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Thread: Oxy-LPG cutting

  1. #16
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    Hi Guys,

    Not quite off topic

    This is the reason that in the camper at 10,000 ft in the Alps there is almost no flame on the gas hob. It wasn't just the cold but altitude that virtually stopped the LPG from vaporising !
    Best Regards:
    Baron J.

  2. #17
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    I dont remember using much more oxy when cutting with lpg compared with cutting with acetylene, most definatly not 4 times as much and if you did then you would want to be replacing some o-rings. The minimum sized bottles that i used for cutting would be E's.
    I dont think a D size would get you too far.

  3. #18
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    Quote Originally Posted by shedhappens View Post
    I dont remember using much more oxy when cutting with lpg compared with cutting with acetylene, most definatly not 4 times as much and if you did then you would want to be replacing some o-rings. The minimum sized bottles that i used for cutting would be E's.
    I dont think a D size would get you too far.
    My understanding of the 4x thing is its just a neutral flame that uses that proportion of oxy. Once you hit the cut lever then the preheat oxygen usage is eclipsed by the cutting oxy usage anyway.

    I can confirm that a D size oxy doesn't go very far when cutting...

    Steve

  4. #19
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    Quote Originally Posted by OxxAndBert View Post
    My understanding of the 4x thing is its just a neutral flame that uses that proportion of oxy. Once you hit the cut lever then the preheat oxygen usage is eclipsed by the cutting oxy usage anyway.

    I can confirm that a D size oxy doesn't go very far when cutting...

    Steve
    You are bang on there. While it is technically true that LPG requires roughly 4X the oxygen that Acetylene does to maximise combustion, the usage of Oxygen by the cutting jet uses far more than the preheat flame. My observation is that the people who make a big point of the 4X Oxygen spec are typically those trying to sell you Acetylene. In any case, Oxygen is a cheap gas compared to Acetylene (I'm paying $40 for a 10M3 G size Oxygen fill at present) and this paired with the cost of LPG in comparison to Acetylene soon negates the extra Oxygen usage. If excess Oxygen use was that big an issue, LPG wouldn't be fitted to most profile cutters and the scrappies wouldn't choose it. Acetylene may have a slight advantage in preheat speed, but once you're cutting they are line ball.
    There is one little mentioned advantage that Acetylene has in some applications, that being that it is lighter than air and will disperse whereas LPG will not. We were not allowed any LPG equipment underground and I should imagine that there could be other worksites where LPG may be banned for similar reasons.
    The earlier point made regarding cylinder draw off interests me as it is exactly the opposite of what I have always been told and my personal experience. You can run a far larger superheating tip from LPG than you can from Acetylene unless the Acetylene is from a manifold pack. We aren't quite the Antarctic, but Tasmania does get cold in winter but I've never had an issue running Superheating tips from LPG, even from 9Kg cylinders.
    I swapped to LPG almost 10 years ago and never yet have I regretted it.

  5. #20
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    Interesting thread. I just looked up one of these Oxy/LPG kits, the Cigweld CutSkill Tradesman oxy/lpg kit 208011, current price about $400. I suppose that's a good price on this kind of kit? Or not?

    What I'd really like to know though, is there any outright-ownership option on the oxy bottle?

    I see from this:
    https://www.boc.com.au/shop/en/au/fill-for-less

    that you'd be paying $79/year for an "Oxygen D-Plan".

    Some years I might not use the kit at all. So I wonder if there's a better way on the oxygen.

  6. #21
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    there are other suppliers, like One Gas where you pay upfront for the bottle ( no annual rental ).When you run out you just pay the refill price and swap the bottle for a full one.

  7. #22
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    Quote Originally Posted by Bigcam View Post
    there are other suppliers, like One Gas where you pay upfront for the bottle ( no annual rental ).When you run out you just pay the refill price and swap the bottle for a full one.
    Looks like you're well catered for over there in the West, with One Gas. They don't have any stockists on my side of the continent, but you've put me on the right track. I see for example
    https://www.totaltools.com.au/weldin...-oxygen-d-size

    which is a filled outright ownership oxy-D bottle for $269, swap over when empty. So long as I live for another 4 years and only use it occasionally, I come out ahead over the annual bottle plan from BOC; if there's nothing else I've overlooked.

  8. #23
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    Quote Originally Posted by Gunnaduit View Post
    that you'd be paying $79/year for an "Oxygen D-Plan".

