Page 1 of 3 123 LastLast
Results 1 to 15 of 31
  1. #1
    Join Date
    Mar 2017
    Location
    USA
    Posts
    29

    Default Transfer compressed gas from a full cylinder to an empty one?

    Something that's reasonable for a D.I.Y. , with simply the right connections, or more along the lines of
    "are you (edited to "flaming nuts" ) nuts ?!" . I'm talking hypothetically about having one cylinder full of , say, Oxygen, and wanting
    to put some of it into an empty cylinder . Would it just be a matter of connecting the two tanks, with a valve in the middle, and then
    opening the valve to equalize the pressure between the two ?

  2. #2
    Join Date
    Jan 2011
    Location
    Far West Wimmera
    Age
    63
    Posts
    4,049

    Default

    Quote Originally Posted by dogboy View Post
    Something that's reasonable for a D.I.Y. , with simply the right connections, or more along the lines of
    "are you fleecing nuts ?!" . I'm talking hypothetically about having one cylinder full of , say, Oxygen, and wanting
    to put some of it into an empty cylinder . Would it just be a matter of connecting the two tanks, with a valve in the middle, and then opening the valve to equalize the pressure between the two ?
    Here we are again.

    Around here "fleecing nuts" means pinching nuts.

    Are you flaming nuts make more sense.

    There was a thread about this a while back. I can't find it. Maybe someone else can. I believe most people were of the impression that it was best avoided.

    To transfer gas such as LPG (propane) the delivery cylinder has to have liquid at the outlet. The ones used for this have a tube down to the bottom of the cylinder. You don't need an extra valve. There is one on each cylinder. Joining the 2 would work as you say providing that only liquid was involved. With oxygen you must not get any oil at all near the oxy. Compressed oxygen can explode without a spark in the presence of oil.

    Years ago a mate took a hydraulic cylinder to a hydraulic shop for them to do something to. They had to take it out the back to extend the ram. After waiting some time he felt he should check what they were doing for some reason. He walked out the back in time to see them just about to crack the valve on an oxy cylinder hooked up to the ram. They had taken so long because the argon cylinder normally used for this was empty. He nearly had kittens on the spot, but managed to stop them before the launch was initiated.

    Dean

  3. #3
    Join Date
    Mar 2017
    Location
    USA
    Posts
    29

    Default

    Quote Originally Posted by Oldneweng View Post
    Here we are again.

    Around here "fleecing nuts" means pinching nuts.

    Are you flaming nuts make more sense.

    There was a thread about this a while back. I can't find it. Maybe someone else can. I believe most people were of the impression that it was best avoided.

    To transfer gas such as LPG (propane) the delivery cylinder has to have liquid at the outlet. The ones used for this have a tube down to the bottom of the cylinder. You don't need an extra valve. There is one on each cylinder. Joining the 2 would work as you say providing that only liquid was involved. With oxygen you must not get any oil at all near the oxy. Compressed oxygen can explode without a spark in the presence of oil.

    Years ago a mate took a hydraulic cylinder to a hydraulic shop for them to do something to. They had to take it out the back to extend the ram. After waiting some time he felt he should check what they were doing for some reason. He walked out the back in time to see them just about to crack the valve on an oxy cylinder hooked up to the ram. They had taken so long because the argon cylinder normally used for this was empty. He nearly had kittens on the spot, but managed to stop them before the launch was initiated.

    Dean
    Okay, no more Experimental Australian Vernacular for me ! I came to this forum to stay out of trouble, not to get into more .

    So, how about this ? : instead of a high pressure transfer, one with a normal regulator on the full bottle, and therefore a controlled release of, say, 75 p.s.i. into the empty bottle ?

  4. #4
    Join Date
    Jan 2011
    Location
    Far West Wimmera
    Age
    63
    Posts
    4,049

    Default

    Nope. The regulator releases gas, not liquid. Don't put liquid thru the regulator. It is not designed for it. It has to be a liquid / liquid transfer. You can turn the delivery cylinder upside down to get the liquid out, but playing with this sort of thing has the potential to be very dangerous. I have done this sort of thing with LPG a number of occasions at my previous job. With LPG there is a little valve to release pressure in the receiving cylinder. When liquid comes out you stop the transfer and close the valves. This is how it done at the hardware shop when they fill your cylinder. I am not sure about welding etc gases. Auto LPG uses a pump to increase the delivery pressure.

