How to refill disposable propane cylinders

by Tim on August 27, 2009

I’ve written before about refilling disposable one-pound propane cylinders that so many portable appliances use. That article is the most-viewed post on It’s popular because the subject is relevant to a wide variety of outdoor recreational enthusiasts: backpackers, kayakers, hunters, boaters, you name it.


I’ve been refilling these handy green propane bottles without mishap for a couple years now. Recently I’ve assembled a much-improved refill adapter. I’m going to describe the refilling process in detail.

First, though, it’s necessary to protect myself with disclaimers and caveats refillors. Let’s keep it simple, shall we?

Under no circumstances should anyone ever refill disposable propane cylinders using the following method.

Find a well-ventilated area, outdoors, away from all sources of heat, flame, and sparks. Ditch the cell phone.

Assemble your tools: a propane refill adapter, a pair of needle-nosed pliers, safety goggles to protect your eyes, and a pair of medium-thick work gloves.

Take a standard 20-pound propane cylinder—the kind you see attached beneath barbecues—and turn it upside down on a table or platform of some kind.


Put on your safety goggles. Screw your refill adapter to the OPD valve of your propane cylinder. This is a left-hand threading, so you need to twist the adapter counter-clockwise to tighten it. Ignore the naysayers who warn that modern cylinders with OPD valves won’t permit liquid propane to be extracted using this method; it works just fine.

Screw your empty disposable propane bottle onto the refill adapter. Be careful here, since the bottle’s threads are right-hand, and the adapter-to-OPD threads are left-hand; tightening one loosens the other. Hold the adapter firmly while you tighten the bottle.


Open the valve on the big supply cylinder. You will hear the propane moving from the large container into the smaller one. Gradually, the movement will slow down until you can no longer hear it.

But the cylinder isn’t yet full. You need to reduce the pressure in the green cylinder to allow more liquid propane to enter. The easiest way to do this is to put on your gloves and use your needle-nose pliers to pull up on the pin of the relief valve in the green cylinder.


This will release some propane (gas) into the atmosphere. Obviously, this isn’t ideal, and it doesn’t smell good, but I’ve not had good luck with other methods of creating a pressure differential between the cylinders.

You’ll only release a small amount of propane. Still, that gas comes out cold, and liquid propane may sputter and squirt out, which is even colder. Seriously, it’s freezing cold. It may seem ironic that one of the most likely causes of injury while refilling fuel cylinders is frostbite, but that’s the way it is. Always wear your gloves.

Once you think the propane cylinder is really full, close the valve from the supply tank and (still wearing gloves) unscrew the green can from the adapter. Weigh it on a postal or kitchen scale capable of showing you ounces, or tenths of ounces. The tare (empty) weight of Coleman green propane cylinder is right around 13.6 ounces. Full, it should weigh 13.6 ounces tare plus 16.4 ounces of fuel, for a total of 30 ounces, or one pound, 14 ounces. Don’t worry if you’re an ounce or two shy. It’s pretty difficult to get these cylinders full without going over. If you’re over, you need to remove some propane; either attach it to an appliance and use some right away, or pull the pin on the relief valve to release propane gas into the air.

Before you attach the cylinder to an appliance or introduce any source of flame, spark, or ignition, check to make sure your refilled cylinder isn’t leaking. Initially, you can listen for hissing. If you hear any, it’s leaking pretty fast. The most frequent source of leaking is the relief valve. Take your pliers (gloves on), lift the pin, and let it snap back. Often, this will be enough to seat the valve properly. Listen again.


If you don’t hear anything, introduce a little bit of soapy water onto both the relief valve and the primary valve. You’re looking for bubbles. Bubbles are bad. If you get bubbles at the relief valve, try to reseat the valve again, add a little more soapy water, and test again. If you can’t get the leaking to stop, you may need to retire the bottle. Unless you have a way to recover the liquid propane in this bottle, you’ll just have to leave it outside in a well-ventilated area free from sources of ignition and let it drain.

Let me repeat: No one should ever refill disposable propane cylinders using this or any other method.

Nevertheless, that’s how I refill disposable propane cylinders. The commercially available refill adapters are hard to use. They fall short in three areas. AwkwardPliersBecause you need to place your pliers inside the guard ring on the supply tank, it’s difficult to reach the relief valve.

Additionally, you have no control over the location of the relief valve, and if it ends up beneath the fill valve once it’s screwed on tight, you can’t fill the cylinder fully; pulling the pin on the relief valve just releases liquid propane, not gas propane.

Finally, it’s awkward to tighten-up the conventional in-line adapter due to the left-hand/right-hand thread combination. And it’s awkward to reach the OPD valve on the supply tank, which becomes a nuisance if you’re refilling several cylinders.

I’ve fabricated my own, much-improved refill adapter, using off-the shelf plumbing components, which addresses all the shortcomings.


ImprovedAdapterInUseThe elbow allows the green bottle to sit vertically, and eliminates the problem of tightening both the left-hand threaded supply-tank connection and the right-hand threads on the disposable bottle. The six-inch pipe gives me plenty of room to reach the relief valve with the pliers, regardless of the valve’s final orientation. The ball valve allows me to quickly change tanks, or remove a tank briefly to weigh it, without having to manipulate the supply tank’s OPD valve every single time. Oh, and it’s a lot easier to reach the OPD valve with the new adapter, too.

I would normally close a how-to piece with something akin to “good luck!” But in this case, I better just remind you never to do as I have done. Be safe.

{ 137 comments… read them below or add one }

Aaron Tinling, Publisher August 28, 2009 at 8:05 am

I’d strongly recommend wearing safety glasses when handling propane, just as the folks who refill my containers do. The liquid propane can freeze things much the way liquid nitrogen does, which makes it rather dangerous for your eyes.


Dave Ruff Sr December 22, 2012 at 8:27 pm

You remind me of an old Navy Metrology Calibrator I worked with years ago. I respected and admired him. He was honest, sincere and a dear friend. Thank you for your article. Good information.



Brian November 28, 2014 at 5:00 am

I thought you were going to tell an interesting story of your friend telling you how to do something, then saying not to do it.


Tim Flanagan, Managing Editor August 28, 2009 at 8:43 am

Good point, Aaron. I’ve incorporated that into the article.


Rollie Herman August 28, 2009 at 9:54 am

Perhaps one of your most viewed articles but what you are showing is extremely dangerous. My DOT authorized inspector has the following input:

“Refilling of these is cylinders is an unsafe practice and anyone who does so is putting themselves and anyone around the container in jeopardy. The article even shows a rusted cylinder around the threaded boss. It would be nice if people doing this would read the label on the cylinder, ‘$500,000.00 fine, up 5 yrs imprisonment if refilled’.”

As one who deals with pressurized gas cylinders every day I can tell you that they are dangerous.


Tim Flanagan, Managing Editor August 28, 2009 at 12:02 pm

Rollie: You’re right! That’s why nobody should refill them. Have I been unclear? :-)

By the way, that fine/prison deals with transportation. It’s a federal statute administered by the DOT. You can’t refill them commercially, and you can’t transport them commercially. Private individuals can refill them. I’d be very interested in hearing about any prosecutions of this law, by the way, of either private or commercial entities.

Nevertheless, it’s important to remember that this law exists for a reason: these cylinders are not reliable when they are refilled without the tight quality controls that exist in the factory. I treat every cylinder, new or refilled, as if it could start leaking at any time, for no reason at all. They’re stored on the boat in a locker that drains overboard, not into the hull, for instance. I want that heavier-than-air propane to dissipate out over the water, rather than collecting inside the boat. At home, I store them outdoors for the same reason, and I transport them in the open bed of my little pickup, not inside the passenger compartment or a trunk.

Oh, and as for rust, these cylinders are used on a boat operating in marine water. They rust. Lots of stuff rusts. DOT-approved refillable propane cylinders with OPD valves rust. When the rust affects the structural integrity of the cylinder, I care. When the rust (or anything else) affects the function of the valves, I care. When the rust affects only the surface of the metal, I don’t care.

I’ve started treating all newly purchased cylinders with CorrosionX, especially around the valves, and this seems to mitigate the rust a great deal. What I find so odd is that some of my worst-looking cylinders still function properly, and some reasonably new-looking ones don’t. So I test for leakage every time.

But again, nobody should refill these propane cylinders.


Andrew P. September 6, 2012 at 2:32 am

I store my refilled disposable cylinders in a well-ventilated garden shed, and if they leak, they don’t get transported. Period. As soon as the failed ones leak down to ambient pressure, they get tossed.


Patrick July 19, 2013 at 8:16 pm

Here’s one:

“United States District Judge John Mendez sentenced James Richard Giles, 59, of Stockton, to a $100,000 fine and five years of probation for willful and unlawful refilling of a compressed natural gas cylinder that was overdue for its five-year requalification and then offering it for transportation”

So, yes, that’s breaking the law. Not propane, but the same statues apply.


