Page 261 - Root Cause Failure Analysis

Fans, Blowers, and Fluidizers 249

Table 20-2 Common Failure Modes of Blowers and Fluidizers

THE PI
P-

Source: Integrated Systems, Inc.

ures occur due to process instability, caused by stadstop operation and demand varia-
tions, and mechanical failures due to close tolerances.

Process Instability
Blowers are very sensitive to variations in their operating envelope. As little as a 1
psig change in downstream pressure can cause the blower to become extremely unsta-
ble. The probability of catastrophic failure or severe damage to blower components
increases in direct proportion to the amount and speed of the variation in demand or
downstream pressure.

StartLStop Operation
The transients caused by frequent start/stop operation also have a negative effect on
blower reliability. Conversely, blowers that operate constantly in a stable environment
rarely exhibit problems. The major reason is the severe axial thrusting caused by the
frequent variations in suction or discharge pressure caused by the stadstop operation.