Oxygen Levels in Knotlow

[jasonbirder]

Don't know if this is of interest to anyone - but did a trip into Knotlow on Wednesday night with a friend who brought along a Neotronics gas monitor from work...We went down the climbing shaft through pearl chamber and down Waterfall pitch...

Most of the time it read 20.9% oxygen, which is normal fresh air. There were long periods of 20.6% oxygen which is no cause for concern. The lowest it measured was 20.2%. At the foot of the waterfall, where bad air has been noted, the oxygen level was 20.9%. The wasn't a trace of hydrogen sulphide, carbon monoxide or methane.

Not very scientific - cos we just clipped it to a belt and read the readings when we got out but anyway...there you go!

 

[caverholic]

I think (as with most bad air problems in caves) that its not the low oxygen but the high CO2 thats the problem.

Think the problem has resolved itself somewhat in knotlow although if you head of left from the bottom of the whalf shaft the mud down there releases some nasty smells!

 

[Cave_Troll]

do you mean Walf or fourways?

 

[caverholic]

Not sure the junction at the end of the coffin level

 

[AndyF]

I think (as with most bad air problems in caves) that its not the low oxygen but the high CO2 thats the problem.

Yep, CO2 is probalby the most dangerous gas in cave/mine exploration...

IIRC it's CO2 levels that actually trigger the bodies mechanism to take a breath. With high CO2 (bizarally) the body gets confused, and just forgets to carry on breathing. Then you fall over and die..... :shock:

You can work in high CO2 IF you can remember to consciously keep breathing....

Miners called it "blackdamp", and I've experienced it in the FOD in New Dunne Mine. It's like having a blanket thrown over you - very weird....

 

[Peter Burgess]

H2S (hydrogen sulphide) is pretty nasty stuff too.

At very low concentrations, it smells disgusting, and won't kill you necessarily. At higher concentrations, you can't smell it and it is lethal. So if you can smell it, then the smell 'goes away', you may well be just about to die.

More prevalent in old mines rather than caves. Often a product of decaying mine timbers.

 

[paul]

I think (as with most bad air problems in caves) that its not the low oxygen but the high CO2 thats the problem.

Yep, CO2 is probalby the most dangerous gas in cave/mine exploration...

IIRC it's CO2 levels that actually trigger the bodies mechanism to take a breath. With high CO2 (bizarally) the body gets confused, and just forgets to carry on breathing. Then you fall over and die..... :shock:

You can work in high CO2 IF you can remember to consciously keep breathing....

Miners called it "blackdamp", and I've experienced it in the FOD in New Dunne Mine. It's like having a blanket thrown over you - very weird....

It depends on the concentration of CO2. See http://wasg.iinet.net.au/Co2paper.html for very useful information.

A group of us had a nasty encounter with CO2 in Meccano Passage a year or two ago and as this connects about 18 metres up in Knotlow's Waterfall Chamber that is possibly the source.

The DCA are monitoring the situation (see http://www.thedca.org.uk/). Its is believed that the CO2 is connected with possible organic pollution.

If you have any encounters with "Bad Air" in the system it would be worth contacting the DCA via the above website.

 

[Cave_Troll]

CO2 exposure may at first be indistinguisable from exertion or raised adrenalin levels from excitement or conern.
Shortness of breath, headache nausea all follow.
come digging down Robins and we'll show you :twisted:

 

[andymorgan]

I think (as with most bad air problems in caves) that its not the low oxygen but the high CO2 thats the problem.

Yep, CO2 is probalby the most dangerous gas in cave/mine exploration...

IIRC it's CO2 levels that actually trigger the bodies mechanism to take a breath. With high CO2 (bizarally) the body gets confused, and just forgets to carry on breathing. Then you fall over and die..... :shock:

You can work in high CO2 IF you can remember to consciously keep breathing....

Miners called it "blackdamp", and I've experienced it in the FOD in New Dunne Mine. It's like having a blanket thrown over you - very weird....

As CO2 levels in the blood/lungs (?) are the cue to breath it probably with no CO2 the body doesn't 'remember to breath'. At highish CO2 levels you are breathing really hard like after running

 

[Peter Burgess]

It reminds me of a drift iron mine in Ironbridge where I was once on a led trip. We were advised that when the atmospheric pressure was rising there was no problem, but when it was falling, and the mine was 'breathing out', the air got very bad. We were told it wasn't CO2 that was causing the problem, it was that something in the strata removed the oxygen leaving mostly just nitrogen. When the pressure was high, the strata 'breathed in' and the air was refreshed, and when it 'breathed out', the 'stale' air in the rock filled the lower parts of the mine. When we were there, there wasn't enough oxygen to keep a candle alight, or a match, and we didn't hang about. It was only in the lowest sections there was a problem. We didn't feel out of breath, if I recall correctly.

Peter

 

[susie]

[quote="Peter Burgess"We were told it wasn't CO2 that was causing the problem, it was that something in the strata removed the oxygen leaving mostly just nitrogen. [/quote]

Probably pyrite, which is found in anaeoribic sediments. When it weathers it consumes an extraordinarily large amount of oxygen (15 oyxgen molecules to 4 pyrite molecules).

 

[darkplaces]

Its good to see people buying the kit and using it, its not cheap or easy kit to get. I know of a few DP members who have brought air monitors, lowest monitored O2 yet was 14%.

Like decent headlamps the kit will filter down into more common useage. One expensive item people are trying to get hold off are compact self-rescuer systems, the same shiny checmical ones in common useage. If anyone knows of any going cheap let us know.

 

[AndyF]

Like decent headlamps the kit will filter down into more common useage. One expensive item people are trying to get hold off are compact self-rescuer systems, the same shiny checmical ones in common useage. If anyone knows of any going cheap let us know.

I did see some once in miltary surplus once, they use them I think on ships when they are on fire. (!) Might be worth trawling the web for military surplus sites to find some..