Refill Disposable Propane Cylinders!

by Tim on April 17, 2008

UPDATE: check out this more recent post to learn how I assembled my own super-duper propane refill adapter!

It’s my new manifesto, sort of. See, these 16-ounce "disposable" propane cylinders are such a convenient size for camping and cruising on smaller boats, sometimes there isn’t any other alternative. In the lazarette aboard Two Lucky Fish, A C-Dory 22, this is really the only propane storage solution that doesn’t involve a costly custom propane installation.

Propane_Fits

So go ahead and use the 16-oz cylinders if you can’t fit one of the DOT-approved refillable cylinders. It’s a shame that even major suppliers such as Coleman have no recycling recommendations for them.

But I’ve learned that they CAN be refilled. The reason you don’t hear much about it, though, is that these cylinders aren’t DOT-approved for refilling. This means that you can’t take your cylinders to the local propane-equipped service station and have them refilled. That’s against the law. And refilled cylinders can’t be sold commercially. And commercial operators can’t transport refilled cylinders across state lines. There are all sorts of limitations and potential liabilities associated with refilling these cylinders.

It’s perfectly legal to refill them for personal use, however.

Obviously, because it’s propane, you need to handle it properly and observe all the best-practice safety protocols.

First thing, though, you need to purchase one of these little adapters from Mr. Heater or one of their distributors.

I got mine at Joe’s (which was G.I. Joe’s when I was a kid, and actually sold military surplus gear, but I digress). Cabela’s sells a similar item called the Mac Coupler, and it’s worthwhile to read the negative reviews on their site.

The negative reviews, which are by far the minority, describe some of the difficulties people experience using this adapter. This can be helpful, because there are a few tricks to refilling these cylinders. To obtain the best results, it helps to understand a little bit about how propane works.

At normal atmospheric pressure and temperature, propane is a gas. It’s heavier than air, so it will tend to settle and collect in low spots, such as the bilge, cockpit, or cabin of a boat. That’s what creates the explosion risk when there is a propane leak, and that’s why propane storage locations must be designed to vent overboard, not inboard. This is absolutely crucial. Don’t cut corners here.

The propane we purchase is "Liquefied Propane Gas" (LPG), which has been compressed into a liquid and is stored in cylinders designed to keep the propane compressed. The propane is always under pressure, and will tend to escape if you let it. So the integrity of your storage cylinder is another extremely important safety factor. Don’t skimp. I don’t know what the lifespan of refilled "disposable" cylinders is, but if they leak or they’re visibly damaged, it’s time to get ride of them.

Myth: larger propane cylinders generate more pressure than small tanks. This is false, they all generate the same pressure, which is dependent on temperature. Lower ambient temperatures produce lower internal cylinder pressures. Higher temperatures produce higher pressures. That’s why one of the guidelines for refilling disposable propane cylinders is not to do it in direct sunlight or on hot days; you could be dealing with very high pressures indeed under those circumstances.

See, what happens inside the cylinder is that the liquid gas vaporizes just until the pressure is sufficient to prevent additional vaporization, which depends on the temperature.

Whuh-huh?

Pressure keeps the propane a liquid, right? And the vaporized propane gas exerts pressure, right? So just enough of the liquid vaporizes to maintain the pressure inside the cylinder to prevent any more of the liquid propane from vaporizing. Got it?

Then you come along, open the valve, light your grill, and thereby release some of the pressure inside the cylinder. Propane abhors a vacuum, so the liquid starts vaporizing again to "fill the vacuum" left behind due to your cooking.

So here’s an interesting feature of propane systems: As long as some liquid propane remains in the tank to vaporize, whether it’s 90% full or 10% full, the pressure inside the cylinder remains constant. That’s why you can cook just as well with a nearly-empty tank as with a full tank.

OK, back to the subject at hand: refilling disposable propane cylinders. The goal is to move LIQUID propane into the empty cylinder. It does no good to move GAS into the cylinder. The heavier liquid sits at the bottom of a cylinder, and the lighter gas sits at the top.

So there are two tricks involved in getting liquid out of your big DOT-approved cylinder and into your small one. First, you need to turn the big supply tank upside down, so that the pressure inside the cylinder pushes liquid, not gas, out through the valve.

Second, you need to create a pressure differential between the supply cylinder and the cylinder being refilled. There are two ways to do this: The official way is to chill the empty cylinder. Remember how propane pressure depends on the ambient temperature? If you can keep the supply tank at room temperature and chill the empty cylinder in the fridge for 15 minutes, you can create some temperature differential, and therefore some pressure differential.

But even so, many users report that they only get about a half-full cylinder this way. It may take some experimenting to get it to work optimally. Chill the empties longer? Freeze them? I’m not really sure. Feedback from readers is most welcome on this!

To get a full refill, you could reduce the pressure in the cylinder another way, though. It’s possible, I learned, to take a pair of needle-nose pliers and pull the pin on the pressure relief valve of the cylinder you’re refilling. This reduces the pressure and allows the liquid propane to fill the cylinder.

If the instructions that come with your refill adapter don’t mention this method, though, it’s probably because it entails more potential risk than the manufacturer’s liability attorneys are willing to accept. Obviously, you should not use these refill adapters in any manner that differs from that described in the documentation.

Still, if you were to give it a try, as I did, you might discover that it works so well that you can overfill an empty propane cylinder. I used a postal scale to compare mine to a new, full cylinder, and I got about two ounces more into the cylinder using the pull-the-pin method. So if one were, hypothetically, inclined to use this method, which one should take care NOT do, of course, I would strongly urge one to weigh one’s cylinders to ensure one is not overfilling them.

Regardless of the method you use, though, once you’ve refilled a cylinder, you should place some soapy water on both valves (the pressure relief valve and the regular valve you connect to your appliance) and check for bubbles. Bubbles = leaks. I had some extremely slow leakage from my overfilled cylinder, barely perceptible, coming out the pressure relief valve. I left the cylinder outside overnight where the propane would tend to dissipate and not collect. In the morning, the cylinder weighed about the same as it had the night before, but it was no longer leaking. I assume the relief valve was working as designed.

I cooked with it at home until it weighed the same or less than a new, full container, before taking it to the boat. I cooked aboard the boat last week while the kitchen floor was being refinished at home, and now I’m cooking with this cylinder at home again. It seems to be working just fine.

I’ve intentionally avoided providing a step-by-step procedural description of the refill process. I’ve probably put myself at enough risk here already! The adapters all come with instructions, and you should follow them.

For liability purposes, I should once again advise you NOT to pull the pin on your cylinder’s pressure relief valve. If you do so, you do so at your own risk.

Hopefully, though, I’ve given you enough background to understand how the process works and why the instructions are written the way they are.

