![]() A Global Solution. Aware of the impending HCFC-phaseout, the major chemical suppliers found evidence in 1994 that R-410A (Puron) would become the accepted replacement for R-22. Allied Signal, Dupont, Elf Atochem and ICI have shifted investment capital away from R-22 and into Puron for residential applications and R-407C and R-134A for commercial applications. Allied Signal has since licensed the right to produce Puron to both Dupont and Elf Atochem. There were several factors that contributed to the emergence of Puron for residential applications. First, Puron is a hydrofluorocarbon (HFC), meaning it does not contain chlorine and will not harm the ozone. Furthermore, it is as safe as R-22, due to its low flammable nature and low toxicity. In fact, it is one of only a few replacements approved under the EPAs Significant New Alternative Policy (SNAP) guidelines. The EPAs SNAP program has the responsibility for evaluating and approving or rejecting refrigerant candidates. This involves measuring the refrigerants ozone-depletion potential, toxicity and flammable nature, as well as any other application limits. Upon evaluation and approval, Puron earned a best possible A1/A1 rating by the American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) for both flammability and toxicity. However, the EPA approval does not evaluate a refrigerants performance within a refrigeration system. And it is Purons outstanding performance that leads to its emergence as the replacement for R-22. R-22 is a single compound, recognized for its ideal heating and cooling capabilities. No single compound replacement candidates could match its performance and meet the EPAs criteria. This is the primary reason other refrigerant blends, such as R-407C, have been rejected as replace-ments for R-22 in residential systems. Although Puron is not a single compound (it is a 50:50 mixture of R-32 and R-125), it acts azeotropic meaning it behaves like a single component refrigerant. It has a glide of less than 0.3° F and simplifies charging while negating any performance effects due to a leak in the system, unlike other compound blends. A system leak involving a non-azeotropic mixture would result in one component of the refrigerant leaking more than the other, potentially leading to a system performance problem. There are additional differences between Puron and R-22, such as higher
operating pressures. Purons operating pressures are 50 percent to 70 percent higher
than those of R-22 (typical operating pressures at 95° F are suction: 140 PSI; and
discharge: 400 PSI.) Specific equipment, including a recovery machine and manifold gauge
set are available for use with Puron products. Nevertheless, the basic procedures for
charging a system are the same. Puron systems are lubricated using a synthetic polyolester
(POE) oil, instead of mineral oils and alkylbenzenes used with R-22. Since POE oils have
an affinity for moisture, it is required that a liquid line filter drier always be
installed and is included with each Puron system.
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