18 Reliable Plant
|
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reliableplant.com Machinery Lubrication
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machinerylubrication.com 2025 Annual
A N N U A L E D I T I O N
Bennett Fitch | Noria Corporation
CONDITION MONITORING
Is it true that a
lubricant's life
is cut in half for
every 10 degrees
C (18 degrees
F) increase
in operating
temperature?
Yes, this is
generally true
and is based on a
well-established
scientific
principle known
as the Arrhenius
Rate Rule.
How Heat Affects Lubricants:
Understanding the
Arrhenius Rate Rule
The Arrhenius Rate
Rule Explained
e Arrhenius Rate Rule, named after the
19th-century Swedish chemist Svante Arrhenius, explains
the relationship between temperature and the rate at
which chemical reactions occur. e rule is pivotal in
various fields, including lubrication, which helps predict
and manage lubricant degradation.
e Arrhenius equation is as follows:
Where:
k is the rate constant of the reaction,
A is the pre-exponential factor,
e is Euler's number
Ea is the activation energy of the reaction,
R is the universal gas constant,
T is the absolute temperature (in Kelvin).
In practical terms, this equation tells us that the rate of
chemical reactions, including those that lead to lubricant
degradation, increases exponentially with an increase in
temperature. Specifically, for every 10°C (18°F) increase
in temperature, the rate of lubricant oxidation doubles,
cutting the lubricant's life in half.
