R32 as substitute for R22
As described earlier, R32 belongs to the HFC refrigerants, but initially it was mainly used as a component of refrigerant blends only. An essential barrier for the application as a pure substance so far is the flammability. This requires adequate charge limitations and/or additional safety measures, especially with installations inside buildings. In addition there are very high pressure levels and discharge gas temperatures (compression index higher than with R22 and R410A).
On the other hand, R32 has favorable thermodynamic properties, e.g. very high evaporating enthalpy and volumetric refrigerating capacity, low vapor density (low pressure drop in pipelines), low mass flow, and favorable power input for compression. The global warming potential is relatively low (GWP = 675).
Looking at these favorable properties and taking into account the additional effort for emission reductions, R32 will increasingly be used as a refrigerant in factory produced systems (A/C units, liquid chillers, heat pumps).
It was proven in flammability tests that the necessary ignition energy is very high and the flame speed is low. Therefore, R32 (like R1234yf and R1234ze) has been placed in the new safety group A2L according to ISO 817.
The resulting safety requirements are specified in the revised EN 378 (amended version 2016).
R32 is also considered an alternative for systems with larger refrigerant charge, e.g. liquid chillers for air conditioning and process applications and heat pumps previously operated with R410A. However, depending on the installation site of the system, appropriate refrigerant charge limits must be observed. On the other hand, there are no such restrictions when installed outdoors (without access to unauthorized persons) and in machine rooms (for example, according to EN 378-3: 2016). It should be noted, however, that R32 pre-charged chillers may be subject to special conditions during transport (according to the Pressure Equipment Directive, R32 is classified under Fluid Group 1).
