How to completely refill a 1lb "disposable" propane Bottle

Summer Is here and its time to go camping! I go through a lot of the small 1lb cylinders of propane. They are used for my stove, Lanterns, Heaters, etc. At  $3 to $4 a Piece, they really start to add up, not to mention that when you are done with them, they are then thrown into a landfill. No more! for about $30 you can build a refill station and refill those bottles completely for about 50 cents a bottle!

I know what you are thinking, why build this when you can buy a refill adapter ready made for your tank. I used to use one, but you can only fill your bottles about 2/3rds full. This method allows you to completely fill a bottle. much the same way as they were originally filled in the factory. and with the quarter turn valve, the refill process is quick and easy.

Disclaimer: this is the way I refill cylinders. I do not claim to be an expert, and I take no liability for mistakes you make. BE SURE TO DO THIS OUTSIDE preferably with a bit of a breeze and no near, flames, sparks, cinders, etc. Propane is highly flammable and this can be dangerous if you don't use common sense. If you blow yourself up, don't blame me!

Step 1: The Anatomy of a 1lb Cylinder

A 1lb Cylinder has a pressure relief valve. This is a safety feature that will vent excess pressure from a bottle. This is also used to vent the gas during the filling of the bottle. It looks much like a valve from a tire.

Comments

[Lovetobowl]

So is the male POL fitting that goes into the 20lb tank a full flow design ?

[thedustycelt]

Yes it is full flow. There is nothing to restrict the flow except the size of the connector in to the 1lb bottle.

[GeeDeeKay]

While this works -- I have one of these adapters myself -- it is very important to understand that any propane canister is only as good as its hydrostatic test results. This method should have significant safety warnings attached beyond "don't blow yourself up." Ignition during the transfer process is only one concern. If the receiving canister is somehow weakened by age or handling, it could explode unexpectedly with catastrophic results.

My local gas dealer will always check the hydrostatic test date on my 20# grill tank before refilling, and if there's any question, they will not refill the tank. They're the experts so I respect their professional opinion. I go and swap the tank out for a new one at my local orange or blue mega-store.

Pressurized, flammable gas is nothing to fool around with, and any time one refills a container under pressure without a way to measure the resulting pressure of the container, especially in reference to its maximum safe internal pressure, could create a massive safety hazard.

Yes, perform this at your own risk, but understand that the larger tank could impart a significant amount of pressure on the smaller one, beyond its capacity. This could create a timebomb in a 1-lb propane canister.

[lime3D]

I have one of these refill adaptors. The problem is that it is straight, which means the 1 pound tank lies on its side during refill. Do you think it would work better if I turned the source tank (20 lb) on a 45º angle, or as much as possible, so that the liquid propane level is still about the level of the valve?

[thedustycelt]

It might allow you to get more in there. I used to use one of those adapters, but was unhappy with it, that is why i put this rig together...

[Sir Lunch-a-lot]

On thing to consider is that, while it appears as though there are no laws against refilling these (note: I am not a lawyer), you cannot legally transport these once refilled (depending on your countries laws). I live in Canada, and on one of my disposable Coleman propane tanks it reads: FEDERAL LAW FORBIDS TRANSPORTATION IF REFILLED - PENALTY UP TO $500,000 AND 5 YEARS IMPRISONMENT (49 U.S.C. 5124). So, something to be aware of if you're going to do this as those are some steep penalties.

[alaskanbychoice]

I would suggest that you wear face protection and insulated gloves that won't absorb the liquid propane. I would highly recommend that you also where clothes that do not cause static electricity and ground the bottle when doing this. Commercially propane bottles are not filled past the 90% mark and are normally filled by weight. You can research it more under the CGA Compressed Gas Association.

[Lorddrake]

what size bit did you use to bore out the stem tool so that it fit the propane cylinder valve?

[thedustycelt]

Sorry :-(
I don't recall... Just Eyeball it... It needs to be slightly larger than the pin sticking up. Some valve stem tools might not even need to be bored. What is important is that the slotted portion of the tool can reach the threaded screw.

[heathbar64]

I like your setup, but I believe it is incorrect to completely fill the bottle with liquid propane. they need some headroom for expansion. I'm not an expert so you would have to check the exact amount with one of them, but I know the big tanks in your yard are only filled about 80 %. when I get my grill tanks refilled, they weigh them to know how full to make them. I guess You could weigh A new bottle and then refill until that weight is reached.

[thedustycelt]

Perhaps I should have clarified... When I say completely full, I mean the are filled to the 1lb mark. The way the bottle is designed, the bleed valve/pressure relief valve has a tube body that protrudes down into the bottle about 1.5" So if you stop filling when you start getting liquid out the bleed valve, that will leave a head space of approximately 1.5" I have filled numerous bottles this way. When I first started, I would weigh the bottle before and after to see that I had only added a pound of propane. I have found though that it always fills correctly and have never had an overfill situation.

[heathbar64]

AH! I get it. thanks for the clarification.

[heathbar64]

AH! I get it. thanks for the clarification.