Oil Seal N23 - Rotary Shaft Seal

Construction and design of the N23 oil seal

Typical applications and why the N23 is suitable

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

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

FAQ