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MESYS Calculation Software

The contamination factor eC  is used for the calculation of life modification factor aISO. It is considering the cleanliness of the lubricant and can be calculated according to ISO 281 Annex A with the viscosity ratio, the bearing size and a selection of oil cleanness according to ISO 4406. The selection according to ISO 4406 defines how many particles of certain size may exist. The selections for grease lubrication also use ISO 281 Annex A to calculate the contamination factor eC.

In addition an own input of the contamination factor can be selected and the factor can be entered using the all_img3-button.  The contamination factor eC is in the range from 0.1 to 1 and guide values can be selected according to (ISO 281, 2007):

Contamination level


Dpw < 100mm

Dpw ≥ 100mm

Extreme cleanliness
Particle size of order of lubricant film thickness, laboratory conditions



High cleanliness
Oil filtered through extremely fine filter; conditions typical for bearings greased for life and sealed 0.6

0.9 to 0.8

Normal cleanliness
Oil filtered through fine filter; conditions typical for bearings greased for life and shielded

0.6 to 0.5

0.8 to 0.6

Slight contamination

0.5 to 0.3

0.6 to 0.4

Typical contamination
Conditions typical of bearings without seals; course filtering; wear particles from surroundings

0.3 to 0.1

0.4 to 0.2

Severe contamination
Bearing environment heavily contaminated and bearing arrangement with inadequate sealing

0.1 to 0

0.1 to 0

Very severe contamination




Note that for small bearings, the values for the contamination factor eC calculated according to ISO 281 Annex A can be much lower than in the table. A user input might be preferable in this case.