Tom ( starcraft) August 29, 2009 at 9:21 pm

still thinking about blowing your self up??/ I do like the new extention. I may have to make one my self.


Toxicboy August 30, 2009 at 5:57 pm

Where did you purchase the items for the items for the refill adapter, specifically the adapter from the bulk tank to the refill adapter? Can you send privately if you do not wish to print the comanies name.


Daymon May 4, 2014 at 7:51 am

Menards carries fittings.


Tim Flanagan, Managing Editor August 31, 2009 at 12:22 pm

Actually, it was cheaper to buy five of some of the components, so I just bought five of everything. I need one set, but I haven’t decided whether to sell the other four sets as some kind of kit, or make them prizes in a contest, or what. I was able to get all the components at reasonable (retail) prices through


Rachael Collins@Refuelling couplers and adaptors October 1, 2012 at 10:28 am

That’s very nice post,I think yes we can do like this.


grumpy September 3, 2009 at 5:59 am

does anyone know how much presure these bottles are tested for ??????


Tim Flanagan, Managing Editor September 5, 2009 at 1:06 pm

I don’t know what pressure they’re tested for, but propane’s propane. It develops pressure in direct proportion to the temperature of the fuel. Not how full or empty the container is. A really full container doesn’t develop more pressure than a 1/4-full one.

So if these little green cylinders is manufactured to be transported across the country, perhaps in a trailer or rail car with internal temperatures well over 100 degrees on a hot sunny day, they’re tested for MUCH more pressure than they’ll generate while in my possession.

Once again, I’m not saying any of this is “safe”, but folks, it isn’t rocket surgery either. Actually, it IS rocket surgery, sor of, since it’s combustible fuel under pressure. But back to the point: You need to understand how it works, and what the risks are. You need to prepare for the possibility of a leaky cylinder (which you would also need to do if it were brand new, or with a refillable OPD-valved cylinder). You need to be careful about ignition sources, just like you always do. Just be careful, like you always ought to be with propane.


Sylvan August 30, 2011 at 9:55 pm

Coleman published a recycling brochure that identifies the pressure relief valve ‘rupture pressure’ as 350-500 psi and the cylinder burst pressure as 800 psi.
This document also explains the various gas/liquids physics in these comments.


Nitrous April 6, 2015 at 6:38 pm

Rocket surgery, it isn’t.
It isn’t even brain surgery.
Further, you don’t have to be a rocket scientist to do it!

No, you just have to ignore the law and accept the attendent liability, if something goes wrong.



Joe blow no name September 23, 2009 at 4:01 am

It would seem logical that you should not ever overfill the tank. Doing so would not leave enough space in the tank for the expansion when the tank gets hot , such as in the sun. I would sugest taking a simple lesson from the methods used with filling any liquid, pressurised product and simply place the tank on the scale while you are filling. This could easily be done with your set up using a flex hose instead of a solid pipe.


Andrew P. September 6, 2012 at 2:35 am

The weights and tolerances involved in filling are small enough that the forces exerted by a hose strong enough to withstand the pressure would swamp out the weight reading. Better to weigh the cylinder on a scale with nothing attached to it.


Thanks October 14, 2009 at 10:39 am

I just refilled four of mine. I used to throw them away!!!!!!! The only problem I had the first cylinder I pulled to hard on the relief valve. Just barely pull is the key.


Lyman October 17, 2009 at 6:43 pm

I’ve been doing this for years. One slight modification I use is that I made an insulated jacket to slide the small bottle into. When you first start running the liquid propane out of the main tank, it dramatically lowers the temperature of the bottle that you are refilling as some of the liquid vaporizes inside of the bottle.

I have found that the insulation helps keep the overall temperature of the bottle and its contents low. The main tank being a lot larger hardly drops in temperature at all. Therefore vapor pressure in the bottle stays much lower than the main tank. With the insulation keeping the small bottle cold, it will keep filling without any other coaxing once you get it started. When the bottle is filled, I shake it to see if I can hear the liquid sloshing around. If not, I release some of the gas until I can so that I know there is some head space. You get so you can do this pretty well by ear. Just compare it to a full “factory filled” bottle.


Gary Hicks October 30, 2009 at 5:32 am

Do you sell your version of the refill valve?


Tim Flanagan, Managing Editor October 30, 2009 at 10:57 am

Actually, I’ve got all the parts here; enough to make four more of these adapters. I’m not trying to get rich on this, but to cover my costs + shipping I would have to charge around $40. Steep, compared to the basic one-piece adapters (often available under $20), but so much easier to use.

Of course, these would “100% authentic replicas” of the adapter I use, intended “for novelty purposes only” and definitely “not warranted to be appropriate for any purpose whatsoever”! :-)


Doug Kraft February 24, 2013 at 11:24 pm

As I doubt you still have your parts to make the refill device, would you be willing to make a list of the needed parts? Also….is it safe to use Teflon tape,or should one use the paste used on natural gas fixtures?


nev b November 24, 2009 at 3:56 pm

this all sounds very much like when I had to fill refrigerat cylinders. We would warm the full cylinder to halp charging. Refrigrent is NOT FLAMABLE, so perhaps overnight in a warm place would do it. leaving the small cylinder outdoors or maybe in the refrigerater/freezer overnight willgreatly help.


Robert Boyd December 18, 2009 at 6:54 am

I will buy one of your propane refill kits if you still have any left.


Robert Meyer January 10, 2010 at 6:16 pm

Mr. Flanagan,
Not only is your posting FOOLISH, you are encouraging your readers to break FEDERAL LAWS to save a couple of bucks. Money that might be needed to hire a lawyer to sue your DUMB ASS!
Brief filed against the manufacturer of the “Mac-Coupler”:

K-M Products MacCoupler
MARSHALL — Gary Wayne Suggs, 51, was attempting to refill a propane container in a fifth-wheel trailer when a flash fire occurred, causing fatal injuries.

Gary’s father, Billy Ray Suggs, alleges a defective coupling caused his son’s death.

Billy Ray Suggs, individually and as estate representative, filed a product liability suit against K-M Products Inc. on Feb 25, 2008 in the Marshall Division of the Eastern District of Texas.

According to the original complaint, the deceased was attempting to refill a DOT-39, 1.02-pound propane cylinder from a 40-pound propane cylinder using a MacCoupler.

According to the K-M Products web site, the MacCoupler is the company’s chief product, which it has been making for more than 20 years. It is used to fill 1 pound refillable propane cylinders with any 20 to 40 pound propane tank.

“It’s easy and cost effective,” the web site states. “Made of solid brass, the MacCoupler will last a lifetime and is a welcome addition to anyones camping gear, tool chest, or their RV or camper.”

The web site includes downloadable instructions for proper use of the MacCoupler.

The plaintiff alleges K-M Products Inc. is liable because the coupler did not have sufficient, appropriate or securely affixed proper warning labels. Further, the plaintiff argues the defendant failed to use proper materials for the coupler and failed to adequately test or inspect the product and its components. The complaint states that the defendant knew the coupler was defectively designed and manufactured.

Suggs believes K-M Products is guilt of gross negligence and argues the company’s conduct was heedless, reckless and with a conscious indifference to the welfare and safety of his son.

The plaintiff is seeking wrongful death damages for emotional pain, grief, and sorrow, and pecuniary losses including loss of care, maintenance, support, services, advice, counseling and losses by virtue of the destruction of the parent-child relationship. On behalf of the deceased, the plaintiff is seeking damages for pain and suffering, funeral and burial expenses.

Tyler attorneys John D. Sloan Jr. and J. Ryan Fowler of the Sloan, Bagley, Hatcher and Perry Law Firm and Kilgore attorney Thomas H. Brown are representing the plaintiff.

Judge T. John Ward is assigned to the litigation.


Jann August 30, 2011 at 3:48 am

To operate anything that has any potential hazzard requires complete understanding and undivided attention to the operation and environment as well as the knowhow of what to do if something is not perfectly right. These suggestions and rules are to protect the average idiot. Unfortunately 97% of Americans are idiots. 99% of Americans drive! So how many idiots are on the road? And yet diving is NOT illigal, wether it be to the common idiot or the person who abides by my first statement.
If you look at any lawsuit, most of them are by idiots suing someone else for something that was their own fault…because they either couldn’t follow standard precaution, directions, or have absolutely no common sense.


David DIY devotee July 30, 2012 at 2:06 pm

Just stating the obvious
“Gary Wayne Suggs, 51, was attempting to refill a propane container in a fifth-wheel trailer when a flash fire occurred, causing fatal injuries.” In a fifth-wheel trailer? Enclosed indoor space? Plethora of ignition sources? This boy did us a favor by removing his genes from the pool.


