Refill Disposable Propane Tank From a Standard BBQ Cylinder




I refill my littles 1 pound propane bottles from a big one. I'm going to show you how...

Step 1: Safety First & Disclaimer

Disclaimer : Whenever there is propane there is risk. If you decide to refill your propane tanks yourself, you have to understand that you do it at your own risk. These cylinders aren't DOT approved for refilling. This means that you can't take your cylinders to the local propane-equipped service station and have them refilled. That's against the law. And refilled cylinders can't be sold commercially. And commercial operators can't transport refilled cylinders across state lines. There are all sorts of limitations and potential liabilities associated with refilling these cylinders. It's perfectly legal to refill them for personal use, however.

There is some safety precautions that you have to take when refilling your disposable propane cylinders and you will need to handle it properly and observe all the best-practice safety protocols.

#1 Always do the refill process outside.

#2 Never smoke during the entire process.

#3 Be sure there is no open flame in the area.

#4 Wear safety glasses and protection gloves for added safety.

Again, I am not responsible for any accident that can happen when you refill your own disposable propane tank.

Step 2: What You Will Need

First you will need a propane tank refill adapter from Mr.Heater also called Mac Coupler. They are easy available on the Internet on Ebay or on the Cabela's Web Site.

Link for Ebay:

Link For Cabela's :

You will also need a standard propane tank at least 50% full, empty disposable cylinder, a kitchen scale an a notepad to keep track of the weight of your cylinders. For added safety I also recommend safety glasses and gloves (not show on the picture)

Step 3: Collect Empty Disposable Cylinders

I collect empty cylinders form the campgrounds I visit. Most of the peoples trow them away in the recycling basket I collect them. I also collect the plastic caps because I always store my cylinder whith them to protect the tread and the Shreader valve. Look for bottles that have not dents or rust and the ones that are not to old (the production date is stamped on the bottles)

There are 2 types of disposables tootles :

Type #1 With plastic Base (Coleman Type)

Type #2 With metal Base

I have a preference for type #2 because the metal base wont go off the bottle like the plastic cap but both type work. They have different empty weight and we gone a check this in step #6

Step 4: Chill Empty Cylinder

Chill Empty Cylinder for 1 hour for best result. This operation lower the pressure in the cylinder. To refill the cylinder, you have to create a pressure differential between the giver and receiver tank.

Step 5: Warm 20 Pounds Cylinder

Put your BBQ cylinder in warm water (not hot) for about 1/2 hour. This operation increase the pressure in the giver tank. If your bottle is under the sun a warm and sunny day, just skip this step, you don't need to do that.

Step 6: Weight Empty Cylinders

Weight the empty cylinders.
I give you my result after I weighted about 24 tanks :

Type #1 With plastic Base (Coleman Type)
Average empty weight : 384g
This mean a 100% full tank will weight 849g (384g tare weight + 465g of propane)

Type #2 With metal Base
Average empty weight : 417g
This mean a 100% full tank will weight 882g (417g tare weight + 465g of propane)

Step 7: Do the Refill Process

To do the refill process, do those steps :

#1 Plug the refill adapter on the big tank FIRST

#2 Screw the little thank on the adapter.

#3 Flip the tank over like on the picture.

#4 Open the valve. The instruction say to let in open for 1 minute but you will hear the flow of propane stop after 30-40 seconds. When the sound of the flow stop, close the valve.

#5 Flip over again the big tank and remove the little one of the adapter. Some propane will escape from the adapter during this process.

Repeat the operation until you have filled all of your tanks.

Step 8: Weight Refilled Cylinder

Weight the cylinder to check the results:

On the first image you see a coleman type tank filled at 89% (797g total weight)
797g (total weight) - 384g (empty) = 413g Propane Weight
413g / 465g = .888 or 89% full.

On the second image you see metal base type tank filled at 87% (822g total weight)
822g (total weight) - 417g (empty) = 405g Propane Weight
405g / 465g = .870 or 87% full.

I never refilled a cylinder more than 100% but if you do it, I suggest to put it on a gaz burning appliance so the extra gas will escape to the safe weight.

Step 9: Check for Leaks and Store Refilled Cylinders

Once you've refilled a cylinder, you should place some soapy water on both valves (the pressure relief valve and the regular valve you connect to your appliance) and check for bubbles. Bubbles = leaks. A leak never happened to me but it's better not to take chance.