    Dean

  5. #5
    BobL is offline Member: Blue and white apron brigade
    Join Date
    Feb 2006
    Location
    Perth
    Posts
    7,182

    Default

    I don't recommend doing this especially for flammable gasses, but recently I experimented transferring CO2 liquid from a D & E size cylinder into Soda Stream bottles (~400g of CO2) and thought you might like to hear about what happened.

    After filling about a dozen small bottles and striking a raft of problems I decided to buy a D bottle size cylinder and put it under the house and plumb the gas up through the floor and the kitchen cupboard and direct to the Soda Stream soda water maker. This works well.

    After this I still did a few transfers for my son's Soda Stream bottles but I got tired of dragging my cylinder out from under the house so for Xmas last year I bought him his own cylinder and transfer line. We put his D cylinder on the bottom shelf of a tall kitchen cupboard and his Soda Stream maker on the shelf above - also works well.

    As Dean says you need to use the "transfer from" cylinder that has a "syphon tube" that goes to the bottom of the cylinder. The alternative is to tip the cylinder upside down. To do his safely you need a proper stand that will safely hold the bottle upside down. I cannot even imagine doing this for a large cylinder.

    I made this stand up, and as a stand it worked well.
    Tip the stand over, insert bottom of cylinder into the base ring and move and lock the U shaped collar down to hold the cylinder in place.
    The collar was able to hold it the cylinder by itself but for extra security a chain was added fully wrap around the collar. An extra chain was used to hold the stand up agains something even more secure.

    The small bottle then pokes out at right angles to the other cylinder.

    IMG_6612.jpg

    Using the right connections incorporating a pressure relief valve on the transfer line was able to get about 200g of CO2 into the small bottle - this is about half the amount of liquid it can hold. Then I realised the peculiarities of CO2 restrict the amount that can be transferred on a single pass. I then looked up the pressure/temp profile of CO2 and using a freezer to precool the small bottle I eventually was was able to fill it (i.e. 400g) of CO2 in two passes.

    The fill rate was still hit and miss and the whole process was filled with headaches and woes and DANGER - especially for a newby.
    I list these to show how dangerous this sort of thing can be AND bear in mind this is CO2 - so non-flammable.
    Some of these problems are peculiar to the behaviour of CO2 but other gasses will have their own difficulties.

    Even though it's non-flammable I decide to do the transfer outside in case I gassed myself, and just as well I did

    On the first transfer I did not fully open the relief valve and when I unscrewed the small bottle the CO2 had been transferred into, there was still pressure in the line which generated a loud BANG! and the small bottle shot across the back yard. Most irritatingly the chunky O-ring also shot out of the connection and I never found it again. Even though I was outside, the bang was ear-ringing to the point of hearing loss for about 5 minutes and that's when I decided to wear muffs during the transfer. This is not good because you do want to hear the faint hissing sound to know when transfer has stopped.

    You are dealing with liquid CO2 so it's cold and appropriate PPE is needed to handle the fittings and bottles. I've see folks doing this with bare hands but they must not value their hands as much as I do.

    By pre-cooling the receiving bottle too much, it is possible to over fill it with too much liquid. If you put too much liquid into the bottle then when the bottle warms up to room temp the CO2 liquid expands and ........ This means the bottles need to be weight using reasonably accurate scales and if too much is transferred the excess CO2 must be bled off.

    The process always involves gas loss especially if you over fill. Using a short transfer line helps but you still lose.

    Then you can never get the last 1/6th of the CO2 liquid out of the cylinder as liquid because at that point ALL the CO2 is as a gas so all you are transferring is a smaller and smaller amounts of of gas. This is ferkingly irritating because if you just have gas you have to keep changing the soda syphon bottle over and over, because as a bottle full of gas only lasts 1/6th as long as one full of liquid. I quickly realised that this would wreck the threads.

    Some of the small Soda Syphon small bottles have a valve that does not permit transfer - there are U-tube vids sowing how to modify the valve but that's when I decided to go for a plumbed in system.