{ 84 comments… read them below or add one }

Terry Sargent April 24, 2008 at 3:47 pm

Hi Tim,

Have seen your postings on Panbo and just discovered your site … I will be mining it in the future.

Here’s a posting on my site about filling propane tanks overseas.
http://yachtvalhalla.net/projects/lpg/lpg.htm

I now have aluminum tanks which have a relief valve that can be opened with a screwdriver. As you can see in my posting I am careful to not over fill by using a scale. You’ve provided an excellent description about this process … spot on, matey!

Terry

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Tim Flanagan, Managing Editor April 24, 2008 at 8:47 pm

Wow! Thanks, Terry. I really appreciate your comment and the link to your page on LPG.

Truth be told, I appreciate your positive comment even more than you might imagine. See, I’ve been WAITING FOR and DREADING a comment to appear on this post. Something along the lines of “You’re recklessly irresponsible for telling people how to refill disposable propane tanks, and you’re going to fry in hell for it, right after you fry in your boat when your refilled propane tank explodes!”

So perhaps you can imagine my relief at reading a positive response from somebody with a heck of a lot more experience at this that I’ve got! :-)

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edward hailstone May 28, 2008 at 1:50 am

can you fill the 1 lb bottles from a 100lb tank with the above adapter?

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Tim Flanagan, Managing Editor May 28, 2008 at 8:38 am

Yes, theoretically. As long as your 100lb tank uses the standard valve body you see on the common 20lb tanks, the adapter will work. Contrary to popular belief, larger propane tanks do not produce more pressure. Propane pressure in an enclosed tank of any size is a function of the temperature.

But here’s the problem: can you turn your 100lb cylinder upside-down? The supply cylinder needs to be inverted so that liquid propane, rather than “evaporated” propane gas, moves from the supply tank to the 1lb bottle. So in practice, the answer is probably “no, you can’t do that.”

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RC Rivenburgh, Saratoga Springs NY June 4, 2008 at 5:43 am

I have had the little adapter to fill my “puggies”, (1# tanks ), for a couple of years now. Can’t begin to tell you how much I’ve saved by refilling my own tanks AND those of other campers. If you’re safe about it, you’ll have no problems. Just inspect your tanks, don’t try to refill an old or dirty tank and make sure there’s no sand or dirt in the tanks valve. At best, you’ll get about half a fill up. That’s okay. With the price going up constantly, propane is getting more expensive too. Walmart wants $5.29 for 2 puggies.
Refill your own and save the money.

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Stella Montgomery June 19, 2008 at 11:07 am

I recently brought a Weber Q120 grill that uses 16.4oz propane cylinders. Is there any type of gauge for the small cylinders to tell you when you are running out of propane? Your articles on propane cylinders were very helpful. I don’t know alot of propane. Thank you.

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Dave C. June 21, 2012 at 7:27 pm

I realize this is a very old post. This is for any newcomers.
Simple way to gauge how full the cylinder is (and this works for bulk cylinders as well!):
Simply take a cup of hot tap water and pours it down the side of the cylinder. Run the back of your finger top to bottom until you feel the sharp change in temperature. It will go from warm to cold. That’s your propane level. Simple, safe, and effective.
Very convenient for outdoor grills as you don’t have to yank off the cylinder to weigh it.

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Tim Flanagan, Managing Editor June 19, 2008 at 12:06 pm

The answer is probably “no…and yes”. There isn’t a gauge you can just screw on to act as a kind of fuel gauge, but…you can weigh the cylinders with a reasonably accurate postal or cooking scale to figure this out. In general, empty cylinders from the same manufacturer are all going to weigh exactly the same, within an ounce or less.

So weigh a brand-new, full cylinder, and weigh an empty one, and write these figures down. Then you can compare your not-sure-how-full-it-is cylinder with the known full and empty weight figures, and you’ll know just how much propane remains inside.

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Dave C. June 21, 2012 at 7:28 pm

See above Tim. It ain’t rocket science.

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Hal June 19, 2008 at 7:23 pm

Curious…I want to use a 100lb tank for my gas grill but cannot locate anywhere, what is needed to adapt hoses, regulators, etc. Can you help? Love this site by the way! Thanks!

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Tim Flanagan, Managing Editor June 19, 2008 at 7:37 pm

Oh, it all depends on what sort of valves you’ve got on the supply tank, and what sort of fitting is on the gas grill. You CAN get an adapter hose that connects the conventional valve you find on most 20# cylinders with the fitting designed for the 1# disposable bottles we’ve been discussing here. I used one in the photo here. That might work with your 100# tank as well.

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Doug July 18, 2008 at 10:42 am

I was chief inspector for the largest manufacturer of propane, mapp, and ether disposable 16 oz cylinders. The company also manufactured refillable 16 oz cylinders. We also made the fitting used to refill the refillables. Now….any 16 oz cylinder CAN be refilled. The reason for making refillables is what most people are not aware of. All cylinders have a relief valve. These are preset at the factory at fill time. In refilling a refillable, after you have the adapter on and the cylinder is screwed into it and you turn the main gas valve on….you back out a fitting…CONTAINING a relief valve. When refilling a disposable…you have to back out the relief valve itself, very much like a valve core in a tire . After the cylinder is filled and white mist appears…then a person has to screw the relief valve back in….and in doing so…negates the properties of the relief valve entirely. Thus…no safety ….and in esscence….have created a bomb. Sooooo…there ya go.

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Otter August 29, 2008 at 4:43 pm

Hey Tim can you not store a cute little 5 pound propane tank on your boat? I mean gee I can fit one in my Boler trailer it’s only 13 feet long with no below deck hold. Just worried about the “bomb” you are making ;)

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Tom Elliott September 2, 2008 at 10:56 am

Hi, Tim. I have been using a refill valve for years. I have not tried the opening of the releif valve and would not recommend it. In a past life I was a propane driver and tech for 4 years. I do however freeze my tanks over night before filling them. I also sit the big tank in the sun for a hour before I do the refill. Works great ,you get full tank this way and no danger of making a bomb, which is a miss nomer. Propane tanks don’t explode from over pressure , they rupture. Now if they are near a flame sourse they will ignite. If they have intact relief valve’s ,that have not been damaged by some guy and a par of pliers ,then you can not over fill the little tanks as the relief valve will go off before you do. One more tip. when filling the little tanks wait ten minutes. Most of the tank will fill in under a mintue but if you wait the rest of the tank will fill. Good luck.

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littleThing September 13, 2008 at 8:50 pm

I found a great little thing for refilling your propane tank. It’s called the Tank Nanny, and it keeps your 20lb propane tank from falling over or tipping in your car or truck when you go to get it refilled at the filling station. You can even seat belt buckle it in for more safety. Great for those weekend barbeque sessions or cookouts. You can get it from most stores or at http://www.tanknanny.com if you can’t find it.

