Yes I know it's a topic that has been around before but...

After a couple of recent low oxygen situations, I have decided that I will treat myself to a proper detector. I seem to have an innate ability to break lighters, the power of ochre or something so that isn't a first choice.

I am looking for a single gas monitor (I can't afford a 4 gas one and since I'm primarily concerned about oxygen it's a bit of overkill), just not sure whether to spend a bit more and get one that has a replacement sensor or just use a disposable.

Does anyone have any advice on what works or doesn't.

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If all you're interested in is oxygen levels and knowing when things are getting a bit low, there's always the old-school solution of a safety lamp? There are regularly ex-GPO Wolf lamps on ebay for not a vast amount of money, or Protectors with relighters, and there are plenty of people on this forum can advise you on their use and maintenance.

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I think the Crowcon O2 meters are only about £60 - and work done by Alan Brentnall and Christine Wilson at the TSG has shown that in most 'normal' situations in caves and mines, depletion of O2 is proportional to increases in CO2 - so 18.8% O2 will usually correspond to 2% CO2. Which means you don't necessarily need a fancy CO2 monitor.

Obviously this isn't guaranteed, but seems to be case most of the time - certainly all the figures Al's compiled have reflected this relationship. If you're more likely to hit Carbon Monoxide, Methane or Hydrogen Sulphide, then you will need a 4-gas meter.

Given I can destroy a lighter in nothing flat, a safety lamp isn't an option. I can offer a 'mine worn' service whereby I can turn your pristine lamp into one that looks like it had a very hard paper round in a single trip. :)

If you can tell me where to get a Crowcon at £60....

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Given I can destroy a lighter in nothing flat, a safety lamp isn't an option. I can offer a 'mine worn' service whereby I can turn your pristine lamp into one that looks like it had a very hard paper round in a single trip. :)

If you can tell me where to get a Crowcon at £60....

If you do that to a lighter how is an expensive piece of electronic equipment that needs to be kept dry and clean going to fare any better?!

Carry a lighter in your helmet, never broke one yet and always end up at least beard (if I could grow one) in ochre....

I can put sensitive small thing into a safe place easily, either tucked into oversuit or in a carry case, same as the camera. Not quite such an easy thing to do with a safety lamp.

I break lighters by using them, this is because I am a clumsy oaf whose hands are perpetually wet and muddy (ok only mostly when underground).

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Couple of things I picked up from Steve at Shropshire Caving and Mining Club who has used several types of O2 meter over the years.
They like to be switched on and stabilized out in fresh air, not underground.
They seem to be affected by altitude.
They do not like being stored in plastic boxes.

You might like to contact him for his ideas.
I don't know if he responds to this E-mail [email protected]
If not I can PM his personal E-mail if you want.

Disposable O2 meter (keep it in a fridge, with a O2 stripper and the sensor will last longer). Unit fails when O2 sensor fails.

Or half decent 4 gas meter like a BW with individual sensors and keep it for the long haul. I don't like Crowcon or Neotronics (or whatever they are calling themselves). You don't want something as big as a radio.

I'd hesitate to draw any parallel or prediction from O2 and CO2 concentrations. I've nearly snuffed it in both.

One of the things to bear in mind is that a lot of mines will have depleted oxygen, to the point that your disposal meter will be shouting/flashing at you. This is SPECIFICALLY the reason I shelled out more and got a 4 gas. You want user definable alarm points.

A lamp running kerosene goes out at 15% (mine did, when I calibrated it to my meter). A butane lighter will not light at 13.5%.

Personally, I draw the line at 11% on the flat, although I have been in less. Things start getting exciting below 11%.

It's pointless having a meter if you don't know the significance of the numbers. Setting an alarm point at X% and sticking to it either ensures perfect safety, or monitors the point at which you turn around.

I genuinely abide by the original cavers method. Proceed slowly, notice how your body is responding, know the signs, be careful. Then accompany this approach with a meter. Then you'll know where YOUR own line is.

