In This Issue:

• Up Front: Worth Another Look

• Book Bits: The Basics of Multigrade Lubricants

• Today's Tip: Better Filter Indicators

• Q & A: Getting the Dirt on Dirt Contamination
  

Up Front

Worth Another Look

Just relying on the oil analysis lab technician to give the right diagnosis is not always enough! While reviewing oil sample reports for a Cummins 855 big cam, we noticed that fuel content of the oil had been reported at 2.4 percent on the last sample. This was well within the trigger point for the lab, but when viewed against the average of 1.2 percent in the previous reports, we were concerned.

We checked the maintenance records and found that an injector change-out had been performed 150 hours before this sample was taken.

On investigation, we found one of the fuel-sealing O-rings had been nicked. This could have escalated into a fully blown seal with consequent severe fuel dilution. If this problem had not been found, it could have easily cost more than $50,000 in downtime and repair costs.

This is a perfect example that secondary diagnosis by house personnel is a good idea. (Submitted by Jack Denz, Aggreko International. Thanks Jack!)

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Book Bits

The Basics of Multigrades

From "The Practical Handbook of Machinery Lubrication":

Multigrade oils are made by blending a low-viscosity oil with special additives called Viscosity Index Improvers. For example, when these polymer additives are blended in the correct proportion with an SAE 15W oil, the oil flows like an SAE 15W oil at low temperatures and like an SAE 40 oil at high temperatures. The result is an SAE 15W/40 oil that will provide wide protection over an extended temperature range.

Multigrade oils have five main advantages over single grade oils. These oils offer:

(a) One oil for year-round use.

(b) Improved low-temperature starting.

(c) Excellent high-temperature performance.

(d) Improved overall fuel economy by providing less battery drain on cold starts, less idling time and faster warm up.

(e) Faster, full-pressure lubrication over a wider temperature range. That is, an SAE 15W/40 oil provides full flow lubrication in approximately 1 minute, and 45 seconds at -25°C compared to an SAE 30 oil which requires approximately 3 minutes and 15 seconds to achieve full flow lubrication.

More information about "The Practical Handbook of Machinery Lubrication".

Today's Tip

• During the cold start (wintertime) of a hydraulic system the pop-up indicators on the filters can alarm (turn red). When the system is operated by a skilled technician who understands the reason, there is no problem.

  However, when an operator mistakenly thinks that the indicator popped up during a cold startup (nuisance alarm) when actually the filter is plugged with dirt, the filter goes into by-pass and the system can be contaminated.

  To solve this problem, most of our systems also have pressure differential and temperature sensors. An alarm will sound only if the pressure differential setting is exceeded at 40°C. We have found this to be more reliable. (Submitted by Remco Bolderink, Project Coordinator, KENZ offshore Service. Thanks Remco!)

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Q & A

Getting the Dirt on Dirt

"What are the elements I should look for in elemental analysis to detect dust and dirt contamination of my lubricants?"

Solid particles are one of the most destructive contaminants. Dust and dirt getting into the reservoirs from the environment and poor lubrication practices are the most common source of surface damage and wear. Maintaining lubricants free of dirt is a smart proactive action that can significantly increase the life of your machinery.

Consider this: silicon (Si) is an indicator of dirt in our lubricants. The earth's outer layer, is 4 to 60 kilometers thick. The crust, as this layer is known, is rich in oxygen and silica with lesser amounts of aluminum, iron, calcium, potassium, sodium and magnesium.

Average composition of the earth's crust:

SiO2 - 58.09%

AlO3 - 15.35%

FeO3 - 7.29%

Ca - 3.6%

Na - 2.97%

K - 2.57%

Mg - 2.11%

This indicates that the predominant elements are silicon (Si) and aluminum (Al). Keep in mind, however, that not all the places in the world will have the same metals in the same proportion. For example, the presence and proportion of metals in mining environments differ from those in coastal or industrial environments.

Dust and dirt composition in the working environment are also affected by process materials. If you want to know their exact composition, place an open container with new lubricant next to your equipment for several days. Shake the sample, send it to your lab, and compare the analysis results with your new oil base line for elemental analysis elements increase.

Use a ratio of elements present to identify dirt ingression (for example, Al:Si:Ca = 1:4:2).

Note that emission spectroscopy can not detect 100 percent of the elements because of particle size bias.

Gerardo Trujillo, Senior Technical Consultant, Noria Latin America

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