The Tetenal product is available in the US via Jobo. You can get it from places like B&H (maybe not until they get their hazmat shipping back available), Adorama, etc. The stuff is a mixture of butane and propane. The can is designed to dispense at a fairly low rate to avoid splashing.(posted 8564 days ago)It works. I used it to preserve some Ilfochrome chemistry stored in glass bottles, partially full. According to Ilford the life is 2 months in full bottles. I used it almost 4 months after mixing and it was fine.
Another great way to preserve chemistry is to go to your local welding shop and pick up a small tank of nitrogen with regulator. Purge the bottles with nitrogen. CO2 will also work, but not quite as well.