Disposable Gas Bottles

Larger gas bottles still belong to Calor or Bottogas etc our dump stores them for return to the owners

Yes quite right. I don’t suppose it’s strictly legal cutting up old gas bottles to make wood fired stoves etc out of them?

Renting bottles is expensive, I use about 2 bottles of 2.2l per year at £35 per bottle disposable £70 per year.

Renting a 10 litre bottle is about £90/ year plus £65 for the gas - so gas for 2 years is about £245.

Something has recently changed making MIG quite expensive !!

Bottles are available from Poland - cheap, can't re-fill in France, UK, Lux,Germany etc !! also use non European gauges !! Have a look on e-bay for cheaper gas !

Bob

Speedy,

I too live in France and I reckon I know the type of bottle you are talking about. Being Argon and CO2 there is no explosion risk, but you can put your regulator valve back on but let the valve vent to the open air and leave it open for a bit. Often on the bottles like that you can remove the little valve on top. I used to use the disposable oxygen bottles that are used with the little Camping Gaz oxy propane set, till I bought an oxy acetelyne set 2nd hand. I have found that those bottles when empty are quite useful. I have used rings cut from them on my press. If you don't want them, after full depressurisation cut them in half and stick them in the same local recycling containers as your tin cans.

If you need more gas it is long term more economic to buy a small "real" bottle of gas, Air Liquide for instance and then go and change it for a refilled bottle. Yes there is the bottle outlay to begin with, but there are some French welding supply companies who sell on line. That is how I bought my argon bottle for my TIG set.

Paul

I don't pay rent Same as you don't pay rent for Calor

Edited By Dave Halford on 16/01/2021 17:17:39

Dispose of them? I call mine "materials for re-use"!! Also very usefull for bending sheet metal around to form a cylinder, but it you have a gas bottle of the right diameter, you already have a cylinder! All pressure vessels are marked with their SWP, which makes them even more usefull.

Phil

It's against most council by-laws. Litter bins are for litter not domestic rubbish. There have been cases of councils threating legal action aginst people putting addressed junk mail in them.

Robert G8RPI.

That is really bad advice and I'm surprised you repeated it here. Hazardous waste regulations are there for the protection of us, workers, the environment and future generations.
loose asbestos can be very dangerous. Depending on the exact type only tiny amount can cause health problems.

Robert G8RPI.

Yes I dont think I would knowingly throw asbestos in the rubbish bin as it is a risk to depot workers -- although I worked with the stuff for years on fullsize boiler and pipework lagging so probably already at risk myself.

Several of my dad's old marine engineer mates died from asbestos inhaled in engine rooms 30 years earlier. So it does happen.

Edited By Hopper on 17/01/2021 02:29:32

I reuse my old mig and other pressure bottles,when they are empty
i drill out each end, the paint seems a bit tough so i chuck them into the
wood burning stove and burn off the paint .
Seen here used as a water trap on the airline system and in the
next photo the adapter fitting is silver soldered in the top,
the supply comes in through the middle and exits about 2/3rd's
down via an elbow which spins the air inside the bottle.the air exits
though the top .a short piece of pipe at the bottom collects the
water to drain off.
Also used here in the photo as a refillable propane bottle for
model gas turbine starting about 75 % liquid gas filled.

Apart from that they are useful pieces of steel tubing ,why chuck them away.

John

Be careful repurposing second-hand pressure vessels because their pressure ratings aren't guaranteed. In particular disposable bottles are lightly made because they don't have to withstand the repeated inflations and deflations that cause metal fatigue.

Rechargeable pressure vessels are stronger and have a limited life after which they are withdrawn before they become dangerous.

As always level of risk depends on the circumstances. Occasional recharging of a small second-hand bottle at reduced pressure in a home workshop is much safer than repeated recharging to full pressure of a large time-expired bottle in a busy factory.

As a matter of interest, does anyone know what happens when an old bottle fails? Copper boilers as used on 'our' steam locomotives leak and split rather than explode because the copper and joints both give way gradually. Steel is much stronger than Copper but likely to shatter. So although steel vessels hold a lot more pressure they fail in a blink and the pent up energy is released all at once in an actual explosion. I vaguely remember reading gas cylinders are weakened at the neck so the top blows off and they vent upwards. This in expectation they are stored vertically bottom down and can't take off like a rocket.

Anyone tried doing a hydraulic test on an old disposable gas bottle to see how safe they actually are? Harder to test than a locomotive because gas pressures are higher, for example Propane about 200psi and Carbon Dioxide 900psi. Argon could be at 3500 psi.#

Dave

# This implies it's safer to repurpose an Argon cylinder for reduced pressure work than one that contained propane!

Normal propane bottles are tested to about 350psi. Butane is quite low, in fact on a freezeing day butane will not vapourize. BOC argon or oxygen are filled to 3000psi so test will be about 4500psi. If the bottle is NOT marked with it's test pressure treat with caution. SODs assumption does not hold, as the limit is the design pressure NOT the type of gas. A compressed gas can be charged to a suitable pressure, whereas a liquified gas is dictated by the vapour pressure. Butane, propane are liquified gases, oxygen, argon are commpressed, NORMALLY ! Noel

Yeah, but no but yeah in that the design pressure is decided by the type of gas. Noel makes a good point though, because re-using containers needs a certain amount of thought. How does the original design relate to the cylinders new job?

Nitrogen offers an extreme example. Liquid nitrogen is stored at low-pressure in a sort of giant thermos flask with a vent to stop pressure building inside as it warms up. It lasts as long as it stays cold. Compressed Nitrogen is stored in a heavy steel cylinder designed as Noel says to be charged up to a design pressure. The cylinder doesn't need to be well insulated, and there's no vent. Same gas stored in two completely different ways.

