High Temperature Corrections

When a foot-mounted process pump must
operate at elevated temperatures, some adjustment
will be necessary to allow for the thermal growth
that takes place between the cold condition and the
high operating temperatures. As the pump heats up,
the shaft centerline will be moved up, creating an
offset with the motor shaft.

One method of handling this situation is to
misalign the motor by the amount of growth anticipated
from the pump prior to starting it up. Most
pump manufacturers can provide the cold setting
figures corresponding to the higher operating temperatures.
This will require the pump and motor
shafts to run in a misaligned setting until the pump
is fully up to temperature, by which time, the
expansion of the pump will raise it into position to
align with the motor.

A second method is to start the pump and
motor following a cold alignment, without any
adjustment. As the pump heats up and expands, it
will gradually move up, out of alignment with the
motor. When the pump is fully up to temperature,
the unit is stopped and hot alignment takes place.
For both of these methods, a flexible coupling,
capable of accommodating the total amount of
anticipated misalignment, will be required.