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How to Decant Butane from Spanish Bottle to US Propane Bottle

See also this excellent article on getting bottles filled in UK and Europe.

American style propane bottles can be filled up with butane in Sao Miguel, Azores. But once you get to Portugal and Spain you will have no such luck. You can almost always use all your appliances on either butane or propane without problem but do check first.

In Portugal and Spain everything is done on a bottle exchange system. You buy a bottle, and then when you want a refil, you just take it in to a gasoline station where they will exchange it for a new one.  Of course, you always have to take it back to the same brand. Repsol and Galp seem to be pretty common.

There are 6Kg and 12Kg bottles. In Cadiz we were able to buy a 12kg bottle from Cepsa. We are told that in Cartagena, they won’t let you buy a 12kg one unless you have certificate showing that your installation meets local requirements. However, you can buy a 6kg bottle with just some ID and an address (use the marina’s).

This is our Spanish 12kg bottle. Note, however, the rim goes all the way around, which means we could not connect the decanting hose as the connector fittings (D in photo below) hit the rim where the arrow points above. Make sure you get bottles that have a gap there to allow your connector to fit without problems. Shown here is the normal connecter complete with integrated regulator.

You will need an adapter to connect the bottle to your propane system. You can buy these in most hardware stores (called Bricolajes in Spain).

Now you have two options. Either you connect your Spanish bottle to your system, and forget about using the propane bottles. The problem with this is that you have no backup when your Spanish bottle is empty. Unless you buy two of them.

Or you continue to use your propane system, but top it up by decanting from your single Spanish bottle.

Since we have 2 x 10 lb and 1 x 20 lb propane plus now 1 x 12kg butane we have done both. We filled up all our propane bottles by decanting from the Spanish butane AND we have a full butane. And we have connectors to fit both. That should give us about 6 months supply of cooking gas. Especially since we now have a pressure cooker too.

How to decant from one to the other.

Apparently you should never put propane into a butane bottle. I believe the reason for that is that propane develops a higher pressure in the bottle, so the butane bottles may not be designed for that higher pressure. The other way around is fine.

Different connectors: A & B fit modern US propane tanks. However, B has a one-way valve making it useless for decanting. C has no valve, but only fits old-style propane tanks that don’t have a safety valve in them. D fits Spanish butane bottles and has no regulator. A + D is the decanting hose.

The first thing you will need is an adapter that fits the Spanish bottle at one end and the US bottle at the other. But there is a catch (of course!) These connectors must NOT have two safety features:

1) A regulator. The Spanish connectors all come with a built-in regulator. That won’t allow liquid gas to pass by, and so is useless. You will need to find one without the regulator. Fortunately we were able to borrow one from an British yacht in Cartagena (Thanks John!). However, I believe that you can order them from some UK motorhome, RV and caravan suppliers. Do a search for Gaslow Jumbo adaptor, which is D in the image.

2) A valve. Modern connectors have a one way valve in them that allows gas to leave the bottle but prevents anything from flowing back into it. Obviously that would scuttle your decanting attempts. It also restricts flow, making the whole process slower. The Jumbo adapter shown above has a valve like that in it, but it can be easily removed. Many of the connectors for propane also have such a valve. In those cases the valve can’t be removed so you need a different adapter.  Check before ordering.

Once you have the two end fittings without regulators and valves, just connect them together with some high-pressure hose.

Now you are ready to decant. We will assume you are transferring FROM the Spanish butane TO the US propane bottle.

decanting butan to propane bottle1) Do all of this OUTSIDE, preferably with a nice breeze, where there is no possibility of stray gas getting inside your boat. As long as any leaking butane can just blow away there is no danger. Obviously avoid smoking or any naked flames or sparks.

2) Weigh your two bottles. You MUST NOT fill the receiving bottle with more than it’s designated capacity, or 80% volume. If you have a plastic see-though bottle, like our large one, it makes it easier to watch what is happening. Otherwise you will need to weigh your bottles to know how much you have transferred.

3) Attach the hose to both bottles.

4) Turn ON the butane bottle, but leave the propane bottle OFF. Check carefully for leaks, using some soapy water on all the joints. If it leaks, it will produce bubbles. Tighten it all up, maybe using PTFE joint tape, until there are no more leaks.

5) Turn the butane bottle upside down and raise it above the level of the propane bottle. But the butane bottle in the sun, and the propane in the shade. This increases the pressure in the butane bottle, which helps to push the gas through into the propane bottle.

6) Open the valve on the propane bottle. You should hear the liquid gas transfering from one to the other.

7) When you have transferred the correct amount (check by weighing), take down the butane bottle and stand it the right way up, but still higher than the propane bottle. This will remove the liquid from the hose pipe. Now close the valves on both bottles, and remove the connectors from both.

8) You should now have a full propane tank. Check the weight to make sure you have not over-filled it. If you have, vent it off into the open sky until you have the right weight. An over-filled bottle is at risk of bursting from hydrostatic pressure if the liquid gets warm and expands.

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