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Mine Exploration Forum

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Author Digital Altimeters?
The Fresh Prince of Portreath

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Digital Altimeters?
Posted: 14/06/2019 15:45:22
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Simple, get 2 of them. P1 and P2. dP is your depth. (proportional to).

Put P1 on the surface to give your baseline at fixed altitude then the variability of P2 is what you are experiencing underground which has a major depth component. It would need to be bloody accurate though.
IP: 194.35.117.181 Edited: 14/06/2019 15:46:30 by The Fresh Prince of Portreath
TwllMawr

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Digital Altimeters?
Posted: 14/06/2019 16:28:07
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sinker wrote:


Works just as well Thumb Up
I'm assuming we don't require 0,3mm accuracy?? Wink


No, but you’ll need calibrated eyelashes for levelling the bubble. That particular £30 Bosch one has a thread for tripod mounts as well... which is nice.

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''''Nitrate of Ammonium: If not too generously applied these explosives make an excellent manure" IP: 78.146.27.91
sinker

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Digital Altimeters?
Posted: 14/06/2019 16:41:34
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TwllMawr wrote:



That particular £30 Bosch one.....



I thought that the range might be limited on that one?
5m for a line, 20m for a dot in ideal conditions.
With moisture etc you may only get half that.
Would that be enough?



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Yma O Hyd.... ta-ta ty hâ... IP: 88.97.24.95
Willy Eckerslyke

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Digital Altimeters?
Posted: 14/06/2019 16:46:53
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Line of sight in there is in the order of 3m in the passage, 1m through the squeeze, perhaps 6m in the chamber? IP: 147.143.12.215
The Fresh Prince of Portreath

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Digital Altimeters?
Posted: 14/06/2019 16:55:40
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A laser level is a great idea with a staff. You'd get it very bang on every time. IP: 194.35.117.181
AdM Michael

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Digital Altimeters?
Posted: 14/06/2019 22:05:15
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I don't have a GLL 3-50 but plenty of experience with the GLL 3-80. You can get up to 30 m on rocksalt. Slate will reduce the range 15 m. You'll usually get a much better range underground than what the manufacturer says. I used ISO 800 F 4.5 and 1 second exposure for the photo.



(click image to open full size image in new window)

The downside of theses lasers is that you need a line of sight and enough space to move around with the equipment without destroying any stations.

Another option could be a hose scale. A lot simpler than using a hose an trying to measure the pressure.

I'd still go for the altimeter. It's probably not as cheap as you expect as you'll need a fairly accurate device. I use a Greisinger GTD 1100 which sells at £ 130. I also know of at least two of these being used in the Peak District.



(click image to open full size image in new window)

The resolution of the altimeter should be ok:

-1640 … -655 ft ~5ft
-654 … +1999 ft ~2ft
2000 … 19999 ft ~5ft

The big advantages are that you don't need a line of sight between start and end point and there is no need for intermediate stations. You can actually cover quite long distances between the stations. Small pressure differences due to ventilation can be more or less neglected. You'll have to compensate atmospheric pressure changes during your survey for a better accuracy unless the time between the readings is very short.



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Willy Eckerslyke

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Digital Altimeters?
Posted: 15/06/2019 10:33:16
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Some great pointers there Michael, thanks very much. IP: 143.159.16.46
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