GAS BLENDING ,,, I JUST DONT UNDERSTAND

[Dyson Diver]

think im gonna have to ask some one, it seems as if my understanding was wrong , or bsac guides for gas blending are wrong , or everyone os ignoring the new rules.
i will have a look online and see if a drager test covers the 8478 spec , which would in effect mean its the same thing.

[Dyson Diver]

There are different levels allowed by the two standards, one for normal air and the other for mixes or clean air.

The EN 12021: 1999 sets out the criteria for air certs and breathing air, I think the 8478 then goes further with the levels of impurities.

So an air test is done under EN 12021: 1999 but any air used for mixes must pass 8478.

Rebreathers don't use high pressure partial mixing.

You don't breathe off the loop at 232 bar unless your verrryyyyyyy deep.
:0

thats true , but your still mixing pure O2 in with the air , regardless of pressure , the bsac guide says it has to be 8478 for mixing with O2 , as of 2006. as far as ive read it didnt mention pressure , just high O2 levels. same as in a rebreather , but thats not my concern , im more interested in the bit about nitrox blending , have the cyls ive filled in effect been incorrect. and if thats the case , ill bet im not the only one
HERES A THOUGHT ,,,, OUT OF ALL THE PEOPLE READING THIS WHO FILLTUBES OF GAS FOR THEMSELVES OR OTHER PEOPLE HOW MANY HAVE A BS8478 STICKER ON THEIR COMPRESSOR.
ive never seen one , and ive filled a fair few cyls. but if the bsac guide says as of 2006 thats the standard that applies , then it must , hse enforce the standards as far as i know, so where do things stand.

[bubbleless]

You would be more amazed at the number of shops dive centres and clubs that don't air test!!

Individuals are just that its upto them what they do or don't do.

[nigelH]

You would be more amazed at the number of shops dive centres and clubs that don't air test!!

Individuals are just that its upto them what they do or don't do.

You mean they don't have a gas analyser?

OK, I know I'm a bit of a geek but even I have a Dräger tube box.

[aqua0]

Dude, you really need to get outside more often

OK, I know I'm a bit of a geek but even I have a Dräger tube box.

[nigelH]

Dude, you really need to get outside more often

That's what I have a hang glider for.

Oh and, as you guessed, I am a beginner pilot with state of the art instumentation.

[Mark Powell]

The BSAC guidelines are correct and have been updated to reflect the new standards.
http://www.bsac.com/core/core_picker...ending+Centres

You are right that BS 8478:2006 is now the relevant standard for air used in Nitrox blending. It is in effect the standard for what has previously called "clean air".

There is some useful information in this thread, including the relevant quality.
BS8478:2006 Air for use in NITROX systems.

There are some issues with the implementation of BS 8478:2006. The standard is considerably higher than previous standards and there are not many places that can test whether air meets the standards.

You may not have been aware of it because it is relatively new and people have in effect been ignoring it. This is likely to become more of an issue as people become more aware of the standard. Many of the centres providing Nitrox today will not meet the standard.

[Mark Powell]

You mean they don't have a gas analyser?

OK, I know I'm a bit of a geek but even I have a Dräger tube box.

Nice bit of kit, but do you know if it can test to BS 8478:2006? My understanding was that the Dräger tubes couldn't test to this standard.

[nigelH]

Nice bit of kit, but do you know if it can test to BS 8478:2006? My understanding was that the Dräger tubes couldn't test to this standard.

Grief no....
I just want it to check I'm not breathing oil after I do the annual on the compressor.

I buy time on a top line mass-spectrometer for work stuff but for what we pay for that I'd rather breathe oil and keep the money.

[bubbleless]

We Had our compressor tested he used tubes but I don't think they were drager ones.

He tested our normal air then the double filtered mix air as you said this was more strict. we did well passed on both counts.

i only found out about Air certs being Compulsory recently.

Its to protect the diver its like an mot every three months and should be displayed in a prominent place!!

i know of two or three dive centres near me that have them ,I also know of several who don't.

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