Gas detector advice/info welcome

Hey guys,

The clubs been thinking of  buying a gas detector recently for some upcoming trips this year.
Couple of queries if someone doesn't mind helping me out here without getting too technical, bearing in mind I know little about gas and nothing about gas detectors!

What do I need to know about one in regards as to making sure it's suitable for caving and or mining?

Are they all suitable? What do others use?

I ask because I have the chance to buy a second-hand one which has just been calibrated and fitted with a new o2 sensor.  I can't remember the model but sure it's made by 'Honeywell?'and cost ?300 odd quid new. 

It's never been used, Not properly anyway in an environment where it might actually be of use! and not just to tick a bloody box!
Just a couple of years old and re-calibrated twice as it won't let you use it if out of date.

I had a play with it the other day at work and it sounds like my mates farts and my burps  are not as bad as they may first seem, I think they just smell a bit bad and a little anti social perhaps?!?  Certainly not life threatening or too disturbing.....Fact!!

But I  digress, Any info greatly received here as I'm not sure what to offer for said detector or even if it's what we need.


Any info greatly received as I may be onto a bargain here!

JRB

Cheers chaps!

If the model you have the chance to buy is made by Honeywell then, as Honeywell are a well-known manufacturer of heating and ventilation controls, I would say it is a fair bet that the model in question is for flue gas analysis. So not at all suitable for what you want. I have a flue gas analyser and I wouldn't contemplate taking it underground.
GCRG have gas detectors, and hopefully one of our members with a better memory than me will reply here soon with the model details.

without wishing to offend anyone as i'm sure there are those on here that can answer your queries,
but you may alsofind answers on the mining forums

Thanks for reply Badger, Its not Honeywell! I was thinking out loud there, Stupid me once again!

I forget the name but will be back tomorrow as said bit of kit is at work.

If I'm honest, I was generally asking for info about how they work and learn a bit more about gas detectors!

If anyone could point me in the right direction then great stuff!!

I know of one that could be for sale, I would be happy to buy it for our club as the idea of buying one has been brought to light recently.

If anyone could give me a heads up on them, then I'm all ears!!

Regards,

JRB



Regards

JRB

My club (Crewe CPC) uses pair of IndSci oxygen meters (single gas units) for testing the atmosphere in caves and mines. One is a disposable unit Gasbadge Plus which you can buy for less than ?100, and lasts until the battery runs out (about two years). The other Gasbadge Pro, which comes with a lifetime warranty for everything but the sensors, and comes in at just uner ?250 - replacement sensors cost just over ?100.

As these are both oxygen meters, they can be calibrated using fresh air, but be warned - as they are only measuring oxygen, there is always the danger that the displacement gas may be something other than carbon dioxide, although all the instances in the Peak which I have investigated so far (using a CO2 meter) have been caused by CO2 build up.

Needless to say, the advice from IndSci is to calibrate using their kit and a sample canister of oxygen, they also recommend bump testing prior to each use.

Hope this helps. If you do decide to use a meter in the caves and mines of the Peak, I am building a database of information which may help us to understand the occasional problems which we get in this area with CO2 intrusions, and I would be grateful of any figures which you could supply - preferably date, time, cave/mine name, passage/area of cave/mine sampled, type of meter used, weather conditions, cave/surface temperature, and any other relevant data.

Obviously you may not wish to record everything in such great detail, but I am happy to receive whatever you send. Please email data to gasman at TheDCA dot org dot uk.

Cheers
Al

Honeywell are one of the world's largest manufacturers of industrial controls and sensors. They sell personal gas monitors under the brand name 'BW Technologies' and the model name 'Gasalert'.

For any normal caving activities, personal gas monitors are completely unnecessary.

For locations where you may encounter poor air quality (e.g. cave digs, or some abandoned mines) you need to have some idea of what the nature and cause of the problem is before deciding what type of gas monitor to use and what the settings need to be. There are standard settings based on HSE guidelines, but these are not necessarily appropriate for cavers in a non-workplace context.

Remember also that the only protection a monitor gives you is to warn you when you enter a region of poor air. If you are unable to do anything about the air quality it once you get there then all they are is an annoying nuisance. Your own natural reaction to carbon dioxide (once you know how to recognise the symptoms) will tell you when it's time to turn around and go elsewhere, and if the situation is bad enough that you are incapable of getting yourself out then the detector on its own isn't going to help you. You need procedures, training and backup to remain safe.

OTOH, I've carried a detector in caves and it's often interesting to see what it tells you, but if I ever thought I was going somewhere that relying on it would save my life then I would take a very different attitude to preparations for the trip.

It's a big topic, and I don't have time to go into it in any more depth, other than to point out that people have died when they have relied on detectors when they should not have done, and also when they have not relied on them but should have done.

Nick.

nickwilliams said:

For any normal caving activities, personal gas monitors are completely unnecessary.