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mike December 9, 2008 at 9:42 am

can you put compressed air into a 16.4OZ tank?

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Tim Flanagan, Managing Editor December 9, 2008 at 11:41 am

I don’t see why not. Out of curiousity, though, what for?

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Jerry January 1, 2009 at 7:05 pm

The relief valve is just a plug that would allow gas to vent out of the cylinder all the time, if it wasn’t for a spring of the correct tension pushing against the pressure of the gas. If the gas pressure goes too high, it overcomes the spring and gas vents until once again the gas isn’t pushing as hard as the spring. Not much to damage by gently pulling the valve out for a few seconds, as long as you don’t mangle it.

Tim, I constructed my own refill adapter so I didn’t have instructions. After trying it twice I was disappointed that I couldn’t get much gas into the empty can. I was about to give up when it occurred to me that there might be something about my method to blame. Checking the Internet I ran into a couple of sites advising freezing the cylinders, then I came across yours. Works like a champ, in seconds instead of fifteen minutes + time to freeze the bottle. Good thinking!

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Bill February 21, 2009 at 7:49 pm

WOW, I knew it could be done just wasn`t sure how, Thank you for a very informative article. I did see about the cooling and freezing issue. But how long do you freeze, or cool the tanks before refilling them ? Seems to be the most important part. Once again thanks. My friends will think I`m a god.

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TBird March 17, 2009 at 8:21 pm

Just a couple suggestions:

If your going to fill one of these tanks, do it outside. That way any leaking propane disapates into the air instead of building up in your house or garage until they find a source of ignition. Don’t smoke, and don’t have any electrical or electronic devices (cell phone, MP3 player…) on you.

DO NOT FREEZE YOUR PROPANE TANK! If you put the tank in a freezer and it leaks you could fill the freezer with propane gas. Now when you open the door it could explode. Instead put the tank in a bowl or pot of ice water for 10 or 15 minutes before you fill it, and keep it in there while your filling it (if possible). Be sure to keep the water off the valve area.

To know how much propane you put in the tank is easy. Just weigh the tank before and after you fill it. And don’t try to fill it all the way. Just fill it 1/2 or 3/4 of the way. You can always refill it again when it runs out. But by trying to fill it all the way greatly increases your chances of overfilling the tank (which is dangerous).

Where ever will you get a scale on a boat? Hey what about a fish scale? And when the tank is empty, before you refill it, weigh it. Write the weight of the empty tank on it’s side with a sharpee marker. Now any time you want to know how much propane is still in the tank just weigh it.

Or with a new tank write the full weight on the side. Again by weighing the tank you will know how much propane is left.

Hope this helps!

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Michael March 20, 2009 at 10:55 am

Ive been refilling the 16 oz bottles for years, what I do when I refill them is I would boil them to get the pressure up in the bottle then I would put my refill adaptor on the 16 oz bottle to vent the pressure. After venting pressure I would immediately hook it on to my 20 lb bottle open the valve on the big bottle and drop it in ice water to cool the warmed cylinder. I used to fill them to the point that they had ZERO gas in them, they were all liquid. I know stupid to do and dangerous, but we were just blowing the refilled bottles up in the first place so we didnt need any gas in there for pressure regulation.

but my point being mostly that you dont need to use needle nose pliers to vent the bottle from the relief valve, you can just screw your refill coupler adapter thinggy on and vent it like that

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Tony April 1, 2009 at 3:31 pm

Thanks, got some really good (and bad) advice from you guys, so let me help you guys and share my experience. just tried the chilled bottle deal with upside down 20# and after weighing, only got less than a third in my little puggy. while still hooked to bottle, used the advice of pulling releif pin out with needle nose pliers for 5 sec and let go, I could hear the gas leaving the big bottle entering little bottle, got nervouse after almost a minute and shut big valve off. took off little bottle and weighed it, had just a verry little more than a new bottle, so it worked great, so I think it was great advice and in my opinion, after letting go of the releif valve, before you get a dangerous level in your puggy, the releif valve should release any pressure that is too much for the little puggy to hold. I hope this helps and be careful. Thank You Very Much, Tony…………..

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Wheels April 19, 2009 at 6:50 am

I have been refilling the small disposable cylinders for a couple of years now and no problems. What I did discover is that the coated fiber seal on the tank adapter frequently leaks and fails to make a good seal when filling. I replaced the fiber seal with one made on heavy rubber gasket material. Much better seal! I have been thowing my small tanks in the freezer overnight and they seem to fill about half way. Repeat this operation and they fill 100%. Then leave them outside for several hours if they need to vent any minute excess gas. I have yet to have a problem with these tanks, and I am refilling them for about 28 cents a fill. Considerably cheaper than buying them at the store.

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Harvey Smith April 20, 2009 at 11:14 am

My 5 gal. cyclinder I use to refill my 16 oz. bottles nolonger allow me to dispense propane. Harve reversed it and hit with rubber mallet.

Any suggestions? I live 20 miles from town.

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Blake April 27, 2009 at 5:35 pm

I’ve bean using an old car ac pump and electric motor to fill my tanks. It has the advantage of pressurizing the propane an extra 20-30psi to force the gaseous propane to liquid and let me fill the tank completely without having to flip the main tank around. I fill my tanks from a 500lb tank .

This is the same method that is used commercially (but probably not as crude).

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Scootery May 1, 2009 at 7:51 pm

As much interest as there seems to be about refilling those little 16oz tanks, why hasn’t a company started making refillable ones?

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Blake May 6, 2009 at 9:55 am

Scootery
Because they make more money selling disposable ones, think repeat business.

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Andrew P. May 14, 2009 at 2:41 pm

I’ve been refilling cylinders from a 20-lb bulk tank for years without problems. I own one cylinder that was specially made to be refillable; it has a relief valve that can be opened with a wrench for bleeding. Also, I have a refilling adapter that was originally sold under the Turner Cleanweld brand name (Sycamore, Illinois), same as the refillable cylinder. The adapter looks quite different from the ones now being sold by Mr. Heater and Harbor Freight. It has a 0.31-inch O.D. brass extension tube about 8 inches long, and the disposable cylinder fitting has two ports on it, so the tube can come into the side of the fitting or into the top. This allows one to set up the bulk cylinder and the cylinder to be refilled such that the bulk cylinder is oriented valve-down and the cylinder to be refilled is oriented valve-up. This is simply not possible with the stubby, cheapo Mr. Heater version. The idea is that one should be transferring liquid propane into the small cylinder, not gaseous propane. The relief valve of the cylinder needs to be topmost for bleeding. One lets the liquid propane flow in until a mist of liquid propane blows out of the relief port. (Use needle nose pliers to pull on the relief valve stem to open it for bleeding. Beware the propane mist, as it is very cold and can cause frostbite; wear safety goggles and do this in a well-ventilated area away from ignition sources.) This way, the cylinder gets filled 100%. Then, one bleeds off a bit of the gas until the cylinder contains the net weight of propane specified on the label. (Weigh the empty cylinder with a sensitive kitchen scale before beginning to refill.)

