Rotary Seal Design Guide - Seals Unlimited

ProTech Bearing IsolatorsCatalog EPS 5350/USAEngineeringDesign EngineeringThe important considerations in selecting abearing isolator are:• For best oil splash retention, avoid designs thatuse simple inboard oil grooves.• For long term performance, select a design thatdoes not rely on an internal seal such as anO-ring, V-ring or other internal component toachieve sealability.• For best contaminant exclusion, select a sealthat is purposely designed to control laminarflow.• Avoid designs that require special installationtools. The easier the seal is to install, the lesschance seal damage will occur duringinstallation.• Select a material that will not introduce harmfuldusting into the bearing cavity.Further Considerations• Determine what impact upgrading to a bearingisolator will have on the total cost of sealingbased on return on investment (ROI).• Standardize on a material that provides thebroadest chemical compatibility throughout yourfacility.• Avoid designs that are sold on features that arenot scientifically sound.• Select a manufacturer that has extensiveknowledge in the science of sealing and is anindustry leader in design innovation.• Ask the manufacturer for documented copies oftest results for IP55, IP56, IP66 and IP69k thathave been conducted by third parties (such asU.L.) in order to verify performance claims.Upgrading to Bearing IsolatorsThe cost of downtime in today’s manufacturingenvironment has been the primary driver behindthe decision of companies to convert keyequipment such as pumps, motors, gear boxesand split pillow block bearings from a standard lipseal to a bearing isolator type seal.While the initial cost of a lip seal is much lowerthan a bearing isolator, the total cost of the sealingsystem over the life of the equipment should beevaluated as part of the decision-making process.Bearing isolators are able to extend the Mean TimeBetween Failure (MTBF) because true non-contactisolators will never wear out as compared tostandard lip seals that have a typical life of 3,000to 5,000 hours. Bearing isolators permanentlyexclude contaminants, which means the seal isno longer the limiting factor for the bearingapproaching the L10 life rating stated by thebearing manufacturer. The primary cost savingsare a result of fewer rebuilds and less unplanneddowntime over the life of the equipment. Additionalsavings result from lower torque consumptionmeaning less energy consumption and lowermaintenance costs. Energy savings alone canoffset the costs of the upgrade.Once the decision has been made to upgradeto bearing isolators, the next step is to select abearing isolator design. The two basic designtypes are contact and non-contact. The contactdesign relies on an internal seal for excludingcontaminants while the non-contact design relieson labyrinth technology and provides zero wearingcomponents. ProTech Bearing Isolators are noncontact.The ProTech bearing isolator consists of twocomponents, a rotor and a stator.StatorAn external O-ring at theProTech stator OD maintainsa press fit in the seal housingand provides a static seal foroil retention. Because this isa static seal, it will not wearout over time.88ProTech Stator03/28/068-7 Parker Hannifin CorporationEPS DivisionToll Free: (800) 233-3900www.parkerseals.com