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A very good point Nick 

Nick,
I managed to find the user guide and have a quick scan at work today and although I forgot to bring it home I remember seeing 'microclip XT gas alert' on its cover.  You  mention BW Technologies and Honeywell.  This does ring a bell (if you'll excuse the pun!)  I'm sure it's the right bit of kit the club is thinking of buying as if it covers everything we may encounter when entering a live sewer system then I can't imagine how it wouldn't warn us of anything nasty in an old mine.

I don't know, I'm certainly no expert and looks like I have a bit of homework to do!

And Al, If it's the right bit of kit and the gaffer decides to roll with it then no problem at all sending you any info it gives us.

Thanks for info folk

JRB

JRB, you say the club has some trips lined up that you want the monitors for.
I'd suggest finding out what the likely gas risks are in these caves/mines, then thinking about how a monitor will help reduce the risks. (Unless it is for interest not safety reasons).
As Nick suggests, a monitor that goes off as you walk (or abseil) into a toxic concentration of a gas won't be much help, other than to tell others where your body is... (sorry if that sounds insensitive).

One application could be to lower monitors down a suspect shaft to give an indication of air quality before entering (careful not to lower it into a pool though!). This does not guard against changes when you are down there, e.g. changes in airflow from weather, build up of CO2 from activity in an unventilated small downhill dig, stirring up decomposing organic matter, or punturing inflated dead pigs with falling stones at the bottom of a pitch....

Industry generally uses gas monitors hand in hand with escape breathing apparatus sets (that usually only give 10-15minutes forced air). Or, if its known to be toxic, full BA would be used from the outset. Neither are very practical options for recreational caving...

Interesting reply Mark, Thanks for that as these are points I wouldn't have thought of.

Makes me think If we really need one actually as we don't go anywhere too 'off-piste'.  Mainly sporting trips to Derbyshire and Yorkshire.  So it probably would end up being used out of interest.

CM, I'll have a chat with the guys but you may have just saved me ?150! Nice one! 

If they are thinking of a one off trip that may need one then I will just borrow the new shiny one from work!!

Easy really, I'm so thick at times.....

Cheers

JRB

jonnyrocketboots said:

If they are thinking of a one off trip that may need one then I will just borrow the new shiny one from work!!
JRB

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If you really don't know what you are doing and still think you need a gas meter then my advice would be to avoid the trip. You aren't going to be rescued from an unbreathable atmosphere.

Kitty

A standard confined spaces setup won't include CO2. You'll have O2, flammable, CO and H2S on these instruments. With the flammable sensor you'll need to find out for which gas is used as reference. It'll be CH4 most times.

Mining setups will most likely differ from confined spaces and include CO2 and/or NO2. The flammable sensor will be calibrated to CH4. SO2 can be important for some mines as well.

Taking a gasmeter with you is one thing but knowing what to do when one of the many alarms goes off is another. The alarms will be set to industry standard levels far away from danger. Stick to these alarm levels and you might not get anywhere. You should have one for short term exposure and one for longterm exposure and you need to be aware which is which.
Common approach on the recreational side though is quite often to ignore the alarms and decide on your own how far to go as people believe that the alarms are for industry and not for caving or mine exploring. In this case save the money as it'll just 'tell others where your body is' as you won't have a selfrescuer like in the mining industry and depending how far you ga past the alarm it'll be too late anyway.

Please keep also in mind that buying a gasmeter is one thing but keeping it in working condition (testing, calibration and replacing sensors) is another which can be quite costly depending which one you buy. Sensors are also easily destroyed by playing with the meter. Using gas from a lighter or the exhaust of a car to demonstrate or test the instrument will most likely kill one or several sensors same as going past certain alarm levels will do.

There are also many influences on the sensors or the instrument itself which will give you interesting readings or even set off false alarms. Which means you should be aware of things like cross sensitivity or radio interference.

It's been many years since I used a gas detector so the technology may have moved on, but on one tunnelling job I did we had several incidents where the tunnel was evacuated because one alarm went off when others didn't. This was eventually tracked down to the gas monitor getting damp.

We use them quite regularly however they are expensive to run with one or other of the sensors invariably needing replacing and a re-calibration always seeming due.

Unless you're spending time in the sort of places where they are essential then as stated by others above, I really wouldn't bother

Thanks guys for your info and advice. Interesting reading as well, I didn't realise they are so complicated or so sensitive.  I thought I'd found a bargain and as the club was looking at buying one I thought I would be saving us a few quid.
I'll give the chaps the heads up and let them make a decision as  to whether we 'need' one or would 'like' one,  But from what I've heard I think we could do without one.

Thanks again!
JRB

If its cheap enough and you can get the specs for it, would it be worth buying and selling on at a profit for club funds?, there are a few folks on the mine exploration or urbex forums that may be interested??

Nothwithstanding that I remain of the view that gas detectors have no place in normal caving, I know that several people who have been following this thread will be interested to hear about a report which HSE have just published:

RR973 - Review of alarm setting for toxic gas and oxygen detectors

It's available to download from the HSE web site: http://www.hse.gov.uk/research/rrhtm/rr973.htm

Regards

Nick.