gas bottle filling problem

Bosun Higgs

Bosun Higgs

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Doing the usual pre season refilling on my camping gas bottles ( done in the open air, cylinders carefully weighed, care taken) I found that one cylinder would not fill past about 50%. Its empty weight was the same as my other cylinders and its easy to measure accurately the weight of gas that has gone in. First thought was maybe some water in it ( its the first time I have re-filled this particular cylinder so I dont know its history) but that wouldnt work since liquid water is heavy.

So any ideas? Why wont this cylinder refill when all the others both before and after this one filled normally.
 
Bosun Higgs said:
Doing the usual pre season refilling on my camping gas bottles ( done in the open air, cylinders carefully weighed, care taken) I found that one cylinder would not fill past about 50%. Its empty weight was the same as my other cylinders and its easy to measure accurately the weight of gas that has gone in. First thought was maybe some water in it ( its the first time I have re-filled this particular cylinder so I dont know its history) but that wouldnt work since liquid water is heavy.

So any ideas? Why wont this cylinder refill when all the others both before and after this one filled normally.
Click to expand...

how do you do that then??:confused:
 
why don't you buy " camping gaz" or change to other type regulator if price is to much for camping gaz unless you are filling of auto gas of course

it could charge different due to temp and if you charge and the gas transfers boiling rather than liquid as you may well known you must not fill from auto gas to cylinder and you have no auto shut off or pressure relief valve
If you FIT a cylinder in you boot with a quick release fittings and fit it a relief valve and auto shut unit in the line then when you get to boat you can unhook your tank out of car boot and place it in the lpg boat system ... and stay legal and safe
 
paul-essex said:
why don't you buy " camping gaz" or change to other type regulator if price is to much for camping gaz unless you are filling of auto gas of course

it could charge different due to temp and if you charge and the gas transfers boiling rather than liquid as you may well known you must not fill from auto gas to cylinder and you have no auto shut off or pressure relief valve
If you FIT a cylinder in you boot with a quick release fittings and fit it a relief valve and auto shut unit in the line then when you get to boat you can unhook your tank out of car boot and place it in the lpg boat system ... and stay legal and safe
Click to expand...

The OP is probably refilling Camping Gaz cylinders from a large Calor butane cylinder. Its a well known trick if the gas locker wont take Calor cylinders and one does not want to pay the stupid price of C.G. refills.
 
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Then again those of us who've seen a boat explode and burn to the waterine after a snag with a gas bottle are happy to take precautions like one piece gas pipes, gas detectors with alarms and stumping up a few quid to have replacement bottles filled ! :rolleyes:
 
We've drifted from Bosun's original question about a particular cylinder not filling. I'm GUESSING that this cylinder is full of air (maybe even a faulty valve?) that because it doesn't compress easily is preventing the fill. With some butane in the cylinder have you tried venting it and then trying again??
 
VicS said:
Not so sure about that.
Autogas is 90% propane. It might not be wise to fill a CG cylinder, intended for butane, with Autogas or propane due to its higher pressure
Click to expand...

A pedant (with an LPG car) writes:

You are quite right that Autogas is mostly propane, but the actual composition varies with time of year. They put a bit more butane in when it's warmer, I believe, to decrease the volatility.
 
the pressures is not that much different its the icing point mainly that sets them apart but CN G is very high pressure

if you decant for cooking and heating in a boat to save the difference in cost and cant or wont make room for a std lpg bottle perhaps you cant afford boating.
I can see auto gas to other cylinders to run engines as it amounts to a fair bit in £ but not the amount for cooking

edited to add please note
I am LPG gas cops 11 trained and passed and on the question about legal filling of bottles at a supply station
Its a few years back now but my last understanding is to fill up

1 the bottle /tank cylinder ect has to be restrained/fitted to cops 11 std ie well strapped in so in a crash it will stay put as in a caravan from new should do
2 over fill and pressure relief devices
3 a filler point fitted to the car/van /truck/caravan body
that is all folks easy done

as to the OP camping GAZ might have put stronger springs in the bottle to stop people refilling , perhaps you can use a fitting that depresses the spring when filling
 
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Without making comment on the safety issues of gas filling of secondary cylinders by non-professionals, this sounds like an issue of partial pressures.

Each gas compound present within a vessel exerts its own partial pressure, and if more than one compound is present these add together to make up the total measurable pressure. When the overall pressure equals that of the source compound pressure, which would normally be warmer to create a higher local pressure and hence a flow, the flow stops.

