Unwrapping The Mystery Of R-407C
This article will focus mainly on R-407C.
The TimetableDue to regulations imposed by the Montreal Protocol, production and use of HCFC-22 for air conditioning and refrigeration applications will be gradually phased out. (This, by the way, is a production ban, not a use ban.)
R-22 is scheduled for phaseout in all new equipment by 2010. This means that all original equipment manufacturers (OEMs) must begin using R-22 alternatives. All new equipment built after that date will need to use R-22 replacement refrigerants, such as HFCs R-410A, -407C, or -134a.
After 2020, there will no longer be any new R-22 produced for refrigeration and air conditioning service, although sales and use may continue. Use of reclaimed refrigerant will still be permissible; however, R-22 supplies may be limited.
Currently, major refrigerant suppliers are still making R-22 for use and sale in the air conditioning and refrigeration marketplace. (For more detailed information on sales and support for the refrigerant, contact your local refrigerant representative, who will help you keep abreast of developments.)
What’s NextDue to the phaseout of R-22, several new refrigerant fluids have been developed to support the transition from HCFCs to HFCs.
The leading refrigerants in this transition are 410A and 407C, both of which are now available. R-134a (for chillers, large rooftops, etc.) and R-404A/R-507 (refrigeration) will replace R-22 on some applications as well.
R-407C is a zero-ozone-depletion blend of HFC refrigerants R-32, R-125, and R-134a. It has been developed to approximate the properties of R-22, and will be used for many air conditioning and refrigeration applications in either new equipment or in retrofitting existing R-22 installations.
R-407C must be used with polyolester (POE) oil, since its solubility with mineral oil or alkylbenzene is limited.
When retrofitting an old R-22 system, it will be necessary to flush out the mineral oil or alkylbenzene lubricant in the system and replace it with POE. New equipment designed for R-407C will be charged with the OEM-recommended POE lubricant, ready for use with R-407C.
Retrofitting, ChargingAlthough R-407C approximates the properties of R-22, it is not suitable for use in all R-22 systems.
One case where R-407C would not be suitable would be in a flooded evaporator system. This is due to the tendency of R-407C’s components to separate (fractionate), which could greatly alter system performance. Please consult the equipment manufacturer’s guidelines for help when deciding if retrofitting is appropriate for the system you are working on.
R-407C should always be charged as a liquid. Due to its zeotropic nature, it will fractionate if charged as a vapor, causing poor system performance — and, possibly, system failure.
Additionally, the refrigerant supply in the cylinder may become out of spec if discharged as a vapor.
In situations where vapor is normally fed to the system, such as in adding a refrigerant charge to a running system, install a valve in the charging line to flash the liquid to vapor while charging.
It is important to remember that POE oil is extremely hygroscopic and can be easily contaminated if moisture gets in the system. You must take the appropriate measures to keep the system free of moisture.
As with all CFCs, HCFCs, and HFCs, R-407C must be re-claimed. Check with your authorized refrigerant dealer for details on reclamation.
Rolotti is technical manager of Atofina Chemicals Inc., which produces refrigerants including R-22, -410A, -407C, and -134a under its Forane® brand name. For more information, visit www.forane.com.
Publication date: 02/03/2003