Foul Air

gus horsley

gus horsley

New member
Some time ago I was digging a crawl and after a short time had to pack in due to the air becoming a bit nasty.  Apart from retreating for a while, has anybody got any easy-to-lug, easy-to-use ideas for extending the amount of time in such a dig.  I know there are some who will argue that the lack of a draught means a dig isn't worth bothering with, but the one in question did eventually "go" despite the lack of air flow.

Cheers
 
AndyF

AndyF

New member
When 'told timers were digging wells, they used to lower a bag of slaked lime down the hole overnight. it sucked all the CO2 out. Don't think it would work during a dig though...

We have used a load of plasic pipes and a 12v fan on the end out of a PC. Although the air shifted is quite small, it was enough to allow digging to continue. If the fan stopped you noticed very quickly!

That was in a draughtless dig that also "went"
 
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darkplaces

Guest
is it best to push air in out pull it out. Thinking about it pull it out seams the best idea as your pulling against a smaller cross section of area, the air going's  in via the larger hole. Would I be right and apart from digging a shaft and lighting a fire at the bottom seams the only reliable way of ventilating a dig.
 
Pitlamp

Pitlamp

Well-known member
Didn't someone from the Orpheus once get a major telling off from the committee for absconding with the hut vacuum cleaner in a Heath Robinson style attempt to ventilate a dig?

 
AndyF

AndyF

New member
Pitlamp said:
Didn't someone from the Orpheus once get a major telling off from the committee for absconding with the hut vacuum cleaner in a Heath Robinson style attempt to ventilate a dig?
Click to expand...

That was what they claimed it was for  :-[
 
AndyF

AndyF

New member
c**tplaces said:
is it best to push air in out pull it out. Thinking about it pull it out seams the best idea as your pulling against a smaller cross section of area, the air going's  in via the larger hole. Would I be right and apart from digging a shaft and lighting a fire at the bottom seams the only reliable way of ventilating a dig.
Click to expand...

Definitely pull air out. Fans work more effeciently pulling air out of a pipe than pushing it into a tube. We've tried it both ways.

Andy

 
SamT

SamT

Moderator
Whist clearling out douse hole recently - john beck was telling me that they had a pipe in to the dig face - and just an office fan in a wooden box blowing air *into* the pipe.

Now Im sure andy is right - and fans are more efficient at pulling air out. But at least with a fan pushing air in - you are guaranteed that it is thick fresh air full of oxygen, not just some more bad air being sucked/displaced from another part of the cave/mine.
I know this sounds unlikely, but in certain circumstances e.g. somewhere like knotlow - you might want guaranteed fresh air. I guess it all depends on what the source of the bad air is - resident CO2 or just CO2 build up from diggers excertion.
 
nickwilliams

nickwilliams

Well-known member
AndyF said:
Definitely pull air out. Fans work more effeciently pulling air out of a pipe than pushing it into a tube. We've tried it both ways.

Andy
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I'm not going to say you're wrong because if you've actually got empirical evidence on this for a computer type fan then you're a step ahead of me, but I've always worked on the principle that it is better to blow good air in, since then at least you know you have a supply of good air at the end of the pipe, if nowhere else. I've usually been dealing with bang fumes which are positively toxic, however.

This also seems to be the way that most miners and tunnellers work, although whenever I've asked them they've said that's because it's the way they have always done it rather than point to any hard evidence that it works better for some unarguable reason.

I'm also sure that not all fans suck better than they blow. This is primarily a function of the fan blade design, which is a pretty high powered topic all of its own. I have several 'high pressure' blower fans which will defintely blow better than they suck and which are available for loan if anyone wants to try them. They are not battery powered, however.

Nick.
 
Hughie

Hughie

Active member
I believe our technical/fabricating crew use a surface mounted space heater with a 100mm flexible pipe running to the bottom of the dig. There are several large coils of this pipe stored in the dig out of the way to fascilitate easy pipe extension at the sharp end.
I haven't seen it working (as I go to the site on different days), but know that the air is sucked out. Not sure what alterations have been made to the heater to allow it to do this - but will have a look when I'm next there.
However, it is very effective, enabling the bang crew to return to the site of a bang after having a cup of tea, allowing several drilling and banging sessions per day. Our thoughts are that it's better to remove the bad air rather than try to dilute it by pushing good air in. Gas tests have proved this theory.
 
P

Pete

Member
Depending on how far the dig face is from the nearest decent air and how many people you have we've used a carry mat as a giant air wafting device quite successfully down Aggy, I think it was a trick borrowed from the Daren diggers.
 
whitelackington

whitelackington

New member
We used to have a dig high up in old shit, off Bertie's Paradise, Tyning's Barrows Swallet.
We had permission from Farmer Reakes,"As long as you don't bring anything to the surface"
yeah, likely, I don't think.
Anyway, myself and Treemonkey werealright, being skinny and young and healthy and nonsmokers but other guest diggers used to run out of air.
some used to complain of deisel fumes but I never smelt it but i don't have much sense of smell.
Anyroad up we fitted a twelve volt aip pump, quite noisy it was too.
It worked best when you sucked fresher air into the dig from higher up and dumped used air lower down the cave. :doubt:
 
paul

paul

Moderator
Pitlamp said:
Didn't someone from the Orpheus once get a major telling off from the committee for absconding with the hut vacuum cleaner in a Heath Robinson style attempt to ventilate a dig?
Click to expand...

That would be the vacuum cleaner with "Dig Ventilation Unit" written on it? It's still at the hut!  :clap:
 
Duncan Price

Duncan Price

Active member
There was a meeting organised by the Derbyshire CRO on the subject a few years ago.  IIRC Phil Paprad gave a very interesting presentation on dealing with foul air in mines.  I believe that they used a petrol driven blower to blow foul air up a pipe made out of flexible plastic - the sort of stuff you see coming out of a film blower.  As CO2 is denser than air it is better to suck it out rather than blow fresh air in.

There were also talks on testing for bad air and BA sets.

The bellows that was installed in the Bunker dig in Aggy only made the foul air situation worse when the wood it was made out of started to rot.
 
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Peter Burgess

New member
As CO2 is denser than air it is better to suck it out rather than blow fresh air in.
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You can think of the CO2 like a liquid sitting at the bottom of your shaft, or pit. If you blow air into it, it just shoots back up again, a little like bubbles in water. So, yes, it is better to suck the CO2 out, and let the fresh air displace it.
 
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Peter Burgess

New member
I have heard tales of how it is possible to remove CO2 from the bottom of a well by using the bucket. You lower the bucket into the pool of CO2, pull it up slowly, and pour it out away from the shaft. I wouldn't recommend it as a reliable way of clearing CO2 from a blind shaft though! Apart from anything else, anyone watching would think you have totally lost it.
 
whitelackington

whitelackington

New member
We have been told by older Axbridge diggers, that's what they used to do in Banwell Bone Cave
but I thought they were having me on.
 
gus horsley

gus horsley

New member
Maybe I should have taken a bucket to Ogof Pant y Llyn.  I went into the "normal" entrance, a vertical body-sized tube to a low muddy crawl and ascending slither into a chamber, only to find that the crawl was full of Co2.  The original entrance had collapsed a little way inside, thereby cutting off the air flow.  It was a slightly panicked caver who exited, doing fish impressions.
 
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