As you indicated, Tim, the refilled cylinder should be checked for leaks with soapy water. If the refill valve is leaking, try to put the cylinder to use on a stove, lamp or torch immediately. If the relief valve is leaking, set the cylinder in a well-ventilated area and let it leak down until it is empty; don’t even try to use it or transport it. Sometimes the relief valve has frost or dirt in it. You can try pulling the relief valve stem and quickly releasing it, to see if it seats properly on the second attempt. Discard any empty cylinder with valves known to be leaking. In my experience in camping and picnicking use, the valves will fail before the steel walls of the cylinder rust through. If the walls do rust through, they will most probably develop one or more pinhole leaks, slowly venting the gas instead of rupturing catastrophically.

I have no idea why the Turner-style adapter has disappeared from the market. It’s the only tool that would allow an individual to properly refill a small cylinder. Maybe the theory behind the Mac Coupler/Mr. Heater/Harbor Freight adapter is that the design actually prevents filling a cylinder 100%, so a sloppy user is less likely to cause injury. However, I’ve studied the standard propane adapter offerings from Mr. Heater, and it would certainly be possible for someone with moderate metalworking skills and access to a small metal turning lathe to construct a similar adapter from off-the-shelf parts.

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Andrew P. May 14, 2009 at 3:09 pm

By the way, the method I use to refill the disposable cylinders is identical to the “official” method printed on the Turner Cleanweld refillable cylinder label, except that I need to use needle nose pliers to bleed the disposable cylinders, since their relief valves don’t have the threaded fitting that can be operated with a wrench. The comment left by “Doug” on July 18, 2008 is largely nonsense. He may have been a chief inspector in a plant where the cylinders are made, but he clearly doesn’t know what he’s talking about. It is NOT necessary to unscrew the relief valve core to refill the cylinder, and gently pulling on the relief valve core stem with pliers will NOT damage the valve. The worst thing that can happen is that the valve MIGHT get damaged, the gas will leak away and you’ll have to toss that cylinder into the trash. Big deal!

Further, empty disposable cylinders CAN be recycled. Make sure they’re completely depressurized by depressing the valve core with a nail, then mutilate the cylinder by gently piercing the thin steel wall with a heavy nail, awl, or similar tool. Coleman and other vendors probably won’t ever recommend this, because there are plenty of dummies who’ll toss a cylinder into the trash or recycling bin that still has liquid propane in it, never giving a thought to the possible consequences.

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kelly June 17, 2009 at 8:54 pm

im a total noobie when it comes to propane. i just got my refill adapter today, and found that it would only fill half way when i decided to read the instructions:) whattaya know! it fills better when its cold and totally empty. so here i am with a 25% filled tank that was room temp. hrmm…so i took a nail opened the valve core carefully emptied all of the contents from the cylinder (outdoors of course..i may be a noobie but im not an idiot). guess what happened…i ended up with a totally empty tank, that was totally frozen:) i hooked it back up to my master tank, and it filled completely in about 15 seconds.
so if you have a tank that is completely empty, just hook it up to the master, put a little liquid into it, release it through the core valve, empty it, which will freeze it, then fill it up completely. just be outdoors, and be careful..it gets really cold, really fast.
oh yeah….and i Never advised Anyone to do this;)

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portable cooling solutions June 22, 2009 at 12:50 pm

That is so neat! I didn’t know you could re-fill the little propane tanks! I buy so many of them for camping and small grill outs. This will save us some money im sure.

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kelly June 22, 2009 at 10:16 pm

yeah im sure you will save tons of money. i think it was someone on this site that was saying they calculated cost at 23cents each. haha. i, just yesterday, saw a 12 pack of non-coleman propane for 36 dollars and some change. its easy to see how much more cost effective it is to refill. oh..and how do you get empties without having to buy them and use them first?…i put an ad on craigslist in the free section saying that i will come to you and take them away for free:) it works i have picked up several like that. i usually drop off one full cylinder when i pick the empties. everyone’s happy like that.

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Bob August 12, 2009 at 8:05 pm

That comment about putting a little propane in the tank and then releasing it to chill off the tank for a full refill makes me wonder why one couldn’t instead fill the tank with compressed air first, release it chilling the tank, and then filling it with propane? Compressed air is a whole lot cheaper.

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Renee August 28, 2009 at 4:39 am

If you need empty cylinders then just wait until you go to a campground and grab them out of the recycle bin usually located by the dumpster. There are usually dozens and you can pick and choose the (newest looking) best ones. PS I never pull the pin while filling because 60% to 75% full is good enough for me.

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Franklin October 9, 2009 at 10:31 pm

What are the consequenses of overfilling a pug tank? Doesn’t the excess gas escape through the relief valve?

When the guy at the propane station fills my tanks on my travel trailer he opens a relief valve and stops the filling process when a mist of gas starts spewing out then closes the relief valves. He’s in no hurry and the amount wasted could easily fill a small pug. Same principal I would guess.

Someone mentioned that all the manufactuerers pug tanks will weigh the same. Anyone have a weight they want to share? I’d like to compare.

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Tommy February 7, 2014 at 7:20 pm

16.4 oz cylinder weighs 15 to 16 oz EMPTY

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Franklin October 9, 2009 at 10:32 pm

Actually when the guy at the propane station fills my tanks, there is a constant mist. He only stops when it appears to be liquid coming out.

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Buster November 7, 2009 at 9:44 am

I’m wondering about the empty tank having air inside.
Is it not possible to have spontaneous combustion?
All my working life, I was a welder and pipefitter in oil & gas industries. Spontaneous combustion became a safety issue in later years. Thanks OSHA

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Buster November 7, 2009 at 9:48 am

“When the guy at the propane station fills my tanks on my travel trailer he opens a relief valve”

I think this also is to vent any air in tank.

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blowndodge December 6, 2009 at 12:38 pm

I just did this! I put my 20Lb. tank in the tub with warm water 90+ degrees for about 30 minutes and made sure my small disposables were empty and put them in the freezer for 1/2 hour as well.

Took all of this ouside and gave it a shot as instructed above.

All 5 disposables filled to max and 2 actually vented for about 30 seconds from being slightly overfilled (outside of course!). All measured the sam weight 1.15.14 as a new can did exept the 2 that were slightly hissing. they weighed slightly more. No need to pop the vent valve to get a full charge! What a savings…! thanks for this idea!

