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Question - Multigas detectors


CantClimbTom

28DL Full Member
28DL Full Member
As far as I see it, gas detectors (for exploring) fall into 3 rough categories

1) brand new, very expensive ~£450 or something. May require pump, possibly sample gas and other bits and bobs to recalibrate every 6 or 12 months. Sensor like variable maybe 2 years, maybe 3 years lifespan before replacing the thing, although there's a US certified one that's more like high 200s

2) New and perhaps same models as above, but strangely cheaper, ~£250 or something but when you look closely they are old stock, have less sensor life left and maybe need recalibration asap

3) Cheap Chinese, in the £100 to £150 range, the same one seems to crop up all the time but the original manufacturer is not clear

I know the "would you buy an amazingly cheap parachute?" argument, and how do you know it's working? (Without sample/calibration gas)

* Is there any practical use for the cheap detector and accepting a 12 month lifespan in return?
* Is there any way to check the thing works (smoke for CO, butane (lighter) for LEL, joke shop stink bomb broken in plastic bag for H2S?
* What about carbon dioxide? Is there any way to detect other than it displacing oxygen?

Not all of us can borrow from work :(

Anyone have advice, thoughts, comments, vigorous-gestures???
 

alex17595

Down t'pit
28DL Full Member
Buy one from a reputable brand. I bought mine off ebay and the days till recalibration due on the o2 reading doesn't even go down! The o2 sensor has given up now anyway. The MSA Altair is the one I saw reccomened on adit now the most.

You can get a 5 gas for CO2 but they are pretty expensive.

As for testing I just held mine over the hob till is started beeping or breathing on it to drop the o2 down.
 

CantClimbTom

28DL Full Member
28DL Full Member
Can really help but you might enjoy this. "This is it" LON

Thanks! Enjoyed that :) I need to get one of those lamps and paper kits! My only disappointment is they didn't play the Thames TV jingle at the end, maybe showing my ages but it was very distinctive and I clearly remember it
 

Down and beyond

The true source of englands wealth is coal
Regular User
A lot of suggestions as I have got the confined spaces ticket for training for the 4x from previous employment company.

before I start messaging a load of stuff the first thing you need to think of really is what do you exactly plan on doing with it mate ? Any confined space is dangerous drains can be seriously dangerous if they are full of rotten vegetation, mines any type of mine can be dangerous if the ventilation is not working . Atmospheric pressure is a major influence.Happy to chat for everyone to see for future references to others or pm .
 

CantClimbTom

28DL Full Member
28DL Full Member
I am only planning to go into low risk confined spaces, where I believe it's fairly unlikely (but maybe possible if particularly unlucky). My thinking is to lower it in on a rope/string for a minute or two before entering and then to carry it during trips. I am *not* planning to enter coal or sites known for air problems.

Is this the info you were asking D. A. B?
 

Down and beyond

The true source of englands wealth is coal
Regular User
Yes Tom .

if Your entering places that are quite often well trodden I would personally say the risk of gas itself would be noted in previous trip reports . the hazard then evolves when you wish to enter a place with lake of circulation which many places have . Correct with lowering it down a shaft for example it’s very often you travel to a place and do this.


a gas detector is only as good as it’s user .

every gas detector I have used always needs bump testing before you turn it on .

Altair are very good gas detectors .

you Can’t ever bring money into the gas detector world in my honest opinion when a sensor is out of date it needs replacing by a professional or throwing into the recycling bin.

the issue is unless your trained or component it’s very dangerous even having one because you don’t just walk into a mine and switch it on .
 

pirate

Rum Swigger
Regular User
Don’t piss about………if you’re going in mines with gas invest in proper calibrated equipment everything else is a risk
 

CantClimbTom

28DL Full Member
28DL Full Member
Understood calibration can only be performed with the correct calibration gas, and that it costs roughly £200 per small cylinder (unless anyone knows a cheaper source?) But bumping to make sure it works... Seems to my research that bumping is essential, or you could get false security from a non working sensor and be more likely to get into trouble than someone with no meter.

I know nobody can advise or officially encourage home made bumping, but in real life, does anyone do this?
Thinking LEL can be done with butane (e.g. from a lighter) low oxygen from a tealight candle in a really big glass jar, screw on lid and wait for candle to extinguish hopefully about 17% O2 and enough CO to detect? H2S is tricker but trace can be obtained from stink bomb broken into clear plastic bag left in daylight for 5 minutes (Ammonium Sulphide in solution, it decays to ammonia and hydrogen sulphide trace in daylight). If it can detect this low a level the detector would need to be working very well

OK this isn't going to be health and safety endorsed, but out of interest does anyone do home made bumping?
 

Down and beyond

The true source of englands wealth is coal
Regular User
My mate breaths his fag into ours this always works , also when you pass 17% o2 you would no yourself your their mate it is horrible . dropping from 21-15 can happen within 2 steps so it’s risky even with your 4x . Your best bet is some hardcore reading into what causes the gases to try to understand where your going to find them .

when we are 5 minutes away we always turn it on and exhale onto it many times to watch it some times you can just get the bump test on hire with it though this is the safest option .

best option is stay in mines that are well walked this way you haven’t got the issue !
 

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