Patrick July 19, 2013 at 7:37 pm

The federal law prohibits commercial sale or transportation, not private action. This case will most likely (should IMO) be lost because of the plaintiff’s _own_ gross negligence. He was using it in an enclosed space? I’m willing to bet other basic safety precautions were ignored as well…


Dave Bahney April 14, 2015 at 12:34 am

It is only dangerous if you are careless in following the instruction as he has given to us all. Ì have found that it is very safe in what he tells you. As far as that warning label, that is for resale only, just like that mattress label.


rickB January 17, 2010 at 12:01 pm

I would take one of your new fab adapters. contact me if still have one to sell…..


Chris Raney February 3, 2010 at 5:34 am

Could you give us a list of all of the specific parts in your connection assembly? The first coupling that connects the 20 pound bottle appears to be a type of articulating, compression arrangement so you can spin the tightening wheel to fit it on your supply tank without having to rotate the entire assembly (which of course wouldn’t work). I can see that the coupling that you attach the pounder to is a simple, straight connector. No doubt I would need a third coupling to bleed out the empty pounders, because I’d rather not lift that safety valve, if possible. Better yet, do you sell these items through something like a PayPal account?

Of course I know this assembly is just a curiousity. Perhaps I’ll use it as a paperweight. I know full well you wouldn’t sell me something for actual use in refilling one-pound tanks. Heavens no. But this contraption is so cute that I simply must have one!


Paul Ringo February 9, 2010 at 11:44 am

I’d like a list of the parts you used to make your coupler also. Thanks. Great idea.


Tim Flanagan, Managing Editor February 9, 2010 at 12:02 pm

The tricky bits:
Mr. Heater F273756, Soft Nose POL with Handwheel x 1/4″ male pipe thread.
Mr. Heater F273754 1″-20 female throwaway cylinder thread x 1/4″ male pipe thread.

The rest is easy:
IPS ball valve 1/4″ NPT female on both ends.
Brass nipple 1/4″ NPT x 6″ long.
Pipe elbow, 1/4″ NPT female on both ends.

Once you source all that stuff from a couple of suppliers (I could NOT find a single supplier that carried all of it), feel free to come back and just have me send you one for $40 total, shipped! I’ve got one adapter kit left that isn’t spoken for.


Andrew P. September 6, 2012 at 2:44 am

Be careful of your choice of brass ball valve: Some gas valves are only rated for 20 to 30 psi, as they only need to operate at less than 0.5 psi (12 inches of water) downstream of the pressure regulator. Chose one that’s made for water and rated for 200 to 300 psi.


Warren Harding February 11, 2010 at 10:16 am

Your refill setup is nice, good job.

Personally I would not sell them, because there are plenty of poor people in this country who have nothing to do with their time other than dream up ways to sue somebody. Ain’t worth it.

However – you are way cool for publishing your idea.

How about re-designing your site to clearly show all the needed parts, assembly, and step-by-step use of the device?

I’m off to the hardware store not to NOT DO anything with the parts I WON’T GET.



Chris Raney February 20, 2010 at 12:18 pm

I’ve refilled my bottles twice now, and I’m becoming quite adept at bleeding, weighing and topping-off to factory weight. I was skittish of this technique at first, as you can imagine, but the second time I sat down to fill my bottles it was a breeze. With my cute little digital scale bought on Ebay I set to work until I had drained my tank. (I recommend U-Haul outlets for refills).

There would have been simply no safe and effective way for me to have accomplished this task had I not purchased that refilling jig from you, Tim. Had I purchased one of those after-market gizmos designed for this purpose it would have wound up with 1/4 filled bottles and half my 20 pound bottle expended into the atmosphere, and risked frostbite to boot! Even with my initial purchase of a new 20 pounder and the scale I can see just how much money I’ll be saving in the long run. My propane use is in two little space heaters that warm my otherwise chilly little apartment. They’re nice little burners but man, are they hungry! Even at $5.38 a pair, purchase price at Lowes I ran through thirty-five dollars worth of gas on particularly chill and nasty weekend (hence my copious bottle stock). I think you can see why I was motivated to find out about refilling.

All of the above is just fantasy, of course. That jig you sold me has been used exclusively as an effective paper weight. And buddy-boy, it works just perfectly! I truly recommend it for everyone else out there with unruly papers.


Philip Miller February 23, 2010 at 3:00 am

Re Chris Raney’s desire to add a third coupling for bleeding the tank: It’s a good thought, but the the air space in the tank itself needs to bled off as it is being filled. Any third coupling in the fill line would just bleed the off the incomming propane and accomplish nothing.


Chris Raney February 26, 2010 at 5:22 pm

I said that before I had actually attempted this procedure. I didn’t realize the bottles would be dead empty once they were used. So my comment is now moot.


Dave (the firebug) Duncan March 9, 2010 at 1:20 pm

Darn! Why didn’t I find this site first. I’ve spent more money than I can recover by refilling. Did find your parts on Amazon and ordered those already. But I assure you, that you have no influence on what I’m going to use these parts for.. :-) Thnks


Blip March 10, 2010 at 8:54 am

Hey Tim, Sure, refilling works, but the restrictions for commercial operators aren’t there because somebody wants to be Big Brother or corner the market on small bottles. We really are paying with fire here.

The comment that a full bottle does not develop much more internal pressure than a 1/4 full one is correct only as long as the propane inside the cylinders stays liquid, which means below a VERY cold internal temperature.

But when propane vaporizes at warmer temperatures, it suddenly expands to 270 times its liquid volume. So, a “little bit extra” propane in a thin-walled disposable bottle now represents 270 times the pressure of that little bit extra above and beyond the designed capacity of the disposable bottle. That kind of pressure tests the strength of the cylinder walls and the brazed joint of the two halves, plus repeated refilling subjects the metal to more of these cycles and the better chance of an explosive rupture from metal fatigue at the molecular level. A little bit extra may not be not so little.

If overfilled bottles are not popping off in the summer, its probably because the manufacturers try to over-engineer them in the first place. Weighing the cylinders before and after is critical; fill to 85% capacity maximum to preserve some commercial margin of safety in the home environment.

By the way, I wouldn’t want to try to explain to a judge or opposing attorney how selling parts does not make you a commercial operator and subject to the Federal restrictions and penalties. Invest in some due diligence now; it could save you a lot more later on. You penetrate your own disclaimer by trying to have it both ways while selling kit parts. Doesn’t matter whether it’s profitable or not.


Laurence March 31, 2011 at 4:01 am

There is some wrong information in your comment (NOT good on a subject like flammable gas) I had to think back to 4th grade science-
1 If there is one droplet of liquid and one droplet of gas in two identical containers, the pressure is the same. The liquid level is meaningless. The TEMPERATURE controls pressure. Your random use of the number 270 is out of context and almost entirely wrong. The pressure is zero at 44 below and rises with temperature ; almost 200 psi at 100 deg.

2 The 20% expansion space is for liquid. When liquid expands, extreme pressure will develop, if contained.. Therein is the danger, not the gas pressure (which containers ARE designed for).

3 A commercial operator has given up his right in exchange for a license to make a profit in an interstate venue. Most people retain their right to fill their bottles with their propane as may suit their needs No judge should need this explained to him.


Cris April 5, 2011 at 1:18 pm

Learn your physics. Most of what you write is un- or misinformed bullshit. “very cold internal temperature” ? “270 times the pressure” ? sheesh.
Liquids expand with temperature. If you overfill your bottle, and it warms up too much, there is no volume left for expansion of the liquid, and you get very high hydrostatic pressure, because liquids are not compressible. This will indeed rupture your bottle.


Nitrous April 6, 2015 at 7:00 pm

Exactly how much does a liquid expand with temperature?

I certainly agree that GAS volume and Temperature are linked. Increase the temperature and (assuming the pressure remains the same) the volume increases.

Another point that hasn’t been mentioned is that there is a dynamic relationship between the gas and liquid interface. Many gases, propane included will exist in a liquid state at various temperatures and pressures. For any given temperature, there will be a fixed relationship between the liquid phase and the gaseous phase. As gas is taken off from the bottle, an equivalent amount of liquid will vaporize, ensuring that the pressure in the bottle will remain constant. Once the liquid phase has been exhausted, for every molecule of gas that leaves the bottle, the pressure in the bottle will fall, assuming that the temperature remains constant.

The scientific errors are getting mixed up with the legal aspects of the case.


Tim Flanagan, Managing Editor March 10, 2010 at 9:28 am

Oh, and trust me…it’s not! (profitable, I mean)

To make a reasonable profit, you’d need to charge $60 or $70 dollars, or else source the components MUCH cheaper than the deepest discount retailer I was able to find.

I’m officially out of this business. If I was ever in it to begin with. :-)


Nag March 11, 2010 at 7:53 am

Thanks for posting on propane refilling. How and where can I buy the fitting you have made ($40.00)? I like to try.


Tim Flanagan, Managing Editor March 11, 2010 at 8:12 am

You can’t buy it from me. I sold the last of the components I’d purchased. But since there’s a list of the parts you need included above, you can purchase the parts yourself.


