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  1. #27
    Quote Originally Posted by mark beiser View Post
    While I agree on principle, my experience in over a decade of refilling the smaller 1.25# RBK-6 mini tank, from a 20# cylinder I keep on my truck, is that the chances of over filling the tank are pretty much zero, unless you stick the smaller tank in the freezer for a couple of hours first.
    And on the six ponder the best you can get is about 3.25 lbs refilling from a larger tank... and that was pulling the MBK 6 into a vacuum .

  2. #28
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    Quote Originally Posted by hvac5646 View Post
    And on the six ponder the best you can get is about 3.25 lbs refilling from a larger tank... and that was pulling the MBK 6 into a vacuum .
    thanks .. what grade Co2 is everyone using ... bone dry grade is hard to find around here and more expensive than nitrogen. can't seem to get a straight answer from local gas supplier as to purity of food grade, industrial and medical grade purity?

  3. #29
    Quote Originally Posted by cy View Post
    thanks .. what grade Co2 is everyone using ... bone dry grade is hard to find around here and more expensive than nitrogen. can't seem to get a straight answer from local gas supplier as to purity of food grade, industrial and medical grade purity?
    Grade III CO2 is all you need. It is a welding shield gas.

    Google CO2 purity.

  4. #30
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    Quote Originally Posted by hvac5646 View Post
    Grade III CO2 is all you need. It is a welding shield gas.

    Google CO2 purity.
    welding shield gas is industrial grade, which is same as food grade according to folks that I've talking to.

    already googled up a storm on CO2 purity ... found all sorts of info, but needed to find out what everyone else is using.

  5. #31
    Quote Originally Posted by cy View Post
    welding shield gas is industrial grade, which is same as food grade according to folks that I've talking to.

    already googled up a storm on CO2 purity ... found all sorts of info, but needed to find out what everyone else is using.
    Sorry, i see what you mean. We buy our dry co2 at Proxair and Air gas. The purity is 99% to 98%.

    If you get that purity than you will be good.

    It's confusing, I know.

  6. #32
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    finally got a straight answer from an old timer at Airgas. he'd been selling Co2 industrial grade to folks for HVAC work for 30+ years. he said Bone dry grade would raise cost so high to be not worth it.

  7. #33
    Quote Originally Posted by cy View Post
    finally got a straight answer from an old timer at Airgas. he'd been selling Co2 industrial grade to folks for HVAC work for 30+ years. he said Bone dry grade would raise cost so high to be not worth it.
    Then you got the wrong guy or something else is wrong. WE buy by part number off Air Gas sit for the 57 lb tank.

    And it ain't high cost at all.

  8. #34
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    Quote Originally Posted by hvac5646 View Post
    Then you got the wrong guy or something else is wrong. WE buy by part number off Air Gas sit for the 57 lb tank.

    And it ain't high cost at all.
    what grade are you buying? Bone dry or plain ole industrial grade?
    Airgas guy is saying the industrial grade works just fine.

  9. #35
    When the Boss first started searching for a CO2 supplier he talked to Air gas. He found there was no consensus from the staff on what Bone Dry really is.

    So now we order by purity...98.9995 to 99.99995.

    But it always comes up the right part number on the invoice.

    I called them to day and the guy was clueless til I told him I wanted a Cat III to IV CO2 purity. He said it "was not in the system" and would call back wit a price.


    Still waiting.

    Like I said...its confusing. Boss knew what questions to ask to get us the right grade.

  10. #36
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    here's airgas Co2 technical description link to pdf ... bone dry is listed as 99.9%
    http://www.airgassgcatalog.com/catalog/pg013.pdf

    Linde food grade Co2 is listed as 99.9%
    http://www.google.com/url?sa=t&rct=j...45645796,d.b2I

    someone correct me if I'm wrong ... from what I've been told by Airgas folks ... most times difference between grades of Co2 is amount of time/effort to analysis gas for purity. have been told by different sources that industrial grade Co2 is identical to food grade Co2. differences are how container is lined.

    back to what the old timer at Airgas told me ... just use the industrial grade Co2 and quit worrying about it.

  11. #37
    Quote Originally Posted by cy View Post
    here's airgas Co2 technical description link to pdf ... bone dry is listed as 99.9%
    http://www.airgassgcatalog.com/catalog/pg013.pdf

    Linde food grade Co2 is listed as 99.9%
    http://www.google.com/url?sa=t&rct=j...45645796,d.b2I

    someone correct me if I'm wrong ... from what I've been told by Airgas folks ... most times difference between grades of Co2 is amount of time/effort to analysis gas for purity. have been told by different sources that industrial grade Co2 is identical to food grade Co2. differences are how container is lined.

    back to what the old timer at Airgas told me ... just use the industrial grade Co2 and quit worrying about it.
    See what i mean about confusing?
    Did he say as a braze purge or just to blow out drains?

    Around here food grade CO2 is soda fountain CO2.

    Industrial MIGHT come under the category of shield gas for welding and that is what we use.

    It is a Cat III rating.


    The Bone Dry is 9 PPB according to the chart you posted. I don't think nitro even comes anywhere near that.

  12. #38

  13. #39
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    Quote Originally Posted by hvac5646 View Post
    See what i mean about confusing?
    Did he say as a braze purge or just to blow out drains?

    Around here food grade CO2 is soda fountain CO2.

    Industrial MIGHT come under the category of shield gas for welding and that is what we use.

    It is a Cat III rating.


    The Bone Dry is 9 PPB according to the chart you posted. I don't think nitro even comes anywhere near that.
    airgas guy specifically stated his customers had been buying industrial grade Co2 for pressure testing HVAC systems. unless one is pulling a deep vacuum before pressure testing odds are there will be traces of moisture inside system anyways. Co2 has been used as a shielding gas for welding for decades.

    we are way over thinking this

    costs for a 50lb cylinder exchanged, industrial Co2 is about $50 ... vs 3x-4x higher costs for bone dry Co2 ..

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