Ideally the cylinder should only contain the gas compound being filled, and in the case of LPG this should condense and liquify. This will happen simply by keeping the receiving cylinder a few degrees cooler than the donor cylinder. If another gas of mixture of gases (e.g. air) is present in the cylinder then the partial pressures added by the air will add to that of the LPG compound's partial pressure, but the air won't liquify so the pressure simply increases to the point that the receiving cylinder pressure equals that in the donor cylinder, flow stops as does the increase in cylinder mass.

This is a basic and common fault found in fridge systems where air has been left in. In an LPG cylinder giving the cylinder a good vent blast should remove most of the air and the flow should be restored once the air has been blasted out by the boiling liquid LPG when the valve is opened and the cylinder pressure drops.
 
Bosun Higgs said:
Doing the usual pre season refilling on my camping gas bottles ( done in the open air, cylinders carefully weighed, care taken) I found that one cylinder would not fill past about 50%. Its empty weight was the same as my other cylinders and its easy to measure accurately the weight of gas that has gone in. First thought was maybe some water in it ( its the first time I have re-filled this particular cylinder so I dont know its history) but that wouldnt work since liquid water is heavy.

So any ideas? Why wont this cylinder refill when all the others both before and after this one filled normally.
Click to expand...

the first bottle is say at 10 psi and you decant to camp gaz bottle 1 at 80% of supply bottle ie 8 psi and lowering supply bottle to 8 psi
supply bottle is now 8 psi and you decant to camp gaz bottle 2 and you wont get the same charge because of the lower supply

plus what he said above :)

a note for you all a few farmers get propane cheap and turn the bottles up side down to decant them into their LPG range rover as one would
then we get a job as the system stops and we say you have bean using bottled propane and they say no I haven't,
so I tell them to let their petrol station know their lines are full of rust and crud then as the range rover LPG fuel filters are blocked solid
the reason gas bottles are used upright and get filled over and over and the **** builds up on the bottom and when it is turn up to decant the liquid the **** comes out to and this can also stop the valves sealing
 
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paul-essex said:
the first bottle is say at 10 psi and you decant to camp gaz bottle 1 at 80% of supply bottle ie 8 psi and lowering supply bottle to 8 psi
supply bottle is now 8 psi and you decant to camp gaz bottle 2 and you wont get the same charge because of the lower supply

plus what he said above :)
Click to expand...

The pressure in an lpg bottle is determined by the temperature, at least while there is liquid present. That is why when filling one bottle from another you maintain a small temperature differential, with the donor bottle the warmer of the two. The pressure wont fall until all the liquid has gone if the temperature is maintained.

You mentioned CNG , compressed natural gas, in an earlier post. That is a totally different matter. It is not liquefied. It is simply stored at a much higher pressure than butane or propane.

You also said there is not much difference in the pressures of butane and propane. Infact at 20C the vapour pressure of butane is only about 1.2 bar whereas the vp of propane is about 7.2 bar.
 
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VicS said:
The pressure in an lpg bottle is determined by the temperature, at least while there is liquid present. That is why when filling one bottle from another you maintain a small temperature differential, with the donor bottle the warmer of the two. The pressure wont fall until all the liquid has gone if the temperature is maintained.
Click to expand...

Many years ago a pal of mine and his father were filling the family Land Rover's tanks from a Big Red propane cylinder. It was winter, so they were doing it in the garage. To get the required pressure difference, they had a standard portable gas heater (rectangular with 15kg butane bottle inside) running under the propane bottle, which was just inside the garage door.

The rubber hose they were using came off the car, gushing liquid propane on the floor. That liquid and the cloud of vapour above it move inexorably closed to the gas heater. There was no other exist from the garage, so my pal and his father could only watch as the white cloud got closer to the naked flame. Closer. Closer. Closer. And ...




















Snuffed it out.

Thank goodness for upper explosive limits, eh?
 
JumbleDuck said:
Many years ago.......


Snuffed it out.

Thank goodness for upper explosive limits, eh?
Click to expand...

Nice one. We forget about the upper limit usually ( 9.5% for propane)

Trouble is to get from 0% to above the UEL you have to pass through the LEL and the range over which the mixture is explosive. I reckon they were lucky!
 
VicS said:
Trouble is to get from 0% to above the UEL you have to pass through the LEL and the range over which the mixture is explosive. I reckon they were lucky!
Click to expand...

I reckon they were very, very, very, very, very lucky. My guess is that the propane was sucked in through the air inlet a the bottom of the stove and snuffed out the flame from within, if you see what I mean.
 
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