For the past year or so, I've been experimenting with Isobutane. I used to get it in relatively cheap canisters of r600a from amazon.co.uk and AliExpress, and that worked fine. Now, however, AliExpress has NO purchase options for r600a, and amazon.co.uk will not ship it to the US, even though they used to do it for me. This is really bugging me. I cannot find any information about the laws of isobutane in the US, at all. Has it been banned? I don't know. Either way, I need something to replace it for my experiments if I can't find a place that sells it. The kind of gas I'm looking for is one that can be sold in small canisters at a relatively cheap price, not big cylinders. I want it to have a vapor pressure of at least 30 psi (~200 kpa) and have a boiling point of around 0°-30°F (not near room temperature). As you can see from these conditions, Isobutane was absolutely perfect. But, now that I can't get it anymore, so these are the gases I've looked at. HFC-227ea - Looks promising. It is not very toxic. I'm not using high temperatures, so is it a big issue that it can turn into hydrogen fluoride at high temperatures? Another problem is I can't find it sold in small canisters. I think it is the propellant in some Inhaler cartridges? But if I get it in the inhaler cartridges, it would also have the medicine in it too, right? That might be a problem. Butane - Looks equally great. It has a boiling point of about 32°F, a little high but I'm willing to look past it if its my last option. It is sold in canisters (as fuel, kinda iffy). I don't plan on lighting it on fire, but theres always the risk. Then again, there was that risk with isobutane also. Its easy to get, and I doubt it'll disappear like r600a. Two questions: Is the inhalation risk bigger than it was with isobutane? And should I be worried that If it did catch on fire, nitrogen dioxide would be created? Isobutane/Propane Blend - This is also very available. It is fuel of course, and it is a blend, so I can't find any information on what temperature and pressure it condenses at, but I'm willing to try if someone else says it might work. I don't like the propane part, but in some cases thats only 20%, but it does have a bigger health hazard than isobutane. This is just a compilation of facts that I've put together. I thank anyone who took the time to read all that stuff, and especially thank those who have something to add (and if anyone knows a way to get back to buying isobutane like I used to, it would be much appreciated).