[Gavin Yates]

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<font color='#000F22'>My LDS - darling that they are insist on charging me over £11 for a nitrox fill for my twinset. So does it make financial sense to get a supply of o2 and partial pressure blend my own by getting a mate to do a top-off for me.

If I were to do this I would do the appropriate course before embarking yadda yadda yadda ....

Thoughts and who do you buy from?

 

[peter k]

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You can get medical quality O2(make sure it's medical quality and not welding quality) from BOC. Alternativly go to your local hospital and liberate a few tins. The idiots just leave it lying about in the corridors. Obviously I am not advocating this criminal and downright scumbag method, but it is an option. You can do the course at Fort Bill.

Peter

 

[jasondrake]

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medical o2 is full of moisture. Not so good for your cylinders. Aviation  o2 is cleaner. Industrial o2 can be just as clean or cleaner than 'breathing' o2. It's the testing procedure which differs-allowing the higher grade labelling and price of breathing gas-not the production method. Unless your using lots of nitrox it's not worth setting up your own. You need at least 2 cylinders or a booster to get decent value, and rental can be expensive. Getting gas suppliers to sell you gas is tricky too-most regional suppliers won't bother with such a small volume client and will often run a mile if you say your wanting to dive with their stuff. That said lot's of people do it.


(mate works for boc!)

 

[DecoWarrior]

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it does make sense to buy in your own o2

that stuff about medical grade O2 is crap i have been using medical grade O2 that has been liberated from the Nhs in my rebreather for ages i have just had th take the valves out of my bottles for a trip and they are immaculate the only problem is the pressure seems to be a bit lower

 

[Dominic]

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I'd be surprised if medical grade had more moisture than any other type - All the Oxygen that a company sells comes from the same tank, and they don't usually contaminate it..

http://www.subaqua.co.uk/reference/gas-suppliers.shtml is a list of people who'll sell you Oxygen (and Helium)

Given that a J of Oxygen is around the £20 mark, three fills and it's paid for itself at your shop prices.

Having a cascade or a booster pump could be helpful if you wanted accelerated deco mixes, but given that you only need 10 bar or so to get a 32% mix, a single 200 bar J should give you more than enough fills to make it plenty worthwhile.

Of course, you have to pay for the decanting assembly as well. Subaqua products is a good place to go, they sell a complete decanting unit for £255.88 - so you've got to do rather more fills to make the whole thing pay for itself. However, it'd probably pay for itself in the space of a year..

 

[steve-k]

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its a question of quantaty, unless like decowarrior you have a source you will need to rent 2 cilinders  at about 5 per month each, medical grade has an introduced moisture content, that in theory can accelerate the decay of your tank, and also is only charged to 130barr breathing grade is charged to 230 barr and is only slightley more expencive,
we hire o2 if we are going on trips where there is a high expected use or the local shops dont offer a fill
apart from the relevent course you will need a filling whip (£250-£300) And an o2 analiser (£200) +60 a year for a new cell

you can also have the problem of shops doing a top-up of clean air, especially when you try to explane why the finished cooled pressure is so important, they become verry reluctante,

i never atended a blending cource befour i mixed my own, i suppose you need to determin your own level befourhand, and decide what course you need

conclusion
unless you intend to ues nitrox on every dive, it is not worth the finantial outlay and running costs to mix your own nitrox, it becomes more feasable if you have a diving partner to share with, furthermore it can be a bit of a hastle, and is so much easer to just drop your tanks off, then to pick them up filled,
all this said we run a trip down south where we rely on our own o2 because of thr time constraints of the local shop, we 1/2 our deco penelties by filling our stage cyilinders with our own o2, we even get it delivered to the local pub  lol

 

[Dominic]

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Quote[/b] (steve-k @ Mar. 25 2003,22:06)]

Quote[/b] ]medical grade has an introduced moisture content

Live and learn..

Quote[/b] ]you will need to rent 2 cilinders  

Given that Gavin is intending to fill his twinset with Nitrox, I think we can safely assume he'll be running mixes of less than 40%. Why then does he need more than one cylinder of Oxygen? He doesn't need high pressures.

Quote[/b] ]And an o2 analiser (£200) +60 a year for a new cell

Surely anyone who dives Nitrox should have one of these, so it can't be considered an extra cost...

 

[Gavin Yates]

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<font color='#000F22'>Sorry lads - I should have said.

I already have a delightful o2 decanting whip complete with needle valve and funky pressure guage for sub-aqua products and an o2 analyser. I also have a personal filter with all the atachments one could ever need - also from sub aqua products.

The info I was after really was how much a J cost and where to get one from. I understand that without a booster I'm gonna lose some o2 on every J but does it still make financial sense after taking that into account.

Also how does one go about getting the stuff from BOC? or elsewhere.

 

[ANDY 64]

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<font color='#0000FF'>RIGHT here goes from a Commercial divers point of view.


O2 j bottles, get a mate in your local scrap yard QUICK, buy the O2 from them direct normally £ 10 - 15 , return J when emptied and get a refilled one.

Scrappies get thou a load and get a good discount, if you have a good mate there you get it for the price they pay, unless he is a REALLY good mate and ' dare i say it ' . just return it later when empty.

At work, we get thou about 5 bottles on a normal working week,having said that , we got it hooked up 24/7 just in case of a bit of cutting is required  

Reference the MEDICAL   O2....... Some has moisture in and some Don't... look at the RED tags ( MOISTURE induced), i forget which health problems it is needed for ( I had some , coz my uncle is a director of nursing ) and he showed me years back.

