While reviewing Noria Corporation's message boards, I ran across a post that I believe deserves an in-depth answer.
The question asked "What tests should be performed on new oil to ensure that you are receiving quality oil? What are the advantages and disadvantages of elemental testing (such as ICP) versus IR spectrum on new lubricant samples?"
In an attempt to adequately answer both questions, each will be addressed separately.
Testing New Lubricants
Testing new lubricants is vital when establishing a condition-based maintenance program. Most incoming lubricants are not necessarily clean lubricants when compared to target cleanliness levels. Unfortunately, lubricants may also be delivered in a drum or other bulk container that is not consistent with the original order.
Testing new lubricants can take place with on-site screening equipment in addition to running a full commercial lab test slate. Some of the tests that can be performed on-site include viscosity and particle counting.
Because viscosity is the most important property of a lubricant, on-site testing can take place before accepting a delivery. This will allow a general level of confidence because most incorrect deliveries are viscosity-related rather than product-line errors. This, however, is not to say that full commercial quality testing should not take place.
Cleanliness Levels, Commercial Quality Testing
Particle counting indicates the cleanliness level of a new lubricant delivery. This will provide a good idea of the level of filtration that needs to occur prior to putting the oil into service. It is not uncommon for a new oil sample to have an ISO cleanliness level of 22/17 or worse, which is above any target cleanliness level for equipment where reliability is important.
While viscosity and cleanliness levels can be screened on-site, this still does not ensure the correct product is being received. Each new lubricant batch should be sampled and sent for commercial quality testing. For most industrial applications, the following tests should be run on new oil:
Elemental Analysis - ASTM D5185
Viscosity at 40°C - ASTM D445
Viscosity at 100°C - ASTM D445
ISO Particle Count - ISO 4406:99
Karl Fischer Moisture - ASTM D1744 or ASTM D6304
Fourier Transform Infrared (FTIR) Spectroscopy
Acid Number - ASTM D664
Other tests may be necessary depending on the type of lubricant and associated application; however, the above slate should be considered as a minimum.
Elemental analysis and FTIR are important tests. Elemental analysis measures the actual metallic components in a lubricant. These results have been known to identify delivery truck pump failures as well as additive concentration changes from the oil manufacturer.
While sampling new lubricants, elemental analysis denotes the starting values for additives. When trending used oil, these values help identify cross-contamination during top-ups or the use of an incorrect lubricant during an oil change. Simply stated, elemental analysis helps identify a lubricant.
FTIR, on the other hand, indicates the health of a lubricant in addition to identifying various contaminants in used oils. To properly monitor and set alarm values for used oil samples, the current values for new lubricants must be available. Lubricant manufacturers change formulations as product lines are improved. These formulation changes can affect the values derived with FTIR.
To gain the most value from an oil and a condition-based maintenance program, new oil sampling must include the multiple tests that will most appropriately monitor oil conditions. Established alarms and limits of lubricant properties are generally assigned from a baseline sample. The lack of a baseline sample severely limits the accuracy of lubricant health analysis in used samples.
It has been said that "the only downside to oil analysis is finding the time to use it to its fullest potential." New oil sampling is just the beginning of the oil analysis process, and must be utilized to its fullest extent.