Don't mix them up! Filling a steel cylinder intended for compressed nitrogen with the liquid and screwing the top on is extremely dangerous because the pressure inside will certainly rise well beyond design capacity as the liquid evaporates. Bang. Likewise, filling a thermos flask with compressed Nitrogen is a waste of time unless the safety vent is blocked. And if the vent is blocked, the thermo flask will go pop...

I'm not aware of any Model Engineering injuries due to pressure vessel failures. I guess partly because we know enough not to be completely daft, and partly because small-scale accidents tend not to be scary dangerous. Plenty of pressure related fatalities in industry though!

Dave

Posted by SillyOldDuffer 17/01/2021 10:41:32

Be careful repurposing second-hand pressure vessels because their pressure ratings aren't guaranteed. In particular disposable bottles are lightly
made because they don't have to withstand the repeated inflations and deflations that cause metal fatigue.

Rechargeable pressure vessels are stronger and have a limited life after which they are withdrawn before they become dangerous.

As always level of risk depends on the circumstances. Occasional recharging of a small second-hand bottle at reduced pressure in a home workshop
is much safer than repeated recharging to full pressure of a large time-expired bottle in a busy factory.

As a matter of interest, does anyone know what happens when an old bottle fails? Copper boilers as used on 'our' steam locomotives leak and split
rather than explode because the copper and joints both give way gradually. Steel is much stronger than Copper but likely to shatter. So although steel
vessels hold a lot more pressure they fail in a blink and the pent up energy is released all at once in an actual explosion. I vaguely remember reading
gas cylinders are weakened at the neck so the top blows off and they vent upwards. This in expectation they are stored vertically bottom down and
can't take off like a rocket.

Anyone tried doing a hydraulic test on an old disposable gas bottle to see how safe they actually are? Harder to test than a locomotive because gas
pressures are higher, for example Propane about 200psi and Carbon Dioxide 900psi. Argon could be at 3500 psi.#

Dave

# This implies it's safer to repurpose an Argon cylinder for reduced pressure work than one that contained propane!

-------------
The Bottles mentioned in my last post have a maximum rated pressure of 165 bar
2,400 psi ,i would not consider these to be lightly made ,if you cut one
open the wall thickness is at least 3/32 inch or greater.

Pressure of propane gas at 20 deg C is 7 to 9 bar.
Of course if you happen to live in Death Valley you would need to observe that the gas
pressure would increase ie at 50 deg C is 15 to 19 bar.
Less for butane however at 50 deg C butane pressure rises to 3 to 7 bar, 103 psi,
the throw away camping gas containers that butane is supplied in is 0.017 inch
wall thickness.

Air line pressure used in these mig containers is about 115 psi .
Unless you make a pig's ear of soldering on the fittings these things are no less
safe than using copper for the pipework or even plastic and it is as well
to point out the the the supplied air tank with the compressor is a great deal
thinner than these mig bottles.

When the first model gas turbines were sold by JPX in France
these run on propane and used an aluminium container as a fuel tank a
similar size to the mig gas type bottles but very much thinner ,having had
the opportunity to repair one of these engines and examine these parts
the container for the gas was so thin you could easily press in the
sides when empty.

John

One other factor to bear in mind is volume. The stored energy and thus hazard depends on both pressure and volume. This is reflected in the regulations. There is a lower limit for gas pressure vessels of 250 Bar/Litre below which the regulations don't apply (note: steam is specfically excluded from this exemption).
When used at airline pressures most disposable cylinders are below the linit e.g. less than 2.5 litre volume at 150PSI (10 Bar).

Robert G8RPI.

For a starter, I doubt it’s ‘hard paint’ that the woodburner solved - I would suggestbit has been heat treated, so softened! Most likely the bottles are hardened sufficiently to avoid puncture by mechanical damage?

Liquified fuel gases generally (hopefully) fail vertically so the fuel is gassed off before the thing actually explodes in all directions?

Full scale steam boilers have exploded, killing people in the blast (and the expanding steam?). Only twenty years ago, there was an occurrence at Medina. They found the PRV likely did not work at 250psi (that would still be less than the melting point of the fusible plug). One part was found to be only 87 thous thick (from 3/8&rdquo.

Precharged pneumatic airguns operate at up to 3000psi (200Bar) in the cylinder.

A normal pop bottle will withstand as much as 100psi - over 6 Bar - and more. As do some glass bottles.🙂 (champagne)

Problems generally only arise when the safe working pressure is exceeded or items have degraded.

Plastic bottles placed in the re-cycle bin should not have their caps fitted - for two reasons safety and the volume collectable by the bin lorries (they hydraulically compress the waste to maximise the rubbish load).

Of course, some could make a pig’s ear of soldering, too.🙂

Anyone know the pressure at which compression fittings are no longer deemed safe? I’ve seen them fitted on vehicle hydraulic braking systems before now, but I would only use the proper flared pipe fittings in such an application.

Sort-of relevant to the thread: I have an argon/CO2 bottle with my MIG set and it says "Do not let the contents escape into the atmosphere" or words to that effect (I can't check it at present).

Given that the gas was obtained from the atmosphere in the first place, what's that all about?

George B.

George. B So what happens when you pull the trigger on your MIG set ?

G.B,

It may refer to that part of the atmosphere one might be breathing at the time? Confined spaces or similar?

Ummm. The gas... escapes... into the... atmosphere......??