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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 that air (and moisture) can penetrate plastic
containers. Metal or glass containers with gasket in the top will slow moisture entry.
In conclusion, a single element of an oil analysis should not be used as the basis to estimate the
overall internal condition of a Daikin chiller. The characteristics of the lubricants and refrigerants,
and knowledge of the interaction of wear materials in the chiller must be considered when
interpreting a wear metal analysis. Periodic oil analysis performed by a reputable laboratory and
used in conjunction with compressor vibration analysis and operating log review can be helpful
tools in estimating the internal condition of a Daikin chiller.
Normal Sample Intervals
Daikin recommends that an oil analysis be performed annually. Professional judgment must be exercised under
unusual circumstances, for example, it might be desirable to sample the lubricating oil shortly after a unit has been
placed back into operation after it has been opened for service, as recommended from previous sample results or
after a failure. The presence of residual materials from a failure should be taken into consideration in subsequent
analysis. While the unit is in operation, the sample should be taken from a stream of refrigerant oil, not in a low spot
/ quiet area.
D–EIMWC00808-16HU - 57/64
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