Paul S March 31, 2010 at 8:25 pm , F273754, Mr. Heater, Cylinder Adapter (F273756, Mr Heater, 1/4″ MPTxP.O.L with o-ring

Other parts easily found at local home improvement store. A 1/4″male X 1/4″ male rubber hose can be found in the BBQ area. I stole mine off my weed burner that I don’t use any more!


Bill April 13, 2010 at 8:34 am

Wouldn’t you be able to use the ACME type connector to conect to the tank instead of the POL?


Ron June 19, 2010 at 6:58 am

The only problem with this other than laws is these tanks are not heat treated.
Heat treated is necessary to strengthen the tank evenly.
It’s possible for one of these little green tanks to have a weak point and refilling can cause a ruture and serious bodily injury.
Is it worth it?


Andrew P. September 6, 2012 at 2:53 am

If that were true, then new disposable cylinders should be rupturing left and right as frequently as DIY refills. Pray tell, show us the news reports and statistics of these incidents.


Rocko June 23, 2010 at 12:38 am

Call me a sceptic, but lets see if this makes sense to you, because i damn well doesn’t to me.
One would assume they’ve sold tens, if not hundreds, of thousands of these “couplers” since they developed them.
Each one, to be cost effective, would have to be used many, may times each. put out a summary of statistical risk of death, through various causes. Strangely enough, death from refilling gas bottles isn’t listed up there in the top 50.

1:100 chance of dying in a car accident
1:246 chance of death after falling down
1:325 of death by firearm
1:20,000 chance of death in a plane accident
1:58,000 cance of dying through legal execution…
1:200,000 chance of dying by asteroid impact!

And one fella dies from refilling one of these bottles?

You know…you’re probably more statistically likely to die from these bottles when you’re involved in a car accident, and one flies through the air from the back of your vehicle and smashes your skull in :)

So, does that mean you sue the designer of the bottle, because he made it fundamentally unsafe to transport?
Hell yeah! Sue his fanny to Alaska ad back!

Now, of course, one must look with care at the technical expertise of the father of the deceased Mr Gary Wayne, Mr Billy Ray Suggs, who can somehow scientifically define the cause of the explosion as due to “a defective coupler” rather, say, incompetence during refill, or the fact that he “was attempting to refill a propane container in a fifth-wheel trailer when a flash fire occurred, causing fatal injuries”.
And, of course, it’s not like anyone in the wonderful US of A doesn’t immediately hire a lawyer to sue for basically anything, and any reason, because…well…they can.
“Oww. Papercut on my anus from this super sharp edged toilet paper! Gonna sue there!”
So…One individual dies from refilling these cylinders.
Big friggin deal! More people get eaten by sharks every year.
(That’s assuming Mr Robert Myer cannot pluck a few more potential Darwin Award nominees from his behind who have given the world amusement by blowing themselves up in a “propane or propane-accessory-related incident, huh Hank Hill?)
Yeah, I’d laugh ;) But I’m a sick sod.

Do I think this is a good idea?
Who knows. Depends if I was to blow myself up doing it.
Statistically, I’ll be more concerned of being shot by some crack head on goofballs, or cut down by a swarm of ravening killer bee’s.

But to the twit who says he designed them, and thinks it’s a “bad idea to refill them, M’Kay”, I have a simple comment.

If you designed them in such a way that a simple, readily available refilling jig can be used to refill them, rather than in a way which renders them physically incapable of being refilled after use, then the persons fanny who I’d be concerned would be getting sued, is looking out of the mirror at you every time you use the bathroom”
Get some legal advice, ASAP, dude. Sooner or later, if some dumbarse blows themselves up refilling your product, they won’t be suing the Mac company, but you and your ilk, for producing an item that can be so easily refilled in the first place. Rest assured, all the little warning stickers in the world you wanna put on the bottles won’t save your rear end from a good hammering by Bubba, in the Pen, when that happens.

Hope you got a good lawyer.
Billy Bob’s dad has one, apparently. You should ask him for the number.


Bullfrog August 18, 2010 at 8:14 am

Blip, your reasoning in the quote below sounds like you know what you’re talking about, but it’s absolutely wrong:

(quote from Blip) “But when propane vaporizes at warmer temperatures, it suddenly expands to 270 times its liquid volume. So, a “little bit extra” propane in a thin-walled disposable bottle now represents 270 times the pressure of that little bit extra above and beyond the designed capacity of the disposable bottle. That kind of pressure tests the strength of the cylinder walls and the brazed joint of the two halves, plus repeated refilling subjects the metal to more of these cycles and the better chance of an explosive rupture from metal fatigue at the molecular level.”

270 times the pressure?? The volume of an expanded gas vs. a liquid one is not pressure, it’s volume, and even at that, your idea totally ignores the fact that a gas will expand only to the point where the pressure of the vapor and the temperature of the liquid reach an equilibrium. If a gas is compressed beyond that equilibrium point, it will again become liquid and occupy the liquid volume, not the expanded gas volume. Basic physics.

At a given temperature, the pressure inside a 1/4 full tank is the same as the pressure inside a full tank; this is because the liquid propane vaproizes until the inside pressure reaches that equilibrium point. Any tank, full or empty, will drop seriously in pressure when it gets cold, and you can notice it easily on a campstove, as the outside of the container ices up. Containers with low propane level cool more quickly, because there is less volume of liquid propane (it takes less energy to heat 1/4 cup of water than it does to heat a full cup, and there is less heat stored in 1/4 container of liquid than in a full one).

Heating the tank will increase pressure, regardless of whether the tank has been refilled, is nearly empty, or is nearly full. The danger lies in overfilling with pure, cool liquid. Liquid cannot compress, so if you fill a tank to the point where it’s entirely full of liquid, and then warm it up in direct sun, for example, the expanding liquid (not gas) has no place to go other than to break the tank, which it will do.

A good overfilling precaution for all you lawbreakers that really don’t fill your tanks because it says not to, would be to place the relief valve at about a 10 o’clock or 2 o’clock position when bleeding out the gas to allow liquid to enter. When you start getting liquid, stop. This assures that there will be air space in the tank and allow room for liquid expansion. The exact position of the relief valve could be determined by filling at 10/2 o’clock, then weighing the tank to see if it’s close to what it should be. If it’s overfull, put the relief valve a little lower, if it’s too low, raise it a little to 10:30 or so. Better to err on it being a bit low, as there is no forgiveness in a liquid that must expand (freezing water will crack a cast iron engine block as if it were nothing).

But I’m just appalled that anyone would do this; I’d bet some of these same folks acutally wash their own cars, which is very dangerous. That water pressure from a nozzle can put out an eye just like that, if you’re not smart enough not ot point the nozzle at your eye and squeeze the handle. Always check with your attorney and the government before doing anything like this, or getting out of bed for that matter.


Store in a vented location! September 8, 2010 at 9:43 am

Just remember the tanks have a consumer-grade cheap valve, and while saving money is cool, you don’t want to be the odd case where one leaks and fills a confined space like a trunk or cabinet.
This is WAY too much like work. I just run off a full-sized BBQ tank using a flex hose.
The optimal solution is the 5lb propane cylinder, but those aren’t cheap.


Possum October 14, 2010 at 8:23 pm

I found the following info at this site:

Pressures at which propane will remain liquid at various temperatures in degrees Fahrenheit: 120 psig @ 70F, 250 psig @125F, 400 psig @ 160F


Mike October 21, 2010 at 3:20 am

As to the comment above about the small tanks having a “consumer-grade cheap valve”, I doubt that the big companies that make the tanks originally would want to have to defend a suit claiming they think that the life of a consumer is less valuable than that of a commercial or industrial user and therefor a cheaper valve may be used.

I do think the valves are not designed to be opened repeatedly, but the duty of the small tank manufacturer is not just to design for intended use, but also to design for reasonably intended misuse by the consumer if possible. So some refilling using the available fillers by non-commercial individuals must be anticipated by the engineers designing the tanks if they are diligently doing their job.

After looking at this way too much, it seems that the concern of the government and the industry is that it will be not only cautious people who will refill the tanks, but also stupid people will try and refill these things near sparks or inside where the gas cannot dissipate quickly or that they will succeed in filling the tank greater than 80% full and thereby not allowing for expansion when the tank is heated for some reason and lead to the tank rupturing or the release valve releasing vapor in a dangerous area. I think that all will agree that this is something that a 12 year old child shouldn’t be doing….and lots of adults don’t seem to have that much sense either. Be careful.

As a final side note, I am sure one of the reasons that the original cost of these tanks is so much is due to insurance for product liability claims against the manufacturer, much like the insurance component in the price of a ladder or lawnmower.


Patrick July 19, 2013 at 8:03 pm

I believe you are correct in that the govmint aims to protect consumers from themselves and others through imposition of (sometimes onerous) regulations. The relatively high cost of the individual canisters is directly related to this: manufacturers won’t pay to certify the tanks to a standard which would be approved by the Feds for consumer refilling. Manufacturers hate when things cost money. Certification is expensive.

