These seals combine elements of contact and non-contact seals (see Fig. Example of a shaft-slinger seal that combines contact (1) and non-contact seal types Special long-relief isolators are used in sleeve-bearing applications to accommodate the bearing’s axial end float.įig. This prevents vapor ingress while the machine is off and eliminates friction/heat when it’s running. Labyrinth-design isolators: Another variation of the bearing isolator has a labyrinth design and an O-ring or other elastomer element that keeps the labyrinth channel closed when the shaft is stopped and expands by centrifugal force to open the channel when the shaft is rotating. Although contacting isolators stop all solid and vapor contamination, they have surface-speed limitations-a maximum of about a 4″ (100 mm) shaft at 3600 rpm. 4) uses rare-earth magnets to apply tension to lapped contacting faces, just like a mechanical pump seal. A newer version called a contacting isolator (Fig. Contacting-type bearing isolator ( courtesy of Isomag)Ĭontacting isolators: The first bearing isolators were non-contact labyrinth seals that greatly reduced contamination ingress but didn’t stop moisture or other vapors. Although bearing isolators are more costly and require more physical space than contact or non-contact seals, they deliver more effective sealing.įig. They also can be used with either grease or oil lubrication, and with sleeve or rolling bearings. Such seals afford more protection than individual contact or non-contact seals. 3), but use the contact features to “drive” part of the seal at the shaft’s rotating speed. Example of a combination contact and non-contact bearing isolator sealīearing isolator seals: Bearing isolators combine the characteristics of contact and non-contact seals in a single unit (Fig. Unfortunately, non-contact seals also allow lubricant to leak out of the bearing chamber and liquid, and permit physically small contaminants to enter.įig. 2) produces much less friction (if any) and heating than a contact type. Non-contact seals: A non-contact seal (Fig. Example of a non-contact seal used for a ball bearing If a less effective sealing method is acceptable, an alternative is a non-contact seal.įig. These seals make it difficult for fluids or solids particles to penetrate the sealed area, but direct contact with the shaft creates friction and heat that can degrade the seal and damage the shaft’s surface finish. 1) forms an effective sealed interface by applying continuous pressure to the surface with a resilient material. The contact-grease-seal arrangement on the left is better for protecting against dust and liquids entering bearing chamber the arrangement on the right is better for retaining lubricant in the bearing chamber.Ĭontact seals: A contact seal (Fig. The labyrinth seal is a non-contacting type normally used with sleeve bearings.įig. The types of seals most commonly used with rolling (ball and roller) bearings are contact or lip seals non-contact seals and, to a lesser degree, various types of bearing isolators that combine the functions of contact and non-contact seals in different ways. To select the appropriate seal for an application, match the relevant factors from the above list with the characteristics of the following external seal types. Key factors in making the right choice for an application typically include: The focus here is on what to consider when selecting external bearing seals. Custom designs are available for higher speeds, axial movement and high misalignment (STBM) conditions.Some seals are integral to the bearing others aren’t.Pillow block design meets OEM specifications IEEE-841 to provide premium bearing protection on severe-duty electric motors Standard profiles are available to meet specific design requirement andĪnd multiple expulsion (drain) ports when directional installation is a concern Some cases, the energy savings alone offsets upgrade costs. Lower torque consumption which results in.With a bearing isolator solution, the seal is no longer the limiting factor for the bearings reaching the basic life rating stated by bearing manufacturers (L 10 rating). With true non-contact ProTech designs there is nothing to wear out thereby extending mean time between failure (MTBF). Manufacturing environment has been the primary driver behind companies’ decisions to convertįrom standard lip seals to bearing isolator-type seals. Utilize labyrinth technology for complete lubricant retention and contaminantĮxclusion, thereby extending bearing life - withīearing isolators are an upgrade from standard lip seals, however when one considers the total cost of the sealing system over the total life span, it is well worth it for key equipment such as p umps, m otors, g ear boxes, and split pillow blocks. The permanently assembled rotor and stator
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