Safe to refill 1lb propane cylinders?

[WilCo]

Is it safe to refill "disposable" 1lb propane cylinders? I see a number of adapters being sold for that purpose (which doesn't mean it's safe, just that it has't been enough of a problem to result in laws or lawsuits).

Seems to require turning the source cylinder upside down briefly, which I understand one generally should not do because it prevents the pressure-release valve from working, but presumably refilling a 1lb tank does not require leaving it for hours in the hot sun.

I would like to refill them mainly because there seems to be no way to dispose of them properly short of driving to a hazardous waste facility, a 40-60 minute round trip for me!  (I suspect most people just toss them into the trash for curbside collection, even though you're really not supposed to.)  It's cheaper to refill too, but thats not a big deal if there is much risk. (There is a trade-off between the risks of driving 40-60 minutes vs refilling; the former risk is "known" but the latter is not.)

(As far as disposal options goes, I've seen Bernzomatic's CylinderSafe program, which just sends me to my local government body that handles these things, which I know already. This local body might have upcoming neighborhood collection events, assuming I find out about it before they actually happen. A lot of this stuff has been cancelled for the last couple of years.)

I am talking about both the green Coleman tanks sold for camping, which are 1# 1 pound 16oz and the blue Bernzomatic bottles that are sold for torches, which are 14.4oz. (I am sure everyone knows what bottles I mean but for the sake of searchability, I thought I'd add the things I tried to search for.)

[ThomasPowers]

I cut the tops off and use the bottoms to hold stuff on the workbench.  They tend to leak with age and if you are going to buy an adaptor---get the one that hooks your tools/lights to a BBQ grill sized tank!

[TWISTEDWILLOW]

I throw them in the scrap trailer with all the other metal from the shop, an let my scrap guy haul them off

[SHC]

Are you using these on torches, like the bernzomatics are sold for? You may consider looking for an adaptor and hose that will let you attach a torch handle to a regular propane cylinder. You wouldn’t have to worry about safe disposal, just exchange them like normal. 
I’ve no idea if that’s even a thing, I haven’t needed it so I haven’t looked for it. 

[Irondragon Forge ClayWorks]

We bought one of those adapter hoses off Amazon, to use with a BBQ instead of the 1 pounder cans.

[WilCo]

On 3/12/2022 at 7:00 AM, ThomasPowers said:

I cut the tops off and use the bottoms to hold stuff on the workbench.  They tend to leak with age and if you are going to buy an adaptor---get the one that hooks your tools/lights to a BBQ grill sized tank!

How do you make sure they're empty? Puncturing and putting them in the regular recycling is a disposal option but that scares the bujeebus out of me!

I'm not sure what other adapter you mean.

On 3/12/2022 at 7:28 AM, SHC said:

Are you using these on torches, like the bernzomatics are sold for? You may consider looking for an adaptor and hose that will let you attach a torch handle to a regular propane cylinder. You wouldn’t have to worry about safe disposal, just exchange them like normal. 
I’ve no idea if that’s even a thing, I haven’t needed it so I haven’t looked for it. 

Yeah, I have one of these hoses. The trouble is that I have only one 20# tank and I like to use the torch for starting my forge and preheating my anvil, which I can't do with the forge burner already using the tank. (Not to mention the inconvenience of having to lug a 20# tank where it's needed. I do it occasionally, like today when my kid wanted to have a fire in the fire pit and all the wood was soaked.)

So while the hose mostly eliminates the need for 1# bottles, it doesn't do away with it altogether.

[JHCC]

8 hours ago, WilCo said:

How do you make sure they're empty?

When the tank is no longer putting out enough propane to run your torch, it should be basically empty. Test this by pushing in the spring-loaded ball in the middle of the screw fitting to release any remaining gas and/or pressure. Then you remove the stem from pressure relief valve next to screw fitting on the top. I believe this takes a standard Schrader valve core removal tool, but you can make your own from a rod with a slot cut in the end.

[SHC]

Get more tanks! I’ve got 4. Nice to have spares on hand. 

[ThomasPowers]

In the city I to live in; folks would junk gas grills in the fall instead of storing them; often with tanks still attached, often full!

So free tanks and propane.  I heat a slab of scrap steel while the forge is heating and warm the anvil up with that---when it's to temp put the cold workpiece in the forge and the slab on the anvil.

