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Domsel oil seals are radial shaft seals for rotating shafts that keep oil, grease, air, or other media inside, or keep them out. Unlike many “classic” oil seals with a garter spring, Domsel uses an optimized lip geometry and an internal reinforcing ring, so the seal remains stable with relatively low friction. In practice, this means less heat build-up, less shaft wear, and often a longer service life, especially in applications where a standard oil seal runs hot, wears faster, or is sensitive to (slight) overpressure and varying operating conditions. Within the Domsel range there are multiple type variants, including compact SF versions and double-lip types for heavier or more complex sealing requirements.
The material choice for the sealing lip mainly depends on the medium, temperature, speed, and any cleaning/CIP chemistry. NBR is the most common choice for oil and grease at normal temperatures and offers a strong price-to-performance ratio, but it ages faster at consistently high temperatures or with more aggressive chemicals. HNBR provides extra mechanical strength and better temperature resistance than NBR, making it interesting for higher loads or longer service intervals. You choose FKM (Viton) when temperature and chemical exposure become more demanding; it remains stable at higher temperatures and with many oils/fuels, but is generally more expensive and not always ideal with (hot) steam or certain strongly alkaline media, depending on the compound. EPDM is well suited to hot water, steam, and cleaning agents, but is unsuitable in oil/grease environments. VMQ (silicone) performs well at low temperatures and is inert, but is mechanically less robust under high load. FFKM is the option for extreme chemicals and heat when FKM falls short, but you only make that choice when it is truly necessary. Besides the lip, the execution can also be relevant: in corrosive or hygienic environments, a stainless-steel (metal parts) version can be more logical than zinc-plated steel.
|
Material |
Temperature range (indicative) |
Key properties |
|
NBR |
−20 to +100 °C |
Strong in oil/grease, all-round industrial, cost-effective; less margin at high temperature/chemical exposure |
|
HNBR |
−30 to +140 °C |
More wear-resistant and mechanically stronger than NBR; better temperature margin for heavier duty |
|
FKM (Viton) |
−30 to +200 °C |
Strong at high temperature and broad chemical exposure (e.g., oils/fuels); higher cost, attention with steam/strongly alkaline media (compound-dependent) |
|
EPDM |
−40 to +150 °C |
Excellent with (hot) water, steam, and cleaning agents; not suitable for oil/grease |
|
VMQ (silicone) |
−60 to +200 °C |
Very good at low temperature and inert; lower mechanical strength, more vulnerable under high load |
|
FFKM |
−10 to +250 °C (and higher, type-dependent) |
Maximum chemical and thermal resistance; very expensive, only for extreme requirements |
You mainly see Domsel oil seals in applications where friction, heat, and shaft wear are the limiting factors, or where a standard oil seal no longer sits comfortably in its operating window. Think pumps and compressors, drives and gearboxes, spindles and other high-speed rotating shafts, or machines with frequent start/stop operation where a lip more often has brief “dry” contact. The double-lip variants are often chosen when you want extra protection against contamination, when you want to create a lubrication/grease chamber, or when you want to keep two media better separated. The SF variants (A-SF and B-SF) come into play when installation space is limited, or when you want a more compact seal without immediately switching to a completely different sealing principle.
Within a single category page, it helps a lot to briefly describe the types so visitors immediately understand which side seals and why there are multiple variants. Type A and type B are the basics: both have one sealing lip, but with a different orientation (which side the medium is on often determines your choice). Type AB and BC are the heavier double-lip versions where both lips work in the same direction; this provides extra sealing margin and can create a grease chamber, which is particularly interesting for gas, pressure, limited lubrication, or when you want a more robust seal. Type AC is the double-lip version with lips in opposite directions and becomes relevant when you want to seal both sides or when you want to keep two media separated.
The A-SF and B-SF variants are more compact versions for situations with tight installation space. The “SF” design is typically intended to require less axial space, while still maintaining a reliable lip seal. In practice, you choose A-SF or B-SF when a standard A or B does not fit in terms of build height, or when you want a compact upgrade for higher speeds or challenging installation conditions, without moving straight to a cartridge seal or a PTFE-lip solution.
Selection always starts with the dimensions: shaft diameter (d1), bore diameter (D), and installation width (b). Then you determine the sealing direction: is the medium on the installation side or on the outside, and do you mainly want to keep it in or keep it out? That often leads you to A or B as the base choice, and to AB/BC if you want extra margin or if pressure/operation is demanding. If you need to seal both sides or keep media separated, AC is more logical. If installation space is limited or you want a more compact version, you end up with A-SF or B-SF.
Next, you check the operating conditions: temperature (continuous and peak), speed/peripheral speed, lubrication (sufficient oil film or more “dry” starting), and any (slight to moderate) pressure load. If pressure plays a role, installation quality becomes more important: a clean bore with the correct fit, a proper lead-in chamfer, minimal eccentricity/runout, and a shaft surface without burrs or grooves ensure the lip seals stably and does not wear prematurely. Finally, you choose the material based on the medium and cleaning: NBR for oil/grease at normal temperatures, HNBR for extra mechanical and temperature margin, FKM for higher temperatures and more aggressive media, EPDM for hot water/steam, and VMQ for low-temperature applications; you keep FFKM in reserve for extreme chemicals and heat.
Domsel Oil Seals offer exceptional sealing performance, heat management, and versatility across various applications. With their robust construction, temperature resistance, and different types to suit specific sealing needs, these seals provide reliable and long-lasting solutions for ensuring the efficient operation of moving machine parts. Trust in Domsel Oil Seals to enhance the performance and reliability of your machinery.
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Both are single-lip oil seals, but the lip orientation differs. You choose based on where the medium is and which side you want to seal (keeping in vs keeping out).
If installation space is limited or you want a more compact seal, the SF variants are logical. You keep the Domsel sealing principle, but in a design that fits more easily in tight housings.
AC has two lips that work in opposite directions. This is useful when you want to seal on both sides or when you want to keep two media better separated around a single shaft passage.
For oil/grease at normal temperatures, NBR is usually the safe start. If temperature or chemical exposure becomes more demanding, FKM is often the logical upgrade. For hot water/steam, EPDM is usually more suitable than FKM.