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jp December 10, 2009 at 7:00 am

Does anyone kwow were u can pickup plastic lids for ur refills? I bought a MacCoupler online and filled about 6 small cylinders with limited success (about 40% full) but I dont think it will take much to comeup with a hose type refill so u can weigh ur puggies while refilling. Its a great idea and something that has bothered me for years, using these once and pitching them in the trash! Waste not want not!!

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Frank December 19, 2009 at 10:22 am

The key to getting a full fill WITHOUT disturbing the relief valve is to make sure the pug is totally empty and at atmospheric pressure (about 15 psi). Propane at 60 degrees creates a pressure of about 90 psig which is 6 times the atmospheric pressure. When refilling, the gas in the pug is compressed by the absolute pressure ratio. Any residual pressure in the pug will inhibit this compression. Freezing the pug can reduce this pressure but not by enough to care about. Warming the pug and venting any pressure completely before filling would be more useful. Warming the supply tank will increase the propane pressure but don’t warm it to more than just being in the sun.
Even without warming or cooling, a completely vented tank, and supply tank at 65 degrees, should be able to fill with liquid leaving 1/7th of the tank as vapor. That is an 85% fill and that should be both safe and easy.

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Jon Biehl January 14, 2010 at 8:49 pm

I have one of the re-fill adapters….think I bought it at Cabellas years ago. Haven’t used it yet. I keep buying more disposables, but I’ve been saving them……I must have a hundred by now.

Anyway…….I live in Calif. and someone told me that in the past year or so….with the replacement of all the “old” style 20# cylinders…..that the new 20 # ones are DIFFERENT. That there is a float valve inside, so that when you turn the bottle upside down…..you won’t get any liquid out (and into your 16 oz’er).

I asked a guy at Pro-Gas if the float could simply be removed……..he said “yes, but we would know immediately and would refuse to refill it!”

Is ANY of this true??????

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Mike January 21, 2010 at 6:53 am

Jon,

That’s exactly why I read through all these posts. I had the same question. Newish 20# tanks can’t be turned upside down, right? So, how do you get liquid out of a 20# grill cylinder that has that float mechanism inside?????

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Tim Flanagan, Managing Editor January 21, 2010 at 8:36 am

Newer cylinders have what’s called an OPD valve. OPD stands for “Overfill Prevention Device”. If there is a standard EVEN NEWER than that, I don’t know about it.

It’s easy to tell if you’ve got an OPD valve: it’ll have “OPD” cast or stamped into it. I’ve got an OPD valve, and liquid propane comes out just fine when it’s inverted, if there is a fitting attached. If no fitting is attached to a properly-functioning OPD valve, nothing comes out when you open the valve, regardless of the orientation of the tank.

Again, though, if there is some newer standard, I haven’t heard about it, which is pretty unlikely the way some folks panic when they see this post. It would be odd if NOT ONE of them had come up with the “Well you can’t do this anymore anyway because of the new valves!” argument.

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Mike January 22, 2010 at 6:32 pm

Thanks for the explanation, Tim. I didn’t know the valves were merely for overfill protection. I guess since they tend to flip-flop around inside the cylinder, I assumed it was an internal float or safety shutoff in case the bottle tipped over. I’m gonna get busy with these empty pugs this weekend. If I have trouble I’ll post again. Thanks for the posts!

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John Moore January 24, 2010 at 9:50 am

For boating, I’ve always wondered why Butane isn’t used instead of Propane, as Butane is lighter than air and therefore inherently safer in a boat. I understand that in the US there is currently a large stock of camping gear based on Propane, which is ok for outdoors use and is most appropriate for trailers and RV’s, from which a leak can dissipate out an open door. A boat is different. Butane would be safer.
Back in the 70′s I motorcycled/camped through Europe with a small butane stove that worked great. Surely there is butane equipment out there; why no butane market?

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Jon Biehl January 30, 2010 at 8:49 pm

thanks, Tim. Whoever told me that the new valves will not allow liquid propane to flow when the bottle is inverted, just didn’ t know what he was talking about. Now I understand how it works and have tested,….. with and without a fitting attached. Thanks again.

Hope you get around to responding to John Moore’s question in regard to Butane. Can a standard propane bottle be filled with Butane? Drawbacks?

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Chris February 1, 2010 at 12:12 pm

They use a lot of butane to cook at resorts and conventions, omelette stations and so forth, and the stoves are fairly easy to operate, as well as inexpensive. Check any Restaurant Supply store. The fuel comes in cans that resemble spray paint or hairspray cans.
That part is not really that inexpensive, however. And for land use, there is an adapter to run those off your pugs!

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Ron February 15, 2010 at 8:33 pm

Chilling a tank is not going to be that effective IMO. The first inrush of propane gas is going to cancell out any benefit 80F is going to net you. The most effective way this might help would be with a completely empty tank. Vent the tank to the atmosphere, then heat the open tank. Once the tank and the air it contains is throughly heated and at it’s lowest density, seal the tank, then cool the tank. Starting from a low density warm air, the tank will pull a vacume as it cools. This will make the tank the most receptive to filling with liquid propane. I think warming the supply tank is more important. The problem with venting the tank is that it lets in air. Air has O2(and moisture) and propane has moisture. Both inside a steel tank = rust… If you lay the 16oz tank on it’s side with the pressure relief valve at the highest point, pulling the pin while filling will result in about 85% full tank when liquid gas starts to vent out of the safety…

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Tommy February 7, 2014 at 7:27 pm

You are incorrect about “the inrush of propane gas”
If the supply tank is inverted, the “inrush” will be liquid
Propane-not gas.

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Bobby D. March 24, 2010 at 2:09 am

Hi Tim,

So glad I found this site! I live and work most of the year in England. I’m a travelling entertainer, and spend most of my time in a camper trailer, with a Coleman ProCat for heat. Recently used my last 1 lb. bottle of propane. Checked a local camping supplies retailer, and the local retail price for Coleman bottles is 6.50 English pounds. Now depending on the pound/dollar exchange rate, that means that one single Coleman 1lb cylinder now costs in excess of TEN DOLLARS. I don’t have access to a refillable American-type BBQ propane tank, but in the UK there is a well-established network of exchange tanks, so that’s not really a problem. My questions are:

1. Do you or any of your readers know if there is a way to attach a flexible hose-type bulk tank adapter from a ProCat to a UK-standard propane tank?

2. Also, I think it’s a crying shame to throw away perfectly good empty Coleman cylinders, and I’d like to have a try at refilling them. Your refilling adapter looks like it would work, if the fittings were compatible with the UK-standard tanks. Does anyone have any experience with this (admittedly obscure) situation?