I store my refilled cylinders outside just for precautions, in case of a leak.

I also put a protective cap like on the picture to protect the threads of the boottle.

Good luck refilling.



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138 Discussions


1 year ago

Hi, I'm from the Netherlands and used this type of adapter to make it fit on the Propane tanks we have here. I tried to do the refilling however after the inverting thing and opening the valve I only get a gas flow of one second and no more gas comes through. I made sure that the bottle was cold enough but it seems that no more gas fits in. I have also tried to see what happens when I pull the "over pressure valve", but this function normally. I thought maybe it was the difference in pressure we use here in the tanks, but 10 bar equals to 145 psi what is normal as far I can find on the internet. I really can't find anything on the internet that can explain why this happens. I have three Coleman propane tanks and all three show the same. Hopefully, someone can help me out.

2 replies

Reply 1 year ago

make sure you got the right adapter for filling... I like to get my small tanks cold before i fill them...


2 years ago

thnx for sharing


2 years ago

Thanks for sharing. I have an electric one. But to be honest I didn't install it by myself, I used services of heating denver to accomplish this task. And I'm completely satisfied with its work. It's very fast and not expensive. Plus, they helped me with all the settings

3 replies
Ananta Sesad

Reply 2 years ago

Thanks MrDrSmith, for your well thought out myth debunking.


Reply 3 years ago on Introduction

BradS, maybe you should mention that you are affiliated with propane-refill so we can all appreciate where you are coming from.


Reply 3 years ago on Introduction

BradS, maybe you should mention that you are affiliated with propane-refill so we can all appreciate where you are coming from.


3 years ago on Introduction

OK. Enough nonsense about the dangers of overfilling.

Valid Concern #1) Vented propane is flammable and is a hazard once it's out of the tank. It's more of a hazard than you might think because once it's out of the tank it mixes with oxygen in air. Rather than the calm flame you see in a stove or lamp it can explode as it burns all at once.

Nonsense #1) The tank can explode if overfilled.

No one has been able to find a photo of a failed tank because there's a safety pressure-relief valve to vent it if need be. The tank itself will never fail. OK. Maybe if you remove the safety valve and replace it with a bolt. Somewhere around a thousand PSI.

Nonsense #2) The pressure after filling is important.

The pressure of propane vapor (a gas over some amount of pure liquid) is a function of temperature. Only. There's a graph. In the tank the molecules of propane go back and forth between the liquid and the gas. There's a balance reached between the evaporation and condensation rates. The evaporation rate depends on temperature but the condensation rate doesn't so the balance depends on the temperature. The warmer it is, the higher the pressure of the vapor. If there is any amount of liquid and any amount of gas, that graph is obeyed. Nothing you can do will change the vapor pressure. All tanks containing between 1% and 99% liquid have the same pressure if they are at the same temperature.

Nonsense #3) The relief valve is carefully calibrated at the factory.

It's set to a quite high pressure. It's there to stop the tank from rupturing. It's a steel tank. That pressure is high. It's somewhere around 360-480 PSI. That's something like 25 bar if you're looking at the vapor pressure graph. Put the tank in boiling water and the pressure will want to rise to double that. (The valve should open to prevent that). The tanks are required to have a minimum burst pressure of 960PSI so they are actually designed somewhat higher. Call it 1200PSI. There's a wide difference between those pressures.

Valid Concern #2) If the pressure relief valve opens it might not reseal well.

These tanks are meant to be discarded after a single use. The valves are c*ap. They aren't meant to open and close repeatedly so when they do open they have a closing-failure rate. Over time a small leak can release the entire contents into an enclosed area like your trunk or a storage cabinet and you're facing Valid Concern #1.


If you fill the tank to 100% with liquid, there is no vapor and the graph above no longer applies. I don't have the complete data on the physical properties but Wikipedia says that the volume wants to expand 1.5% for each 10 °F. (there should be some pressure/compressibility terms decreasing that for our situation). If you nearly fill the tank then warm it up the liquid will expand, shrinking the gas until you have liquid pressing in all directions and then the pressure can rise very rapidly. How many 10's of degrees are between a frosty tank and the temperature in your car parked in the sun on a hot summer day? Looks like 80-85% full is about right.

