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  1. #1
    Join Date
    Jan 2004
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    Mackay North Qld
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    Default Close down and start up procedure for Oxy Acetylene plants

    Hi Guys
    Given one of our members has had an incident with an oxy Acetylene Set I think its timely to visit the close down and Start Up procedures.

    Shut Down and Start Up procedure for Oxygen Acetylene cylinders.

    Please bear in mind that an Oxygen cylinder can contain 2000 lbs of pressure.


    Shutdown

    Close both cylinder valves
    Bleed gas from hose and regulator systems - regulators should indicate zero
    Back out regulators
    System is shut down and regulators are unloaded
    Ensure torch valves are re closed.


    Start Up
    Check regulators are unloaded ,showing no pressure
    Slowly open each cylinder valve
    Slowly wind each regulator to its recommended operating pressure

    I hope it jogs memories and makes operators safer.

    Grahame

  2. #2
    BobL is online now Member: Blue and white apron brigade
    Join Date
    Feb 2006
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    Perth
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    5,586

    Default

    Grahame,

    Very good.

    It would be useful/helpful add the protocol for changing bottles to the above.

    Thanks

  3. #3
    Join Date
    Jun 2005
    Location
    Helensburgh
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    337

    Default

    And if an Acetylene bottle has been laid down always allow 30 minutes before using it.
    CHRIS

  4. #4
    BobL is online now Member: Blue and white apron brigade
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    Default

    Quote Originally Posted by Chris Parks View Post
    And if an Acetylene bottle has been laid down always allow 30 minutes before using it.
    Back in the 1970's I was told at least a couple of hours, but now see BOCs recommendation is
    [QUOTE]If the cylinder has been transported horizontally, place it in an upright position for 12 hours prior to use, or for at least as long as the cylinder has been laid flat. This will allow the acetone to re-settle within the cylinder.[/QUOTE]

  5. #5
    Join Date
    Jun 2005
    Location
    Helensburgh
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    337

    Default

    You could be right but I was told 30 minutes and it seems to work for me, mind you it was a long time ago that I did all my welding courses. I always wondered how the time was arrived at and I guess it was from on the job experience and not much more.
    CHRIS

  6. #6
    Join Date
    Apr 2019
    Location
    Adelaide
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    Default

    And label the outside of your shed/garage so that us firefighters know there is acetylene inside........

  7. #7
    Join Date
    Oct 2008
    Location
    Mole Creek
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    41

    Default

    Quote Originally Posted by Mk1_Oz View Post
    And label the outside of your shed/garage so that us firefighters know there is acetylene inside........
    Very good point! A lot of hobbyists wouldn't necessarily think of that.

    What should we label with? And any tips on where to source said labels?

    I don't use acetylene, as my budget doesn't allow it, but I do use oxy/LPG. Is it the acetylene that is especially dangerous in this situation? (i.e. worse than LPG.)

    Should we still have signage for the LPG? Or do you, as a fire fighter, assume that all garages/sheds are likely to have a BBQ gas bottle or two in there?

    Cheers,... Jon.

    Sent from my Lenovo YT3-X50F using Tapatalk

  8. #8
    BobL is online now Member: Blue and white apron brigade
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    Quote Originally Posted by Jonno_G View Post
    Very good point! A lot of hobbyists wouldn't necessarily think of that.

    What should we label with? And any tips on where to source said labels?

    I don't use acetylene, as my budget doesn't allow it, but I do use oxy/LPG. Is it the acetylene that is especially dangerous in this situation? (i.e. worse than LPG.)

    Should we still have signage for the LPG? Or do you, as a fire fighter, assume that all garages/sheds are likely to have a BBQ gas bottle or two in there?

    Cheers,... Jon.
    Speaking to an ex firey at the mens shed and he said any extra signage, even for something like compressed air, is helpful.

    The OHS requirement for signage at workplaces depends on the volumes of materials held in stock. At the mens shed the local Council (who own the building) said we needed signs for even the D cylinders and for more than 1L of any solvent. We had a fire resistant flammables cabinet (has a water jacketed walls and doors) but it was not certified so it could not be used.

    Ideally you'd have a sign for each potentially dangerous thing, or at least a generic sign
    The larger OHS compliant signs can be purchased at places like BOC and Blackwoods but they are pretty exxy.
    https://www.boc.com.au/shop/en/au/pp...y/safety-signs
    Bunnings has some generic signs that are a bit cheaper.
    https://www.bunnings.com.au/search/p...er&pageSize=60

  9. #9
    Join Date
    Mar 2011
    Location
    Adelaide
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    Default

    Quote Originally Posted by Mk1_Oz View Post
    And label the outside of your shed/garage so that us firefighters know there is acetylene inside........
    I had HazChem placards on the shed in a house I rented a while back. Council requested I remove them after a neighbour complained it made the neighbourhood look too ‘industrial’.

