R508B, a PFC-based refrigerant, is the industry standard replacement for R-13 and R-503 in very low temperature applications [below -40°F to -150°F (-40°C to -101°C)] such as medical freezers and environmental chambers.  It offers advantages over R-23, including significantly lower compressor discharge temperatures, making it the best choice to ensure optimum systems reliability for critical applications.  R508B can be used in new equipment and can also be used to retrofit existing systems.

Replace 
R-13, R-23, and R-503

Applications
Very low temperature [below -40°F to -150°F (-40°C to -101°C)]: 
medical freezers
environmental chambers

Benefits
Endorsed by many OEMs. 
Longer equipment life: Lower discharge temperature than R-23, increases compressor service life.
Increased cooling capacity: 30% greater cooling capacity than R-13. 
Best match for R-503.
Lower retrofit cost than R-23.