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Refrigeration Lubricants - Lubricants for Natural Refrigerants

The use of natural refrigerant gases is not new. Ammonia and propane have long served as important refrigerants and are familiar to most people in the industry. However, the renewed interest in these refrigerants is leading to rapid application developments where lubricant technology can play a significant role in system performance.

CPI is independent from influence by the large global refrigerant manufacturers and is base stock independent as well. You choose the application, we optimize equipment performance through proper lubricant selection.

Hydrocarbon refrigerants, such as propane, are considered highly soluble in a lower viscosity and reduced oil film thickness. The washing away or lubricant absorption of lubricants into the gas phase in the compression cylinder may result in loss of lubrication. These problems have led to the widespread use of CP-1516 SERIES polyglycols. The CP-1516 SERIES are specially selected polyglycols which are "resistant to dilution" by hydrocarbons as they have lower solubility. The polar nature of these fluids help to preferentially wet lubricated surfaces. The high viscosity index of the CP-1516 SERIES fluids help to provide a higher viscosity for sealing compressor rotors while remaining a lower viscosity needed for good oil return from the low temperature side of the refrigeration system. Reports by rotary screw compressor developers have indicated up to an eighteen percent improvement in volumetric efficiency over mineral oil in propane compression. High pressure reciprocating compressors have benefited by up to a twenty-fold increase in the life of pressure packings while cylinder oil feed rates have been reduced. Other more miscible synthetics have been used in very low temperature systems (such as -180°F (-118°C) ethylene) for their low volatility. Separators can effectively control the amount of lubricant in the low temperature side of the system. Careful selection of oil viscosity provides enough lubricant film to lubricate compressor components in the presence of the gas while the small amount of miscible lubricant is diluted in the evaporator and can be easily returned. There is no problem of wax or viscous liquid formation found with mineral oils.

AMMONIA

P-4600 SERIES fluids and "semi-synthetic" high viscosity index (HVI) hydro-treated isoparaffinic mineral oils (our CP-1009-68) have been found to provide several performance advantages in ammonia systems. Better thermal and chemical stability with ammonia results in reduced sludge and varnish and has resulted in extended drain intervals. Lower solubility helps improve lubrication and reduces foaming. Lower volatility reduces oil consumption and improves heat transfer by limiting the amount of oil in the system and on heat exchanger tubing. The excellent low temperature fluidity and high viscosity index of the CP-4600 SERIES fluids allow evaporator temperatures below -50°F (-46°C) and maintains viscosity for higher compressor operating temperatures. The good low temperature fluidity of the CP-1009-68 facilitates oil removal in most systems. A large food producer undertook a yearlong evaluation of the CP-1009-68. Reciprocating and rotary compressors were both found to have reduced oil consumption of sixty-four percent to eighty-three percent. Bearing problems that were frequent in two rotary screw compressors were eliminated. Maintenance personnel reported much cleaner discharge valves in reciprocating compressors and cleaner piping and system components.
SPECIAL NOTE: CP-1009-68 has been used in selected R-12 applications to reduce oil carryover through separator elements.
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