![]() ![]() Bearing isolators provide several benefits, including long service life and a noncontact seal configuration that will not damage shaft surfaces.Ĭontact lip oil seals are a simple solution to retain lubrication in rotating machinery. There are several reasons why a bearing isolator would be selected as an OEM option or as a retrofit in existing equipment. In many instances, bearing isolators can fit in the same space as an oil seal without requiring modifications to the geometry of the seal location. This design prevents ingress of contaminants into a bearing arrangement. ![]() The assembly of these components creates a narrow labyrinth path through the seal. In simple terms, a bearing isolator consists of a stationary component (stator) and a rotary component (rotor). Benefits of Bearing Isolatorsīearing isolator labyrinth seals are used to protect the bearings and bearing lubrication in rotating equipment-such as electric motors, gearboxes, pumps and split pillow block bearings. In a time when facility managers are focused on maintaining costs and limiting production losses due to downtime or unplanned outages is critical, bearing isolator labyrinth seals offer several benefits. Bearing isolators can provide improved reliability and protection of the bearing and extend the mean time between failure (MTBF) of equipment. Manufacturers, repair facilities and users often select bearing isolators for use in harsh applications where conditions such as contamination, shaft misalignments and equipment vibrations are a concern to avoid frequent replacement. Moisture is also a very serious contaminant.While the use of oil seals to retain lubrication in rotating machinery is common, bearing isolator labyrinth seal technology is often selected to protect bearings and lubrication. Reasons why the housing may be opened would include changing the lubricant, replacing any components including bearings or simply inspecting the components. Any time the bearing housing is opened for any reason, care should be taken to prevent ingress of contaminants. Keeping contaminant out of the housing during operation is only part of the challenge. Some friction is created but heat generation should be less than a lip seal but more than an isolator seal. While there is contact between the face seal surfaces, seal life is still substantially longer than that of lip seals. These seals can prevent ingress of contaminant (including water wash down) as well as retain lubricant. The magnetic force compresses and aligns the mating surfaces so the seal is perfectly adjusted for life. ![]() Similar to the isolator type seal, one of those face seal surfaces is part of a rotor driven by the shaft and the other is part of a stationary body attached to the housing. These seals use magnets to provide the force necessary to keep precision lapped face seal surfaces in contact. Magnetically charged face seals may also be a viable option to seal bearing housings. If needed, the seal can be optimized to the environment and types of contamination to which the isolator seal may be exposed. Other materials can be utilized including PTFE, stainless steel and aluminum. These designs are typically more expensive than a lip type seal but there is no wear and no heat generation making them a long term investment rather than a wear part.īearing isolators can be manufactured from various materials. Since there is no contact in this seal when it is operating, no friction is created and no heat is transferred to the bearing. Another benefit is that when the o-ring is expanded, the housing can breath and allow warm air to exit. When the shaft rotates the o-ring then expands dynamically eliminating friction between the o-ring and the seal components. Often, the seal may integrate an o-ring that prevents ingress of moist air when the shaft is static. Lubricant is also prevented from exiting the housing keeping leakage to a minimum. Additionally there are typically ports at the bottom of the seal to allow any contamination that has entered the labyrinth to then exit through these ports. The axial or face labyrinth created by the nesting of the rotor and stator makes it extremely difficult for any type of contamination to pass through the seal. This is an excerpt from a paper," Bearing Maintenance Practices to Ensure Maximum Bearing Life" presented by Brian Dahmer of SKF USA at the 2013 International Pump Users Association. The rotor provides a flinger effect throwing contaminants off of the seal when it is rotating. Using nomenclature similar to that of motors, the rotating element is typically referred to as the rotor and the stationary element is typically called the stator. Labyrinth seals may come in a variety of forms but certainly some of the more common and effective are cartridge type labyrinth seals (often referred to as isolator type seals) that include a rotating element that is mounted on the shaft and a stationary element in the housing. ![]()
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