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 Navagear.com. 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. 
Because 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.
The 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.
33 responses so far ↓
craschworks » Blog Archive » links for 2009-08-28 // Aug 28, 2009 at 2:03 am
[...] How to refill disposable propane cylinders | Navagear.com 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 Navagear.com. It’s popular because the subject is relevant to a wide variety of outdoor recreational enthusiasts: backpackers, kayakers, hunters, boaters, you name it. (tags: propane survivalism seasteading) [...]
Aaron Tinling, Publisher // Aug 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.
Tim Flanagan, Managing Editor // Aug 28, 2009 at 8:43 am
Good point, Aaron. I’ve incorporated that into the article.
Rollie Herman // Aug 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 // Aug 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.
links for 2009-08-28 « Mandarine // Aug 28, 2009 at 8:06 pm
[...] How to refill disposable propane cylinders | Navagear.com (tags: sailing hack) [...]
Tom ( starcraft) // Aug 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 // Aug 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.
Tim Flanagan, Managing Editor // Aug 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 AceHardwareOutlet.com.
grumpy // Sep 3, 2009 at 5:59 am
does anyone know how much presure these bottles are tested for ??????
Tim Flanagan, Managing Editor // Sep 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.
Joe blow no name // Sep 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.
Thanks // Oct 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 // Oct 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 // Oct 30, 2009 at 5:32 am
Do you sell your version of the refill valve?
Tim Flanagan, Managing Editor // Oct 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”!
nev b // Nov 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 // Dec 18, 2009 at 6:54 am
I will buy one of your propane refill kits if you still have any left.
Robert Meyer // Jan 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.
rickB // Jan 17, 2010 at 12:01 pm
I would take one of your new fab adapters. contact me if still have one to sell…..
Refill Disposable Propane Cylinders! | Navagear.com // Jan 21, 2010 at 8:42 am
[...] UPDATE: check out this more recent post to learn how I assembled my own super-duper propane refill adapter! [...]
Chris Raney // Feb 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 // Feb 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 // Feb 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.
Warren Harding // Feb 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.
Thanks!
Chris Raney // Feb 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 // Feb 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 // Feb 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 // Mar 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 // Mar 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.
Tim Flanagan, Managing Editor // Mar 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 // Mar 11, 2010 at 7:53 am
Tim,
Thanks for posting on propane refilling. How and where can I buy the fitting you have made ($40.00)? I like to try.
Nag
Tim Flanagan, Managing Editor // Mar 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.
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