:Polyolester
{{distinguish|Polyester}}
{{Short description|Family of synthetic refrigeration lubricants}}
File:Polyol Ester (Penta) Structural Formula V.1.svg]]
File:Polyol Ester (Di-Penta) Structural Formula V.1.svg]]
Polyolester oil (POE oil) is a type of wax-free synthetic oils used in refrigeration compressors that is compatible with the refrigerants R-134a, R-410A, and R-12.{{cite web |title=Definition of POE oil |url=http://autorepair.about.com/library/glossary/bldef-624.htm |url-status=dead |archive-url=https://web.archive.org/web/20070814111853/http://autorepair.about.com/library/glossary/bldef-624.htm |archive-date=2007-08-14}} POE oils are used as a lubricant in systems using the refrigerant HFC-134a when replacing CFC-12, as these systems traditionally use mineral oil,{{cite book |author=Ananthanarayanan |title=Basic Refrigeration and Air Conditioning |publisher=Tata McGraw-Hill Education |isbn=978-0-07-049500-5 |page=83 |date=1 April 2005 |url=https://books.google.com/books?id=gniJE5lK0YAC&pg=PA83 |access-date=30 October 2012}} which HFC-134a does not mix well with.{{cite book |author1=Frank Kreith |author1-link=Frank Kreith |author2=Shan K. Wang |author3=Paul Norton |title=Air Conditioning and Refrigeration Engineering |publisher=CRC Press |isbn=978-0-8493-0057-8 |page=113 |date=6 December 1999 |url=https://books.google.com/books?id=8Bk0YrDHHh4C&pg=PA113 |access-date=30 October 2012}} These oils are used with chlorine-free hydrofluorocarbon (HFC) refrigeration systems, as they provide better lubrication and stability and are more miscible with HFC refrigerants compared to synthetic and mineral oils of similar application.{{cite book |author1=Theo Mang |author2=Kirsten Bobzin |author3=Thorsten Bartels |title=Industrial Tribology: Tribosystems, Wear and Surface Engineering, Lubrication |publisher=John Wiley & Sons |isbn=978-3-527-32057-8 |page=408 |date=11 January 2011 |url=https://books.google.com/books?id=m-iWM8Umr98C&pg=PA408 |access-date=30 October 2012}} The dispersion behavior of POE oils has been studied for applications in nanotechnology.{{cite book |title=Advances in Nanotechnology Research and Application: 2011 Edition |publisher=ScholarlyEditions |isbn=978-1-4649-2058-5 |page=2034 |date=3 January 2012 |url=https://books.google.com/books?id=RdZwdt-JPlYC&pg=PA2034 |access-date=30 October 2012}}
Properties
The properties of POE oils are best described in comparison to lubricant mineral oils. POE oils are more hygroscopic,{{cite web |title=Polyolester Oils: Handling the New Lubricant in R-410A Systems |url=https://www.achrnews.com/articles/108365-polyolester-oils-handling-the-new-lubricant-in-r-410a-systems |access-date=November 1, 2012 |publisher=Archnews}} and react in air to form carboxylic acids. They typically have lower viscosity indexes than polyalkylene glycol (PAG) or poly-alpha-olefin (poly-α-olefin, PAO) oils, and higher viscosity grades are required in order to attain useful kinematic viscosity at higher oil temperatures.
= Issues in application =
The same properties that make POE oil a solvent for oils also make it a solvent for other pieces of matter left behind during the manufacturing of a unit, such as dust, dirt, residue from soldering, small metal bits, and oxidized metal from the tubing. The residues collected can clog the system filters and cause excessive wear or damage to components such as the vanes or valves.{{cite web |title=Working With POE Oils Requires Forethought |publisher=Airconditioning news |url=https://www.achrnews.com/articles/102899-working-with-poe-oils-requires-forethought |access-date=November 1, 2012}}
See also
References
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