Refrigerant is not used for pressure testing because it is a specialized fluid used for cooling and is not an ideal medium for detecting leaks in a system. Refrigerant can be harmful to the environment if it leaks out, so using a different type of fluid, such as nitrogen or a specific leak detection solution, is preferred for pressure testing purposes.
Oxygen
Disposable refrigerant containers are only used for virgin refrigerant.
Well I've seen ultraviolet reactive refrigerant that will indicate leaks, when a UV light is shinned on it.
condensable gases condensable gases
Refrigerant are used in refrigerator for cooling and dehumidifying indoor air.
Leak detectors can be used to find any kind of leak. Whether it be, refrigerant, oil, fuel, hydraulic, water or even a gas leak. Just make sure to use the right type of leak detector. Electronic leak detectors are used to find small leaks, whereas most other leak detectors are used to find gas leaks.
The refrigerant typically used in refrigerators is called R-134a.
The five gases commonly found in a fridge are refrigerant gas (such as R-134a or R-600a), nitrogen (used for pressure), carbon dioxide (found in some systems for cooling and as a refrigerant), oxygen (present in air in small amounts), and trace amounts of moisture.
They can either used dyed HCFC-22 refrigerant, and look for dye leakages, or they can use a halogen sniffer. Some DIY-ers say to cover your refrigerant lines with soapy water, and look for any instances of bubbling. This, however, is a bad idea, as it can lead to the mixture getting into the AC system and contaminating the refrigerant and compressor oil.
134a refrigerant
The oil used to lubricate the compressor is cycled with the refrigerant.