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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 EPA’s Significant New Alternative Policy (SNAP) guidelines.

The EPA’s SNAP program has the responsibility for evaluating and approving or rejecting refrigerant candidates. This involves measuring the refrigerant’s 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 refrigerant’s performance within a refrigeration system. And it is Puron’s outstanding performance that leads to its emergence as the replacement for R-22.

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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 EPA’s 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. Puron’s 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.
In most instances, replacing an outdoor R-22 unit with a unit containing Puron does not require a line set change nor a coil change. However, upgrading the indoor coil is strongly recommended for top performance. Any metering device or TXV on the indoor coil must be replaced with one specifically designed for Puron.
Carrier also is introducing a line ofindoor fan coils with Puron that provide maximum performance.

Refrigerant Most Likely Application Pro Con
Puron TM • Residential and light commercial equipment under 15 tons • Offers improved efficiency over R-22
• Does not separate from its blended state
•Non-toxic/non-flammable
• Higher operating pressures
• Requires some product redesign:
    •Lubricant,    burst strength and compressor displacement
R-134A • Large commercial equipment above 75 tons • Near drop-in for R-12
• Does not fractionate (separate)
• Equipment redesign required
     Compressor,
     lubricants and
     coil circuiting
• 40% lower capacity than R-22
• Significantly reduced efficiency (for larger units)
• Significantly higher system cost in residential products
R-407C • Commercial equipment 15 tons through 75 tons • Near drop-in for R-22
• Limited redesign required (lubricant)
• Reduced efficiency of approximately 5 - 7%
• Fractionates
     •Leaks can allow only one component to escape
     •More difficult to service (loss of efficiency if charge is imbalanced)
Propane • None at unitary charge levels
• Small refrigerators
• Near drop-in for R-22
• Little redesign required
• Service and transportation risks
• Extremely flammable

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