This article will answer the following questions:
- How dirty is my lube oil and how do I check my lubrcating oil cleanliness?
- What are ISO 4406 and NAS SAE 4059 particle counts?
Everyone loves an underdog, but this is one example where you don’t want them to win.
Dirt particles smaller than can be seen with the naked eye may appear small when compared to towering machinery. However dirt particles are one of the number one causes of premature machinery failures. Although the particles may be small, they get trapped between moving surfaces and over time cut away at the metallic surfaces causing wear, which can eventually lead to failure.
Taking an oil sample for particle counting and elemental analysis is the best ways to help identify dirt related problems early so you can correct them. Particle counting measures the size distribution and number of particles in the machinery to give an indication of how dirty the oil is. Elemental analysis allows identification of contamination elements such as Silicon in sand and Silicon + Aluminium as dirt to confirm contamination ingress. Likewise elemental analysis of the wear metals gives a clue as to what components are wearing such as: chrome from rods caused by a seal failure on a crawler excavator or iron from a hydraulic pump.
When choosing your lab for particle count it does not necessarily matter what method is used, but it is important to keep using the same method as there can be lots of variation between the ways particles are counted and even between different lab instruments and variations on methods.
I personally prefer dilution based particle counting methods as the best way to measure particles in group I to IV oils and visual patch for group V oils, however, the importance is the consistency in methods. I also prefer using ISO 4406 coding systems to NAS or SAE 4059 systems, but if you are used to these methods or find them easier then feel free to ask your lab for them. Most laboratories can assist on offering both options.
When measuring particle counts there should be no fixed limit to begin with as naturally no dirt is best, but you have to work on what is practical for your equipment. So I would suggest measuring all your equipment regularly for a couple months when first starting to find what is normal for your equipment and then start looking to improve the cleanliness of the system. Your filter supplier and OEM will be able to assist you in setting realistic targets to improve system cleanliness.
The end result is a cleaner lubricant leading to a longer lasting, more reliable and safer piece of machinery.
Any questions about particle counting or oil sampling to assess cleanliness please comment below.
Test your knowledge on Particle counting below.
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