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oldvarnish
29-12-10, 18:18
I know that what I am about to describe comes under the 'don't do this at home' heading, but you are in a faraway place and the propane tank is getting low.
The store has got gas but needless to say the connections don't match.
I've heard of people filling one tank (their own) from another.
Anyone done this?

Salty John
29-12-10, 18:52
Yes, but you have to be able to connect the two tanks together, so the fittings problem doesn't go away, and it takes hours to make the transfer. It's like pouring a liquid from one container to another through a very restricted orifice.
I borrowed some gas from another cruiser this way; it hardly seemed worth the trouble in the end.

TQA
29-12-10, 19:34
I watched this done in Venezuela when the gas guy did not have anything that fitted my calor propane bottle.

First he put both bottles in the freezer overnight.

Then he removed the valves from both bottles.

With the aid of a metal funnel he poured LPG into my bottle from his.

Finally he replaced the valves in both bottles.

JOB DONE!

Tradewinds
29-12-10, 19:52
TQA - now that's the way to do it! :D

Balloonists decant from large propane bottles to smaller, basket size bottles (at least my BIL did back in the 80s). It wasn't rocket science but, as Salty John says, you needed the right pigtails to do it & it takes a while. Standing next to my BIL as he wielded the spanners & fiddled with the knobs scared the s***t out of me - but he seemed relaxed about it!

Some info here

http://www.balloonlife.com/publications/balloon_life/9701/methods.htm

On my travels I carried 2 Calor (propane) bottles & 3 Camping Gaz. I found the CG easier to lug about on a shopping foray.

You could get the CG swopped France, Spain, Med no problem as well as French outliers such as Martinique, Tahiti etc - it can be relatively expensive though.

Most other places you could get both bottle types filled with a gas of some sort - usually a propane/butane mix as in the WI - elsewhere, such as Fiji who knows what the gas was. It seemed OK - I carried spare regulators but never had a flare up.

The only place I hit a problem was New Zealand where I had to buy 2 new bottles with a vent in them - you couldn't fill any other types (though I'm sure someone probably did). I think this mirrors the USA spec, but I stand to be corrected (didn't go there). Buying 2 new bottles (& regulator) was an imposition but a small cost in the overall scheme of things. The NZ requirement bemused me as the bottles used to get warm & burp themselves - hardly the ultimate safety feature in my eyes.

I don't think you'll have a problem if you carry a couple (or 3) of spare full canisters at the start. On the way out from UK you'll soon work out your consumption pretty accurately & be able to plan accordingly (if you havn't already ;) ). Arrive at a place, stop a while & get the near empty one(s) topped up / replaced. Planning ahead is the key.

I'm sure the OCC had an article about gas transfer but I can't find it at the moment - but to be honest, I think you'll find that you're more likely to meet someone with the knowledge you desire as you make your way to your faraway place (see TQA!).

Get it wrong & you will be in a faraway place :D:D

old_salt
29-12-10, 20:35
All the gas bottle manufactures will recommend you don't DIY do it. But it is often done in the refrigeration industry, connecting two bottles together is not difficult you connect them leaving out the reducing valve with a length of high pressure pipe or hose use the one for the bottle to reducing valve the bit you may need extra is a male to female union.
Connect up then invert the bottle from which you are taking the liquid gas from above the one you are filling, open it's valve bleed out at the receiving bottle all the gas in the charge line nip up the connection when you have liquid 'note it will be very cold' then open the receiving bottle and fill the liquid gas flows from the full to the empty when they reach equilibrium thats it job done.
Ideally the bottle you take from should be bigger then the one you are filling in order to maximise the fill.
Right the inverted bottle wait a short while to allow the liquid/gas to settle out of the charge line and any chilling around the valves to disperse they will not shut easily/properly if they are frozen, then shut the valves and be careful on disconnecting there will be a hiss of liquid/gas in the charge line just as you get when filling a gas lighter, take care and do it outside. about 1/2 to 1 minute for a 7lb bottle.
You can clearly hear the charge going over when the sisss stops it's done.
There are no probs you can't over fill they can only equal out from what is in the charge bottle, when the charging bottle reaches it's capacity it will stop flowing though the charge line.
The typical bottle pressure is about 125psi and it holds this pressure from full to very near empty.
If you have a difficulty with connecting the bottles you might have to make up a charge line for the two different bottle valves,
If so use a proper in-line connector.
Don't just connect up with a plane piece of pipe and two jubilee clips that is just heading for a disaster.
Disclaimer.
You do this at your own risk and just don't tell any one you read it here or I told you how to do it.

