Not sure if this clarifies the issue/

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As Morlock's post: 30/09/2020 22:04:01 these numbers and the logic makes sense. Basically, to keep things simple, if the O2 in the mine air sample is exactly half fresh-air level (a horrific 10.465%) you would expect (to keep the same ratios of gasses as fresh air) that the N2 & CO2 would be half too. (39.52% N2 & 0.015% CO2). This would be more akin to "thin air" of maintained ratios experienced at altitude.

However as the N2 & CO2 has not dropped in this mine sample (consider the O2 has simply been removed by iron compounds) then the quantities of N2 & CO2 are still at what was once 79.04% and 0.03% respectively. So, if 39.52% N2 & 0.015% CO2 are what SHOULD be there if fresh air ratio was to be maintained, the remaining "leftover, extra" 39.52% N2 & 0.015% CO2 are allocated to the black damp / stythe. Total 39.535%.

On this basis O2 only needs to be as low as 18.548% for total stythe to be the 9% featured in one of Morlock's other uploaded images of "physiological effects" stating "depression of breathing commences".

Another example is my current avatar of 14.2% O2. This shows:
Experienced O2 level 14.200%
N2 associated with Experienced O2 level 53.625%
CO2 associated with Experienced O2 level 0.020%
N2 contributing to blackdamp 25.415%
CO2 contributing to blackdamp 0.010%
TOTAL Blackdamp 25.425%

The main additional thing to remember here is rather than just removing O2 from the sample, some processes add other nasties. In my situation of 14.2% there were large bacterial blooms bubbling in the flood water like a spa. This was likely giving off CO2 (trace methane was detected too) therefore increasing the ratio of CO2 to N2. If you have biodegrading matter such as timbers, washed-in vegetation, corpses of previous explorers etc then there will be more CO2. I'm not even mentioning coal and natural gas here. That's not my bag!;)


Hope this helps explain the formula in a little more detail using examples!

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If you have biodegrading matter.....corpses of previous explorers etc....

:lol: Or, more commonly sheep, here in Wales! :surrender:

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My limited, and recent, experience with using modern carbon dioxide monitors (Shropshire and Nenthead mines), in non-venting mines, there is always more carbon dioxide than expected. While generally not high enough to be of concern, it does suggest that there are sources of the carbon dioxide and not simply related to oxygen depletion.

In most cases, the measured carbon dioxide was higher on exit than going in but I am looking forward to doing more measurements to confirm this.

Most mines in Shropshire and Nenthead do have air currents - referring to 'non-venting' means those mines with no through air currents.

I believe that decaying organic matter releases carbon dioxide as part of the breakdown process, so rotting timberwork may be responsible?

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I believe that decaying organic matter releases carbon dioxide as part of the breakdown process, so rotting timberwork may be responsible?

Indeed, rotting timber will give off CO2. As soon as my new account allows uploads to my personal album I'll include a photo of the vivid orange, bubbling bacteria that I think gives off lots.

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On one memorable occasion I experienced submerged silt outgassing when disturbed. The locality was in Teesdale, where a branch level along the vein was flooded to chest deep by a partial blockage.

A known (but humanly inaccessible) hydrological connection to a higher level drew water from a surface stream. This had flushed down a lot of silt containing organic matter, resulting in a welly-sucking 8-12" of goo under 5ft of water.

Our attempt to progress through the deep water resulted in a steady stream of small bubbles released with each footstep.

It is supposed that decaying organics released CO2 and Methane, which was then trapped in the silt. The depth of water probably increased the reservoir capacity of the silt as the partial pressure of the decomposition gas mixture was increased by approximately 1/8 bar (2 PSI)

As there was no discernible ventilation in that part of the mine, we decided to retreat and leave the bacteria to their supper!

MARK

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It was blackdamp issues that took Will Smiths life in Aber Las when he surfaced on a dive and decided to go walkabout without the knowledge of mines above the water . Brilliant mine/cave diver but no knowledge or skills above the waterline , in a nutshell it cost him his life 😢

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Brilliant mine/cave diver(

in my view, anybody who dives in mines is an insane and brilliant specimen, regardless of any other faults. Caves and mines are dangerous, diving is dangerous, combining them is a peculiar hobby! The whole additional navigational and respiratory dilemmas those people put themselves in baffles me! I appreciate the overwhelming curiosity of what is the lost beneath the water though. Many a time I have stared into the depths when my path runs out, wondering.