    Some years I might not use the kit at all. So I wonder if there's a better way on the oxygen.
    Bunnings. $200 deposit. No rent. Great opening hours.

    There is a Gasweld in ACT, it looks to be the same deal as one gas
    Last edited by Stustoys; 15th Dec 2020 at 07:19 PM. Reason: added gasweld

  9. #24
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    The bonus with a Bunnings purchase is you get you money back when you no longer need the cylinder.
    Must keep your receipt. Make sure you copy it as all those small receipts fade quickly.
    I scanned mine and keep it on my computer.

    John

  10. #25
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    Quote Originally Posted by Stustoys View Post
    Bunnings. $200 deposit. No rent. Great opening hours.
    Quote Originally Posted by Wimmera Jack View Post
    The bonus with a Bunnings purchase is you get you money back when you no longer need the cylinder. Must keep your receipt. ... John
    Even better. Thanks for the info.

  11. #26
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    If you plan on oxy LPG, then forget "d" size anything and look at "e's" as a minimum.
    BOC plans appear attractive, but if you use more than your 1 cylinder a year, they rapidly lose their shine.
    I have a general rule in life and that is AVOID BOC wherever possible. CIG/BOC have creamed off a lot of people for a lot of years. I know Supagas will beat them and are vastly easier to deal with.

  12. #27
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    You really have to do the calcs based on your own situation.
    For really low usage the Bunnings ones seem the way to go for long term cost.
    As soon as you’re using a D size bottle per year then the BOC D-plan is about the same cost since you get a free fill per year in the plan - and no shelling out the $200 deposit up front.

    As mentioned earlier, there’s not much gas in a D bottle if you’re using it for cutting.

    Steve

  13. #28
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    Found the Bunnings deal -- this one for a size E oxygen, $300 deposit plus gas $129

    https://www.bunnings.com.au/coregas-...xygen_p0013067

    But it turns out it is unavailable in Canberra-Goulburn region stores.

  14. #29
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    Did you see my edit about Gasweld?
    You can buy a E size cylinder for $330*, compared to BOCs "no rent" $169 a year(they seem to be sensitive about the word "rent" these days. It's not rent it's an "annual payment" lol. You can play all the word games you like but at best its $70 a year rent. Now their refills maybe cheaper but I couldn't be bothered logging it to find out).

    So if you use a full cylinder every year the cylinder pays for itself in 4.7 years. If you use less gas it can go as low as 2.5 years.
    You can even up size to G for $149 at a later date if you decide you need more gas.


    *$429 for your first full cylinder

    Given your thread about heating things, are you planning on doing much cutting?
    You could start with a D from Bunnings, see how long it lasts. If it doesn't last long enough get your money back and go to gas weld for an E or perhaps a G.

  15. #30
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    Quote Originally Posted by Gunnaduit View Post
    Found the Bunnings deal -- this one for a size E oxygen, $300 deposit plus gas $129

    https://www.bunnings.com.au/coregas-...xygen_p0013067

    But it turns out it is unavailable in Canberra-Goulburn region stores.
    What you save in rental with that Bunnings deal is eaten up by their extortionate gas pricing. They are charging $129 for a 4.9M3 E size oxygen fill/swap. I currently pay $40 for a 10.3M3 G size and my rent is $16 per month from memory. To put it into perspective, leaving out the $300 deposit, two bunnings cylinders (9.8M3) would cost $258, while my annual cost for rent and one 10.3M3 fill is $232. It would not be too hard to eat up an E size cylinder if you are doing a reasonable amount of cutting or heating on a job. If you primarily silver solder or braze light materials, then an E size will last for ages.
    I understand that it is not practical in many cases to have a G size cylinder cluttering up your home workshop, but the comparison certainly shows that there is nothing free in this world and as OxxAndBert quite rightly said, you need to do the calculations and crunch the numbers.
    When I first started plating around with Oxy Acetylene thirty odd years ago, we had the choice of two suppliers locally and one of them did not really advertise their services, so they remained unknown to me for a few years. Now in the same market, we have at least 7 options, with 3 of those servicing the industrial sector as their primary business. I switched from BOC to Supagas in my workplace (saving a fortune), the BOC cylinders were collected on a Friday and I had the BOC rep on my door 8 AM Monday morning wanting to know why we had swapped and what he could do to win us back. That is how intense the competition can be in the gas market and that competition has driven prices down and I now pay less for gas than I did 30 years ago.

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