Construction and design of the N23 oil seal
From a construction standpoint, the oil seal N23 belongs to the category of high-pressure radial lip seals (often referred to as BAHD type). The seal consists of one primary sealing lip that is constantly pressed against the shaft by a garter spring. This lip is designed to be shorter and stiffer than the one that’s used on standard oil seals, preventing it from folding back or deforming under pressure.
The metal reinforcement ring and spring are standard made of stainless steel, which increases stability and prevents corrosion. The outer diameter is fully elastomer coated, which allows the seal to adapt to the housing and form a reliable static seal. This smooth elastomer outer diameter provides consistent contact with the housing and improves static sealing reliability.
Unlike the TCN oil seals, the oil seal N23 does not have a dust lip. This reduces friction and heat generation, which is better at higher rotational speeds or when the focus is on pressure sealing instead of dirt exclusion.
Typical applications and why the N23 is suitable
The N23 oil seal is mainly used in applications where rotating shafts are combined with internal pressure. It is particularly well suited for twist and press applications, where pressure and rotational movement occur simultaneously. Common applications include hydraulic pumps and motors, industrial drives, compressors, vacuum pumps, and gearboxes in which pressure can build up due to heating or internal flow.
The oil seal N23 also performs well in machines with light-metal housings (like aluminum). The elastomer coated outer diameter compensates for thermal expansion and small imperfections in the bore, preventing leakage during temperature changes. This makes the N23 rotary shaft seal a reliable choice for housings with increased surface roughness compared to metal-cased oil seals. The N23 oil seal is also suitable for shared enclosures, where multiple components operate within the same housing and sealing tolerances are more challenging.
In addition, the N23 is suitable for applications involving low-viscosity media or gas-like mixtures, where standard oil seals often struggle to maintain a reliable seal. The reinforced lip design ensures that the sealing pressure remains stable, even when the medium pressure changes.
Material selection: strengths and limitations
The oil seal N23 is available in various material combinations, with the choice strongly depending on temperature, medium, and expected service life.
NBR (Nitrile Rubber)
NBR is the most common used version. The material has a good balance between wear resistance, elasticity, and cost.
• Strengths: mineral oils, greases, standard hydraulic applications
• Temperature range: approximately -40 °C to +100 °C
• Limitation: less suitable for high temperatures or aggressive chemicals
FKM (Viton®)
FKM is selected when the application places higher demands on temperature or chemical resistance.
• Strengths: high temperatures, synthetic oils, fuels
• Temperature range: up to approximately +200 °C
• Limitation: higher cost, less flexible at low temperatures
The metal components (spring and reinforcement ring) are typically made of stainless steel (material 1.4301), making the seal suitable for humid or mildly corrosive environments.
Materials for N23 oil seals
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Material
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Temperature range
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Key properties
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NBR (Nitrile rubber)
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approx. -40 °C to +100 °C
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Good wear resistance, flexible, suitable for mineral oils and greases, cost-effective
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FKM (Viton®)
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approx. -20 °C to +200 °C
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Excellent heat and chemical resistance, suitable for synthetic oils and fuels, longer service life at high temperature
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Stainless steel spring & reinforcement ring
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n/a
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Corrosion-resistant, stable spring load, suitable for humid or mildly aggressive environments
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Comparison with similar oil seals
In practice, the rotary shaft seal N23 is often compared with other common oil seal types.
Compared with an SC oil seal (single lip, low pressure), the N23 oil seal offers significantly higher pressure resistance. While an SC oil seal is mainly suitable for lubricant retention without pressure, the oil seal N23 is explicitly designed for pressure-loaded applications.
Compared with a TC oil seal, the N23 type lacks a dust lip. This makes it less suitable for extremely contaminated environments, but better suited for higher speeds and pressure, with lower friction.
Compared with a TCN / N21 oil seal (high pressure with dust lip), the N23 is the simpler design. The N21 provides additional protection against contamination, whereas the N23 oil seal is chosen when pressure sealing is the priority and the environment is relatively clean.
Selecting the right N23 oil seal: dimensions, material, and standards
When selecting the correct N23 oil seal, dimensions, material, and operating conditions are decisive.
For reliable sealing, the shaft has to match ISO h11 tolerances and have sufficient surface hardness (preferably ≥45 HRC). The ideal shaft surface roughness lies between Ra 0.2 and 0.8 µm to prevent wear and leakage. In addition, the shaft surface should be torsion-free to prevent pumping effects and premature leakage.
The housing bore is typically manufactured according to ISO H8, with the rubber-coated outer diameter compensating for minor deviations. Typical housing surface requirements are Ra 1.6–6.3 µm, Rz 10–20 µm, with a maximum roughness depth of Rmax ≤ 25 µm. The choice of material (NBR or FKM) is determined by temperature, medium, and required service life.
It is important to understand that the rotational speed and diameter determines the pressure that the N23 oil seal can take. As speed and diameter increases, the allowable pressure decreases. You have to take this into account when selecting the right oil seal N23
If you would like more information about this oil-seal or you don't know what size or material you should have, please feel free to contact us.
FAQ
Yes, the N23 oil seal is designed for pressure-loaded applications and can withstand significantly higher pressure than standard oil seals, depending on size and speed.
No, the N23 rotor seal has a single sealing lip and no separate dust lip. This reduces friction but offers less protection against external contamination.
NBR is suitable for standard oil and grease applications up to approximately 100 °C. FKM is chosen for higher temperatures or aggressive media.
Yes, the rubber-coated outer diameter makes the oil seal N23 very suitable for aluminum or other light-metal housings.
A shaft that is too rough or damaged will almost always lead to leakage or rapid wear, even with a high-pressure oil seal such as the N23