Ok, I now prepare to hit the “submit” button with some trepidation. Please folks, this is my first time. Be gentle…

Happy Trails,

Bobby

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Bobby D. March 24, 2010 at 2:13 am

P.S. One more thing. Some of my empties have developed a mild degree of rust on the threads at the top. Anybody have cleaning tips and/or safety no-nos? Thanks, BDS

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Denny June 13, 2011 at 8:37 pm

Get a stainless toothbrush from a welding shop

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Mike April 1, 2010 at 7:42 pm

After about 20 years of thinking about it I bought the 1# propane refill adaptor from HF Tools. I also bought the big weed Killer torch from HF.

I only had an hour to test but learned a lot ( I even read the directions before I destroyed something beyond repair ( well for the adapter since I know that it was potentially dangerous not the torch, the replacement parts for torch should be here in 6- 8 weeks they are back ordered but that is another topic).

Ok seriously this is what I learned and would recommend.

#1 This is potential Dangerous stuff you are playing with, you must use common sense at all times and this is something to be done outside away from the house or something you or someone you like may care about!

DO IT OUT SIDE ONLY!!!!!!!!!!!!!

#2 I found that for the most part from a new full 20# tank you can only get about 8 oz of propane in the 1# tank or basically about half full on the refill. You may be able to get more by cooling and heating etc but I did not have time to try that. I DO NOT RECOMMEND MESSING WITH THE RELIEF VALVE IN ANY
WAY!!!!!!!!!!!!!!!!!

#3 Cooling the 1# tank and heating the supply tank will get more fuel into the tank being refilled ( I have not had time to experiment with this) if all tanks are at about the same temp I suspect that you will only be able to get about 50% into the tank you are refilling.

#4 If you want to cool the canister you are refilling ( this is sort works really REALLY WELL when you hook that big 500,000 BTU torch to the 1# tank) If you rapidly remove the propane from the 1# tank it will freeze the tank, you could just use a little torch head to empty the tank but if you use something that uses a lot of fuel fast like the big weed killing monster I just bought ( and destroyed the first time I
used it) You will chill the tank and get most the propane out in one step! You could also heat the supply tank by putting it in a pail of hot water I don’t thing you want it to go over 120 deg F because now you are starting to look for trouble (IMHO).

#5 this is LP gas Liquid Propane the key operative word here is Liquid!
WHEN YOU INVERT A TANK OF LP AND OPEN THE VALVE TO RELEASE THE CONTENTS LIQUID COMES OUT (stay with me here)
The liquid is heaver than gas thus we want to transfer as much liquid from supply tank to 1# tank! Ideally we get the most liquid into the 1# tank if it is empty and we are minimizing the vaporized portion because this may limit how much liquid we can transfer?

#6 after you are done it is a good idea to test the 1# tank in a 5 gal pail with some soapy water for leaks ( like you test an inner tube or tire)? THEN DRY IT SO IT DOES NOT RUST! If the tank to be refilled looks questionable just dispose of it properly and trat yourself to a brand new full one (live a little)

#7 There are many potential Dangers doing this BE CAREFUL!.
You can buy a new full 1# TANK for about $3 or less, the adaptor
about $20. Fire extinguisher $10-$40? Pale of water0-$10. Safty glasses a must! $1- $75. You may only be able to get about half the fuel in a refill compared to what a new can will have.

#8 once you refill that 1# can you may be liable if something bad happens one day?

#9 for me it is much easier to carry a 1# tank over a 20# tank and some of my tools use a lot of LP fast so this can be a good money saver!

#10 It is very good gadget and you can save money if you use a lot of 1# LP. Have at least 1 pail of water near by and an escape route if something goes bad. Renenber you don’t want to end up using all that money you saved on the skin grafts at the Burn Center so BE SMART, BE CAREFUL, and GOOD LUCK never hurts to have that on your side. Have at least 1 pail of water near by and an escape route if something
goes bad.

# 11 LP gas is like Freon in that it can work as a great coolant (please don’t try it)! LP converting to gas gets cold enough to get frost bite from too.

Final note here, a little ignorance can go a long way doing a simple refill. You may want to have someone film it at a safe distance and get the Funny video prize money if you mess up lol!

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Mike April 1, 2010 at 8:18 pm

Actually, if I had just read the instructions via the link at the top of this article super-duper propane refill adapter) took me to first it would have covered most of what I wrote about and unlike my writing that author proof read his work befor posting it. Just Be careful with this stuff.

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Jason April 16, 2010 at 6:03 am

Trying to get a full refill sounds tricky… Here is what is at play. Propane has a very low boiling point of −42 °C (−43.6 °F) (-40 °C and -40 °F are the same temp. I learned something new today.) This makes it vaporize as soon as it is released from its pressurized container at any temperature above -40. So what you have as Liquid in the bulk tank quickly starts to vaporize when it is first released into the empty refill tank. It will continue to vaporize in the refill tank until it starts to build up pressure. Once enough pressure is achieved it will then slow the vaporization process down. However now you have quickly filled the cylinder with a good bit of vapor. This slows the liquid transfer from the bulk tank down. Eventually the pressures will equalize between the two tanks and you end up with a partial fill. THIS IS WHY BLEEDING the tanks is so helpful while refilling.

I see no way to prevent the initial liquid from vaporizing when it enters an empty tank. Yes Freezing and cooling the tank will help the process but unless you get it down to -42 or so you can’t avoid some vaporization in the empty tank. Thus a two Stage refill process seems to be a good solution. Perhaps filling a canister at room temp (half full or however much you get) then removing it and using the adapter or a Nail to bleed it from the Fill Valve – Not the Pressure Release Valve then placing the canister in ice water for a few minutes to reduce the internal pressure as much as possible then hooking back to the bulk tank will fill it the rest of the way for sure. No need to warm the bulk tank though it would help some and no need to put empty into the freezer overnight. Avoid taking canisters inside the house when unnecessary. And never take a #20 tank inside your house for any reason.

Another maybe even better idea might be to put 60 psi or so of compressed air into the refill before this process and that way the propane will not vaporize as much on the initial part of the exchange. And Also because propane is heavier than air when you go to Bleed some of the Vapor off you will find that mostly compressed air will bleed off… Thus wasting less of the propane gas. and causing less of a ignition risk. Then cool the cylinder in a cooler of ice water and then try to fill again. I bet money that this will fill 100% or more. — SECOND THOUGHT HERE… One might find that compressed air leads to adding WATER VAPOR in the cylinder… Water Vapor is known to cause malfunctions on those Mr. Heater portable heaters (It clogs the screen filters or something). Thus I have to caution the use of compressed air as it will potentially lead to water vapor in your refill which I personally don’t know all the negative effects of on various propane products.

A note on weighing your tanks… This is probably the most accurate way to determine a full tank and it should be done to avoid overfills because a overfilled tank will potentially vent when stored in a warm environment or left in direct sunlight. Also Remember that you should bleed an “empty” tank before weighing it to make sure that it is definitely empty if you want to be totally accurate because some heater devices will shut off when LP tank drops below a set pressure and thus leave a bit of propane left in the canister. Which could cause you to overfill it if you are weighing it and and thinking it is empty when it still has 2-3 onces left in it.

