Are Three Axes of Data Per Bearing Necessary?

For the majority of applications, it is best practice to monitor the horizontal, axial, and vertical axes. However, when it comes to permanently mounted sensors, monitoring each axis adds additional costs. So, whether or not all three axes are monitored by permanent sensors comes down to the criticality of the equipment. On critical machines it is preferable to have one axial sensor per machine and one horizontal and vertical sensor per bearing. If the machine in question has a back-up and will not cause a plant shut down, one axial sensor and a horizontal sensor on one bearing with a vertical sensor on the remaining bearing should provide sufficient baseline data for most situations.