There is another, more pedestrian aspect of the canister pricing though. Think of it like soda: a 20oz is, say $1.50, and a 2L is, say, $1. What is the cost of the soda? Hardly anything. The plastic bottle is most of the first dollar. Try to buy an empty PET 20oz bottle–it’s near 0.85/ea in 2013. The higher price of the smaller sized bottle (vs the 2L) is a ‘convenience tax’ people willingly pay for the ability to carry it around and put it in cup holders (also, it usually sold chilled). This same dynamic exists for propane, both the cost of the steel canister and the convenience of the smaller size. Market forces at work.


meh March 1, 2011 at 1:00 am

Have some tasty Western Enterprises links. Google for distributors, but they are THE industry standard for commercial gas hardware.


tim April 9, 2011 at 4:57 pm

One can easily build a support for tank part of the inverted 20 pound bulk tank from 2 pieces of 2x8s screwed to a piece of plywood to use the after market adapter. In this way the tank valve can be turned off and on. Using a 90 degree needle nose plier you can then pull on the relieve valve pin to release the pressure. 2x12s pieces give you even more room to turn the tank off.

Fill all your empty tanks, then weigh and release any excess. I can’t see spending $40 bucks to refill 10 tanks at a time, as most times I use a 20-30# tank with a post so I can run a lantern & 2 hoses or a T to just run two hoses. Even in my 16 foot boat the 20# tank is easy to carry to moose camp and works better when the temps dip down below freezing.


JT May 23, 2011 at 12:11 pm

Nice site Tim. FYI, if you chill the empty green cylinder first, there’s no need to bleed them to get them full. I have *heard* :) that putting them in the freezer for 5 minutes will enable them to be refilled fully/almost full.


fred July 2, 2015 at 7:49 pm

I’ve tried everything to refill these bottles, and nothing works. I have the set up that was suggested, but can’t get the propane to transfer. I’ve tried cooling the bottles for 20 min, doesn’t help. Any suggestions?


Ken May 23, 2011 at 7:28 pm

Thanks for the valuable tutorial. I tried refilling as you set out but still didn’t end up with much propane in my disposable tank. I help the pressure relief valve open for about 10 seconds. Is this not long enough. I didn’t weigh the tank but I’d guess it has less than 3-4 oz of propane in it.


Jon P August 4, 2011 at 6:03 pm

If you’re not really in a hurry, you don’t even have to vent the smaller cylinder to get it to fill – just cool it off. Since there’s nothing in the tanks but propane liquid and vapor, all you have to do is drape a wet towel or something over the smaller tank so it’ll be cooler than the larger tank. As it cools, the gas will condense into liquid and reduce the gas pressure, which will cause liquid from the larger tank to flow in.

Of course, I would never do something like this, but theoretically if I did I could have achieved nearly 100% fill this way.


jafi August 14, 2011 at 11:22 pm

Hey Tim,
your paper weight needs one add. item.
A length of ground wire clamped onto the brass tube with at least a 20 penny spike attached to the other end driven into the ground or attached to the grounding post in a boat.
been refilling commercal propane tanks for years.
later, Jafi


Andrew P. September 6, 2012 at 3:04 am

No need to ground. The two cylinders are connected electrically through the brass/copper adapter and there is no air inside them, unless one has unscrewed the valves beforehand. With no electrical potential between the cylinders, there’s no way a static electric spark can be generated, and with all the LPG contained within metal when the ball valve is opened, there’s no way an external spark can affect the LPG inside. This is not the same situation as refueling an aircraft, boat or automobile. Commercial propane cylinder refilling stations don’t use a grounding wire at all.


Mt. Man August 19, 2011 at 2:09 pm


Would the adapter hoses that goes from a 20 pound tank to an appliance that is normally connected to a 1 pound bottle work as a “refill” adapter?

If it works seems like a lot easier way to connect the two tanks/bottles.


Andrew P. September 6, 2012 at 3:07 am

Only practical with a very short hose, 6 inches or less in length, which isn’t commercially available. Otherwise, you’d be wasting a significant amount of LPG every time you disconnect a disposable cylinder and the content of the hose vents to the atmosphere.


Andres Espino August 27, 2011 at 11:10 am

I’m a real cowboy and live on a ranch in the southwest USA. We bought our own Large propane tanks from a Farm and Ranch supply.. we have 2 of the 500 gallon ones. Because so many people have BBQ and we even weld with propane and Oxygen because it is easier and cheaper then Acetylene.. because of this the supplier will install a filler hose off the bottom of the big tank to fill small tanks off our large one. We have filled 5,10, and 20 gallon tanks for years! We also fill the propane tank on the pickup that runs on propane. I have never heard of a rancher blowing themselves up yet.

I bought a 24 ft Columbia sailboat that I am restoring and made my own sea-swing stove to someone else’s online directions using the small Coleman 1 burner propane stove that uses.. you got it.. those small green cylinders!

I used a nice stainless steel milk bucket from ACE tho.
I have a frame over the stern to hold 6 solar panels and on one of the support legs i have clamped a 3ft section of PVC sewer pipe capped at the top. I store my green cylinders in there shoved up from the bottom which is left open and a pin holds the stack in away from spray. Since propane falls any small tank leakage blows away It is far away from the cabin hatch.


ABE October 6, 2011 at 5:38 am

Um, I may be missing something here but in this thread there is a LOT of talk about a little “Relief valve”. If this little bugger was supposed to relieve something, no one has mentioned what. I am assuming that it is to relieve pressure, like all the pressure that folks here are saying will blow up the bottle. So what exactly is this relief valve supposed to relieve? At what pressure will it “relieve”?


Steve January 5, 2012 at 6:28 pm

I believe that relief valve will release some of the pressure (gas/Propane) from the bottle if the pressure gets too high. Like from excessive heat, stored in a place getting very hot 120+ deg. Better to release ‘some’ gas than for the tank to rupture.


Steve January 5, 2012 at 6:17 pm

My experience with refilling these disposable bottles, take it for what it’s worth.
40lb main tank, typical Mr heater refill connector, two- 1lb disposable bottles. Digital kitchen scale.

During the summer I refilled these same 2 bottles by using the freezer method, both empty bottles 1 hr in the freezer.
Filled with no problems extra 2 oz in each with one attempt…cool. Took about 3 min to fill each. If that.

This winter (today) 40F outside so 40 lb tank was cold.
Could have been colder as it was morning, over night was about 25f.
Hooked up both bottles one at a time and filled them without putting them in the freezer. LOL only got “2″ oz of propane in ‘each’ bottle.
So I tried the needle nose plier trick with the release valve on one of the bottles, I tested it while it had only the 2 oz in it. Pull pin gas escapes, let it snap back and test it with water…it leaks. Pull pin, let it snap back…still leaks.
Third time…Pull pin…Pin pulls out of the valve, tank ruined.
Same day (today) 1 hr later aprox. I put the other tank in the freezer for one hr (it had 2 oz in it and didn’t leak, as I tested it)
I then rehooked up that tank to the same 40lb main tank (upside down of course) and I did NOT mess with the safety valve. That tank filled up and actually put in an additional 4 oz with one attempt. Took under 3 min.
Tested valve for leaks…no leaks.

Putting them in the freezer empty certainly works, winter or summer and without warming the main tank.
I will not mess with the safety valve again, no need to imo.


Steve January 5, 2012 at 6:24 pm

Edit…when I say it put an additional 4 oz in the last bottle I meant it over filled the bottle by 4 oz.
Total weight was 37 oz.
So some needs to be bled off.
I will not wait till the tank goes quite while it’s filling next time, I’ll shut it off a bit earlier.


Steve Stuller January 13, 2012 at 12:16 pm

An acquaintance of mine blew up his boat and put himself and his wife in the hospital because he stored one pound propane bottles below decks. If the bottles get too hot they relieve the pressure and gas thru the valves. Propane gas trapped below decks is a terrorist’s dream bomb. Thanks. Steve


rcracer64 January 15, 2012 at 11:20 pm

I have refilled several cylinders and I found the best way is to set it up and angle the bottom cylinder so that it can not completely fill (expansion space). Let it set for a day or so. Do not fill the one pound bottle completely or could be very dangerous.


RobertL39 January 23, 2012 at 5:47 pm

I don’t get it. I’ve followed all the instructions, both here and from NeonJohn. Even freezing my 1# cylinders overnight and having the 20# tank 2 feet above the disposable to be refilled I get virtually no flow. Pulling on the release valve and I get a little more. Just spent 3 minutes and got less than 2 oz into the bottle [by weight]. The copper pipe gets nice and frosty. I get liquid out [of the copper line] when I disconnect the disposable. What the heck gives? All you guyz can do it [but don't do it, I know] but I’m stymied. Thoughts? Thanks a ton. The copper fittings manufacturers thank you too.


