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Author Oxygen detector
The Fresh Prince of Portreath

Joined: 05/08/2015

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Oxygen detector
Posted: 20/06/2016 16:30:01
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Ive got a BW Microclip with the 3 year O2 sensor. It hasn't been used much outside of places where I expect to snuff it.

I think the cavers have got the right idea. Proceed slowly and know thyself.
IP: 81.140.40.222
legendrider

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Joined: 13/07/2014
Location: Darlington

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Oxygen detector
Posted: 21/06/2016 07:06:07
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Cuban Bloodhound wrote:

How low can the oxygen level go before Eccles lamps go out?


Monty Stubble wrote:

... some waxes (the fuel in candles) have impurities that supply some of the oxygen to the flame. What I can't work out is if that affects its burning in low oxygen situations.Shocked


Every fuel has a different Lower Combustion Limit, viz, an O2 level below which combustion is not supported. This varies between fuels, and also varies for a given fuel depending on the composition of the atmosphere. 'Pure' air gives a lower LCL [fuel will burn at lower %O2] than air which is contaminated with CO2 for example.

CO2 suppresses flame propagation by absorbing heat from the combustion reaction.

I do not have figures to hand for wax, paraffin or naphtha, but n-butane (a C4 paraffin) has a 12% LCL in air, newspaper is 14%; you can add up to a couple of % to each for elevated CO2.

I feel an experiment coming on...

MARK



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festina lente IP: 86.156.168.180
dangerous dave

Joined: 12/09/2008
Location: plymouth

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Oxygen detector
Posted: 21/06/2016 09:16:23
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Cuban Bloodhound wrote:

How low can the oxygen level go before Eccles lamps go out?


17-16 % if the lamp goes out get out rule then kicks in but the other lads carry 4gas so then get a back up reading to confirm levels
IP: 213.205.252.37
Jimbo

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Joined: 30/03/2007
Location: Ooop North

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Oxygen detector
Posted: 21/06/2016 10:54:23
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Monty Stubble wrote:

The ones I worry about are the people who venture into a mine using a flame safety lamp, electronic device, magic crystals, candle, whatever ... stating 'it's never let me down yet', get it wrong and then someone else is expected to go in and drag their lifeless pelt out.


This scenario of dragging lifeless bodies out of mines happens all the time then does it? (nop can't think of any).
Shurely it's better to take something in than nothing at all ffs! Thumb Up

As you were chaps! Wink
IP: 213.205.253.135 Edited: 21/06/2016 18:19:28 by Jimbo
The Fresh Prince of Portreath

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Oxygen detector
Posted: 25/06/2016 17:56:05
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IIRC.

A lamp running 10x2mm wick with it set to provide a flame which is approx 10mm high (in total) with a yellow "point" at the top about 3mm diameter (how I set mine) running pump kerosene goes out at 15.0%. Mine is a William's Lamp.

I have forgotten the other figures. My key metric is that if a butane lighter won't light, it's time to leave. I'm happy on the flat, taking it easy at 11.3% I have been as low as 10.6% (with a meter) and it was quite nasty. 11.3% is nasty, but with a margin

IP: 81.140.40.222 Edited: 25/06/2016 17:56:44 by The Fresh Prince of Portreath
legendrider

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Oxygen detector
Posted: 26/06/2016 20:00:33
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Good to have a high- and low- warning that doesn't depend on batteries.

The oil lamp extinguishing at 15% is about what you'd be breathing on your average commercial flight, but then you're doing nothing more energetic than sipping coffee and admiring the flight attendant's embonpoint.

The butane-lighter test at 10%ish is equivalent to an altitude of about 16000ft, Time of Useful Consciousness given as about 30 minutes, but that's quoted for military personnel engaged in flying activities, not clambering over collapsed stope debris. Survivable but not thrivable!

Physiology plays a big part in O2 susceptibility, big No-No's are smoking, obesity and alcohol; fit and young people generally fare much better than old couch potatoes! And a hangover will do you no favours at all, whatever your body type!

The body can acclimatise over time (ie weeks) to reduced O2 levels by increasing production of red blood cells, so a really good time to go underground is right after coming back from a month in Kathmandu.

Observational comments only, no endorsement of respiratory edgeplay!!!

MARK





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festina lente IP: 86.156.169.44
AR

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Location: Knot far from Knotlow in the middle of the Peak District

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Oxygen detector
Posted: 08/06/2017 23:10:07
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Digging this thread up again, I've just picked up a Crowcon Tetra 3 off fleabay cheap, but it looks like the oxygen sensor is shot (or I've used up most of the oxygen in my garage and somehow not died!)

Can anyone suggest a repair/calibration place that's reasonably priced and reliable?

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sinker

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Location: North Wales.

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Oxygen detector
Posted: 09/06/2017 08:34:46
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Crowcon fell out of favour a few years back due to their perceived fragility and dodgy aftersales backup based on a network of "supporting partners" rather than dealing with Crowcon themselves. We still have a couple but the O2 sensors are so expensive bought new that they are not worth replacing. Hence why it was on eBay I guess. That is also true of most detectors to be fair but others seem to be better built and so the expensive bits are better protected and less susceptible to water and dust ingress which seems to be the reason for 9 out of 10 failures. You may be able to get a good, used sensor out of a machine that has been scrapped for another reason.

This is who we use:

http://www.csts.co.uk

They are the cheapest "reputable" company that we know of although when it comes to second hand parts you may need to labour the point that it is to be used for recreational use, not professional use etc Wink

Good luck!

Phil.





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Ah, well, now, you see.... IP: 86.158.212.40
Jachin

Joined: 09/06/2017

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Oxygen detector
Posted: 09/06/2017 09:07:44
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There is also Phoenix Safety Services, (ex CSTS), Mark Cooper, Leacroft road, Warrington is address I think IP: 82.33.34.95
AR

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Oxygen detector
Posted: 09/06/2017 09:56:24
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Thanks chaps, I'll make enquiries and see what costs are like. If it's too high I'll chuck it back on Ebay but without the pelicase it came in, and see if I can get an MSA Altair at a decent price.

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ILT

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Oxygen detector
Posted: 09/06/2017 09:57:16
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I also use CSTS (owned by ARCO). Price as good as anyone else, staff friendly and helpful.

Not sure it's worth replacing the O2 sensor on the Crowcon (never had a problem with Crowcon detectors and still use one) and would agree that's wlikely why the seller was offloading it on ebarf.
Probably better value for money to buy a newer design of detector with longer sensor life.
IP: 81.101.107.191
sinker

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Oxygen detector
Posted: 09/06/2017 12:23:33
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AR wrote:

Thanks chaps, I'll make enquiries and see what costs are like. If it's too high I'll chuck it back on Ebay but without the pelicase it came in, and see if I can get an MSA Altair at a decent price.


MSA Altair 4 is the better detector by a long way regarding features and build quality. The point about the expensive sensors is common to all makes though. Ho hum.

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Ah, well, now, you see.... IP: 82.132.244.112
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