    The direct plumbing method is MUCH better. No noise, no gas loss and it works a treat - Soda water for ~8c/litre versus 33c/L for small cylinder exchange. A cylinder lasts us about 3 months in summer in 6 months in other season. I don't drink grog but do go through a lot of soda water.

    Would I recommend this sort of transfer to anyone - no - leave it to the experts, especially for large cylinders of flammable stuff.

    I should add I have a lot (35 years) of experience in transferring liquid nitrogen between containers but the greatest pressure this was under was about 20 psi. Have lots of stories bout this - not all about me but I think I have written enough.

    .

  6. #6
    Join Date
    Dec 2013
    Location
    San Antonio, Texas, USA
    Posts
    17

    Default

    No. Take the empty bottle to a gas depot and have them fill it. If they refuse buy a new filled bottle. DOT makes transportation of a user-refilled compressed gas cylinder a Federal offense for a reason - it's too dangerous.

    N.B. The last time I gave advice against mishandling of compressed gasses the resultant disregard of my words was near fatal.

    I told a guy I knew about acetylene and how it really really doesn't like to be pressurized above 15 p.s.i. or so.

    He chose to disregard my advice and have some fun so he took a bit of calcium carbide and water, placed both into a pressure cooker in his mom's backyard, closed the cooker lid and then put the whole incipient catastrophe on a camp-fire to see what would happen. He ended up in the hospital for eight weeks because when the thing went off the lid struck him a glancing blow to the face removing the teeth from one side of his head, broke his jaw and the orbit of his eye. The cooker lid came to ground about three blocks away. Don't trifle with compressed gas, especially things like oxygen and acetylene.
    The stone age didn't end because the cavemen ran out of stones...

  7. #7
    Join Date
    Jan 2011
    Location
    Far West Wimmera
    Age
    63
    Posts
    4,049

    Default

    Quote Originally Posted by rob streeper View Post
    No. Take the empty bottle to a gas depot and have them fill it. DOT makes transportation of a user-refilled compressed gas cylinder a Federal offense for a reason - it's too dangerous.
    Do they specify "user filled"? How can they tell?

    Not relevant in the OP's case tho. He would need to check local regulations.

    I know they are getting stricter on transport of compressed gasses. When I bought my cylinder of argon I questioned putting it in the rear of my wagon. I had the trailer at the time for other things, but it is not easy to secure a cylinder in a normal trailer. The salesman said they don't worry about it.

    Dean

  8. #8
    Join Date
    Dec 2013
    Location
    San Antonio, Texas, USA
    Posts
    17

    Default

    Yes, the law says something about user filling. How they tell if the cylinder is user filled I don't know. I do know it's an offense as you find it printed on small propane cylinders sold here. The OP indicates US residency and DOT = Department of Transportation.
    The stone age didn't end because the cavemen ran out of stones...

  9. #9
    Join Date
    Mar 2017
    Location
    USA
    Posts
    29

    Default

    Well, thanks for all the input, gents. I don't want to be an Unofficial Honorary Darwin Award Nominee again ,
    so I will dutifully heed the warnings I like my face , and appendages , etc.

  10. #10
    BobL is offline Member: Blue and white apron brigade
    Join Date
    Feb 2006
    Location
    Perth
    Posts
    7,182

    Default

    Quote Originally Posted by dogboy View Post
    Well, thanks for all the input, gents. I don't want to be an Unofficial Honorary Darwin Award Nominee again ,
    so I will dutifully heed the warnings I like my face , and appendages , etc.
    a wise decision DB.

    I forgot to add that a very technically minded and experiences friend of mine ended up doing the same thing. i.e. started out wanting to just transfer to Soda Stream bottles and ended up plumbing in the cylinder - but he doesn't have his under his house he has it in the kitchen. He still fills some Soda Stream bottles from time to time but that so he doesn't have to carry the cylinder to his holiday home in the country. I also made him a similar stand. When his cylinder reaches the 1/6th left mark he uses up the remaining gas on his soda stream dispenser. In the meantime if he needs more bottles he just exchanges the ones he has.