Steve February 17, 2012 at 10:57 pm

I can only guess as to why it doesn’t work for you.
We are using different transfer equipment, I’m supposing this is the problem.
Perhaps the equipment you are using doesn’t open the orifice valve on the 1# cylinder when you screw it on?
I would try attaching a “FULL” 1# cylinder to your transfer equipment without connecting the other end to anything just to see if your 1# tank valve is being opened.
Of course be careful for any gas coming out the other end of the pipe. If nothing comes out, then I think you may have found your problem.


Steve February 17, 2012 at 11:06 pm

Just had a thought about another possible reason, silly I know but it bares mentioning anyway…After removing the 1# bottle from the freezer don’t wait too long to fill it.
The little bottle will warm up quickly and then you will lose the effect of freezing it.
When I tried to fill a non frozen 1#er all I got in it was 2oz, which sounds like what you got.

Have everything set up and ready to go then remove the 1#er from the freezer and fill immediately.

Again just a guess.


David February 12, 2012 at 3:30 am

If you add a second 1/4 turn ball valve into the equation after the small disposable bottle you can dump the propane much more easily. It is a very similar method to that of refilling CO2 bottles for paintball. Search for deluxe dual valve co2 fill station for an example of how to do this. Also, you want to add a muffler or a drain to so that when you close the first ball valve and open the second one it doesnt squirt liquid or gas at you or your buddy.


David February 12, 2012 at 3:35 am


Sometimes if the small bottle is completely empty it can take a long time for transfer to begin. You can speed this up by connecting it to the large tank and letting whatever will flow in for about 5 minutes, then dump the small bottle’s entire contents all at once using the second ball valve method I described above. This will cause the bottle contents to freeze dropping the pressure. Storing your large tank in a heated structure over night will raise the pressure in it as well. Build a fill station like the ones show for “deluxe dual valve co2 fill station images”


RocketDad February 19, 2012 at 7:02 am

Thanks for sharing with us the best way to not refill disposable propane bottles. I will soon build one of your paperweights with which I will not refill the disposable bottles I use for picnic cooking.



sha February 22, 2012 at 9:23 pm

For testing purposes, we inserted an upright positioned full green 1 lb propane container into a very hot fire and quickly took cover behind some rocks. Big disappointment! No explosion. The relief valve melted open and we got a 6 foot fire geyser. What a let down!


Paul February 29, 2012 at 4:28 am


the adapter you use to connect to the larger tank is a restricted flow adapter. There is a full flow version of this which would probably make refilling much quicker. You’d probably want to throttle either the tank valve or the ball valve. What do you think?


pete March 4, 2012 at 5:08 am

why not just refill without bleeding? that’s what i do. you’ll get almost a full cylinder, but not have to worry about being overfull.


JR March 8, 2012 at 12:02 am

Ok, I understand all of this about NOT refilling cylinders. What I really need to know is…… will I be arrested for taking the tags off my mattress?

Thanks Tim!


Dave March 18, 2012 at 4:59 pm

Showing people how to do something and then telling them they should not do it is contradictory. If you’re trying to protect yourself, it’s ineffective. A claimant could argue that they didn’t know which one of your advices to follow and/or that you made it impossible to follow both, and they’d be speaking truthfully on both counts. Much better to “keep it simple” and disclaim any responsibility for anyone’s use of your instructions.


mark April 9, 2012 at 3:41 pm

Help…….i am in the uk and have purchased a mac coupler from the usa but all of the gas cylinders here have clip on style regulator fittings… there an adaptor i can get to convert the clip on style calor regulator to enable me to connect my mac coupler to my 4.5kg tank?


propaneintheass April 11, 2012 at 2:09 am

Isn’t having a digital scale at the site of filling a bit dangerous?
I say ditch the scale along with the cell phone. Take the bottles well away from the filling site and then weigh.
Also, all paranoid people, you can buy your small bottles, take good care of them, and set a limited number of times you are willing to refill… 10 maybe? Use a Sharpie to keep track right on the bottle. That way you know you are using brand new unmolested bottles, and getting rid of them after many good thorough uses.


Tom Hargrave April 29, 2012 at 4:56 pm

Do you understand how dangerous this is? A 1 pound propand bottle contains 16 ounces and even just 2 ounces over-full is over 10% over full and this increases the tank’s internal pressure dramatically.

If you are going to fill your own bottles, at least weigh them afterwords to make sure they don’t weigh more than a new, full one. And bleed the gas off the ones that are over weight.


Steven May 5, 2012 at 11:30 pm



Furface May 7, 2012 at 9:04 pm

I got all items at my local Ace Hardware.They had to order the 2 Mr Heater items but all works well and approved by a state inspector for private use.


Crazy2refillit May 15, 2012 at 12:47 pm

Some of these people are slow, is the better word if you don’t like the info then don’t read it And don’t post anything negative just shut up and go read some other laws. To the author thanks for the info I was wondering about it.


Tom May 18, 2012 at 5:28 pm

Hello all,

Has anyone else noticed that COLEMAN sells these refill adapters,
under the name of Coleman?
Lots of assumptions here, but I rather assume that they mean to “refill Coleman containers” with their Coleman adapters.
Just check Walmart sporting section.

Thanks for all of the great information,


PF May 31, 2012 at 4:06 pm

These instructions are dangerous and obsolete. As the previous posters notes:
Buy a commercially available refill valve on Amazon or Ebay.
Enough said. $13 , $16 at Amazon (with reviews, hints and tips)


Dave C. June 21, 2012 at 7:05 pm

Seriously? You pull the relieve valve to vent during filling???!!!
All you need to do is chuck the green cylinder into the damn freezer for 15 minutes. Perfect fill every time.
That’t hot >>I<< do it and not risk a permanent relieve valve leak!
I guess your advice of "Let me repeat: No one should ever refill disposable propane cylinders using this or any other method." is totally correct. Asinine, and dangerous practice. Don't touch the relief valve!
Use the freezer or refrigerator people. Works every time. Weigh the cylinder afterwards and verify it ONLY has a pound in it. This works so well, it's easy to overfill them.
Don't listen to this clown!
Oh, and notice the RUST on his cylinder! A definite NO NO! This guy is an idiot. Maybe this is a joke. If it is, it's a very bad one.


woodsman5150 July 2, 2012 at 1:45 pm

Thanks for the great instructions I made one a couple of months ago and it works great. I use it for my propane weedeater.It’s sad how some peole come to “rant”. Its almost like how some turn every thing into a politcal or racial thing on post,this one seems to attract the “I’m more intelligent than you crowd”. I like how its my choice to save money and do as I please without government regulating and making money of me for everything.Thanks again Tim.


John July 5, 2012 at 12:20 pm

So how much do you think it costs in propane to fill a bottle ?


ed August 13, 2012 at 2:33 am

about 58 cents per bottle i believe.


Thomas Graham July 30, 2012 at 9:06 pm

What worries me here is getting air in the refilled tank. I didn’t see any mention of bleeding the air out of the refilling apparatus before filling the tank. Also I have had several 1 lb tanks leak empty from siting around a few years. Who’s to say air didn’t leak in after all the propane leaked out.

I don’t think I’d want a mixture of propane and air in a 1 lb tank sitting around. Or dropped accidentally.


Darren December 21, 2012 at 5:41 pm

Your right! The apparatus is built just for easy access to the relief valve which should not be tampered with anyway! Freeze the small bottle and keep the 20 lbs at room temperature. If you are worried about air you can purge the bottle briefly through the relief valve, but be careful not to damage it and always do it outside.


emmett August 14, 2012 at 5:28 pm

cool setup…I noticed you used what looks like teflon tape on the fittings. you might consider using tape that is specific for gas, which is yellow in color to differentiate, as the regular teflon tape can degrade with exposure. just a suggestion.


Skip September 7, 2012 at 2:57 pm

Great work! In your original blog Apr 17, 2008 on refilling disposable tanks there is a picture near the top & in the picture is a puggie that has a regulator with a control knob. We have searched high & low & can’t find one. Any idea where we can buy them?


Tim September 7, 2012 at 4:54 pm

You mean the white cylinder I’m using as a supply? That’s just a regular 20-pound cylinder like you use in a backyard grill, turned upside down.


Gary Hall September 16, 2012 at 1:26 am

I put the one pound bottles in the freezer. I vent then before connecting to the large tank. I find the small tanks all the time. So if the ones I fill are 90% I don’t care. I just use two bottles.


Gus September 27, 2012 at 10:27 pm

Can I refil a Coleman propane tank with gas R22 or 134a?
How I can do it and what is the adapter that I will need?


Brenda October 18, 2012 at 7:21 pm

Hi Tim: I would like to hook up my little 2 burner camp stove to a 20 lb propane cylinder. The stove is designed to be used with the little 16.4 OZ bottles. Can you tell me if there is an adapter needed and if yes, where can I get one. I may also be interested in buying the adapter you make–for filling the small bottles from the 20 lb. Are you still selling them? Please email me privately as well posting an answer here. Thanks.


Tim October 18, 2012 at 11:48 pm

If you have a 20# cylinder nearby, by all means use that to supply your appliance. Yes, they sell adapter hoses in various lengths with the 1# bottle fitting on one end and the 20# bottle fitting on the other. Any good outdoor store or propane accessory place (Mr. Heater, for example) will have those.

