Probably shouldn't put "empty" propane canisters in the trash and even if it's safe when totally empty, that's a lot of metal to just throw away, and I'm sure the recycle bin isn't ready for them either. What should be done with them? Does (or could) REI or any other outdoor retailer offer a recycling path?
Classic hillbilly tech. The Department of Transportation, at least, doesn't approve. Indeed, if that propane got loose inside a closed vehicle, it could be gnarly.
Inverting a 20lb tank to transfer liquid propane into a DOT 39 (non-refillable) container is a classic example of how YouTube and frugality can create a toxic cocktail. The manufacturer of the disposable tanks clearly disclaims the safety of their devices on the tank label and none of the refillable tank manufacturers suggest or instruct the use of their tanks as liquid propane dispensers.
Pressurized liquids that vaporize into flammable gas at 270x their volume are dangerous enough to warrant a thoughtful moment before choosing a safer solution.
Find another way to save money and switch to DOT 4BA (refillable) tanks.
It's a hack that has worked well for me and others I know. Obviously some care and common sense has to be taken in when/where one does the transfer i.e.. not near any open flame.....like the care one does when using propane in general. The "legit" refillable kit requires the inversion of the large propane tank as well. You can buy the kit including just a single 1lb tank for $49. Or, you can buy a three pack of 1lb's for around 7 or 8 bucks and the adapter for around $8. I'm not seeing a difference between the two different 1lb tanks but, if you do, I'd love to know what it is.
I think the difference (aside from the normal tanks being refilled makes them illegal to transport as has been mentioned) is:
1) The refillable tanks are thicker walled.
The normal ones supposedly can suffer fatigue with each fill and use as the pressure changes - think of bending a piece of paper back and forth on a crease repeatedly.
2) The refillable tanks have a bleeder valve so it can be vented as it's filled whereas the disposable ones do not.
Why they have bleeder valves, I don't know.
I'd be all over the cheap adapter except that 95% of my 1lb tank usage is away from home and I'd rather not break federal law. The refillable tanks were spendy but I'd do it again for the overall money saved and keeping things legit.
The bleeder valve is to eliminate air from inside the tank. Without it, you have a potentially highly flammable fuel-air mixture in your tank. If you want to know what that can lead to, just look up fuel-air explosives online.
Anyone who has ever filled SCUBA tanks knows about tanks becoming weaker with use. Granted propane tanks aren't generally under that much pressure, but stuff happens. Also, while the tank isn't likely to fail catastrophically (i.e., it isn't going to go flying through the air or send pieces of itself flying through the air), even a relatively benign failure risks flooding a space with fuel, leading to the aforementioned fuel-air explosion.
Many of our DOT / FAA / construction / etc. regulations were written in blood. They resulted from accident investigations, post mortems, etc. You disregard them at your own peril, not to mention the peril of anyone nearby.
> It's a hack that has worked well for me and others I know.
That is known in the technical scuba diving community as the "it hasn't killed me yet" argument. 😉
do you have a local "toxic waste disposal" place? We have ToxDrops in Indianapolis. They take household waste like oil and pain as well as batteries. They also take old propane tanks and properly recycle.