Author Topic: Draughtproofing  (Read 12272 times)

Offline graham

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« Reply #25 on: March 13, 2006, 11:05:51 am »
This is straying a long way off topic, but nonetheless....

Andy: where are these woods that were getting along happily before man came along? There are none; man arrived (back) on these islands just as soon as the last Ice Age was over, at the same time as the trees, and has been happily screwing up the woods as long as there have been woods to screw up (or manage).
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Offline gus horsley

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« Reply #26 on: March 13, 2006, 11:10:26 am »
I believe there are a few bits of native woodland that don't get managed, comprising small areas of scrub oak on bouldery ground.  I can think of a couple of examples, but they are rather insignificant in terms of the general area.

Offline graham

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« Reply #27 on: March 13, 2006, 11:28:30 am »
Quote from: "gus horsley"
I believe there are a few bits of native woodland that don't get managed, comprising small areas of scrub oak on bouldery ground.  I can think of a couple of examples, but they are rather insignificant in terms of the general area.


According to Ransome, there are a couple of bits in the Burren of Co. Clare, in Oughtdarra and the Glencurran valley, but there ain't no completely wild wood anywhere in the UK. I would guess that the stuff you are describing is secondary woodland that has grown up on areas that are no longer grazed.
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Offline gus horsley

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« Reply #28 on: March 13, 2006, 11:58:34 am »
Ok, you're probably right.  I just remember there was one in the Gwendraith valley that was a SSSI because it was untouched.  It was dwarf oaks on limestone boulders.  My memory might not be what it was.

Gus

Offline Cap'n Chris

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« Reply #29 on: March 13, 2006, 02:19:19 pm »
Quote from: "gus horsley"
My memory might not be what it was.



... but Nostalgia remains the same!

Offline Cave_Troll

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« Reply #30 on: March 13, 2006, 04:25:21 pm »
Quote from: "andymorgan"

No, if you give an organism an unatural advantage, it maz destabilise an ecosystem. For example more bats=more insects being eaten=less food for other organisms, or rare species of insects going extinct.

   Ok, an extreme example, but what i'm saying is that so called 'conservationists' and 'ecologists' do not always know the long term consequences of their actions..


but people created that change in the first place when we
1) dug the mine
2) stopped working the mine thus allowing the bats to move in
3) gated the mine, potentially stopping the bats.

mean while we also cut down all the trees that the bats used to live in, replaced them with large thatched barns, then removed the barns and put up bat boxes.

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« Reply #31 on: March 14, 2006, 02:35:12 pm »
Only slightly off topic.  Has anyone know of any work that has been done to quantify draughts in caves ?

Offline AndyF

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« Reply #32 on: March 14, 2006, 03:01:28 pm »
Quote from: "twllddu"
Only slightly off topic.  Has anyone know of any work that has been done to quantify draughts in caves ?


I suspect this is very difficult to measure or quantify. I think there has been some work on temperature variation across entrances (on the Black Mountain shakeholes IIRC), but actual draughts in caves may be quite hard to do...

Be interested if anyone has an angle on this...
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twllddu

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« Reply #33 on: March 14, 2006, 03:54:19 pm »
I think you're right in saying it may be quite hard to do !

Offline Peter Burgess

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« Reply #34 on: March 14, 2006, 04:38:00 pm »
Like dye-tracing, I wonder if there might one day be a practical draught tracing technique? I know that the lightest trace of some potent smells can be picked up by cavers' noses, but can a machine do it? Release a harmless smell in one cave, and see if it can be detected in another cave nearby, to check if a link exists, and also how long the smell took to get there. And before anyone who knows me says it, no, I am not volunteering to be the source of the smell !!!

Offline Cap'n Chris

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« Reply #35 on: March 14, 2006, 04:39:12 pm »
Check with Ship-Badger on the FOD regional thread; they used a Disto wind detector to good effect in Miss Graces Lane Cave IIRC. Mind you I think they cost a small fortune.
 :shock:

On Mendip a student used a hand held anerometer for wind gauging in Shatter Cave which, again IIRC, picked up a draft of 0.9m/s but was insufficiently sensitive to be much use on the sort of soft breeze which can occasionally be detected by people.

Offline AndyF

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« Reply #36 on: March 14, 2006, 04:45:47 pm »
Quote from: "Peter Burgess"
Like dye-tracing, I wonder if there might one day be a practical draught tracing technique? I know that the lightest trace of some potent smells can be picked up by cavers' noses, but can a machine do it? Release a harmless smell in one cave, and see if it can be detected in another cave nearby, to check if a link exists, and also how long the smell took to get there. And before anyone who knows me says it, no, I am not volunteering to be the source of the smell !!!


Interesting. The best thing to use may be a short life isotope.

This could be then used with a scintillation counter, or perhaps cruder, a photographic plate.

Problem is you might need to use "a lot" and the draught may blow it all back at you   :cry:
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Offline Peter Burgess

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« Reply #37 on: March 14, 2006, 05:01:58 pm »
Quote
The best thing to use may be a short life isotope.


How about radon? Or perhaps not......

Offline AndyF

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« Reply #38 on: March 14, 2006, 05:22:12 pm »
Quote from: "Peter Burgess"
Quote
The best thing to use may be a short life isotope.


How about radon? Or perhaps not......


Probably thinking about a particulate rather than a gas.

A sticky photgraphic plate could then be used, that way the particle could fizz away at any time and be captured...

You'd need a control plate to compare and remove background radiation of course.

Hmmm, has this ever been tried I wonder...someone must have thought of it..
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Offline Peter Burgess

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« Reply #39 on: March 14, 2006, 05:23:53 pm »
Surely there are some really smelly things like isocyanates (?) that a sniffer could detect?

Offline AndyF

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« Reply #40 on: March 14, 2006, 05:53:17 pm »
Quote from: "Peter Burgess"
Surely there are some really smelly things like isocyanates (?) that a sniffer could detect?


Quite tricky. I used to work with some equipment that used Ion Mobility Spectroscopy to detect explosives vapour.

Problem is it just isn't very good, you need quite high doses to get reliability, and false detection is common.

I suspect a draught would dilute anything smelly too much to be of use.
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emgee

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« Reply #41 on: March 14, 2006, 06:41:17 pm »
Quote from: "cap 'n chris"
Quote from: "gus horsley"
My memory might not be what it was.



... but Nostalgia remains the same!


No definitely not what it used to be.


Well someone had to say it.

Dave H

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« Reply #42 on: March 14, 2006, 08:57:59 pm »
Quote from: "AndyF"
I think there has been some work on temperature variation ...

There's usually plenty of hot air expelled by some cavers - not always from the end the Butcome ravages :lol:  :wink:

Offline gus horsley

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« Reply #43 on: March 15, 2006, 08:16:14 am »
The intensity of draughts also depends on the size of the passage.  How often have you dug a "howling gale" only to find it closes down to zilch after a few feet.  I remember digging a draughting crawl in Greenbridge Cave for a total of 120ft to a point where the draught disappeared completely and the air became decidedly stale.  And it wasn't a seasonal variation, like you get in some systems.

 

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