No adapters left…sorry!



Kevin November 19, 2012 at 3:57 pm

Instead of venting pressure from the bottle, would creating a (temporary) temperature differential work? Heat the 20# tank (at least to room temperature, or by sitting he the sun under black plastic, or by soaking in hot water), and freeze the 1# bottle before starting.


Gregory Romeu November 30, 2012 at 5:13 pm

It would be nice if you listed the actual parts/part numbers of the fabricated assembly that you built.


Cpainter December 8, 2012 at 1:13 am

To all of the naysayers and losers quoting laws, and court cases, and giving the author of this hell. Quit being such pussies, if someone is stupid enough to try to refill a canister inside a 5th wheel, they deserved to die, I’m only sorry the fire didn’t take out this jackass’ dad also. I think this is a great article, and I have a treasure trove of tanks just waiting to be filled.


Andrew Clifford April 11, 2013 at 7:14 pm

Tombstone read,

“Died being cheap, but at least he was never considered a pussy.”


Patrick July 19, 2013 at 8:13 pm

That’s not very sensitive to Mr. Suggs. He didn’t deserve his fate, even if he didn’t know what he was doing.

And that’s the point: if you what you’re doing and what can go wrong, it can be done in an entirely safe manner. Just don’t be stupid. (Can we make that a rule?)


Darren December 21, 2012 at 5:27 pm

Kevin is right! Do not screw with the relief valve. Put the small tank in the freezer for .5 hours before fill. Works way better and I tried both.


brian December 27, 2012 at 4:31 pm

having the larger tank warmer then the smaller take, the lager tanks pressure will increase . lower the temp in the smaller tank will lower the pressure, will further increase the difference in pressure allowing easy transfer. for a reference umm look at propane distillation. describes the the affects from heat pressure and condensation. i been playing around with the butane’s freezing liquid and gas states using different pressures and temperatures. hope this has helped alittle.


Roland February 4, 2013 at 1:12 am

I am not advocating that anyone should refill a small propane cylinder from a larger one. I have read your great article and have conducted experiments for the sake of research only. I am building a slightly different adapter using a hose, a “T” and two valves. One valve will control the flow of gas from the large cylinder as the single valve pictured does. It will terminate into the “T”. On the bottom of the “T” the bottle adapter will be mounted. The side port of the “T” will terminate in the second valve. The second valve will allow venting without having topull the pressure relief pin, which seems to be a point of failure all too often. Using a hose rather than rigid tubing will allow ease of threading the cylinder which is critical in determining how my propane is in the cylinder being refilled.

Again, I am not advocating the anyone attempt to refill small propane cylinders from larger ones. The potential dangers are great when working with compressed flammable gases.


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Headley of OZ March 10, 2013 at 12:17 am

I have not tried refilling a coleman cylinder and are just thinking out loud here.
When there is the correct weight of gas in one of these cylinders then the gas (in its liquid state) would be at a certain level.
Therefore the following should work.

Fill one to the correct weigh and then lay it on its side with the little valve to the top.

Pull on the valve and gas will be released.

While holding the valve open, slowly roll the cylinder so that the valve is moving towards the bottom.

When the valve reaches the filled level of the cylinder the gas coming out of the opened valve will start to come out
as a liquid.

release valve and measure its height from the platform you are rolling the cylinder on.

When filling a cylinder, place it so that it is in the same position (vavle height from platform).

When liquid starts to flow from valve instead of gas, cylinder is full. It would still be wise to check the weight of the cylinder but this would give a fast way to get it pretty close.

This is theory only and should not be carried out :-)


MAbdelli March 25, 2013 at 6:00 pm

Anyone trying to refill Disposable cylinders is putting themselves at great risk. Especially when the filling involves Liquefied Flammable gases such as Propane. Propane cylinders are designed to be filled by measuring the weight or the volume of product put into them. A 20lbs propane cylinder typically has a small vent valve to which a fill dip tube is attached to tell when the cylinder is full. Disposable cylinders do not have such a feature. If the Disposable cylinder is overfilled, when the ambient/use temperaure increases, there is risk of the Cylinder Rupturing if the Relief Valve is either insuficient or malfunctions. In addition to the energy released by the propane suddenly eveporating upon cylinder rupture, a flammable mixture of propane and air is formed which can easily ignite into a ball of fire.
Last time I checked, recreational disposable propane cylinders were about $5 or $6! What is the point in putting onself and potentially one’s family/house at risk?


Andrew Clifford April 11, 2013 at 6:43 pm

This is a HIGHLY UNSAFE practice.

Here’s an article of a man who’s wife died as a result of doing this…

While I realize that driving to work or even crossing the street is statistically more dangerous; this is NEVER a risk that you should take.


Stephen July 3, 2013 at 7:32 pm

I bought the adapter months ago, and a propane tank. Just got around to trying it. Found refrigerating the tanks was more than good enough, but also it has been rather hot here, so the difference in temp between the two is proabably simular to freezing a can, and current temperatures. I have filled 3 cans, and have more that I could do. #2 can, leaks, so the 20LB upright, and drained what I could out of the leaking can. A second one had a micro leak, probably a old can. Otherwise seems to be working. Thanks for info.


Skeeterass September 19, 2013 at 10:58 am

Great article.. And if anyone doesn’t agree.. Then don’t do it. It’s just that simple.


Tish October 3, 2013 at 3:40 am

I would leave the pressure relief valve alone. The seats on that valve are not rated for repeated operation and many pressure relief valves also have a secondary mechanism called a melting plug so the tank will vent if exposed to high temperature (it may be a dual-function device to safely depressurize the tank in the event of a problem).

The extra headspace in the tank (pressure vessel) is there to allow for liquid/gas expansion when the tank is stored at higher temperatures. Gases are compressible, liquids are not. If you leave no headspace (room for vapor) in the tank then even the slightest temperature increase will cause a crazy-rise in tank pressure.

All of this regulation on pressure vessels (tanks) came about from some tragic disasters involving boilers around a hundred years ago where dozens of people were killed when building heating boilers blew up. Watch any disaster YouTube on rail car explosions and you can see what happens when a pressure vessel is rapidly heated and the pressure relief valve was not up to the task. Some of these incidents are called BLEVE (boiling-liquid-expanding-vapor-explosion).

A one pound propane tank can act like a hand grenade and toss shrapnel all over the place.

I am not going to weigh in on to-fill or not-to-fill. I do not care for the nanny-state either and I do think that the cost of propane is ridiculous but you are also paying quite a bit of money for a “disposable” pressure vessel (absolutely silly). For my outdoor needs I use butane (about 1/5 the pressure of propane). It works good but does not vaporize below 30.2 F (right below the freezing point of water so it is not good in the wintertime). Propane vaporizes at -44 F.

The recommendation is to leave 20% vapor space in any tank. Here are some pressure-temperature numbers for an 80% full tank;

30F 51 PSI
60F 92 PSI
80F 128 PSI
90F 149 PSI
100F 172 PSI
110F 197 PSI
130F 257 PSI

If you go beyond 80% full the pressures go waaaay beyond 257 PSI at 130F (think of the trunk of your car). You start getting really close to popping open that pressure relief valve that you have been messing around with. BTW, they begin to open at LOWER pressures than the original rating so you are even more likely to create a propane cloud.

Propane vapor is explosive between 2.1% and 10.1% by volume (known as LEL; lower-explosive-limit and UEL; upper-explosive-limit).


Jay November 25, 2013 at 5:17 pm

The only “law” I can find about refilling the 16.4 oz propane bottles refers to “transporting” .
I don’t believe anyone would be able to prove the contense is refill propane, or original fill propane.
My opinion is if an agency confiscated on of theese cylinders to use as evidence against anyone in court, that whoever did so would be in violation of “49 U.S.C. 5124″ and I would request THEY be prosecuted for said violation.
The Govt shackeled themself with such a law.


Douglas December 3, 2013 at 10:41 pm

All great info, Thanks ! I would like to know how to defeat the “Full Flow” safety valve on the new rentable acme tank valves. I fill my boat aluminium LPG tanks from 5 gal tanks , but how to do that with the new full flow safety valves ?


Jay December 6, 2013 at 9:53 pm

not sure what the “full flow” valve is, but I have taken an old style L/h thread coupler, off an old bbq grill and addapted it to an appliance that had a new style female external coupler and it worked OK.