Just read the posts above last week I thought my gas was all gone in our horse box disconnected the bottle and opened the valve not a phift out of it, turned it upside down and got liquid at about half way over just a drizzle, so took it inside and allowed it to reach room temp then all was well, it was 10 below zero outside.

crisjones
30-12-10, 12:58
As Old Salt has said you need a high pressure hose with the correct end fittings to suit the bottles, no regulators or restrictors in the line. If filling from a similar sized bottle you will need to leave it many hours, even overnight to ensure the remaining liquid gas, after pressure equalization, in the donor bottle is transferred to the host bottle by gravity. It helps if the donor bottle is warmer and the host bottle cooler. The initial fill up to the point of pressure equalization in both bottles is pretty rapid, but it will only transfer about 60% of the liquid if you use equal size bottles, hence the need to let the rest drain across by gravity. Before you start it is best to fully open the valve on the host bottle to ensure there is only atmospheric pressure in it (do this outside!!!), this will maximise the amount of gas transferred before the pressures equalize.

Using a bigger bottle as donor can get more gas across quicker but you still need to let the last bit transfer under gravity.

A set of bathroom scales will allow you to fairly accurately monitor the amount of gas transferred and help ensure the maximum amount of gas is transferred.

Slightly off topic - has anyone tried filling bottles at a car Autogas filling station ? The required adaptors are easily bought over the internet, and a car gas tank is pretty similar to a standard propane tank. I doubt you would be allowed to do it in the UK cos of Health and Safety concerns, but maybe a possibility in Europe where they do not seem quite as concerned especially at more rural filling stations. Any one any experience of trying this?

oldvarnish
30-12-10, 14:29
Thanks everybody. I get the idea. I saw a link somewhere to a firm that did a kit of all possible connectors but I can't seem to find it. If I re-discover it I'll post the address.

Conachair
30-12-10, 16:55
Thanks everybody. I get the idea. I saw a link somewhere to a firm that did a kit of all possible connectors but I can't seem to find it. If I re-discover it I'll post the address.

http://www.socal.co.uk/Toolbox/Regulators/GasBOAT_Regulators/GasBOAT_4018_-_Marine_Universal_Gas_Cylinder_Adaptor_Kit/430/17933

oldvarnish
30-12-10, 17:01
thanks Conachair. That's the one!

DownWest
30-12-10, 19:12
'Somebody' on here told us how he filled his spare bottles from an M-way service outlet. Just kept the camper between the pump and the kiosk.
I regulary fill camping gaz cylinders from 13kg types because the 907 CG ones cost about the same as 13kg domestic!! Use the methods above.
Interesting about NZ, in another thread, an OZ forumite discribed how it was DIY to fill your cylinder at some stations.

Cripes! Just looked at that Socal site 129? Made mine from left over connections 0. OK, lots of bits there for different systems, but..

Tradewinds
30-12-10, 19:32
'Somebody' on here told us how he filled his spare bottles from an M-way service outlet. Just kept the camper between the pump and the kiosk.
I regulary fill camping gaz cylinders from 13kg types because the 907 CG ones cost about the same as 13kg domestic!! Use the methods above.
Interesting about NZ, in another thread, an OZ forumite discribed how it was DIY to fill your cylinder at some stations.

Cripes! Just looked at that Socal site 129? Made mine from left over connections 0. OK, lots of bits there for different systems, but..

As I recall, you could fill NZ gas bottles at a local filling station but no other type. As I alluded, probably some people were able to get their non-NZ tanks filled surreptitiously - but we couldn't when we were there.

Bobobolinsky
30-12-10, 19:46
I made a transfer pump up using a 300mm length of 50mm steel pipe with an intank petrol pump, within. Worked well in out of the way places.

rigman
30-12-10, 20:52
definite candidates for darwin award around here

oldvarnish
31-12-10, 16:25
'

Cripes! Just looked at that Socal site 129? Made mine from left over connections 0. OK, lots of bits there for different systems, but..

Yes, I thought it looked a bit expensive but I can't imagine how else you'd get all the bits together.

