Beginning January 2020 per Air-Conditioning, Heating, and Refrigeration Institute’s (AHRI) Guideline N, Assignment of Refrigerant Container Colors, all refrigerant cylinders should be painted a gray-green color, specifically RAL 7044. This is a change from previous guidelines set by AHRI that stipulated specific cylinder colors for specific refrigerants. However, as more refrigerants have been created, an increased number of cylinder colors have caused confusion and created safety issues in the field. Charging a system with the wrong refrigerant can cause damage to the equipment and to the user.
What will remain the same, is that AHRI mandates specific PMS colors for each refrigerant to be used on the outer packaging, like labels and cartons. You can find that list of colors here. Thus, the carton of each cylinder should remain the main source of identification of the contents inside.
For more information on these guidelines from AHRI, click here.