Many
shaft
seal manufacturers use a legend-based part numbering
system, which is intended to indicate the unique
characteristics of any given seal. These characteristics
typically include shaft size,
bore size, seal
width, seal design (style), O.D. treatment,
and lip material.
R.L.
Hudson & Company uses this legend-based system in
our description, but not as our primary part number.
There are many different applications requiring different
seal designs and materials, some of which are minor,
but important, modifications from the standard designation.
It is possible for two seals to have the same legend-based
part number, but have distinctly different seal designs
(lip interference,
for example) and material properties.
We
individually design our seals for each unique application.
We assign an R.L. Hudson part number, which is generated
by our computer system. What follows is a description
of the legend-based part numbering system, which we use
as part of our description.
SHAFT
SIZE
The first two to four digits of a legend-based shaft seal
part description indicate the shaft
diameter (see Figure 253)
expressed in millimeters or thousandths of an inch.
BORE
SIZE
The second two to four digits of the part description indicate
the housing
bore diameter (see Figure 253)
expressed in millimeters or thousandths of an inch.
SEAL
WIDTH
Following a dash, the seal width (axial length of the seal,
see Figure 253) is expressed
in millimeters or thousandths of an inch.
SEAL
DESIGN
Seal design (style) is specified by a two- or three-character
alphabetic code, which designates the specific lip and case design
of the seal. For more information, see Standard
Seal Designs, and Non-Standard
Designs.
O.D.
TREATMENT
A single letter code indicates the type of treatment required
on the outside diameter (O.D.) of the seal. Table
72 lists the four main options in this area.
For more on O.D. treatments, see The
Case.
LIP
MATERIAL
The last portion of a legend-based part description is
a numeric or alphabetic code for the generalized base polymer
used in the seal lip. Table 73 lists
the variety of choices available. Note that R.L. Hudson & Company
uses a coding system based on actual ASTM D
1418 material designations. For more on materials, see
the Material
Profiles.
SAMPLE
PART DESCRIPTIONS
A sample part description (in inch units) might read as
follows: 10001500 – 375 SBY C NBR
This
indicates a seal for a 1.000" shaft (1000) in a
1.500" bore (1500), a .375" seal width (375)
in the “SBY” design (SBY) with an adhesive coating
on the O.D. (C) and an elastomeric lip
made of nitrile (NBR).
A
sample part description (in millimeters) might read as
follows: 30 60 7 SC R FKM
This
indicates a seal for a 30 mm shaft (30) in a 60 mm bore
(60), a 7 mm seal width (7) in the “SC” design
(SC) with a rubber-covered O.D. (R) and an elastomeric
lip made of fluoroelastomer
(FKM).
SPECIFYING
YOUR SEAL
The “Shaft Seal Specification” form, Figure
D, can help you address all of the questions
that typically must be answered in order to design or select
the proper shaft seal for a given application. Each variable
on this form has been discussed in a preceding section
of this website.
|