I suppose if you're off the beaten track and it's your only chance of a hot cup of tea, you'd think it was worth the price.

serini
31-12-10, 17:30
I am about to have to face this issue myself. Previously where I am it was legal to fill propane bottles at an autogas station but now very much no longer allowed with big fines for transporting the bottles in a car or a taxi (well, the taxis now refuse anyway). The thing about filling at a lpg station is you can measure the amount of gas as it is pumped over. Over filling is very, very dangerous despite the posts here that you can't over fill. You can. There has to be an expansion space left. If you filled the tank up with fluid and it got warm (so expanded) the tank would rupture. So make sure you start with an empty cylinder (or one that you know the empty weight of) and only put the amount of gas in it to take it up to its rated charge. A simple spring balance will let you do this.

old_salt
01-01-11, 01:48
I am about to have to face this issue myself. Previously where I am it was legal to fill propane bottles at an autogas station but now very much no longer allowed with big fines for transporting the bottles in a car or a taxi (well, the taxis now refuse anyway). The thing about filling at a lpg station is you can measure the amount of gas as it is pumped over. Over filling is very, very dangerous despite the posts here that you can't over fill. You can. There has to be an expansion space left. If you filled the tank up with fluid and it got warm (so expanded) the tank would rupture. So make sure you start with an empty cylinder (or one that you know the empty weight of) and only put the amount of gas in it to take it up to its rated charge. A simple spring balance will let you do this.

You are probably referring to my post, If you do it the way I explained you wont over fill. I have filled secondary bottles this way for over forty years.
If any thing it will be under filled you only open the receiving bottle when you have connected up so it will have a residue of gas in it and as the liquid flows in to the receiving cylinder it will expand and thus create the room for expansion.
Also you turn the charging bottle back up right then allow the two bottles to equalise before closing the valves and disconnecting.
As you say a spring balance will enhance the job a good deal and it will
enable you to judge the charge accurately.

serini
02-01-11, 19:28
Old Salt - I see from your profile that you're an engineer. I am only an electronics guy so I accept you know much more about this than I do.

But

Surely the liquid propane needs a volume of gas above it to expand into? If you were to end up with a cylinder full of liquid propane and then closed the valve and if that bottle then got warm then the liquid would try to expand and the stress on the cylinder would exceed its spec. and then, well, bang!

I know that US cylinders have a float inside to prevent over filling and to preserve this space. I have been told that UK cylinders have an over-pressure bleed off but I have looked for this and cannot find it.

What is the step in your process which makes sure the receiving cylinder does not end up completely full of liquid or am I overstating the risk?

rivonia
02-01-11, 19:48
This realy takes me back to the carribean days. When we first wanted our tank filled> we were sent to "Big Joe" and there he filled it for us from a big bottle hanging in a tree. We did not hang around to see the end result as it seemed VERY dangerous to us. However the next day we collected the full bottle. Wonder if he is still there in Grenada-Spice Island?

Peter

old_salt
03-01-11, 00:21
Q:-
What is the step in your process which makes sure the receiving cylinder does not end up completely full of liquid or am I overstating the risk?
A:-
as the liquid flows in to the receiving cylinder it will expand (the correct word is evaporate) it's not the liquid it's the liquid turning into a gas and thus create the room for expansion.
Some do not vent or purge the charge line, that will have the effect of putting gas into the receiving bottle before it gets any liquid.
At any given temperature above it's boiling point Propane 42c below zero and butane 0.5c below zero the liquid will expand and GAS off the governing factor is the pressure at approx 125 to 135 psi gassing off is halted.
If the ambient temperature is is within the norm say up to a max of 26c then that will hold up the gassing off with no problems that is very basic how the gas works.
A quote from Wikipedia also click on the word butane in the article:- Propane requires just 1,220 kilopascals (177 psi) of pressure to keep it liquid at 37.8 C (100 F).
Link to that page of info.:-http://en.wikipedia.org/wiki/Propane
when you have a bottle 1/4 full of liquid it gases of the the point where the psi reaches 125 and fills the void whatever it's size, it is only when you remove some gas ie by burning it the liquid gasses off some more.
Yes a bottle full to the brim of liquid would be dangerous if it became over heated way above the norm there is very little or no expansion (increase of liquid volume) in the liquid it's self but non the less it would probably exceed the safe limit of the bottle.
And as mentioned a spring balance or scales with help to get it right.
And you can always vent some off if you feel you have over filled.
But that takes time or requires a pumped transfer just simple transfer charging
will have reached equilibrium before you have brimmed the receiving bottle.
Just make sure you do any of this in a big open space where any spillages can be safely allowed to disperse.