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[c]0

L-IO = A23 x 1,000,000
60xn
Lubrication effectiveness factor
a23 -
C = Basic dynamic Load rating
P = Equivalent dynamic bearing load
p = Exponent of the Iofe equation (3 for ball brgs.)
n = Pump rotational speed

A number of adjustment factors in the calculation of operating hours of
bearings have been introduced over the years. One of which is based on
the relationship between the viscosity required for adequate lubrication
and the actual viscosity used. By selecting a lubricant with a sufficiently
high viscosity, the bearing life can be increased by a factor as high as
2.5. However, it can also reduce dramatically.
Another adjustment factor that has been suggested involves the effect
of varying degrees of contamination of the lubricant. This implies that
we will lose 40% of our bearing life under what is referred to as
'Normal' operating conditions, which seems to indicate that
considerable improvement is possible on the cleanliness of our bearing
environments.
Condition Adjustment Factor

Very clean = 1.0
Clean - 0.8
Normal - 0.6
Contaminated = 0.5 - 0.1
Heavily Contaminated = 0
It must be noted that these factors are intended to bc combined with
the other relevant data on lubricant viscosity before being applied
directly to the bearing life formula.
Where water contamination is a problem, it is generally accepted that a
mere 0.002% water content in wet oil results in a loss of 48% of bearing
life, and 3% of water content results in a loss of 78% of bearing life.
All of this underscores the necessity for protecting the quality of the
lubricant used to ensure bearing reliability in centrifugal pumps.

7.9 Lubricant protection

A variety of methods arc used to keep the contaminants out of the
lubricant in pumping equipment.

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