We have found that it is best practice to put your portable oil containers on a flushing schedule along with your equipment. Even though we use only new oil in these containers, over time we have found debris in each of them. We filter our new oil straight out of the barrel but somehow these debris particles still show up in our top-up containers.

So we implemented a top-up container flushing schedule to keep our contamination control at an optimum level. Once every 4 months, we clean and flush all our portable containers to ensure the debris does not reach the equipment in the plant. This drastically improves the cleanliness of the oils we put in our equipment. (Kenny Blackwell, Lube Tech Supervisor, Fluor Operational Maintenance)

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Book Bits: A Caution for Hydraulics

From "Fluid Power Maintenance Basics and Troubleshooting"

Low oil level is a serious cause of contamination in the hydraulic system. When the oil level is low, more air gets into the tank and this often leads to destructive cavitation in the pump and to condensation on the tank walls which generates sludge. Sludge decreases the lubricity of the oil, producing scoring and friction on surfaces with close tolerances.

Cavitation is the result of implosion - breakdown - of air or oil-vapor bubbles in the hydraulic system. It can be prevented by making certain that suction screens (if used) are clean and the oil reservoir is always full; this is another good reason for preventing leakage anywhere in the system. A clean reservoir with good return line filtration may eliminate the need for suction screens. Suction screens can be difficult to clean. As a result, they may not be cleaned and pumps may be lost as the screens plug.

More information about the book "Fluid Power Maintenance Basics and Troubleshooting"

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QUESTION: What does BN mean and what does it measure?

Get the answer.

"We recently ran a particle count run on our turbine lube oil. I don't have any reference point for our results, but of our two units, one was much higher than the other. I need to know, what are reasonable numbers for particles?"

Several areas need to be considered when answering this question. First and foremost is the sampling procedure. If the sample is being pulled from a sump drain or via simple drop tube sampling one can expect erratic particle count results because these methods do not result in quality representative conditions of the level of contamination or the level of wear. Best practices include installing a primary sample port in the return line prior to dumping into the sump.

Secondary sample points can be installed inline after each lubricated component (bearings). This will allow for pinpointing a source of a problem noted in the sample drawn from the primary sample point.

Secondly, regarding reference point, the alarm sets assigned to cleanliness levels do not utilize a reference point. The alarms given to cleanliness are target values assigned by the end user based on criteria such as safety, production criticality, cost of downtime, etc. While it is important to test your new lubricant for cleanliness, this value is not used as a baseline reading like those results from viscosity would be used. You can refer to this article by Jim Fitch to learn more about sampling new lubricants.

OEM recommendations for some turbines are as high as 16/13, while others recommend a cleanliness much cleaner, such as 14/11. Significant improvements in reliability and equipment life can be achieved by setting target values lower than those recommended by the OEM. For example, reducing the target cleanliness from 16/13 to 14/11 will allow an extension of 1.5 times the life as a 16/13 target (all conditions remaining optimum).

In order to achieve these target levels, proper contamination control measures should be in place. These include quality desiccant breathers or hybrid breathers, serviceable seals, full exclusion from the environment to include lube top-up and change procedures, and quality Beta-rated filters. Beta ratios are briefly explained in the Sept 8, 2005 issue of Filtration Tips. A more detailed discussion of Beta ratios can be found in Noria's online Learning Center.

It is said that "the cost of excluding a gram of dirt is approximately 10 percent of what it will cost you once it gets into your oil". Paying a premium cost up front to exclude contamination will definitely save you from losing a small fortune due to this contamination.

If you have two like units fitted the same in regard to contamination control and one is showing a higher level of contamination, an inspection as to the source of contamination is warranted. In addition, target values should be in place and any increase in contamination is cause for corrective action.

Matt Spurlock, Noria Corporation

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