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20th May 2020, 08:25 PM #1
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
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20th May 2020, 09:33 PM #2Member: Blue and white apron brigade
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Grahame,
Very good.
It would be useful/helpful add the protocol for changing bottles to the above.
Thanks
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20th May 2020, 10:44 PM #3Golden Member
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And if an Acetylene bottle has been laid down always allow 30 minutes before using it.
CHRIS
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20th May 2020, 10:53 PM #4Member: Blue and white apron brigade
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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]
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20th May 2020, 11:14 PM #5Golden Member
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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
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20th May 2020, 11:49 PM #6Golden Member
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And label the outside of your shed/garage so that us firefighters know there is acetylene inside........
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23rd May 2020, 11:49 AM #7Intermediate Member
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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
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23rd May 2020, 02:06 PM #8Member: Blue and white apron brigade
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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
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23rd May 2020, 10:58 PM #9Most Valued Member
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23rd May 2020, 11:10 PM #10Most Valued Member
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24th May 2020, 01:22 AM #11Golden Member
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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;
- it burns easily from a very lean ratio up to quite rich
- it is very energy rich and makes a big boom boom if the cyclinder gets hot enough to make the steel weak
- 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.......
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24th May 2020, 09:11 PM #12Senior Member
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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.
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25th May 2020, 01:05 AM #13Golden Member
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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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