I have not tried any refilling myself as of yet but after some careful research I have decided that it is definitely feasible and can be done safely with some of the methods listed on this site provided some common sense on the users part. And as for DOT approval – Who’s gonna know it has been refilled and It appears this does not apply to personal use.

I’m looking at different adapters now hopping that one will use a length of hose so that as a previous poster said you can set the refill upright and make the transfer work better. Perhaps some of the vapor trapped in the refill can “bubble” it’s way up into the bulk tank to allow more liquid p to run down into the refill. This would take additional time perhaps 10-15 minutes but would also be a proven method of a 100% fill. But I can’t see where this would be possible with those small one piece adapters. Since your refill tank would be on the side not upright thus trapping the vapors in.

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Erick April 15, 2012 at 1:45 am

I know this is an old thread, but I thought I’d post anyway.

The compressed air idea is FANTASTICALLY STUPID! Don’t even think about doing that. I worked as a design engineer in the alt fuels business for years, and this is one we all avoid. Propane by itself won’t burn. Propane with air will. Propane and air under pressure is a bomb. You can’t be sure you won’t have some propane left, or grab the wrong bottle, or some other mistake, and create an explosive. A mistake like that killed two technicians at a government test facility.

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Don Dinsel April 26, 2010 at 8:36 am

Where and how is the safest way to store small disposable propane cylinders—–in Florida from
May to November in an unocuppied house?

Thank you

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GREG August 21, 2010 at 3:37 pm

Use a small vacuum hand pump (such as mechanics use to test vacuum systems -ie advance timing on older engines) to partially evac the bottle befor refilling – DONT OVER FILL. Another way is to take input line from a small air compressor to evac the bottle.

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Scotty 2Tone August 26, 2010 at 11:37 pm

The big question is how many refills can you do off a 15lb or 20lb tank?

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Jim September 20, 2010 at 4:34 pm

How full is the one pound cylinder? Stand the cylinder in the sink. Add water. An empty tank tips over in 1 3/4 inches of water; a full one at 4 1/4 inches approx. Try your own calibration.

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Ken_More September 27, 2010 at 10:48 am

Just wondering. Today I needed to blow out a small drain line on a grease catcher on the kitchen range. I didn’t have a portable tank for air pressure that I could do the job with. I was thinking if I took one of my empty propane bottles and fitted it with a schrade valve and a hose connection, that might provide a small portable air source for jobs like this. Now, my concern is, what is the pressure rating for these bottles, or, what are they pressurized to when they are filled with propane? What is the relief set at for these bottles? I have a couple refillable aerosol spray cans that I’ve used before for paint. Seems that they are a lot lighter weight construction than a 14 ounce propane cylinder and I think they are set to relieve at 40 PSI or so.

KM

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Taro October 13, 2010 at 2:08 am

Wow…got some real crazy suggestions in this thread. Evacuate a flammable gas bottle using the input to an air compressor? That isn’t going to end well – lot of shrapnel to dig out of your walls and head.

Pull a flammable gas relief valve with a ferrous tool like a needle nose pliers? Can someone say sparks and explosion? Brass tools are your friend here, not steel. At the very least, dip the nose part you’re banging against the tank in liquid rubber to keep it from sparking.

There are others, but I don’t have time to teach engineering to a bunch of fishermen, but I will offer this:

If you have two different fittings that you want on the opposite ends of a hose, it’s no big deal at all. You don’t need any kind of fancy threaded connector that could develop a leak. Take (or mail and call in your credit card) both hoses to any shop that does hydraulic and gas lines. They can chop the unwanted ends off and marry the hoses with a swaged connector for about $20 – no leaks, no problems. Every town has one of these shops. Ask a heavy equipment repair shop who they use, or look under hydraulic hose fabrication in the Yellow Pages, or ask any gearhead where they get their custom braided steel hoses made.

Now go out there and blow yourselves up by smoking a stogie while messing around with bottles not intended for refill. We are tired of hearing about how crappy the economy is under Obama’s train wreck of an administration and need some Darwinian, comic relief. But don’t kill yourself or your kids. That would just be depressing and add to the welfare roles.

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Patrick July 19, 2013 at 6:21 pm

I realize Taro’s post is old but I feel obligated to respond to this FUD.

Firstly, evacuating the bottle is probably the easiest way to generate a substantial (read: useful) pressure gradient between the two tanks. There is no risk of “sharpnel” because a) an overpressurized tank ruptures, not disintegrates and b) it would implode, not explode. Since full vacuum is only ~15psi, there is no risk here. None at all.

And what does the “ferrous” nature of steel pliers have to do with anything? Can I get a pair of brass pliers at Home Depot? Doubtful. Pulling a small pin doesn’t generate “sparks and explosion” nor would coating the gripping surface of the pliers with rubber help in any fashion. (It would, IMO, just ruin the pliers.)

I don’t think it’s appropriate to assume the only people here are fisherman–lots of folks use propane and lots of folks despise throwing away perfectly good steel. As for your qualifications to teach engineering…. I’ll just give you the benefit of the doubt. FWIW, I hold a degree in civil engineering (and work in an atmospheric lab, read: _lots_ of cylinders around) so we should be on the same page.

As for getting a hydraulic shop to make you a hose: why bother? If they ask what it’s for and you don’t lie, they’ll likely refuse service. And the cost will be several times that of an adapter. Which, BTW, has less of a chance leaking through its threads than a custom-made crimped-fitting hose would. (Braided steel would only be OK if it had suitable rubber innards.)

Ohhhh….. wait… you just came here to espouse political rancor. Frankly, that just detracts from the legitimacy of your post. Good luck.

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meh March 1, 2011 at 12:45 am

If you can afford a BOAT you can afford a couple of five pound cylinders.

Little cylinders of air would be useless. Don’t bother. Take it from an experienced mechanic. Bad idea.

Don’t blow out lines with flammable gas. If you are tempted to do so, pay a good friend to hit you in the face until desire fades. Bruises heal quicker than burns!

If you want a useful size air tank, get an obsolete non-OPD BBQ jug, nipples, a ball valve, and the obvious other fittings then have at it. I use them for that and refill with double QD nipples from my air compressor chuck.

The adapter fitting is cheaper than having a CGA-510 + pigtail + disposable cylinder fitting setup. Any doubts, check Western Enterprises brass fitting and pigtail prices. (The stuff doesn’t require fabrication, just use their pigtail generator to produce a part number. Western rocks!)

Refilling little cylinders isn’t hideously dangerous, but they are pathetically small. I quit using them years ago for that reason.

