Machinery Lubrication

Machinery Lubrication March April 2019

Machinery Lubrication magazine published by Noria Corporation

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e results of this method generally are more precise and consistent for moisture concentra- tions greater than 100-200 ppm. It is important to note that ASTM 1744 (Standard Test for Determination of Water in Liquid Petroleum Products by K arl Fischer Reagent) has been discontinued as an approved test method since 2016. While this test was somewhat easier to manage, it was not as accurate. Still, some laboratories continue to utilize it. Relative Humidity Sensors is technology has been employed to measure the moisture content of material in numerous industries for years. Recently, it was introduced to the lubrication field to monitor contaminants in lubricating oils and greases. It is supported by ASTM D7546 (Standard Test Method for Determi- nation of Moisture in New and In-Service Lubricating Oils and Additives by Relative Humidity Sensor). Generally, an instrument heats a sample of test material and volatilizes the moisture, which is carried by a dry-air system through a sensor block containing the relative humidity (RH) sensor. Reagents are not used. e results are reported in ppm or percentage/micrograms of water. Studies on the method's repeatability and reproducibility have not yet been completed. FTIR FTIR is a well-known and frequently used resource for lubricants. It can detect the presence of contaminants such as water, fuel and soot, as well as certain additives and oil degradation. While there are several ASTM methods related to FTIR and petroleum prod- ucts, two are most relevant: ASTM E2412 and D7414. is quick, low-cost test can measure different parameters in oil or grease samples. One drawback is the lower detection limit, which is approximately 1,000 ppm. e results are reported in absorbance units for certain infrared-light wavenumbers. e laboratory may also provide the moisture concentration by percentage or in ppm. Distillation In the distillation process, water is extracted from the oil or petroleum product by heating the oil sample, which previously has been mixed with a solvent. e water is evap- orated and collected in a trap. e minimum amount of water that can be measured is approximately 0.05-0.1 percent. e procedure should follow ASTM D95. is method does not require complex test equipment, but it is labor intensive, which makes it impractical for routine oil analysis. Portable Field Instruments and Tests Field lab analysis involves the use of portable instruments in a workshop or produc- tion facility. e technology is the same as that utilized in the laboratory but with a more www . machinerylubrication.com | March - April 2019 | 43 LABORATORY ANALYSIS Samples are sent to commercial lab for analysis FULL TEST SLATE ROUTINE PORTABLE FIELD INSTRUMENTS AND TESTS FIELD LAB ROUTINE Portable instruments such as FTIR, calcium hydride and crackle test VISUAL FIELD INSPECTIONS DAILY Typically completed daily by examining sight glasses, oil samples, etc. UNATTENDED ONLINE SENSORS REAL TIME Sensors are permanent and dedicated to a single machine or group of machines ML Relative humidity sensors, such as this moisture analyzer from Arizona Instrument, offer an alternative to Karl Fischer titration. This spectrometer from Spectro Scientific uses FTIR spectroscopy to monitor in-service oil.

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