Blasco 409A Article-MWS1
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Retrofitting R-12 Systems to Alternative Refrigerants These days, contractors are faced with a wide array of refrigerant choices when retrofitting systems designed for R-12. About a dozen different R-12 replacement products are marketed by major refrigerant manufacturers, as well as by “boutique” refrigerant companies who mix proprietary blends and market them under catchy trade names. For most applications, however, the choices can be narrowed to a few products that have been extensively tested and approved by compressor and equipment manufacturers. Of these products, Genetron 409A from Honeywell is the leading choice for use in stationary positive-displacement equipment such as: Supermarket display cases Walk-in coolers Beverage dispensers Vending machines Water coolers Domestic refrigerators and freezers Commercial refrigerators and freezers Transport refrigeration Many others Available nationwide and typically lower cost than R-12 and most other retrofit blends, the performance of Genetron 409A is very similar to that of R-12 in low and medium temperature applications, and Genetron 409A performs well over the entire operating temperature range of R-12. In most R-12 applications, Genetron 409A has been used with great success without converting the systems from the original mineral oil or alkylbenzene lubricant. Typically, the charge of Genetron 409A used in systems is 10% to 25% less than the original charge of R-12 that it replaces, adding to its cost-effectiveness. In a few systems that operate at low temperatures with long refrigerant lines that provide marginally low refrigerant velocity, the combination of Genetron 409A and mineral oil may not provide sufficient oil return and steps should be taken to replace at least 50% of the systems’ mineral oil with alkylbenzene according to the manufacturer’s recommendations. Typically, a single change to alkylbenzene will remove 50% to 80% of the mineral oil in a system and is sufficient to provide the necessary oil return and meet the recommendations of most manufacturers. In most large and medium size systems with semi-hermetic compressors, changing the oil is a not a difficult or time-consuming task, and draining the compressor sump of mineral oil and replacing it with alkylbenzene is not a major roadblock to performing retrofits on these systems. For small systems with hermetic compressors, changing the oil can be rather difficult especially where access to the system itself is limited. These systems are usually operated with
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Blasco 409A Article-MWS1_
Transcript of Blasco 409A Article-MWS1
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Retrofitting R-12 Systems to Alternative Refrigerants
These days, contractors are faced with a wide array of refrigerant choices whenretrofitting systems designed for R-12. About a dozen different R-12replacement products are marketed by major refrigerant manufacturers, as wellas by boutique refrigerant companies who mix proprietary blends and marketthem under catchy trade names. For most applications, however, the choicescan be narrowed to a few products that have been extensively tested andapproved by compressor and equipment manufacturers. Of these products,Genetron 409A from Honeywell is the leading choice for use in stationarypositive-displacement equipment such as:
Supermarket display cases Walk-in coolers Beverage dispensers Vending machines Water coolers Domestic refrigerators and freezers Commercial refrigerators and freezers Transport refrigeration Many others
Available nationwide and typically lower cost than R-12 and most other retrofitblends, the performance of Genetron 409A is very similar to that of R-12 in lowand medium temperature applications, and Genetron 409A performs well overthe entire operating temperature range of R-12. In most R-12 applications,Genetron 409A has been used with great success without converting thesystems from the original mineral oil or alkylbenzene lubricant. Typically, thecharge of Genetron 409A used in systems is 10% to 25% less than the originalcharge of R-12 that it replaces, adding to its cost-effectiveness.
In a few systems that operate at low temperatures with long refrigerant lines thatprovide marginally low refrigerant velocity, the combination of Genetron 409Aand mineral oil may not provide sufficient oil return and steps should be taken toreplace at least 50% of the systems mineral oil with alkylbenzene according tothe manufacturers recommendations. Typically, a single change toalkylbenzene will remove 50% to 80% of the mineral oil in a system and issufficient to provide the necessary oil return and meet the recommendations ofmost manufacturers.
In most large and medium size systems with semi-hermetic compressors,changing the oil is a not a difficult or time-consuming task, and draining thecompressor sump of mineral oil and replacing it with alkylbenzene is not a majorroadblock to performing retrofits on these systems. For small systems withhermetic compressors, changing the oil can be rather difficult especially whereaccess to the system itself is limited. These systems are usually operated with
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100% mineral oil with Genetron 409A, and problems with these systems havebeen rare.
The main reason for utilizing alkylbenzene oil is to improve oil return. Thislubricant has been in use for some time and has historically been applied tosystems that experienced poor oil return with mineral oil. These were usually lowtemperature R-502 or R-22 systems. One of the major factors that determinegood oil return is the solubility of refrigerant vapor in the lubricating oil that hasmigrated from the compressor to the evaporator. The refrigerant vapor going intosolution with the oil, lowers the viscosity ("thins out the oil") and allows for easierreturn of the oil back to the compressor.
In addition to lubricant/refrigerant solubility, line sizing that determines refrigerantvelocity, length of lines, elevation changes, and other geometrical factors allinfluence oil return. Temperature also has a strong influence on oil return. Lowertemperature not only increases the viscosity of the oil itself, it also reduces thesolubility of the refrigerant in the lubricant that further increases viscosity. Insome low-temperature freezers where a higher cooling capacity is needed toprovide evaporator temperatures below -10 F, Genetron MP66 is often usedinstead of Genetron 409A, but in nearly all other cases Genetron 409A is therecommended solution.
Genetron 409A is not recommended or approved to replace R-12 in automotiveair conditioners. For air conditioning in cars and trucks, either Genetron 134a orGenetron 134a+UV should be used and the appropriate retrofit guidelinesfollowed.
Your local Genetron refrigerants wholesaler can provide you with moreinformation on retrofit products such as Genetron 409A, and can also provideyou with the most recent copy of the Genetron Refrigeration Retrofit Guidelinesbooklet, a necessary tool for all refrigeration professionals.
Ted Gartland, Regional Sales ManagerGenetron Refrigerants, Honeywell International
Retrofitting R-12 Systems to Alternative Refrigerants
