Gas detectors

[Ali Wiseman]

I have managed to win a couple of gas detectors on ebay.

I know they will need new cartridges and calibrating.
They are Zellweger Analytics Impact models, seem to be fairly standard for industrial use, and do the 4 important things (Methane, O2, CO & H2S).

Any pointers on where to get them?

I don't care about fancy certificates, as long as they work as they should after calibration.

[Tim Watts]

Nupe, mine is a http://www.gasmonitors.com/main.cfm?page=prodpage&pid=6&cat=23&sub1=20&sub2=90

different sensors i'm sure.

[Ian A]

I can vouch that, once Tim's goes off, you cannot shut the fooking thing up  :whistle:

[Tim Watts]

its not the same one ian. I lent that to joel and it refused to even switch on for him - got a new un since then.

(and it does (did) shut up if you press and hold the right button for 5 seconds - but you of course weren't to know that!) :-)

[Ian A]

Nope, didn't know. Neither did Doug who was as close to a nuclear implosion as I have ever seen him lol  :woohoo:

[Ali Wiseman]

I know they 'aint cheap, but I'm prepared to pay for it, as I have a few places that may well have iffy air in mind. I'd rather know, and GTFO than figure it out when I get woozy.

[Tim Watts]

think you both could have been expected to have known that the big flashing huge 19.2% o2 on the LCD wasn't too hazardous to health though. It did make for an epic video i must admit :-) :-)

Think the O2 had only dipped 'coz the concentration of methane emanating from your behind was rising to such enormous proportions! :-)

teehee

[Ali Wiseman]

I'll start to worry at 17%, and want to GTFO at 15%. I'm more concerned about high CO and flammable.

[Tim Watts]

try calling cbiss in birkenhead.

I used to use them to supply online analytical measurement solutions in my previous life (job) When working as UK Analytical Engineering Manager for Ineos Chlor.

It was over ten years ago though and they only did one major project for me which was a custom built Chlorine (up to 100%) and Hydrogen in Oxygen analyser based on my design using thermal conductivity, and then reacting off the Hydrogen and measuring again before comparing the readings and applying some modelling) which they went on to develop and put into their own product range)

I used to have the names of some contacts there - including the MD but their names escape me at present. They may be able to point you in the right direction for sensors for your detector because they do stock a range of personal gas detection equipment. They can probably supply you with their percentage added but a non-commerical, caving club, helping the community type approach might yield a more sensible (cheaper) route or at least a useful pointer of where else to try.


11 Ark Royal Way
Lairdside Technology Park
Tranmere
Birkenhead
CH41 9HT
Tel: 0151 666 8300
Fax: 0151 666 8329

[Tim Watts]

[quote="NewStuff" post=14471]I'll start to worry at 17%, and want to GTFO at 15%. I'm more concerned about high CO and flammable.[/quote]

Well if you're looking into flammable concerns make sure you understand LEL and UEL and what range the meter uses.

and please don';t underesmimate H2S - bag eggs smell - the thing is over a certain concentration/exposure it diables the nerves in your nose so you can't smell it.

once you can no longer smell it you're really in the shit coz it means the concentration is getting into the knock you on you back like a freight train territory.

you'll find plenty on the web on the subject.

i posted quite a bit of info on here some time ago in the technical area i think - was a goodly while back and can't be arsed looking for it now

[Ali Wiseman]

Off the top of my head, methane's LEL is 5% and UEL is 15%.

I am aware of H2S, but think it more likely to encounter High CO then anything. I'll keep an eye on the meter (no point in getting them otherwise), and if anything is not to my liking, I'll boogie on out.

Once I have them working, and I've been the test dummy, people are welcome to borrow them.

[steven cross]

i bit like a drift mine i was in last week ,strange feeling at back of my throat ,time to get out  :lol:

[Tim Watts]

yes exactly. lel = 5% uel = 15%

in reality less than 5% methane in air you're ok, fuel/air to weak to burn and above 15% you're ok too much fuel for the air available to burn. Although obviously to get through past 15% concentration level you'l have had to go through the danger zone so its kinda irrelevant.

but be aware that most meters (by default) read a % of the LEL scale.

so MOST meters will read 0% - 100% of LEL.

i.e. when the meters shows 100% that actually the 5% methane in air value.

The default alarms will be set much lower than this of course.

My point being, that a reading of say 10% is possibly quite ok if the meters reading %LEL but you're really in the shit if its reading in % concentration scale!

For others wondering what the hell LEL means its "Lower Explosive Limit" i'll leave you to guess what UEL stands for! ;-)

[Ali Wiseman]

[quote="steveturbo" post=14484]i bit like a drift mine i was in last week ,strange feeling at back of my throat ,time to get out  :lol:[/quote]

That's where I want them for mate, 'aint a chance I'm going in there without a monitor.  :unsure:

Even if I can't get these ones sorted, I won't be losing much. I'll give that company a ring tomorrow Tim, cheers.

[Tim Watts]

also for ref - 20.9% is NORMAL o2 level, dipping anything below this IS going to have an effect - dropping below 15% you are on thin ice - 12% you're close to being knocked to the ground and never getting back up - in fact some people might not tolerate less than about 15% - everyone is different.