  10. #10
    Join Date
    Sep 2010
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    Lebrina
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    Quote Originally Posted by Mk1_Oz View Post
    And label the outside of your shed/garage so that us firefighters know there is acetylene inside........
    And that's why as firefighters we love farm sheds so much. Acetylene, paint, solvents, fuel, dynamite and granny's old undies, sheds on farms have it all! Even the shed fridge is exciting in a fire. Surround and drown from behind a large solid object.

  11. #11
    Join Date
    Apr 2019
    Location
    Adelaide
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    Default

    You can get signage from places such as BOC and from eBay.

    Acetylene is extremely dangerous (probably one of the most dangerous) to us for several reasons;
    1. it burns easily from a very lean ratio up to quite rich
    2. it is very energy rich and makes a big boom boom if the cyclinder gets hot enough to make the steel weak
    3. the cylinders are subject to self heating if subjected to a shock/drop or to heat. Once an internal reaction starts they have to be cooled for hours


    Any compressed gas cylinder is dangerous in a fire situation. Although oxygen itself does not burn, if an O2 cylinder fails the rapid availability of oxygen means everything else around it burns that much hotter and quicker (explosively). Other compressed gas cylinders will fail once the steel gets hot enough that it loses strength which could result in shrapnel or flammable gases escaping and burning. LPG can be nasty as it can result in what is called a BLEVE - boiling liquid expanding vapour explosion. Esentially the liquid (gas) inside boils increasing the pressure in the cylinder. If the cylinder is weakened or cannot hold the pressure it ruptures leading to a rapid vapourisation and burning (explosion) of the gas. Look it up on YouTube - "there was an earth shattering kaboom."

    Although a good firefighter will always assume there are nasties in a fire, having the knowledge that they are in a building AND the location within is fantastic info. Labelling for normal domestic quantities of anything (including LPG) is not necessary but oxygen and acetylene or above normal quantities of nasties is a great idea.

    While I am on my soap box, label for any open inspection pits you have in your workshops. Hard to see in the smoke.......

  12. #12
    Join Date
    Nov 2008
    Location
    Sydney
    Posts
    96

    Default

    Quote Originally Posted by Mk1_Oz View Post
    You can get signage from places such as BOC and from eBay.

    Acetylene is extremely dangerous (probably one of the most dangerous) to us for several reasons;
    1. it burns easily from a very lean ratio up to quite rich
    2. it is very energy rich and makes a big boom boom if the cyclinder gets hot enough to make the steel weak
    3. the cylinders are subject to self heating if subjected to a shock/drop or to heat. Once an internal reaction starts they have to be cooled for hours


    Any compressed gas cylinder is dangerous in a fire situation. Although oxygen itself does not burn, if an O2 cylinder fails the rapid availability of oxygen means everything else around it burns that much hotter and quicker (explosively). Other compressed gas cylinders will fail once the steel gets hot enough that it loses strength which could result in shrapnel or flammable gases escaping and burning. LPG can be nasty as it can result in what is called a BLEVE - boiling liquid expanding vapour explosion. Esentially the liquid (gas) inside boils increasing the pressure in the cylinder. If the cylinder is weakened or cannot hold the pressure it ruptures leading to a rapid vapourisation and burning (explosion) of the gas. Look it up on YouTube - "there was an earth shattering kaboom."

    Although a good firefighter will always assume there are nasties in a fire, having the knowledge that they are in a building AND the location within is fantastic info. Labelling for normal domestic quantities of anything (including LPG) is not necessary but oxygen and acetylene or above normal quantities of nasties is a great idea.

    While I am on my soap box, label for any open inspection pits you have in your workshops. Hard to see in the smoke.......

    I am having a problem with (2) for the simple reason that acetylene cylinders are by law manufactured with one or more fusible plugs which are designed to ensure that the scenario you describe does not take place. They will, however, explode if subject to severe shock. Most other gas cylinders have a safety rupture valve incorporated in the shut-off valve to cause venting before the pressure rises to a dangerous level. I would be interested to know under what conditions you have experienced the cylinder failures you have described.

    Chas.

  13. #13
    Join Date
    Apr 2019
    Location
    Adelaide
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    Default

    Thankfully I have not personnally not experienced total failures (other than car LPG cylinders letting go) but have seen a number of training videos covering it. The safety valve/fuse will vent a certain amount (that then burns causing issues of its own) but if the temperature rise is too fast the valve/fuse will not cope.

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