Bearing Isolator Measurement Video

This video is intended to illustrate how to measure common applications, such as pumps, motors and gearboxes, for an Inpro/Seal Bearing Isolator. For measurement guidance on more complex applications such as pillow blocks, steam turbines or sleeve bearing motors, contact your local Inpro/Seal Representative. As always, make sure to wear proper PPE and follow the appropriate safety procedures when measuring your equipment and never measure rotating equipment while it is running.

For demonstration purposes, we are using a sample generic housing featuring elements common to many applications. Before measuring, please have an Inpro/Seal Bearing Isolator Request For Quote, or RFQ, sheet available. You can download and print Inpro/Seal RFQ sheets from our website or you can use our electronic sheet, both of which can be found at The RFQ sheet provides a guide for the required measurements and a place to record your dimensions. Most equipment can be measured with a dial caliper or a micrometer. Verify that your measurement equipment is properly calibrated.

The first, and most important measurement required for any application is the shaft diameter. This is where the Bearing Isolator will sit. Carefully measure the diameter of the shaft and record the dimension on your Bearing Isolator RFQ sheet.

Next, measure the distance between the housing face and first outward obstruction. This provides our engineering team with the maximum allowable protrusion from the bearing housing. Quite often, the first outward obstruction is a step in the shaft, as it is here, a keyway or a coupling. If the first outward obstruction is a step in the shaft that is close to the housing face, we can normally accommodate that with a stepped Bearing Isolator design. When measuring a step in the shaft, make sure to include the distance from the housing face to the start of the step, any fillet radius if present and the shaft diameter after the step.

On many common applications, like pumps, motors and gearboxes, the end cover can be removed. If possible, we recommend doing so to easily obtain the remaining required dimensions.

Now we are going to measure the housing bore. This is where the Bearing Isolator will be pressed in. We recommend measuring the housing bore in multiple locations to verify roundness, making sure it is not egged shaped or worn. Inpro/Seal Bearing Isolators normally use an interference or press fit, so if your housing bore is not round, it may require modification.

Measure the housing thickness. This is important to ensure proper positioning of the O-ring on the OD of the Bearing Isolator.

Next, measure the distance of the housing face to the first inward obstruction. This measurement is critical to understanding how far the Bearing Isolator may insert into the bearing housing and allow sufficient space to provide a lubricant return path to the bearing sump in oil lubricated applications. Quite often a counter bore where a lip seal was pressed against it is present in the housing, as in this case. Depending on the available axial space this may need to be altered or removed to create room for the Bearing Isolator and to facilitate proper lubricant return to the sump. If no counter bore is present, as we are showing here, the first inward obstruction is typically the bearing, a lock nut on the bearing or even a vibration or speed monitor.

Lastly, if your application is oil lubricated, measure the distance of the oil level from the center shaft line. Typically, the oil should be positioned at the center line of the ball at the bottom position of the housing. If the oil level is above the bottom of the shaft, this would be considered a flooded condition and may require a specific or alternate seal design.

Measuring common applications for an Inpro/Seal Bearing Isolator is fairly straight forward. Use the Bearing Isolator RFQ sheet to verify recording all required dimensions. Once all dimensions have been recorded, answer the application detail questions on the bottom half of the sheet as thoroughly as possible before submitting it to your Inpro/Seal Representative. This provides our engineering team all the information needed to design the perfect sealing solution for your application and operating environment.

For questions, contact your local Inpro/Seal Representative or visit

Facts at a Glance

Bearing Isolator Measurement:

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