MACHINERY LUBRICATION- INDIA NOVEMBER-DECEMBER 2019 | Page 16

By Alejandro Meza | N oria C orporation
PERSPECTIVE
Synthetic Lubricants
Guidelines for
SELECTING
High-temperature
LUBRICANTS
N
owadays most industries
have
processes
that
require machines to
operate
at
high
temperatures.
These
applications demand special lubricants
that can handle extreme operating
temperatures by maintaining their
lubrication properties, keeping the
system clean and providing a reasonable
service life. The ultimate goal is to
sustain high machine reliability while
controlling maintenance costs. In many
cases, a synthetic lubricant may be the
best choice.
What is Considered a
High Temperature?
Before selecting a high-temperature
lubricant, you must first know when a
80 %
of lubrication professionals use
high-temperature lubricants
on the machines at their plant,
based on a recent survey at
MachineryLubrication.com
14 | November - December 2019 |
temperature is considered to be high.
Unfortunately, there is no single right
answer to this question. For the sake of
reference, generally an oil that is able to
work at temperatures higher than
210-250 degrees F (100-120 degrees C)
for a normal or extended drain interval
may be assumed to be a high-
temperature lubricant. Of course, other
sources may have different opinions on
this temperature range.
The well-known Arrhenius rate rule,
which relates to lubricant use versus
temperature, states that for every
increase of 18 degrees F (10 degrees C),
www.machinerylubricationindia.com
the oil life is cut in half. This equation
was originally formulated for mineral
oils, but while the lifespan is different
for various product technologies, the
rule is applicable for both mineral and
synthetic lubricants. This means that a
mineral oil with a weak formulation
may be used at higher temperatures if it
is changed frequently, but that is not
practical or cost-effective in most cases.
The same principle applies to the base
stocks used in greases. The grease’s
thickener influences the performance at
higher temperatures due to its oxidation