What refrigerant is classified as a very high pressure refrigerant?

• A. R-22
• B. R-134A
• C. R-744
• D. R-404A

Answer: (C)

R-744, also known as carbon dioxide (CO2), is classified as a very high-pressure refrigerant due to its operating characteristics. When used in refrigeration systems, it operates at significantly higher pressures compared to many other refrigerants. This property is largely attributed to the fact that CO2 has a low critical temperature and a high critical pressure, which necessitates the use of equipment designed to withstand these elevated pressures.

Additionally, R-744 is utilized in transcritical refrigeration cycles, where the refrigerant surpasses its critical point during operation. This requires specialized components and safety protocols to ensure system integrity and operational safety. Understanding the high-pressure nature of R-744 is essential for technicians and engineers working with this refrigerant, as it impacts system design, maintenance practices, and safety measures in handling the refrigerant.