Final answer:
R-744 (Carbon Dioxide) is the high-pressure refrigerant that often does not require recovery because it is naturally occurring and not ozone-depleting. It operates at much higher pressures compared to other refrigerants but does not have the same regulatory requirements for recovery.
Step-by-step explanation:
The refrigerant that is high pressure and generally does not need to be recovered is R-744 (Carbon Dioxide, CO2). This is because R-744 operates at much higher pressures than traditional refrigerants but is not considered ozone-depleting or a greenhouse gas in the sense that it is part of the natural carbon cycle, as opposed to synthetic chemicals like HCFCs and CFCs. Furthermore, since CO2 is a naturally occurring substance, its release into the atmosphere during servicing is not regulated as strictly as synthetic refrigerants. However, it's important to note that proper procedures should still be followed due to the high pressure. In comparison, refrigerants such as R-22, R-134a, and R-404A are typically not high-pressure refrigerants and are regulated substances that must be recovered due to their potential environmental impact.