clear it.


So can co2 be present at a dangerous level in a iron mine and o2 still be at a acceptable level ? This is my only question left as I don’t cleary understand it’s answer they must of made a 5x for a reason in my view ? As the sensor alone costs a fortune !

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AR

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Oxygen levels
Posted: 01/10/2020 09:09:26
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It's possible to have elevated CO2 levels in the open air - there have been still mornings when I've been tipping stable muck onto our (sizeable) heap and I've had breathing issues stood on top of it, thanks to the processes of decay giving off lots of carbon dioxide and there being no wind to disperse it. Potentially the same could happen underground where there's a lot of decaying organic matter.

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Oxygen levels
Posted: 01/10/2020 09:12:16
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Down and beyond wrote:



So can co2 be present at a dangerous level in a iron mine and o2 still be at a acceptable level ? This is my only question left as I don’t cleary understand it’s answer they must of made a 5x for a reason in my view ? As the sensor alone costs a fortune !


In short, yes. From an explorer's point of view, you can go down to the mid teens percent o2 and be OK. However, if the cause of the low oxygen percentage is extra co2 then you are in trouble.

Slightly off topic but also beware that daily atmospheric pressure changes can make a big difference very quickly in a large volume pillar and stall iron mine. For instance, this coming weekend would be a bad time to venture in an iron mine with a large low pressure forecast over the UK.
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Down and beyond

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Oxygen levels
Posted: 01/10/2020 09:40:33
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Thanks everyone for the answers my questions have been answered 5x it is Thumbs Up

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ChrisJC

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Oxygen levels
Posted: 01/10/2020 10:03:19
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Also explains that 12% oxygen at the top of a mountain is OK because the CO2 level is insignificant, whereas 12% down a mine could be a problem as the CO2 might well be 8%...

So as Tom says, you need to measure more than just O2 to know what is going on.

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Oxygen levels
Posted: 01/10/2020 11:28:45
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Link for anyone interested in co2 and what happens


http://www.hceaproud.com/response-to-co2-concern.html

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