Case History No. 11

Industry & Location:

A chemical plant in the east

Problem:

Frequent bearing replacement

Source of Detection:

Continuous failure and excessive vibrations

Cause of Problem:

Excessive thrusting occurs to the inboard bearing of a single inlet fan. Overhung fan wheels of this type impose higher bearing loads to the inboard bearing than the outboard bearing. Also, the inboard bearing is exposed to slightly greater heat because of radiation from the fan housing. This combination results in shortened bearing life.

Overhung, Single Inlet Fan

Solution:

At a reasonable cost, an overhung fan wheel can be converted to a center hung fan wheel by increasing the shaft length and adding a second bearing pedestal. Such a procedure is not uncommon and is almost assuredly a fix-all to a problem of this type.

Centerhung, Single Inlet Fan