Very low temperature refrigeration systems typically operate in two or more stages (cascade type systems). It would be nearly impossible to achieve low temperatures in a single stage with an inexpensive compressor. The traditional cascade system has a low temperature stage which uses the lower boiling point gas, such as R-13, R-503, R-23, or R-508B, and a high stage which typically uses R-12, R-22, R-502, R-134a, or R-404A. The high stage evaporator provides the correct condensation temperature for the low stage so that compressors in both stages can run at “normal” pressures.
|5R13||5 LB. CYLINDER|
|9R13||9 LB. RETURNABLE CYL.|
|23R13||23 LB. RETURNABLE CYL.|
|80R13||80 LB. RETURNABLE CYL.|