Blending ,,,,,, Why get the ticket ? only reason i saw from it was . that my house insurance and garage went up by £ 5.57 a year for reason of storing high pressure O2,,,,,

What you learn from any course, you can learn from someone that has done it or better still someone that has been a GARAGE BLENDER for years...



ANdy

 

[Dominic]

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Quote[/b] ]how much a J cost and where to get one from.

*tut* Why do I bother posting links..?

As mentioned previously: http://www.subaqua.co.uk/reference/gas-suppliers.shtml - suppliers of Oxygen and a price list as well.

 

[Gavin Yates]

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<font color='#000F22'>I'm supposed to read it  ... sorry I missed that bit. Nice one.

 

[steve-k]

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Quote[/b] ]Surely anyone who dives Nitrox should have one of these, so it can't be considered an extra cost...

at our local diving shop/school and local clubs most people with a nitrox ticket dont have an analiser, if they get a mix then it is analised in the shop of purchsce


also i was under the impression that you did not own the cyilders and that you had to rent them?

Quote[/b] ]Given that Gavin is intending to fill his twinset with Nitrox, I think we can safely assume he'll be running mixes of less than 40%. Why then does he need more than one cylinder of Oxygen? He doesn't need high pressures

agreed to a point but when a j bottle is 1/2 empty you wont be able to get a 40% Mix in a twin12s, you are then left with the dilema of renewing a 1/2 full cyilder or being restricted with your mix, (not sure of the exact content and cant be arsed working it out, so please dont correst me)


but if gavin has all the equipment and fanceys a go then why not? there are more reasons for mixng your own than finantial

 

[Chris Hall]

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Nice read so far, I have TDI blender cert & own O2 analyer. Will help anyone if needed.

 

[Gavin Yates]

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<font color='#000F22'>Nice one Chris.

I've got all the gear - minus the gas - and i've got a copy of the oxy hackers handbook and it all seems pretty simple if you follow a sensible approach.

What  I think I could do with is a master class from a Scottish-based garage blender or are there any Scots on the boards that fancy splitting the cost of a few Js?

 

[parahandy]

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Gav
Just had a look back at some blurb B.O.C. sent me a while back, when i used to take the o2 kit in for re filling at their depot.

Don't know if its current, but you used to hire the cylinders, very reasonable charge per month I remember the fill charge wasn't that bad.  The down side was that there was a minimum transaction charge of £20 probably gone up.
The card they gave me says Medical Grade oxygen, with all the gen.

 

[Andy Winterburn]

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Eh?
Surely the best way is to go into your local dive shop and see what they do, the type of kit they buy, the pipe work they run and the checks they do, the money spent is wasted. Or at least according to what I have read so far

Gav before you go killing yourself, or A N Other, give Andy Hayhurst a bell. For 48 quid and a days course he might just save your life.

With all respect I cannot believe some of the advice given. Sorry if this offends anyone BUT he might just do it you know.

 

[Dominic]

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Quote[/b] ]agreed to a point but when a j bottle is 1/2 empty you wont be able to get a 40% Mix in a twin12s, you are then left with the dilema of renewing a 1/2 full cyilder or being restricted with your mix, (not sure of the exact content and cant be arsed working it out, so please dont correst me)

I did some quick working and concluded that you can get a decent Nitrox with about 75 bar left in the J. After that you're down to 50 bar and stuck to weaker mixes.
But since it takes about 25bar out of the J per fill, you'd still get at least 5 fills per J.
I don't think I can be bothered to work out if it's more cost effective to hire two at once to get the longevity or one and send it back partially full..

Quote[/b] ]before you go killing yourself

How exactly do you think he'll do that??
Mixing the wrong %age, Oxygen fire, or what?

 

[Gavin Yates]

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Quote[/b] (Andy W @ Mar. 27 2003,08:10)]Eh?
Surely the best way is to go into your local dive shop and see what they do, the type of kit they buy, the pipe work they run and the checks they do, the money spent is wasted. Or at least according to what I have read so far

Gav before you go killing yourself, or A N Other, give Andy Hayhurst a bell. For 48 quid and a days course he might just save your life.

With all respect I cannot believe some of the advice given. Sorry if this offends anyone BUT he might just do it you know.

<font color='#000F22'>Andy - before getting on your high horse - read what I wrote on my opening post.

It has always been my intention to get certified for blending. I would do it any other way. Andy H would be my port of call as he is a garage blender supreme.

It's pointless talking to my LDS about partial pressure blending cos they don't really do it.

When folk starting talking about others killing people it puts them off posting for info at all. Thanks mate

 

[simon]

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Guys,

You want to blend at home ?

you can get O2 from various places -

BOC- if you tell them its for diving they wont sell you it.

Air Products - They do their own DIVING GRADE, price £18 + vat and £8 + vat rental on cylinder, 200 bar

Lindy - They do DIVING GRADE if you haggel you could get it for £12 + vat @200 bar and £5 rental.But you tell them your usage and they deliver that every month.


[/B]but given that you only need 10 bar or so to get a 32% mix

In fact you would need 27.85 bar of O2 for a 32%@ 200 bar mix.

I hate it when people assume things.

Gav its realy up to you if you think the cost is benifical, running two cylinders would be better than one, then you arnt sending it back with 40 - 50 bar in it , but its really pence.

Why not try and do a deal with your LDS,



Simon

 

[Dominic]

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Quote[/b] ]but given that you only need 10 bar or so to get a 32% mix

In fact you would need 27.85 bar of O2 for a 32%@ 200 bar mix.

That's impressive - I managed to typo and misremember the amount at the same time

Meant to write 20 - I was going from vague memory as I couldn't be bothered to look it up.
The actual point still stands that you don't need high pressures of O2 to do backgas fills..