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Yerk March 21, 2011 at 3:01 am

I think I’ll just buy another cylinder.. :O

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Jerry December 28, 2011 at 1:44 am

I purchased a small heater to heat 300 SQ. FT. room, the heater says it must use a 100 lb. propane tank, but since I want to be able to move this heater to different places, can a 17 to 40 gallon propane tank be used as long as it has a regulator on it?

Jerry

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mark April 9, 2012 at 3:33 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…..is 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?

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Propane Worker April 25, 2012 at 10:30 pm

Why would someone go to all this work, and EXTREME RISK, to refill a bottle that can be replaced for about $3.00 …? If it is a recycling/green thing there are 1 pound cylinders that are designed to be refilled. They cost about $70 and are about $5 to refill them, but there is no risk and no bottle that gets thrown away. I would NEVER do this and I work with propane for a living (emphasis on living…not dying ! !) Anyone who tries this is an idiot; anyone who advises other how to do it is even beyond that. There are SO MANY DANGERS involved in this I can’t even imagine taking such risk except maybe in some type of post-apocalyptic world….but in the real world, there is just no reason for it. Best of luck to all who think this blog contains any good advise….but as for me I’ve seen what propane can do.

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Propane Worker April 25, 2012 at 10:45 pm

Yes, propane is heavier than air so will seek the lowest point. Guess what else is heavier than air….you are. In a word, google ‘BLEVE’

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Propane Worker April 25, 2012 at 11:02 pm

Different metals (such as those found in relief valves and other internal or external tank/cylinder appurtenances) expand/contract at different rates unseating all kinds of troubles. An over-filled cylinder (and/or one laying on its side or upside down) will release liquid propane if the pressure is greater than the pre-set release point. Liquid expands approximately 270 times in volume as it goes to a gaseous form. Propane boils at -44 degrees Fahrenheit (yes, minus 44 degrees) so, left unchecked it will go to gas and expand readily and rapidly. It also has a flammability limit/range of between 2.15% and 9.60%, which means it does not take much in a specific area to become a flammable, ground-hugging mixture with the ambient air content. Guess how long it takes the atmosphere directly around you to reach a combustible ratio when you introduce liquid propane to it. If you round it off its about zero seconds…how fast are you? I would recommend at least increasing your insurance coverage (except of course because you are doing something so stupid that your insurance won’t cover the hospital bills, or property loss, or even your piece of crap grill or whatever it is you think is worth risking your life/lives of those close to you/and the future of those who depend on you…but hey, what do I know?

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Propane Worker April 25, 2012 at 11:07 pm

…also, at the very least the liquid involved will not only freeze your skin but also, and at the same time, give second and third degree burns just by exposure, without being ignited.

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Propane Worker April 25, 2012 at 11:07 pm

…but hey, go ahead.

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Propane Worker April 25, 2012 at 11:12 pm

PS: Did someone actually suggest heating the larger cylinder that is upside down so that it releases liquid propane from the service valve into the small disposable cylinder with a torch? Its hard to believe that there is really an over-population issue today….particularly anywhere near that guy. Dude, you are truly a dumb ass.

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Patrick July 19, 2013 at 6:28 pm

Yes, several people have suggested gently warming the large tank to increase the pressure differential. No one is saying “stick the BBQ tank on the BBQ to heat it up”… The suggestions here amount to a) put it in the sun or b) put it in warm water bath.

Could it be that this “dude” is actually smarter than you? Smart enough to do it safely? He/she was smart enough to post their thoughts in less than 6 consecutive entries….

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Tom Hargrave April 29, 2012 at 5:02 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.

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Dave December 11, 2012 at 3:20 pm

Don’t bleed propane into the atmosphere please!!!

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Brian June 6, 2012 at 6:39 pm

Lay your canister on its side with the releif at 12:00 o”clock.Fill by jentley pulling the releif valve , When propane starts comming from valve, STOP. Close valve and disconect. This is the same method as filling a Propane vehicle and gives you 80% fill ,20% expansion. You end up with the same amount each time in every bottle. It goes without saying:outside and well vented.REFILL and ENJOY

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Andrew P. June 6, 2012 at 9:36 pm

Tom Hargrave, there’s a reason why a disposable cylinder is equipped with a spring-loaded relief valve: It will open well below the rupture pressure of the cylinder, regardless of how much the cylinder is filled. Even factory-filled cylinders will vent if left in a hot enough environment.

Propane Worker, you provide NOTHING of value to this discussion. Your posts amount to alarmist rants. People have been successfully and safely refilling disposable and reusable cylinders at home for decades using the techniques discussed in this ‘blog. Where are the news reports of maimings and disasters?

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Dave C. June 24, 2012 at 2:30 pm

I just don’t get people.
Chucking an empty cylinder in the freezer for 15 minutes has ALWAYS yielded me a complete fill! I have to weight them to ensure they’re not overfilled. I use a MacCoupler (great device) and fill in my kitchen.
Common sense goes a LONG way. I don’t mess with relief valves, heat anything, nor have ever had any venting.
The alarmists on here amuse me.
Oh, and another thing for the “expert” about vapor pressures and what not. When the liquid enters the pug, it’s temperature decreases which just further aids the refill process.
Freeze, invert, fill, done.
15 seconds, full cylinders, every time. This debate is killing me.

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julius December 4, 2012 at 8:57 pm

Hi guyz! Can I use my Butane cylinder to fill Propane gas?

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Dave December 11, 2012 at 3:18 pm

You can get a 1-pound refillable from Manchester or Worthington. The safety is worth the added one-time expense. Careful with the disposables because once you change the valve you cannot be assured of a safe tank–one that cannot be overfilled. Hopefully, propane filling stations won’t fill a modified tank, but…just keep it away from your face if they do.

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G GO May 11, 2013 at 7:20 am

I think you answered your own question, while I was readingyour article, some folks may be getting only partial propane transferred. The first thing I thought of was the liquid is expanding as it blows to the other tank taking up volume with its vapor, thus the tank has no more room to allow a full tank of LP. Why, because as we know the pressure and temperature are related, a layman’s Gas Law is PV=T. We have volume in here as well, which acts inproportional to pressure. So yea, as we have noticed when filling our 5 gal tanks , the service person opens a screw and vapor blows out until the tank begins to fill then a little mor liquid and vapor becomes heavy (liquid like).

So yes, the small tanks need a bleed valve to push the vapor out ahead of the fill. Some tanks have this valve similar to an intertube needle. I suppose that is what it is for. But, you always have to leave some space for vapor, and if you notice, the service personnel does not allow the a 5 gal tank to fill completely with Liquid. I suppose it would be safer to bleed the small tank as it begins to or some while it is filling , to purge some vapor, thus you are allowing more capacity for the liquid. But I wouldnt try to fill the small tank 100% liquid. Leave some room for expansion due to temperature increases. Just assuming here, someone chime in……

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