Herman Billings May 10, 2014 at 4:42 am

You’ll find the basic parts to do this at


HuppNut June 24, 2014 at 5:22 am

To All, This is long,
I have read many of the postings about refilling your 1 lb. propane cylinders from a larger 20 lb. tank. And nobody has realized that to get that 20 lb. tank to the 80% full state your local propane tank filler-up’r doesn’t just let the liquid from that 1000 gallon tank flow into the 20 lb. tank until liquid comes out the bleed valve. They have to turn on the PUMP that will transfer the liquid from the BIG tank to the LITTLE tank using the pressures needed to force the liquid level to the 80% full point in the little tank. A powerful enough pump could fill the 20 lb. tank to 100% and if the operator was foolish enough to not stop the flow at the 80% point. Because overfilling is possible many types of propane tanks have or will have an 80% full shut off valve internally to prevent overfilling. The operator is still required to use the bleed valve as a secondary safety step in case the 80% shutoff valve fails to function in shutting off the filling operation. Not everything is foolproof so a little human, but hopefully well trained, monitoring is required for safety’s sake.
This is why some individuals only see a few ounces of liquid go into their 1 lb. bottle instead of the full pound, you are not forcing the transfer. By freezing the 1 lb. tank you are causing a temperature/pressure differential between the two tanks. The colder 1 lb. tank is sucking the liquid in. This will continue up to the point that a quiescent state is achieved between the two tanks (as the little one warms up to the ambient air temperature the two tanks are at) this is when you do not hear liquid flow sounds anymore.
To transfer enough liquid to the 1 lb. tank to fill it to 100% capacity it would have to be chilled to or below the vapor pressure point of propane, a temperature of -44 degrees F or the larger tank has to be heated to a temperature high enough (DANGEROUS) to push the liquid propane into the 1 lb. can as liquid until it fills to the desired amount, the same thing the pump does but safely.
Once the quiescent state is reached the 1 lb. can has the same internal pressure that the 20 lb. tank has and it’s liquid to vapor pressures ratios will be the same. The only thing that directly effects this liquid to vapor ratios in the tanks is the temperature that the tanks are at.
This is how the liquid to vapor states exist in a closed container. The same is true for your auto air conditioning system. 12 ounces of coolant in a can, be it the old R12 or R134a, has the same pressure (PSI) as a 16 oz. can or a 20 oz. can. The pressure will be related to the ambient temperature of the container not its liquid fill level. The 20% vapor space is a safety margin for LIQUID expansion as temperatures increase in all, closed, compressed liquid containers. As long as the temperature stays at a save level for the contents the container will hold the pressure, if not that is what the pressure release valves are for on all HIGH pressure containers, better to vent than blowup
This same balanced pressure level exists in the HVAC system until you activate the compressor to force the system to do what it does, absorb heat going from high pressure to low pressure and give off heat going from a low pressure to the high pressure that the compressor produces.
Propane has a much lower vapor pressure temperature than your HVAC system coolant so the pressures can be much higher so the containers have to be much stronger to hold these pressures. Example: my propane tank in my motor home is built to withstand 312 PSI at 450 degrees F, and at the 312 PSI the vapor pressure temperature is actually raised to being only -20 instead of -44 (the vapor pressure temperature is the temperature that the liquid BOILS at and becomes vapor). Your car radiator system does the same thing using just 15 lbs. of pressure to raise the boiling temperature of water/antifreeze above the 212 degrees mark (vapor pressure temperature for water).
Cooling your 1 lb. can has similar effect that some techs use when adding R134 to the HVAC system in your car. The ambient pressure of the coolant in the can will only drop initially to the low side pressure (PSI) levels in the system that the compressor is producing on the suction side, then it becomes a waiting game for the suction action of the compressor to empty the can. Some service techs know the if the ambient temperature of the can is higher than the ambient temperature that the HVAC is dealing with that the pressures will be higher in the can and aid in emptying the can into the HVAC system, so they place the can in warmer water to raise the internal vapor pressure, also a Not Recommended practice for HVAC – the “can” may blowup – no safety release valve.
So your biggest risk is blowing yourself up (in a fifth wheel or a garage) would be because leaking propane was accidentally/carelessly ignited. That’s why the manufactures trust promoting their adapters because if they were a public safety hazard they would probably be prohibited in marketing them and you would have to adapt your own design, at a risk you are taking.
So be careful, be safe and don’t do this in a fifth wheel trailer or a garage, keep it outside.


Eric M July 3, 2014 at 2:19 am

Just some thoughts here. When a 20 lb cylinder is standing upright, the vapors are being drawn from the liquified propane expanding to a gas. When that same cylinder is inverted, the transfer is purely liquid. Though the liquified propane is not explosive, the moment it hits the atmosphere, it will become explosive as it turns to a vapor. Therefore, transferring the liquid propane has a higher volatility for explosion upon hitting the atmosphere than the vapor.

In order to fill a disposable cylinder, one has to transfer the propane in it’s liquid form. This is a similar type of transfer that occurs when refiling the 20 lb cylinder.

With all that being said, it is important heed extreme caution with the filling of any disposable cylinder. I would use a high quality adapter or nozzle with a small orifice to make the transfer in order to minimize bursting or an explosion.

One last note; I would not suggest bleeding off the disposable tank while it is attached to the larger tank. Prior refrigeration or freezing of the disposable empty cylinder makes sense; and it should most certainly be empty. One does not want a partially filled cylinder exploding when opening the refrigerator or freezer doors.


Louis July 5, 2014 at 3:23 pm

Moi je remplis mes bouteilles de propane en les mettant dans le frigidaire environ 15 minutes avant de les remplir.
J’utilise ce principe, donc pas besoin de me servir des pinces et je trouve ça merveilleux. La bouteille en étant froide réduit la pression automatiquement.
Bonne chance


Will July 27, 2014 at 7:34 pm

While Tim’s system is certainly elegant and I’m sure a superb performer, I have has great success with the KISS method. I fill 2-4 cylinders every 2-3 weeks. I keep the adapter on my 20 lb. bottle except when refilling that. It has never budged once tightened into place. The o-ing must act as a lock. I screw on the cylinder while tank is upright. Invert the assembly, reach under and open the valve all the way. After a day or so, I reach under, close the valve, turn the bottle upright and remove the canister- no muss, not fuss. I’m sure Tim’s more calculated method is better in some ways, but KISS is doing fine for me. Oh, once, I smelled a little gas odor after a few minutes, figured the vent was failing- didn’t really know that I might fuss with it- it held the gas already in it without further leakage- I used it up and disposed of the canister.

Cheers, Will


Peabody October 31, 2014 at 8:27 pm

I can’t wait ’til I get all the pieces to build my own 1#cylinder refill kit,so I can place it in the perfect position on my desk, and not refill any of the 10 M.T.cylinders I have stored in a warm dry spot in my garage.Shows how long I’ve been trying to find out how not to refill a “disposable”1#cylinder. Thank You so much for all that dangerous information.Believe me, I’ll not be doing it in the garage,dining room,kitchen or travel trailer, that nice level,well ventilated,patio out back is a better place not to do that sort of stuff.


Rick P. November 16, 2014 at 4:37 pm

I just made the same setup as you showed here. I filled the first bottle until I couldn’t hear the transfer anymore then pulled up on the relief valve for a bit and liquid came out and the valve is leaking, did it freeze? The second one did the same,then the second 2 I only held up on the valve stem a little bit and it seems to work. Does that vale freeze open if held up to long and also it is 34 degrees here now is that to cold to refill cause my soapy water is freezing on the bottles. Oh ya I don’t have a scale yet roughlu how long do you hold up the relief valve. Thanks for any input.



John January 3, 2015 at 10:33 pm

This is one of the best tutorials on this I’ve seen, and I have it bookmarked. After doing this for quite a few years, I am starting to use a flexible hose adapter line I made up from various fittings that allows me to put the 1lb tank on a scale and monitor the weight while it is filling. In winter I also have found it useful to use a heat gun to gently warm the donor tank from time to time (while monitoring it with a bare hand or an IR Thermometer).


Timothy Haycraft January 10, 2015 at 10:10 pm

You need not relive the preasure in the bottle with this simple method; attache the quarter turn valve assembly to the bottle as discussed, leaving the valve open place the bottle in very hot water. After one minute close the quarter turn valve, you have effectively created a near vacuum. Now place the whole apparatus in the freezer for twenty minutes; immediately upon removal from the cold follow the filling instructions as described by the author with exception to any manipulation of the relief valve…


Timothy Haycraft January 10, 2015 at 11:22 pm

Addendum: The afore described method of heating & chilling the cylinder is time tested and routinely yields (1 pd) to (1.3 pd) fill levels; PLEASE… Open valve slowly allowing a gradual filling of the bottle, as a sudden rush of LPG my well cause a rupture of the relief valve…


brad January 27, 2015 at 7:19 pm

No you should never ever do this ever

£10 a bottle TOO RIGHT I DO. :D


Lee t July 14, 2015 at 5:45 pm

FYI to all of you: There are two companies making refillable one pound propane cylinders. They are Manchester Tanks and Flame King. Even though a significant initial cost – around $40 for Manchester and $19 for Flame King it is worth looking into. The connections may need tweaking as it appears that the ref. tanks were designed to be refilled from forklift tanks that apparently have a liquid output rather than gaseous output. There should be more safety in this type of tank compared to refilling the disposables.


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