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DESIGN AND SELECTION
Selection of Standard Design
Selection of an oil seal design is dependent on whether the operating conditions exceed the limits of the design. The three operating parameters that mainly affect the design's ability to function are eccentricity, pressure, and shaft speed. In this section, these limits are reviewed.
〝S〞AND 〝T〞LIP DESIGN
“S” and “T” lip symbols for general nonpressure applications. The “S” design is a single lip oil seal with a garter spring to provide a consistent radial load against the shaft.
The “T" design uses the same primary lip configuration, with an auxiliary dust lip to provide effective light duty dust exclusion.
Below is a table listing approximate limits of the “S” and “T” lip designs.
NOTE：Higher shaft speeds possible using high temperature materials such as polyacrylate, silicone or fluoroelastomer. Slightly higher continuous pressure possible for shaft speeds below 200 ft./min. Higher eccentricity allowable if shaft speed is reduced.
Total eccentricity consists of two components, shaft runout and shaft-bore misalignment (shaft offset ).
The eccentricity is determined as follows：
〝V〞AND 〝K〞LIP DESIGN
The 〝V〞and 〝K〞type designs are low cost seals designed primarily for retention of grease or similar viscous fluids. The 〝V〞type is a single lip seal. The〝K〞type has an auxiliary lip for light dust exclusion.
NOTE：Higher eccentricity is allowable if maximum shaft speed is reduced. In comparison with the 〝S〞and 〝T〞lip design, the major reduction in design limits of the 〝V〞and 〝K〞type is the result of the absence of a garter spring. However, for grease applications where lubricant's ability to flow is reduced, these nongarter spring seals are very cost effective designs to use.
“WP” LIP DESIGN
THE “WP” design was developed as a dust wiper(scraper) for reciprocating applications such as hydraulic cylinder rods. As a result, the operating limits for the design are slightly different form “V”and “K” types. Maximum shaft motion is linear velocity of 200 ft./min. (1M/sec.). Maximum pressure capability is 4psi (.28kg/cm2 ). Stroke length should be limited to78 inches (1.98m). maximum. Eccentricity considerations involve only shaft-to-bore misalignment. Maximum allowable is ±.004 inch (0.1 mm).
Selection of an oil seal design is dependent on whether the operating conditions exceed the limits of the design. The three operating parameters that mainly affect the design's ability to function are eccentricity, pressure, and shaft speed. In this section, these limits are reviewed.
〝S〞AND 〝T〞LIP DESIGN
“S” and “T” lip symbols for general nonpressure applications. The “S” design is a single lip oil seal with a garter spring to provide a consistent radial load against the shaft.
The “T" design uses the same primary lip configuration, with an auxiliary dust lip to provide effective light duty dust exclusion.
Below is a table listing approximate limits of the “S” and “T” lip designs.
| SHAFTDIAMETER | NITRILE LIP MAXIMUMCONTINUOUS SHAFT SPEED | MAXIMUM CONTINUOUSPRESSURE | MAXIMUM TOTALECCENTRICITY |
| General | 3,500rpm | 5psi | .020〞 |
| .500 | 8,000rpm | 5psi | .004〞 |
| 1.500 | 7,000rpm | 5psi | .006〞 |
| 2.500 | 4,500rpm | 5psi | .010〞 |
| 3.500 | 3,800rpm | 5psi | .013〞 |
| 4.500 | 2,750rpm | 5psi | .017〞 |
Total eccentricity consists of two components, shaft runout and shaft-bore misalignment (shaft offset ).
The eccentricity is determined as follows：
〝V〞AND 〝K〞LIP DESIGN
The 〝V〞and 〝K〞type designs are low cost seals designed primarily for retention of grease or similar viscous fluids. The 〝V〞type is a single lip seal. The〝K〞type has an auxiliary lip for light dust exclusion.
| SHAFT DIAMETER | MAXIMUM SHAFT SPEED | MAXIMUM CONTINUOUS PRESSURE | MAXIMUM TOTAL ECCENTRICITY |
| General | 2,000rpm | 4psi | .005〞 |
| .500 | 4,000rpm | 4psi | .003〞 |
| 1.500 | 3,000rpm | 4psi | .005〞 |
| 2.500 | 2,300rpm | 4psi | .006〞 |
| 3.500 | 1,700rpm | 4psi | .008〞 |
| 4.500 | 1,400rpm | 4psi | .010〞 |
“WP” LIP DESIGN
THE “WP” design was developed as a dust wiper(scraper) for reciprocating applications such as hydraulic cylinder rods. As a result, the operating limits for the design are slightly different form “V”and “K” types. Maximum shaft motion is linear velocity of 200 ft./min. (1M/sec.). Maximum pressure capability is 4psi (.28kg/cm2 ). Stroke length should be limited to78 inches (1.98m). maximum. Eccentricity considerations involve only shaft-to-bore misalignment. Maximum allowable is ±.004 inch (0.1 mm).