Forane® 409A Refrigerant

Technical Specifications:

Forane® 409A (FX-56) is a low ozone depleting blend of HCFC refrigerants R-22, R-124, and R-142b. It closely resembles the properties of R-12 and is used as an alternative to R-12 in retrofitting medium- and low-temperature refrigeration systems. These systems, which typically contain a hermetic or semi-hermetic compressor, are used in air conditioners, commercial food storage, vending/beverage machines, ice machines, and transport refrigeration and supermarkets.

Definition of Terms

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Since Forane® 409A is a zeotropic blend, it helps to understand terms like bubble point, dew point, fractionation, and glide.

Bubble point, or saturated liquid temperature, is the temperature at which Forane® 409A (at constant pressure) begins to evaporate. Or in other words, the temperature where the first bubble of vapor appears in liquid Forane® 409A. Bubble point is equivalent to boiling point for single component refrigerants.

Dew point, or saturated vapor temperature, is the temperature where condensation begins (at constant pressure). Or, think of dew point as the temperature at which the last droplet of liquid evaporates and saturated gas exists. It corresponds to the condensation point of a single component refrigerant.

Bubble point and dew point are used to describe the behavior of zeotropic blends in an evaporator and condenser. Boiling point is not used because the blend's temperature changes as it evaporates or condenses.

Fractionation describes how a refrigerant blend like Forane® 409A changes from a liquid to a vapor or vice versa. For Forane® 409A, fractionation occurs between its bubble point and dew point. Since the components of Forane® 409A evaporate (or condense) at different rates in the evaporator (or condenser), the blend's composition constantly changes between the bubble point and dew point. Once the temperature exceeds the dew point, Forane® 409A is in a superheated vapor state.

Glide describes the difference in temperature between the evaporator outlet and inlet due to fractionation. Glide can vary, depending on the state of the liquid refrigerant at either end of the evaporator (or condenser) or on pressure losses. At most common system pressures, Forane® 409A has a temperature glide of 10 to 12°F (5.5 to 6.6°C).

Lubrication

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For intended applications, Forane® 409A is sufficient for use with mineral, alkylbenzene, or polyolester oils. Miscibility is important for proper oil return to the compressor. In most cases, changing the existing lubricant isn't required, but check with the compressor manufacturer for specific requirements.

Charging

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If a significant leak occurred in a cylinder or the vapor space of a system at rest, fractionation of the blend may cause a permanent change in composition of the refrigerant charge. For this reason, remove Forane® 409A as a liquid during charging operations. In situations where vapor is normally fed to the system, a valve should be installed in the charging line to flash the liquid to vapor during charging.

Follow charging instructions on the cylinder. For most applications, the approximate Forane® 409A charge will be 85 to 90% of the original R-12 charge.

Performance

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Evaporator pressures using Forane® 409A are similar to operating pressures for R-12. High side pressures will typically be 15 to 25 psi (1 to 1.7 bar) higher than the pressure seen with R-12.

Heat transfer characteristics with Forane® 409A should equal or exceed those for R-12. In most direct expansion evaporators, temperature glide with Forane® 409A is not a problem.

Retrofitting with Forane® 409A

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Retrofitting R-12 systems to Forane® 409A is recommended where 134a is not practical. Systems in which mineral oil removal is difficult or capacity is critical are good candidates for Forane® 409A. Most vending/beverage machines, transport, restaurant, home refrigeration systems, walk-in coolers and freezers, and rack systems can easily be retrofitted to R-409A with minimal, if any, system changes. Most systems with capillary tubes can be switched to R-409A with no system modifications.

Retrofit Procedures

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1. Gather baseline data on system using R-12.
2. Recover and weigh existing R-12 charge.

In most cases, mineral oil removal is not necessary. If oil return is a concern at lower temperatures (less than 22°F/-30°F/-18°C), oil return can be improved by using at least 30% alkylbenzene lubricant mixed with mineral oil. Forane® 409A is fully miscible with pure alkylbenzene or polyolester lubricants.

1. Replace filter driers.
2. Evacuate system using a deep vacuum.
3. Charge Forane® 409A refrigerant in the liquid phase only. (Approximately 85-90% of original charge.)
4. Properly mark and identify Forane® 409A refrigerant charge on the system.
5. Start system and adjust expansion valve for proper superheat settings, if applicable.

Note:

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Some original equipment manufacturers (OEMs) may have different lubricant, safety, or retrofit requirements. Consult OEM guidelines for details.

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