oxygen refills

[brightspark]

can anyone remember sumone selling a decantering kit for filling small bottles of oxygen from larger bottles in exchange and mart and are they still available

 

[fridgeman999]

Hi, Do not know about exchange and mart, but Microflame do small cylinders and a short refill hose for a big cylinder. Used them 3 or 4 years ago, used to scare the s### out of me as the small cylinders got hot in your hand when filling them.
Try a refrigeration, or HEVAC supplier.
Good luck.
Chris.

 

[brightspark]

thanks for the info will try them

 

[eil]

These used to do ones for the microflame and the portaflame you could give them a ring.
page 12 near the bottom
http://www.srw.co.uk/pdf/SRW/Tools_Mini_cat_08.pdf

 

[Weldingartisan]

Wow, that sounds a risky business! You obviously don't fill via the regulator, so you are playing with up to 300bar pressure. One spot of oil or grease and you'll certainly be kissing your ass goodbye. Are those small cylinders tested for a 300bar charge? W/A

 

[brightspark]

lol the idea behind it is to get a small portapack oxy bottle and refill of sumone with full size bottle who has an acount the outcome being no rent can only asume the transfer pipe is hydraulic hose with screwed ends to fit oxy bottle not that i fancy experementing with em though

 

[Paul.]

You might want to read through this thread, especially post 12

 

[eil]

I think the small bottles are 200 bar but not sure and they do go warm when you fill them with the de-canting hose also the hose has a restriction kind of set-up on it with just a very small hole I guess that is to prevent overcharging I should imagine.

 

[the snooper]

also the hose has a restriction kind of set-up on it with just a very small hole I guess that is to prevent overcharging I should imagine.

i would think the restriction is to slow down the oxy may be like some fuels fill up too fast and it self ignites

 

[Weldingartisan]

Sorry guys, I think I'll stick to paying the extra and let BOC charge my cylinders. W/A

 

[brightspark]

gonna give srw a ring tomorrow find out what the score is i hope

 

[brightspark]

hydraulic hose runs up to 700 bar so 300 is quite insignificant will.keep debate going

See http://www.mig-welding.co.uk/forum/showpost.php?p=171979&postcount=20

 

[londonsean69]

I've seen O2 whips catch fire, not fun. It has killed a few people as well.

Cleanliness is above godliness when it comes to transfilling O2.

The actual process is not overly difficult, or dangerous, but you really must have the proper kit.

The small hole isn't to stop overcharging, it is a flow restirctor, designed to stop you putting too much in too quick. When mixing nitrox (oxygen enriched air) in the dive shop, our rule of thumb was "If the bottle gets hot, you are filling too quick".

I think something like 4 bar per minute is considered "safeish". It can go wrong, with devastating consequences (ask NASA about oxygen fires) but if done correctly is not really much more dangerous than turning on the Oxy on an Oxy Acet rig (the presure wave inside the bottle can, in theory, go pop - I was told this on my Oxygen Provider Instructor Course)

If you are ever bored, and want to see why things burn so well in O2, take a massive breath of pure O2, then exhale through a lit cigarette

Sean

 

[londonsean69]

hydraulic hose runs up to 700 bar so 300 is quite insignificant will.keep debate going

Thats a pretty scary statement.

On dive kit, HP air is 200-300 bar, and the hole for the pressure guage is about 0.5mm, when the O-ring lets go you know all about it.

They test dive tanks in a liquid bath, filled with liquid, because using gas would be too dangerous if it let go

300 bar is 300 times atmospheric pressure - if that lets go near your ear you may well need a hearing aid.

If a lorry tyre bursts it can kill someone, and they are at about 6 bar (90 PSI)]

You think 50 times that pressure is insignificant?? Also, is 700bar the burst pressure, or the safe working pressure?
Our transfill hoses were 232 bar working pressure, 1200 bar burst pressure.

Eventually, even they let go, with age, an UV deterioration

Sean

 

[brightspark]

srw sells the microflame torch and bottle kits with refill hose included or buy refill transfer hose for £54 down side is the pipe fits boc large bottle but the other end only fits microflame bottle limiting what u can fill

 

[eil]

Reading this thread as well as the others got me thinking and as I am home waiting for an appointment with the flu jab I went and had a look on the ones Ive got all bought legally over the counter. the Portaflame on the left I have one 4,67L cyl and two 1.7L cyl`s and the microflame on the right. looking at the 4.67L cyl it states TP 247 bar and CP150 bar, the smaller cyls the 1,7L have TP 200 bar and CP122 bar, the microflame on the right which is also 1.7L has a TP of 319 bar and a cp of 185 bar. which would suggest that only the microflame would hold up to the large oxy bottle pressure, which would suggest why you cant get hold of the de-canting hose that is on the left in the pic below.

 

[brightspark]

where did u get the hose on the left from sell me it :

 

[mtt.tr]

Hi, Do not know about exchange and mart, but Microflame do small cylinders and a short refill hose for a big cylinder. Used them 3 or 4 years ago, used to scare the s### out of me as the small cylinders got hot in your hand when filling them.
Try a refrigeration, or HEVAC supplier.
Good luck.
Chris.

I did some work in a dive shop and heat in cylinders when filling them is extremely dangerous as it damages the bottle the reason for it though is because they are being filled to quick but to resolve it fill them in a barrel of water keeps them nice and cool

But try to keep cylinder cool when filling them it can be very dangerous as it weakens the bottlle

 

[londonsean69]

I spent years filling SCUBA cylinders, and am a qualified Gas Blender instructor with DSAT (Diving Science & Technology) - Trimix, Nitrox, plus transfilling of Argon, as well as being a service technician (all ratings now lapsed due to me giving up diving)

I never fill cylinders in water. I give them a quick dunk to check for leaks, but filling them in water is pointless, unless they are tiny.

Basically, as a gas is compressed it heats, and cools as it expands (Adiabatic heating). This can be countered by keeping the cylinder submerged, but you have to ensure that the cylinder is totally submerged, and ideally in water that is constantly circulting/being topped up, otherwise, after a filling session, the water is quite warm.

A 12l bottle can get so hot it is uncomfortable to hold, if you do a fast fill.

Also, a lot of cylinders are filled with water, although the neck and valve is kept out of the water. This can lead, especially in certain older aluminium cylinders), to differential expansion, thus leading to cracking around the neck and valve stem, with nasty consequences.
O2 should be filled at approx. 3 bar per minute (45-50psi), this helps to reduce the risks associated with heating of O2, but it will never eliminate them.
It is also imperitive to ensure everything is kept O2 clean, using special lubricants and materials, UK dive shops tend to recommend O2 cleaning every year, but only for kit that will come into contact with >40% oxygen.

Do not underestimate the power of any compressed gas, a 12l tank has the equivalent stored energy of about 300g of TNT. If that lets go, you will know about it

Sean

 

[English Steve]

hydraulic hose runs up to 700 bar so 300 is quite insignificant will.keep debate going

This statement is untrue and is potentially very dangerous - please delete that post Brightspark.

SOME hydraulic hose will operate at higher pressures, but NOT MANY. A good number of single-wire and two-wire hydraulic hoses are rated at less than 150 bar when new, and if used for decanting will fail.
We manufacture hydraulic hose assemblies, and do not have the required equipment for 700 bar - not many manufacturers do.