The Ultimate Guide to Choosing Hydraulic Oil Seal

We just discovered that one of the seals on our pumping system is leaking. Do you have any ideas as to what could have caused this, and can you offer some advice for selecting a good seal?

Link to CDI

The main causes of external lubricant leakage from pumping systems, hydraulic machines, gearcases and sumps are the wrong selection, improper application, poor installation and inadequate maintenance practices that are applied to sealing systems.

These problems can be overcome through a better understanding of the types of sealing materials available, redefined selection procedures and the consistent application of sound replacement and maintenance practices.

A number of variables must be considered when selecting oil seals. There are nine factors that designers and maintenance engineers must evaluate when oil seals are specified:

Shaft Speed

The maximum allowable shaft speed is a function of the shaft finish, runout, housing bore and shaft concentricity, type of fluid being sealed and the type of oil seal material.

Temperature

The temperature range of the mechanism in which the seal is installed must not exceed the temperature range of the seal elastomer.

Pressure

Most conventional oil seals are designed only to withstand very low-pressure applications (about 8 psi or less). If additional internal pressure is present or anticipated, pressure relief is necessary.

Shaft Hardness

Longer seal life can be expected with shafts having a Rockwell (RC) hardness of 30 or more. When exposed to abrasive contamination, the hardness should be increased to RC 60.

Shaft Surface Finish

Most effective sealing is obtained with optimum shaft surface finishes. The sealing efficiency is affected by the direction of the finish tool marks and the spiral lead. Best sealing results are obtained with polished or ground shafts with concentric (no spiral lead) finish marks. If you must use shafts with spiral finish leads, they should lead toward the fluid when the shaft rotates.

Are you interested in learning more about Hydraulic Oil Seal? Contact us today to secure an expert consultation!

Concentricity

When the bore and shaft centers are misaligned, seal life will be shortened because the wear will be concentrated on one side of the sealing lip.

Shaft and Bore Tolerances

The best seal performance is achieved when close shaft and bore tolerances are present. Other factors include shaft eccentricity, end play and vibration.

Runout

Runout must be kept to a minimum. Movement of the center of rotation is usually caused by bearing wobble or shaft whip. When coupled with misalignment, this problem is compounded. Contrary to popular belief and common practice, the installation of flexible couplings cannot correct or compensate for misalignment.

Lubricant

Seals perform much better and longer when they are continuously lubricated with an oil that has the correct viscosity for the application and that is compatible with the seal lip elastomer material. The consideration of seal incompatibility, particularly with certain additives and some synthetic lubricants, should not be ignored, but unfortunately very often is.

Hydraulic systems power critical functions across industries, relying on high-performance seals to ensure efficient, leak-free operation. Inadequate seal choices can lead to fluid leaks, pressure loss, and even equipment failure—resulting in costly downtime and repairs. In this guide, we’ll dive deeper into the essential considerations for hydraulic seal selection and explore advanced materials and design options for optimizing performance in demanding hydraulic applications.

Why Effective Sealing Is Vital in Hydraulic Systems

Hydraulic seals are essential not only for containing fluid but also for maintaining system pressure, reducing internal wear, and extending component life. Seals that can withstand pressure changes, handle extreme temperatures, and resist chemical degradation are crucial in environments where reliability and safety are paramount. Even a minor seal failure can lead to contamination, pressure drops, and component wear, so precision in seal selection is critical.

Choosing the right seal for hydraulic systems is essential to keeping equipment efficient, safe, and leak-free under pressure. By carefully evaluating pressure, temperature, fluid compatibility, and wear factors, engineers can maximize the lifespan of hydraulic seals and reduce the risk of equipment failure. With Advanced EMC Technologies, you have access to custom-engineered sealing solutions designed for your unique hydraulic applications.

If you’re looking for guidance on selecting or designing a hydraulic seal solution, contact our team at Advanced EMC Technologies today. Our experts are ready to support you in achieving peak performance for your hydraulic systems.

If you’re looking to improve the reliability and longevity of your high-pressure sealing systems, contact us today to learn more about how our metal C-rings can solve your most demanding sealing challenges. Our experts are ready to help you choose the perfect sealing solution for your specific needs.

Contact us to discuss your requirements of Automotive Oil Seal. Our experienced sales team can help you identify the options that best suit your needs.