Gas Selection
In the United States, you must have a HVAC license to be able to purchase any commercial refrigerants. For those that do not have a license, you are limited to the gases that you can use. Here is a list of the various single stage gases you can use without a license. I will not be listing all the various refrigerants that can be obtained with a license, if you have a license, you will know what you can get, if you don’t have a license, get one first, then worry about those gases.
Propane- the poor mans gas of choice. This wonderful hydrocarbon is great at roasting steaks, heating water, and cooling computers. Propane is cheap, plentiful, relatively low pressure, and did I mention cheap? Now the downsides, the boiling point isn’t that great, a measly -42.09 Celsius, and it is flammable when exposed to oxygen. Propane is also heavier than air, so if it does leak in a room, it will sink to the floor where it will puddle and form a thin layer of propane gas. Propane naturally has no smell, but the chemical ethanethiol is added to propane to provide it with a distinct smell.
R-134a- this gas is what has replaced R-12 in the refrigerant industry due to its non-ozone depleting properties. This gas can be obtained from various automotive recharging kits and in some rare cases from HVAC stores. R-134a has a very high boiling point of -26.08 Celsius but it condenses very easily and it is non toxic. One note about safety, R-134a is denser than air and it will displace oxygen in lungs, potentially causing asphyxiation if inhaled in large quantities.
CO2- carbon dioxide, while commonly known for its solid form, dry ice, can be liquefied and used as a refrigerant. CO2 has a boiling point of -78 Celsius and it can be added in small quantities to a r290 charged system to drop temperatures. Other types of phase coolers can use CO2 as the primary gas, but that is beyond this guide. CO2 is toxic if inhaled in large quantities but it is relatively cheap and easy to purchase, many Paintball fields can sell you liquid CO2.
There are other gases that you can obtain, but it is either illegal or a complex process to be able to purchase those gases, so I have stuck with these three gases. Once you are very familiar with refrigeration, you can advance to higher pressure gases and lower temperatures. I have had r290 charged systems down to -60 Celsius by pulling a high vacuum, so it is possible to get decent temperatures with these unregulated gases.
Custom phase change cooling
Protams, ir kompresors, radiators, ventilators un vel tur shis tas, kas pienaakas! Kaads negrib arii taisiit phase change cooling??
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Originally Posted by artissco
tikai benzīnā vien. Piedāvājums jau labs, bet nu man galīgi nav izdevīgi... 
