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Understanding seal designations: Part one

Your guide to radial shaft seal designations

The SKF Industrial Shaft Seals catalogue uses codes, not descriptions, for each specific seal design. But this seal designation does give you a full description – if you can understand it. Read this short guide for the insight you need to do just that.

There is a combination, somewhere in the Industrial Shaft Seals catalogue, of letters and numbers that describes the sealing solution your unique applications need. Deciphering it is the key to proper seal selection, can help alleviate unplanned downtime, and ensure a smooth and long operation.

This handy guide can facilitate your reading of the SKF catalogue – so read on to learn about seal designations and exactly what each part of the code signifies.

Inch-size radial shaft seals: Identified by item numbers

For SKF shaft seals (CR Seals), the designation describes all the data required to identify its main characteristics. The style of designation differs between metric radial shaft seals and inch-size radial shaft seals, with inch-size seals being identified by their stock number – which in term is determined by the size of the seal. The larger the diameter of the seal, the longer the number: four digits are used for diameters less than or equal to 1 inch; five digits for less than or equal to ten inches; and six or seven digits for more than or equal to ten inches.

Metric radial shaft seals: Sizes, design, material

For metric radial shaft seals, designation contains more elements. Shaft diameter, housing bore diameter, and nominal seal width (or bore depth for HFS, HSS, and HS seals) constitute the first component of the designation. They are represented numerically (e.g., 55 x 72 x 8), followed directly by the design specification and the material code for the sealing lip.

The design required for an application varies, naturally, and the multiple design types are identified by a series of letters and/or number. When it comes to the material code, the designation is simple: RG or R for nitrile rubber (NBR), V for fluoro rubber (FKM), and T for polytetrafluoroethylene (PTFE). Additional details – such as whether the auxiliary lip is contacting or non-contacting – can also be found and thus used to make the correct decisions. In the end, all of that information will appear like this:

6×16×5 HMSA10 RG

And if the seal – with the same size and design – differs from the original execution, this will be indicated by a number (1, 2…). For example:

6×16×5 HMSA10 RG2

The designation system, as pictured above, is taken from our catalogue “Industrial shaft seals”. Here you find yet more detail on designations! Moreover, if you wanted search our seal product tables, click here. Finally, for more specific CR seal setups, simply enter your search criteria at: www.skfextranet.com/crsealsfinder.