The latest generation cryo saunas in the way they deliver the nitrogen are different than the first cryosaunas when they first came out. I still use the older type as that is what most clinics have but I always ask before making an appointment if they have the vortex type. It's easy to know if it has this because the cryosauna is cooled evenly. It is harder to get frostbite since the nitrogen has less direct flow hitting the body.
The standard for nitrogen output in a 3 minutes session is 3 liters. If someone wants a higher fluence than 1 liter per minute the non vortex types can be too intense. I have seen most cryosaunas at around 23 to 34 psi. Some have them set as high as 32psi. That is way intense and I don't know who would use it at that high. Maybe for 2 minutes but at that fluence I personally couldn't even handle that.
Note: If comparing different cryosaunas I urge first to make sure their is a filtering system. Some of the older generation types let out too much nitrogen around the face. If too much nitrogen is inhaled it can be dangerous. Fortunately, there are not many cryosaunas out there right now that have this problem but there are a few without the filtering safety feature. This does make the cryosauna more expensive.
PSI types: 20 to 22 psi is standard. Anything lower will not be as intense and the fluence will be the lowest. Some cryosaunas have as high as 50 psi. These are in the most expensive range and use double the pressure. They also cost nearly twice as much in nitrogen per session.
Air/Water Evaporators - for those that don't want to use nitrogen - Read the pros and cons of this type
Nitrogen type cryosaunas - for those that don't want to get a lower temperature than the air/water evaporator types - Read the pros and cons of this type vs evaporator types.