Oil Seal PA31 - Rotary Shaft Seal

Construction and operation of the PA31 oil seal

Applications and suitability

The PA31 oil seal is mainly used in industrial environments where reliability under demanding conditions is essential. In the chemical industry, this type of seal is applied because of its excellent resistance to aggressive media and high temperatures. Within machine and equipment construction, for example in pumps, mixers, and compressors, the oil seal PA31 also provides a durable sealing solution at high speeds and under fluctuating loads.

In addition, the PA31 rotary shaft seal is widely used in drive technology, such as gearboxes and industrial drives where low friction, minimal wear, and long service life are important. The combination of pressure resistance, thermal stability, and chemical resistance makes this oil seal particularly suitable for applications in which conventional sealing solutions prove insufficiently reliable.

Material selection and performance

The PA31 oil seal is available in various material combinations, allowing it to be adapted to specific operating conditions. In the standard version, the sealing lip is made of PTFE filled with glass fiber and MoS₂. This composition provides a good balance between wear resistance, dimensional stability, and low friction. The housing is usually made of corrosion- and acid-resistant steel (1.4404 / AISI 316L), ensuring high corrosion resistance in aggressive environments. The elastomer disc is typically made of FKM, due to its good temperature resistance and chemical stability. The oil seal PA31 is compatible with mineral oil-based lubricants, synthetic lubricants, water, and a wide range of acids, alkalis, and solvents.

For specific applications, alternative material combinations are available. For example, a PTFE sealing lip with carbon-graphite can be selected when extremely high temperatures or prolonged dry running are involved. In less aggressive environments, a standard steel housing can be a cost-effective alternative to stainless steel. Other elastomers for the energizer are also available on request, for example when specific media or temperature ranges are required. When selecting materials, it is important to always consider temperature, pressure, circumferential speed, and medium in combination.

The permissible maximum values must always be evaluated in relation to all operating parameters, as the total load on the seal results from the combined conditions.

Material Table

Selecting the correct PA31 oil seal

Selecting the correct PA31 oil seal starts with determining the correct shaft and housing dimensions. The shaft must comply with ISO h11 tolerances and have a minimum hardness of 50 HRC, combined with a very fine and torsion-free surface finish. This is essential to limit wear of the PTFE lip and to ensure stable sealing performance. Compliance with the specified surface roughness values is critical to prevent premature wear of the PTFE sealing lip and to ensure stable sealing performance. The housing must be manufactured according to ISO H8 tolerances and have a suitable surface roughness to achieve a reliable press fit.

In addition to dimensions, operating conditions also play an important role. Temperature, pressure, circumferential speed, and the medium to be sealed largely determine which material combination is most suitable. Because the oil seal PA31 is produced independently of molds, special sizes and small series are also possible without high tooling costs, providing flexibility for specific applications.

FAQ