I would not entertain a disposable meter, because it's only good for working on sites. If you're getting out at 19.5%, you're going to be getting out of a load of places that everyone apart from HSE is fine going into.

15% with a lamp is quite a good indicator. I've done SRT down to about 13% (quite nasty) and 15% is OK, but everyone is different and it's a good idea to carefully learn about yourself and calibrate yourself to numbers on a screen before running into anywhere looking at a screen thinking "I'm OK/Not OK"

I always used to work on the principle; if you get short of breath, light a fag, if you can't light a fag, get out!!, been underground for close on 50 years, still going, but have always tried to avoid gassy places!.

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Sorry, I got my names mixed up - it's the disposable ones that are only £60. We're using one of these expensive jobbies at work at present for doing repair work in long drainage culverts in shaley ground, but so far they're not really registering anything at all most of the time, even though there's a distinctly 'eggy' whiff on entering - we've had a 1-point reading for H2S once and a brief drop of O2 to 20.2 once, but it's good to know that they are ultra-reliable, if pricey:

http://us.msasafety.com/Portable-Gas-Detection/Multi-Gas/ALTAIR ®-4X-Multigas-Detector/p/000080001600001022

pwhole,
This dectector, you use, certainly looks the Rolls Royce, but I am not sure if it could easily be calibrated, by amateurs, which we are, by and large.
The instructions, suggest you need a stream of 'pure gas' for its calibration, and whilst some will have access to these at their place of work, my guess the majority of us would struggle to do this.
The other problem from their site, who, in the UK, is their agent? and what is its cost?

The cheapest disposables I've found are £100+ rather than £60. Any lead on where they might be found at that price?

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keep a eye on e bay just picked up a crowcon t3 with charger and calibration ticket for 50 quid (they had miss spelt crowcon !!);D

I always used to work on the principle; if you get short of breath, light a fag, if you can't light a fag, get out!!, been underground for close on 50 years, still going, but have always tried to avoid gassy places!.

I love this working principle :lol: visit any coal mines? :lol:
I was taught the very same thing, never taken the opportunity to attempt to light up underground yet!
Very useful thread, as a meter is something that I've been considering for quite a while!

I was watching some recon MSA Altairs on fleabay a while back, and I seem to recall that the seller also did recalibration - there's several for sale at the moment though not obviously from someone who does calibration too.

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I always used to work on the principle; if you get short of breath, light a fag, if you can't light a fag, get out!!, been underground for close on 50 years, still going, but have always tried to avoid gassy places!.

I know the principle, the problem is I have a tendency to be interested in what I'm looking at and the getting out of breath tends to not register; hence a handy gizmo that will pointedly remind me that I need to make an informed decision as to my progress or impending demise...

Fleabay here I come...

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Cheapest low oxygen meter is a box of matches
They wont even strike properly when it really bad.

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Clearly from what has been stated, and from previous, postings there is a demand for an Oxygen meter, which is reasonably reliable and will not force you. Into Bankcupcy!
Certainly my first meter cost me an arm and a leg, and needed a new detector after 6 months.
Luckily it measured the air quality in our Scaleburn dig, which Roy should remember.
However we have not heard a great deal from members who have used oxygen meters, perhaps some of them will impart some wisdom to this topic.
After its use in Scaleburn & Wellhope Shaft, I have not been tempted to replace my costly Neotox meter.

Cheapest low oxygen meter is a box of matches
They wont even strike properly when it really bad.

My two-penneth from having explored mines with dubious air.

Even cheaper is your own instincts. You don't need any sort of device to tell you when O2 alone is at concerning levels.

To a certain extent, any sort of meter is potentially deadly as from experience, they can encourage a false sense of security. Its all very well knowing you can push on till you get into 11% O2 but the trouble is, 'bad air' (for want of a better term) is far from static and even the fanciest of doodahs won't tell you how to get out again if something behind you changes for the worst.

Just my point of view but I will state it.

I would rather trust a flame safety lamp, candle, lighter or matches.
Than a second hand gas monitor from the auction site. Whatever pieces of paper come with it!

Nuff said :)