Using the small tanks is NOT cost effective!

 

[George N. M.]

Also, if you buy new tanks I recommend paying the extra and buying 30 lb capacity tanks rather than the 20lb. capacity common BBQ tanks.  When full they are about the largest I can muscle around.  With larger tanks you have to make fewer runs to the propane supplier for refills and because of the larger mass they are slower to freeze up in use.  In fact, I cannot recall ever having a 30# tank freeze but I have had to swap out 20# tanks because of freezing.  I bought a new 30# tank last fall at the local farm supply store and IIRC it was about $85.

"By hammer and hand all arts do stand."

[JHCC]

11 hours ago, JHCC said:

Then you remove the stem from pressure relief valve next to screw fitting on the top. I believe this takes a standard Schrader valve core removal tool, but you can make your own from a rod with a slot cut in the end.

Thus:

[Frosty]

So light your forge with a bit of burning paper or make a torch. By torch I mean wrap the end of a piece of comfortably long steel rod with cotton twine, apply a little charcoal lighter or diesel fuel. Light the torch, light the forge, snuff the torch in a short section of close fitting tubing. You can roll a short tube from old aluminum can "stock," etc. EZ PZ. 

You can keep your forge connected to it's tank. I have a 100lb propane tank in the shop, it was in a pile for the garbage collector when I stopped to check out a moving sale. There were a pair and both passed inspection so I have a full one and gave the other to someone in need. 

I use 40lb. tanks for portable operations but the burners on my forges draw gas fast enough to freeze up 20s in a couple hours.

Propane tanks are easy to find. Our supplier where I have mine filled just exchanges them on the dock, it saves them time inspecting while the customer is waiting and the customers never have to wonder if our propane tanks are safe. They do mass inspections and hydro testing when they've acquired enough to make a day of it. 

Frosty The Lucky.

Don't exchange tanks at one of the outside a store  exchange cage type companies. It costs more and the tanks are usually not filled to the safe free space level. 90%, leaving 10% for vapor. I hear people talk about 15%, sometimes 20% but it's been a long time since I looked up anything official. 

Frosty The Lucky.

[JHCC]

For lighting a gas forge, I like one of those fireplace lighters that's run out of butane but the sparker at the end still works.

[ThomasPowers]

I use a wooden kitchen match; either turn on the gas and throw a lit match at the forge's door---when I need to impress new students; or light it and prop it in the door of the forge and go turn on the propane---how I do it when I'm alone or with my forge friends.

[Frosty]

Get the new guy to hold the match? I've done that to impress new folk. Stupid stupid stupid!

Frosty The Lucky.

[ThomasPowers]

Now even it won't do *that*---unless they are using tongs...

[Frosty]

It? 

Until I built NARB my burners tend to blow too hard to light with a match unless you hold it well outside the door. I held it from the side of the doorway. ONE TIME. 

Frosty The Lucky.

[WilCo]

Thanks folks for all of your advice, especially JHCC with the details about how to empty the little bottles and remove the valve.  I am afraid my unnecessary details -- intended to be motivating examples, rather than the bigger-picture problem that can be answered instead -- have diverted attention from what I really want to know.

I asked this question in the "Safety" section, so to legitimize it's continued existence there, permit me to rephrase my question: Assuming that someone has a valid need for using 1# bottles, what and how great are the risks of using an adapter to refill them from a normal refillable cylinder, like a 20# one?

ThomasPowers has already mentioned that the 1# bottles "tend to leak with age"; this certainly sounds like a risk and I'd like to know more -- How long are we talking about? Is this from personal experience, industry/academic publication, Internet anecdote?

My assumption is that it is not safe, so I would be especially interested in hearing from someone who actually does it.

[George N. M.]

The question I have had throughout this discussion  is whether the 1# bottles are filled to the same pressure as the larger bottles.  If it is the same I see no problem in using an adapter and just letting the 2 equalize pressure.  If the smaller bottles are filled to a lower pressure you will need a regulator such as you use on a propane forge to meter out the higher pressure into whatever is necessary for the smaller.  I do not know how much the regulators which do not have a gauge, such as the one on my salamander heater,  step down the pressure from bottle to appliance.

I have had 1# bottles sitting around for 10+ years and they do not seem to have lost any gas although I did not formally weigh them.