Back on topic, back in my early pre gas monitor days there was that brief period where I understood some basic symptoms and checks and proceeded to explore without readings or alarms and always played it cautiously but still ended up having a few serious reality checks. One was in a mine usually a comfortable 18% O2 with no other surprised but I walked into what I instantly recognised as extreme CO2. Was akin to sticking my head in a fermentation tank at a distillery. Eyes and nose burned acidic as my breath got taken away. That was luckily stationary in a dead near a collapse. I could quickly back away a few feet and was back to breathable air. That and another sudden noticeable O2 drop on another day made me realise the cost of detection was cheaper than life! Since then I ventured to different areas and have experienced insanely fast degrading air quality, 17.5% to 15. 2% walking 30 feet then a further 1% to 14.2% in 10 seconds standing still then the bad air chasing me out and being 2% lower than it was at the same point less than 3 minutes earlier. I now make sure I study the barometer readings and predictions properly beforehand rather than a glance. The sudden low pressure front outside dragged all the bad air forward as I tried to retreat. Still folks venture in with not even a consideration for the air. Baffles me!

For these reasons you will never catch me in coal workings! I don't trust them!

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That's why it takes us sometimes years to get some decent video footage especially when they are virgin. First all the safety lines have to be put in and then a few more dives on top to familiarize ones self with the environment and then if we are ALL happy we will do some filming. We have been diving in another that I wont mention on open forum but in there we have the added hazard of depth and long decompression times . Maybe we will never film this place as one is just to occupied . We as a team always dive to our training and NEVER succumb to peer pressure thats why we stay as close knit group and stay well away from social media there is to much chest beating and bigging oneself up for our liking.
The last vid we did under water was in Diffwys and that one turned out quite nice .

Paul

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Hello mate your videos are good quality no worries their !


Hope you all are ok and hope to see you both again this year

Tom

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NEVER succumb to peer pressure thats why we stay as close knit group and stay well away from social media there is to much chest beating and bigging oneself up for our liking.

Indeed. If one of a team wants out or doesn't want in it has to be respected. Also as you say sometimes social media or the promise of good footage can lead to internal pressure, no peers needed! The modern part of the brain saying "just 10 more metres and that will be great footage or cool memory" whilst caveman brain says "I'm struggling to breathe" or "don't climb that" and "get out!". I'm guilty of being in that position many times!

May you continue to explore where many can't and stay safe!

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Have a visit to our you tube channel " Patterdale Dive & Cave " 😉

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Have a visit to our you tube channel " Patterdale Dive & Cave " ;)

Already a few minutes in! The moment you posted last, I typed "Diffwys dive" into youtube, your one was the top result and I clicked. I'm easily led down rabbit holes! ;D

It is just sitting there on pause now waiting for my day job to calm down! I have a beer in the cooler ready for the play button!

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I don’t mind admitting that the whole ventilation issue, is a major part of the reason I stayed away from mine exploration for a long while, and still treat it with caution.

Caving is different; the constant water-flows through most caves keeps the air good, and usually reasonably fresh. I first went caving in 1970, when the Mossdale disaster was quite recent; but the message was, “weather is critical”, it was a known risk.

A CSM student known to me, suffered fatal asphyxiation in Wheal Jane during my time there. Gave me a healthy respect for confined spaces, reinforced by a double fatality on a tunnel job I had worked on in London in the early 90s

We cave as well but dont mention it on here as people get upset LOL ;(;(

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there are two vids The walk And the dive .

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I don’t mind admitting that the whole ventilation issue, is a major part of the reason I stayed away from mine exploration for a long while, and still treat it with caution.

Caving is different; the constant water-flows through most caves keeps the air good, and usually reasonably fresh. I first went caving in 1970, when the Mossdale disaster was quite recent; but the message was, “weather is critical”, it was a known risk.

A CSM student known to me, suffered fatal asphyxiation in Wheal Jane during my time there. Gave me a healthy respect for confined spaces, reinforced by a double fatality on a tunnel job I had worked on in London in the early 90s

Natural caves is something I have never tried up to now (though Tom on here almost got me down one until lockdown stopped all fun!) as the ingress of water and the potential to become trapped and drown is something that I do not consider myself educated enough about. I have encountered tricky instances before on long mountain travels when a storm earlier on in higher terrain miles away, results in rivers in spate that cut me off from safety and destination. If water does a damn good job of catching me out above ground I don't want to battle it below!;D

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there are two vids The walk And the dive .

Don't worry ... I'm going to be working through the channel!

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hope you enjoy buddy, best on your tv if you can 😉

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We cave as well but dont mention it on here as people get upset LOL ;(;(

The c word ! O gosh :surrender:

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