  11. #11
    Join Date
    Feb 2003
    Location
    formerly from Sydney (north of The Harbour), NSW, Oz
    Age
    68
    Posts
    306

    Default

    Quote Originally Posted by Oldneweng View Post
    Do they specify "user filled"? How can they tell?
    probably by looking for a tag, or stamp, installed by the filling station.
    regards from Canmore

    ian

  12. #12
    Join Date
    Jan 2011
    Location
    Far West Wimmera
    Age
    63
    Posts
    4,049

    Default

    Quote Originally Posted by rob streeper View Post
    Yes, the law says something about user filling. How they tell if the cylinder is user filled I don't know. I do know it's an offense as you find it printed on small propane cylinders sold here. The OP indicates US residency and DOT = Department of Transportation.
    Oops. Gotcha. It was your location I missed. Teach me for being a smart ar5e.

    Quote Originally Posted by ian View Post
    probably by looking for a tag, or stamp, installed by the filling station.
    Not seen that in Oz. I have filled cylinders legally at work. We also filled fork lift cylinders the same way. We did have some training, after we had been doing it for years. It is dead easy. No pun intended. I guess the concern could be over filling and maybe not getting the cylinders tested on time not to mention sheer stupidity. Not sure of the position in US tho.

    Dean

  13. #13
    Join Date
    Jan 2004
    Location
    Mackay North Qld
    Posts
    6,446

    Default

    Oh good,
    All sorted out and and rightfully so
    Intervention was not necessary.
    Seriously this topic comes up from time to time usually as the poster is claiming a money saving measure to decant high pressure gas to avoid a cylinder rental..


    Dean I am sure fork lift propane cylinders are no where near the pressure of welding gases and as you have had training in doing so, therein lies the key.

    You may have seen the BLEVE film used in gas training ,even the lowly propane can pack a wallop.

    Some amateurs just think they are gifted and it is just not so without the knowledge and training necessary. Filling HP cylinders is carried out using trained operators and approved equipment not some lash up cobbled together to do the one job.

    Even U tube can't help the terminally stupid who may not understand the potential differences in practice and regulations between US and the rest of the world as far as gases go.


    Grahame

  14. #14
    Join Date
    Jan 2016
    Location
    Wodonga Vic
    Age
    38
    Posts
    633

    Default

    Quote Originally Posted by BobL View Post
    After filling about a dozen small bottles and striking a raft of problems I decided to buy a D bottle size cylinder and put it under the house and plumb the gas up through the floor and the kitchen cupboard and direct to the Soda Stream soda water maker. This works well.
    .
    I like this idea, Do you have a CO2 detector installed in the house, do you feel the need for one?

  15. #15
    Join Date
    Aug 2008
    Location
    near Rockhampton
    Posts
    6,216

    Default

    Quote Originally Posted by Grahame Collins View Post
    Oh good,
    All sorted out and and rightfully so
    Intervention was not necessary.
    Seriously this topic comes up from time to time usually as the poster is claiming a money saving measure to decant high pressure gas to avoid a cylinder rental..


    Dean I am sure fork lift propane cylinders are no where near the pressure of welding gases and as you have had training in doing so, therein lies the key.
    Welding gasses are just gasses are they not? Hence th every high pressures in the bottle.

    LPG is a liquid as it liquefies at a lower pressure then say oxygen.
    Gold, the colour of choice for the discerning person.

Page 1 of 3 123 LastLast

Similar Threads

  1. compressed aiir powered grease gun
    By BobL in forum METALWORK GENERAL
    Replies: 5
    Last Post: 21st May 2015, 02:02 AM
  2. A thread I posted is empty.
    By moofactory in forum FORUMS INFO, HELP, DISCUSSION & FEEDBACK
    Replies: 1
    Last Post: 17th Sep 2012, 02:32 PM
  3. Transfer screws and Transfer Punches
    By Com_VC in forum METALWORK GENERAL
    Replies: 6
    Last Post: 27th Feb 2010, 09:13 PM
  4. Post Empty???
    By johnomg in forum FORUMS INFO, HELP, DISCUSSION & FEEDBACK
    Replies: 3
    Last Post: 6th Oct 2009, 01:26 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •