Which type of refrigerant is typically used in low-pressure systems?

• A. R-134a
• B. R-404A
• C. R-123
• D. R-410A

Answer: (C)

The refrigerant R-123 is commonly used in low-pressure systems, particularly in chillers and industrial refrigeration applications. It is a hydrofluorocarbon (HFC) that operates at lower pressure levels than many other refrigerants. One of its notable characteristics is that it has a lower boiling point, making it suitable for applications requiring efficient heat transfer at low pressures. R-123 is effective in these systems due to its thermal stability and relatively low environmental impact compared to some older refrigerants.

In contrast, the other refrigerants listed typically operate at higher pressures. For instance, R-134a, R-404A, and R-410A are generally found in medium to high-pressure systems and are used in air conditioning and refrigeration applications that demand higher performance. Therefore, while all of these refrigerants serve important functions in various systems, R-123 stands out for its specific applicability in low-pressure environments.