Then Nonsense #4) the tank will shred sending shrapnel in all directions.

When an explosive bursts a container sending shards, it is, at its heart, an expanding ball of high pressure gas. Like a compressed spring, when you release it, parts fly around.

A 100% full tank though is filled with liquid. When the liquid ruptures the tank (if you defeat the safety relief valve) it's filled with liquid and it's just going to tear the tank and leak out. The liquid propane will want to change to a gas and throw bits around, but it needs heat energy to do that. It gets that heat from the liquid so the liquid cools down and that lowers the vapor pressure. Only some can evaporate before the bulk liquid is too cold to worry about. Its bomb-like-ness is limited, but again you're back to Valid Concern #1).

My actual contribution: Put a piece of scotch tape over the safety valve to keep dust out of it. That might help it not leak.

Many of my numbers came from this report

marc brown

3 years ago

Does the BBQ tank have to be upside down?

I can't get more than 100g into my empty Coleman cylinders.

I just had my BBQ tanks filled by U-Haul.


4 years ago on Step 9

The usual recommendation is not to fill to more than 85%.

By experimenting with a pickle jar filled with water and a hole in the middle of the cap, I had to tilt it to 74 degrees off the vertical before 15% of the water left the bottle. I used an electronic angle gauge to measure the angle.

Worthington cylinders weigh around 31.7 oz new. I refilled a cylinder to 32 oz. When I fitted a torch and lit it, I found I could tilt it 74 degrees before the flame went from [gas] blue to [liquid] red.

This is another way to test a cylinder to see if it is overfilled. It is a bit surprising how close to level you must be able to bring it [i.e. 16 degrees] for it to be safely filled.

The pickle jar had proportions similar to the Worthington. The results are probably different for different shape cylinder.


2 replies

Reply 4 years ago on Introduction

Thank you so much for your technically correct interpretation of the law and everything pertaining to the regulation of life, procedure and safety guidelines pertaining to the safe enjoyment of our lives free from the contamination of any possibility of unsafe practice both in the home, on the highway and at work. Now I tested a camping disposable propane cylinder, and a MAPP Gas, Burnzomatic cylinder last month. I covered them with rags, douced them with petrol and set them on fire from a distance of 20 feet. Each one gently gased off and burned down with out incident, except for a harmless bang at the end when the top came off the thin walled propane cylinder. The last time I heard that Propane was any real danger was when someone parked a large panel van full of it, with explosives, under the World Trade Center. Other than than, I simply have not heard of them being dangerous. Probably they are in some circumstances, but our friend here has it covered.


Reply 4 years ago on Introduction

Thanks for the link. Their proprietary system looks like it's more expensive and complicated than it needs to be, but at least it gives the public a safe option. They probably never saw the original Cleanweld Turner products before coming up with their solution.


9 years ago on Step 7

you know there's a little shrader valve in the side of most of thoes tanks so you can get the AIR out of the tank when your filling it any propane tank has a bleeder valve, that's how you get the tank full even if you had a propane pump to help fill it up

3 replies

Reply 4 years ago on Introduction

There shouldn't be any "air" (nitrogen+oxygen+carbon dioxide+water vapor) in the propane cylinder. It should be 99.999% propane and other flammable petroleum gases. If there's air in the cylinder, it needs to be purged before putting the cylinder to use.


Reply 7 years ago on Step 7

It's not a bleeder it is a safety vent for DOT regulations.


Reply 6 years ago on Step 7

Correct. The valve is to vent excess pressure so the tank won't burst.
The valve may have been used to bleed air on the first factory fill.
But as you use the original fill, propane gas exits only. No air enters the tank.
The "air" in the tank is simply leftover Propane gas at a pressure of approx 1 atmosphere.
To vent this gas is wasteful and you run the risk of overfilling the cylinder too.
What happens then? As the temperature rises the pressure valve releases the extra, wasting more gas.


6 years ago on Step 4

Chilling is unnecessary.
Hook up a full tank (under high pressure) to an empty tank (under less pressure relative to the full one) and open the valve between them and the pressures will equalize. Some of the contents of the full tank are forced into the empty one until the pressures are equal. Close the valve and disconnect. Done.