Domsel Seal B-SF

Design and construction of the Domsel B-SF oil seal

What makes the B-SF oil seal unique is its construction without a garter spring. Instead, a robust metal case provides sufficient pressure on the sealing lip, allowing the seal to perform optimally even without a spring. The lip itself is made of high-quality elastomer and is supported by the metal casing. Thanks to this construction, there is approximately 50-65% less friction than with traditional oil seals. This reduces heat build-up and increases the service life of both the seal and the shaft. The seal also has a symmetrical design, which means it can be installed in both directions, useful for applications with limited space or difficult accessibility. A small integrated lubricant reservoir near the sealing lip contributes to long-term lubrication and improves performance when lubricant supply is limited.

Applications: where does the B-SF perform best?

The Domsel B-SF oil seal is widely used in machine building, hydraulics, pneumatics, drive technology, transport, chemistry, and food production. In all of these sectors, there is a need for reliable sealing of rotating shafts against liquids, greases, gases, or vapors. The high pressure resistance (up to 15 bar), compact size, and low coefficient of friction make the B-SF particularly suitable for high rotational speeds, tight installation spaces, and dynamically loaded shafts. Think of spindles, pumps, compressors, fans, or motor shafts. The seal also performs excellently in environments with extreme temperatures or chemically aggressive media, provided the right material is selected.

Materials and their properties: which elastomer do you choose?

The sealing lip of the Domsel B-SF is available in several elastomers, each with specific strengths and limitations. NBR (nitrile rubber) is the standard choice for applications with mineral oils and greases, water, and mild chemicals. The temperature range is approximately between -30°C and +100°C. This material is cost-effective and wear-resistant, but less suitable for high temperatures, ozone exposure, or aggressive chemicals. HNBR (hydrogenated nitrile rubber) is often selected when you want the oil resistance of NBR, but with improved heat resistance, better mechanical strength, and higher resistance to ozone and aging. This makes HNBR a strong option for more demanding industrial drives, compressors, and automotive-style environments. EPDM is a different category: it performs very well with hot water, steam (application-dependent), glycol-based fluids, and many polar media, and it has excellent resistance to weathering and ozone. However, EPDM is generally not suitable for mineral oils, fuels, or hydrocarbon-based lubricants, so it should only be chosen when the medium matches EPDM’s strengths. FKM (Viton®) is suitable for higher temperatures up to approximately +200°C and is resistant to fuels, solvents, oils, acids, and vapors. This makes it ideal for use in the chemical sector, automotive industry, and high-temperature environments, although it is less flexible at low temperatures. FFKM (perfluoroelastomer) is extremely chemically resistant and temperature-resistant up to +300°C. It is mainly used in critical applications such as the pharmaceutical and chemical industries, but it is significantly more expensive than other materials. Silicone (VMQ) performs well at very low temperatures down to approximately -60°C and is suitable for use in the food industry due to FDA approval. However, the material is less wear-resistant and is not resistant to steam or oil. The choice of material strongly depends on the chemical, thermal, and mechanical load within the application. It is recommended to always analyze the medium, operating temperature, rotational speed, and environment carefully.

Material properties overview

How do you choose the right size and material?

When selecting a Domsel B-SF oil seal, you must pay attention to both the dimensions and the material. The size is determined by the shaft diameter (d1), the outer diameter of the bore (d2), and the installation height (b1). These dimensions should align with common tolerances according to ISO standards or DIN 3760. For proper sealing, the correct fit is essential: typically H9/h8 for the shaft and H8 for the bore. The correct lip direction (pressure side) must also be determined, although the B-SF can be installed in both directions. Regarding material selection, it is important to first identify the medium (oil, gas, water, chemicals), followed by the operating temperature, rotational speed, and any pressure involved. For standard industrial applications, NBR is often sufficient, but for higher demands, FKM or even FFKM is recommended. In hygienic environments such as the food or pharmaceutical industry, an FDA-compliant version is often required, preferably combined with a stainless-steel housing.

In summary, the Domsel Seal B-SF is a reliable sealing solution designed to meet the needs of rotating machinery in the machine building industry. With its reduced frictional moment, impressive pressure and temperature resistance, exceptional chemical resistance, and bidirectional press-in capability, the Domsel Seal B-SF offers reliable and efficient sealing performance in tight installation conditions. Choose the Domsel Seal B-SF for your sealing needs and experience the benefits of a high-quality sealing solution in your rotating machinery.

If you want more information, or do you have any questions, feel free to contact us.

Frequently asked questions (FAQ)