7. LUBRICANT SELECTION
When choosing a lubricant for a particular piece
of equipment, the equipment manufacturer's
operation and maintenance manual should be
consulted. The operation and maintenance
manual will usually outline the required charac-
teristics of the lubricants as well as a
recommended schedule for replacement or fil-
tering. When the maintenance manual is not
available, lubricant manufacturers and distribu-
tors can usually be of assistance. They will
usually request pertinent information on the
equipment, such as operating speed, frequency
of operation, operating temperature, and any
other special or unusual conditions, so that a
lubricant with the proper characteristics can be
chosen. Some discretion should be used when
dealing with a lubricant salesperson to prevent
purchasing an expensive lubricant with capabil-
ities in excess of what is required.
of equipment, the equipment manufacturer's
operation and maintenance manual should be
consulted. The operation and maintenance
manual will usually outline the required charac-
teristics of the lubricants as well as a
recommended schedule for replacement or fil-
tering. When the maintenance manual is not
available, lubricant manufacturers and distribu-
tors can usually be of assistance. They will
usually request pertinent information on the
equipment, such as operating speed, frequency
of operation, operating temperature, and any
other special or unusual conditions, so that a
lubricant with the proper characteristics can be
chosen. Some discretion should be used when
dealing with a lubricant salesperson to prevent
purchasing an expensive lubricant with capabil-
ities in excess of what is required.
When ever possible lubricants should be pur-
chased that can be used in several applications.
By limiting the number of lubricants on site, the
chance of mixing different lubricants or using
the wrong lubricant is minimized.
chased that can be used in several applications.
By limiting the number of lubricants on site, the
chance of mixing different lubricants or using
the wrong lubricant is minimized.
There are a number of tests which have been
developed to define and measure the properties
of lubricants. Most of these tests have been
standardized by the American Society for Test-
ing and Materials (ASTM). Some of the more
common tests and their procedures are de-
scribed in the Appendix. The properties
determined by these tests can be very helpful in
comparing relative performance of several lubri-
cants but it should be noted that many of theses
tests have little correlation to actual service
conditions. When selecting a lubricant, the test
procedures for the required properties should be
reviewed so that relevance of the test is kept in
perspective.
developed to define and measure the properties
of lubricants. Most of these tests have been
standardized by the American Society for Test-
ing and Materials (ASTM). Some of the more
common tests and their procedures are de-
scribed in the Appendix. The properties
determined by these tests can be very helpful in
comparing relative performance of several lubri-
cants but it should be noted that many of theses
tests have little correlation to actual service
conditions. When selecting a lubricant, the test
procedures for the required properties should be
reviewed so that relevance of the test is kept in
perspective.
7.1 Unit Guide and Thrust Bearings
Under normal conditions, the lubricating oil for a
hydroelectric unit's guide and thrust bearings
experiences relatively mild service, but it is ex-
pected to have a long service life. In order to
have a long life, a high quality oil Is required
with various additives to enhance and maintain
its quality.
hydroelectric unit's guide and thrust bearings
experiences relatively mild service, but it is ex-
pected to have a long service life. In order to
have a long life, a high quality oil Is required
with various additives to enhance and maintain
its quality.
In most powerplants, a highly refined turbine oil
is used in the bearings.
is used in the bearings.
typical specifications for turbine oils. The oil
should be rust and oxidation inhibited with an
antifoam additive. The oil should also be resis-
tant to emulsification and separate readily from
water. Antiwear or extreme pressure additives
are not required or desired.
should be rust and oxidation inhibited with an
antifoam additive. The oil should also be resis-
tant to emulsification and separate readily from
water. Antiwear or extreme pressure additives
are not required or desired.
The recommended oil viscosity is usually sup-
plied by the equipment manufacturer and
depends on the operating speed, load, and
temperature as well as the bearing clearances.
The most common viscosities used are the ISO
viscosity grades 32, 46, and 68.
plied by the equipment manufacturer and
depends on the operating speed, load, and
temperature as well as the bearing clearances.
The most common viscosities used are the ISO
viscosity grades 32, 46, and 68.
7.2 Hydraulic Systems
A hydraulic fluid's primary purpose is to transmit
power. To accomplish this effectively, the fluid
must be incompressible and readily flow through
the system. The fluid must also have sufficient
viscosity to seal and lubricate the components
of the hydraulic system. There are a variety of
fluids capable of performing these functions but
the most satisfactory hydraulic fluid is usually
oil.
power. To accomplish this effectively, the fluid
must be incompressible and readily flow through
the system. The fluid must also have sufficient
viscosity to seal and lubricate the components
of the hydraulic system. There are a variety of
fluids capable of performing these functions but
the most satisfactory hydraulic fluid is usually
oil.
A hydraulic oil has many of the same require-
ments as the lubricating oil used in the unit
bearings and in many cases the same oil can be
used. If the system uses a gear pump, operates
at pressures less than 1000 psi, and has similar
viscosity requirements, a turbine oil can func-
ments as the lubricating oil used in the unit
bearings and in many cases the same oil can be
used. If the system uses a gear pump, operates
at pressures less than 1000 psi, and has similar
viscosity requirements, a turbine oil can func-
(FIST 2-4 11/90)
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