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Widow · (This post was last modified: 09-28-2020, 06:25 AM by Widow.)

5: MAINTENANCE REQUIREMENTS - LUBRICATING OILS

5.1: Lubricating Oils

Analysis of the Lubricating oil is performed for the following three reasons:

To determine the machine mechanical wear condition
To determine the lubricant condition
To determine if the lubricant has become contaminated.

It is important to note that there is a wide variety of tests that will provide information regarding one or more of these areas, either individually or multiple results at once. The test used will depend on the sensitivity requited in the results of the test, the accuracy of the results of the test, the cost of the test, and the tested machines construction and application. Lubricating oil must be analyzed bi-annually.

5.1.1: Lubricant Condition

Lubricating oil in Chesterfield Station is typically drained from the equipment quarterly and reconditioned through filtering and/or replacing additives before being re-added to equipment reduce the environmental footprint of Chesterfield Station. Analyzing the oil to determine the lubricant condition must be completed bi-annually. Small reservoirs containing one gallon or less, typically has the oil changed on an operating time basis of 5000 hours.

5.1.2: Lubricant Contamination

Lubricating oil can become contaminated due to the machine’s operating environment, damaged equipment, improper filling techniques, or through mixing different lubricants. The root cause of any lubricating oil contamination needs to be determined and eliminated in order to avoid machine damage. As previously discussed, lubricating oil analysis is performed for three reasons:

To determine the machine mechanical wear condition
To determine the lubricant condition
To determine if the lubricant has become contaminated.

Tests have been developed to address indicators of these conditions and vary in cost dependent upon time and materials needed to accomplish the testing.

5.1.3: Machine Mechanical Wear Condition

All machines with motors of a selected size (in the case of Chesterfield Station, this is 7.5 HP or larger), any critical machines, or any high cost machines require routine sampling and periodic analysis. This will be the same as the vibration analysis periodicity (when using a portable vibration data collector). For machines that have a condition history of over one years worth of data, this is typically performed quarterly or semi-annually. For all other machines this must be performed monthly.

5.2: Standard Analytical Tests

Lubricating oil analysis should begin using simple, subjective techniques such as visual and odor examination before moving onto more sophisticated techniques. The more sophisticated techniques should be used when conditions indicate the need for additional information.

5.2.1: Visual and Odor

Simple inspections of the lubricating oils should be performed weekly by the operator. A visual inspection to look for changes in color, haziness or cloudiness, and visible particles must be completed as a minimum requirement. Although this test is very subjective and dependent on the personal opinion of the staff member performing the tests, this can be an indicator of recent water or dirt contamination and advancing oxidation. A small sample of fresh lubricating oil, in a sealed, clear bottle, can be kept on-hand for visual comparison. A burned smell may indicate oxidation of the oil and other odors could indicate contamination. Odor is more subjective than the visual inspection because sensitivity to smell is different between people and there is not an effective way to compare the odor between samples. The operator must be careful not to introduce dirt into the system when taking a sample.

5.2.2: Viscosity

This typically indicates the lubricating oils flow rate at a specified temperature. An increase or decrease in viscosity over time is an indicator of changes in the lubricant condition or lubricant contamination. Viscosity can be tested using portable equipment if required, however for a more accurate result it is suggested to test the sample in the laboratory on board Chesterfield Station.

5.2.3: Water

Water in lubricating oils will contribute to corrosion and the formation of acids. Free water in oil collects in the bottom of reservoirs and can be found by draining from the bottom. A simple, inexpensive test is performed to provide a gross estimate of solids and/or water in the oil. A sample is centrifuged in a calibrated tube and the resulting volume is measured. This test must be completed quarterly or after a situation where water may have been introduced into the system.

5.2.4: Particle Counting

Particle counting is used to identify metal and non-metal particles contained within the lubricating. Two methods are used and each has advantages and drawbacks. Both methods result in particle counts by size category.

The visual method of particle counting is time consuming and depends on the analyst skill. The benefit of the visual method is that the analyst is able to identify the types of particles such as dirt, seal material, and metal.
The electronic counting method is much faster and does not depend on the analyst’s ability but it does not distinguish or identify the particle make up.

5.3: Special Tests

Special tests are sometimes needed to monitor lubricant conditions on some high cost or critical systems. Usually the special test is monitoring a lubricant contaminate, a characteristic or additive depletion.

5.3.1: Glycol Antifreeze

Glycol contamination can be detected using infrared spectroscopy at levels greater than 0.1% which is considered adequate for condition monitoring.

5.3.2: Water

Water contamination can be detected using infrared spectroscopy at levels greater than 0.05% which is considered adequate for condition monitoring.

5.3.3: Foaming

Some oil may have anti-foam agents added to improve the lubrication capability in specific applications such as gearboxes or mixers. The test blows air through a sample of the oil and then the foam volume is measured. This is considered adequate for condition monitoring

5.3.4: Rust Prevention

Some systems are susceptible to water contamination due to equipment location or the system operating environment. In those cases, the lubricating oil may be fortified with a corrosion inhibitor to prevent rust. Upon inspection, results are either simply a pass or fail.

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