"By hammer and hand all arts do stand."

[WilCo]

It finally occurred to me to check for a subreddit about propane; there is a r/propane and it's a small and active enough sub that there are posts and answers but the volume is low enough that one can look get a sense of which commenters seem to know what they're talking about. And indeed someone asked this very question a couple years ago: https://www.reddit.com/r/propane/comments/gvmhso/refill_coleman_camp_style_1_lb_disposable_bottles/

From that post, majority opinion seems to be that it is neither safe nor legal, which is about what I'd expect but hope springs eternal in the human breast.

Flame King makes a refillable 1# bottle, in addition to the adapters and a kit of other things: Commercial link removed (Also says, "Certified by the DOT as legally and lawfully refillable and transportable. It is not safe or legal to refill and transport disposable 1lb tanks.") Oddly enough, the only adapter available individually is for a forklift tank, although the kit clearly has a different adapter and is shown with a vertical 20# tank. (Unlisted due to supply chain problems?)

Another person mentioned that Manchester (mantank.com) makes one, although I don't see anything smaller than a 5# tank (which looks like an awesome size for camping for a night or two).

3 hours ago, George N. M. said:

The question I have had throughout this discussion  is whether the 1# bottles are filled to the same pressure as the larger bottles.

Yes, they have to be.  Liquid doesn't really compress (for mundane applications like this) but boils to fill the empty space to a given pressure, dependent on temperature. That's the same regardless of the volume of the container.

Edited March 16, 2022 by Mod30
Remove commercial link per TOS

[George N. M.]

OK, that makes sense.  I assume that when you connect a larger volume to a smaller you tap the vapor at the top of the larger tank and as it flows into the smaller it recondenses as the pressure equalizes.  Or am I overthinking this?  It is the same principle as refilling a 20, 40, or 100# tank unless the big tank from which the smaller is filled taps the liquid near the bottom and it is driven by the pressure of gas on top of the liquid to drive liquid into the smaller tank. 

GNM

[ThomasPowers]

No you invert the larger tank so that the internal pressure forces liquid propane into the smaller tank.   There is some inherent risk to the process.  I get my tanks refilled by the propane dealer at their office; except for the house tank that only runs the kitchen stove.  My wife has a delivery on that one.

[Frosty]

Yes George, you have to tap the liquid in the tank to refill another tank. If you're filling a small tank without having a pump bleeding the last of the pressure from the empty tank will let you get more in. The nitrogen in ambient air doesn't compress as easily as propane so it's really hard to get any liquid in an unpurged tank.

To fill a brand new tank you give it a little squirt of liquid propane wait a couple seconds then bleed the pressure off, the liquid propane boiling off in the tank with the open valve purges the nitrogen. Then it will take a proper fill.

Yeah, in the day I worked at service stations you had to take a 3 day propane safety class to be legal to fill propane tanks. 

One of the real dangers of filling your own little bottles is leakage as you fill it AND the tendency of fast moving propane (leaks in your coupling arrangement) to generate static charges. Being in a cloud of propane vapor isn't the place to be making sparks.  The basement is NOT the place to do this!!

I do NOT recommend doing it but for those of you who're going to give it a try be careful REALLY careful! Learn how to ground yourself to prevent static charge and do it outside away from anything you don't want destroyed. Wear COTTON long sleeves and pants, a cap is a good idea and eye protection! 

We bought a Blackstone outdoor cook top, a couple burners, chargrill and flat top that uses IIRC 16oz. propane bottles. The adapter and hose for a "normal" size tank almost had us convinced to just buy the little bottles. Break even was at the 3rd. 6pack of little bottles so we have the hose and fitting. We also carry a 6 pack of the little ones for the times we don't want to haul the large tank along, say when Deb is out on her own, she does NOT like trying to drag even the 10lb propane bottle out of the storage compartment under the RV.

I REALLY wish the propane connections on the RV were on the side with the coach door so I could just plug into the RV tank. Oh well it wasn't designed on my watch or maybe I just haven't taken THAT class. 

Frosty The Lucky.

[MikeT]

I overfilled a 1 lb non-refillable bottle (green bottle).  It sat on my dining table for about two weeks then "BANG"!!  Had there been an ignition source near, it would have been a fire ball explosion.

[JHCC]

As my old tai chi teacher used to say, Let that be a lesson to you!!