Seal-counterface kinematics · documented inputs
Documented Seal-Counterface Surface-Speed Worksheet
Calculate circumferential speed from the actual counterface diameter and rotational speed, while preserving the supplier, application and review record needed for a separate seal-selection decision.
Reference kinematic results
Equations and dimensional check
For actual counterface diameter d in metres and rotational frequency f in revolutions per second:
surface speed v = Cf = πdf
f = n/60, when n is in r/min
angular speed ω = 2πf
Therefore, for d in millimetres and n in r/min:
This is a geometry-and-time identity, not an “ISO 6194 formula.” Metres per revolution multiplied by revolutions per second gives metres per second. Exact conversions used are 1 in = 25.4 mm and 1 m/s = 196.8503937007874 ft/min.
Model boundary and removed unsafe logic
- No nearest-size substitution. The former page silently replaced an entered non-table shaft diameter with the next stored diameter (or the largest stored size), then calculated speed using that different diameter. This worksheet always uses the actual entered counterface diameter.
- No invented preferred-size table. ISO 6194-1 covers nominal dimensions and tolerances for its scope, but an exact permissible part must be verified from the controlled standard and manufacturer product data. Exact tables and tolerances remain
NEEDS_LICENSED_SOURCE. - No universal material rule. NBR, FKM, PTFE or EPDM cannot be selected safely from medium name and bulk temperature alone. Compound, concentration, lip temperature, pressure, lubrication, design, counterface and supplier qualification matter.
- No fixed universal speed limit. SKF states that acceptable speed depends on seal design and lip material, shaft material and condition, lubrication and lubricant; its comparison diagram also assumes normal operation and no pressure differential. Use the limit for the exact product and application.
- No pressure, finish or hardness verdict. Those requirements are not calculated here. Use the controlled drawing, selected manufacturer data, applicable standard clauses, uncertainty and engineering review.
- No conformance decision. ISO 6194 parts address different subjects including dimensions/tolerances, vocabulary, handling/installation, testing and visual imperfections. A surface-speed calculation alone does not prove conformity with any part.
Source traceability
| Claim | Klasifikacija | Evidence |
|---|---|---|
| v = πdn/60,000 for d in mm and n in r/min | General geometric identity; not an ISO formula | Derived above; independently equivalent to SKF CR Seals Handbook metric conversion d × r/min ÷ 19,100 (rounded denominator) |
| Acceptable seal speed depends on design/material, shaft condition, lubrication/lubricant and operating assumptions | Manufacturer application guidance | SKF CR Seals Handbook, Engineering — Special considerations, p. 42 |
| Nominal dimensions/tolerances for seals, shafts and housings; elastomeric elements and low-pressure scope | Current standard scope/status only; exact values not reproduced | ISO 6194-1:2007, Edition 2, published and confirmed in 2023 |
| Vocabulary for elastomeric sealing elements and low-pressure scope | Current standard scope/status only | ISO 6194-2:2009, Edition 2, published and confirmed in 2025 |
| Storage, handling and installation requirements/guidance | Current standard scope/status only | ISO 6194-3:2009, Edition 2, published and confirmed in 2025 |
| General test requirements that may be used for qualification | Current standard scope/status only | ISO 6194-4:2009, Edition 3, published; under systematic review in 2026 |
| Identification/classification of visual imperfections | Current standard scope/status only | ISO 6194-5:2008, Edition 2, published and confirmed in 2022 |
| Proposed material-properties work | Working draft; not a normative source | ISO/WD 6194-6, under development as of 2026 |
| 1 in = 25.4 mm exactly | Exact SI conversion | NIST SP 811, Appendix B.8 |
Accessed: 15 July 2026. Public sources establish the displayed scopes/status and kinematic conversion. They do not establish an allowable value or select a seal for the recorded application. Worksheet URL: https://vibromera.eu/calculators/shaft-seal-selection/
Reference example
For an actual 40 mm counterface at 1,500 r/min: f = 25 Hz, circumference = 125.663706 mm, v = π m/s ≈ 3.141592654 m/s, ω = 50π rad/s ≈ 157.0796327 rad/s, and one-hour sliding distance = 11.30973355 km. This checks the implementation; it is not a seal-speed limit.
Questions
Why does the worksheet no longer recommend a seal size?
A lip seal is not interchangeable merely because a stored diameter is close. Shaft diameter, housing bore, width, tolerances, exact product design and application conditions must match controlled data. The previous nearest-size substitution could recommend a seal for a different shaft.
Can surface speed select NBR, FKM, PTFE or EPDM?
No. Surface speed is one input. Compound-specific chemical compatibility, actual lip temperature, pressure, lubrication, shaft condition, design and supplier qualification must also be checked.
Does a result below a catalogue diagram guarantee suitability?
No. Manufacturer diagrams have stated assumptions and may require reductions or product-specific checks. Use the exact product record, not a generic comparison alone.
Is this calculation ISO 6194 compliant?
The calculation is a general kinematic identity. It does not test the requirements of ISO 6194 or produce a conformance decision. Exact clauses, dimensional tables and tolerances are NEEDS_LICENSED_SOURCE unless a controlled document is supplied.
