Daikin WSC063 Installation And Maintenance Manual page 52

lubricating oil and filter prior to when its needed will reduce the effectiveness of oil analysis as a tool in
determining machinery condition.
The following metallic elements or contaminates and their possible sources will typically be identified in an oil
wear analysis.
Aluminum
Typical sources of aluminum are bearings, impellers, seals or casting material. An increase in aluminum content
in the lubricating oil may be an indication of bearing, impeller or other wear. A corresponding increase in other
wear metals may also accompany an increase in aluminum content.
Copper
The source of copper can be the evaporator or condenser tubes, copper tubing used in the lubrication and motor
cooling systems or residual copper from the manufacturing process. The presence of copper may be accompanied
by a high TAN (total acid number) and high moisture content. High copper contents may also result from residual
mineral oil in machines which have been converted to R-134a. Some mineral oils contained wear inhibitors which
react with copper and result in high copper content in lubricating oil.
Iron
Iron in the lubricating oil can originate from compressor castings, oil pump components, shells, tube sheets, tube
supports, shaft material and rolling element bearings. High iron content may also result from residual mineral oil
in machines which have been converted to R-134a. Some mineral oils contain wear inhibitors which react with
iron and can result in a high iron content in the lubricating oil.
Tin
The source of tin may be from bearings.
Zinc
There is no zinc used in the bearings on Daikin chillers. The source, if any may be from additives in some
mineral oils.
Lead
The source of lead in Daikin centrifugal chillers is the thread sealant compounds used during chiller assembly.
The presence of lead in the lubricating oil in Daikin chillers does not indicate bearing wear.
Silicon
Silicon can originate from residual particles of silicon left from the manufacturing process, filter drier material,
dirt or anti-foam additives from residual mineral oil which may be present in machines that have been converted
to R-134a.
Moisture
Moisture in the form of dissolved water can be present in lubricating oil to varying degrees. Some polyolester oils
may contain up to 50 parts per million (ppm) of water from new unopened containers. Other sources of water may
be the refrigerant (new refrigerant may contain up to 10 ppm water), leaking evaporator condenser tubes or oil
coolers, or moisture introduced by the addition of either contaminated oil or refrigerant or improperly handled oil.
Liquid R-134a has the ability to retain up to 1400 ppm of water in solution at 100 degrees F. With 225 ppm of
water dissolved in liquid R-134a, free water would not be released until the liquid temperature reached -22
degrees F. Liquid R-134a can hold approximately 470 ppm at 15 degrees F (an evaporator temperature which
could be encountered in ice applications). Since free water is what causes acid production, moisture levels should
not be of a concern until they approach the free water release point.
A better indicator of a condition which should be of concern is the TAN (Total Acid Number). A TAN below
0.09 requires no immediate action. TANs above 0.09 require certain actions. In the absence of a high TAN
reading and a regular loss of refrigerant oil (which may indicate a heat transfer surface leak) a high moisture
content in an oil wear analysis is probably due to handling or contamination of the oil sample. It should be noted
52 Centrifugal Chillers IM 1044-2