Fluke 810 User Manual page 132

810
Users Manual
3. Which mounting option is the best?
The Tester's diagnoses are largely dependent
upon the quality of vibration signal it receives
from the tested machinery. The method by which
a sensor is mounted to the machinery directly
affects the quality, accuracy and range of the
signal.
In general, permanent mounts (i.e. stud,
adhesive) yield the best results but are less
convenient. They should be used with machinery
that runs at high speeds and/or frequencies.
This includes machinery with a speed changer
(i.e. gearbox) resulting in an output shaft speed
of greater than 5x the input shaft speed,
machinery (i.e. vacuum pumps) where the
driving unit is running greater than 6000 RPM,
and centrifugal compressors, which typically
include an integrated speed changer. Permanent
mountings are also appropriate when desiring
consistent data tracked over time. Magnet
mounts are generally more convenient and
faster, making them the most widely used for
walkaround measurements, but some accuracy
will be sacrificed.
A-4
4. Can I use a single axis sensor?
The Tester can work with a single axis sensor
but it is recommended to use a tri-axial sensor to
improve diagnostic quality and for convenience:
using a tri-axial sensor can result in significant
cost and time savings as 3 different channels
are measured simultaneously, while single axis
sensors measure one axis at a time. If a single
axis sensor is connected, it is required to take at
least two measurements from each bearing
location to be able to diagnose data.
5. How can I select the right measurement
locations?
If the drive train is horizontal: Place the sensor
on the end, side, top or bottom of the equipment.
If the drive train is vertical: Place the sensor on
the front, back, side, top or bottom of the
components. For vertical drive trains, front, back
and sides are essentially the same. The first
placement will become the frame of reference
for the others. For example, once a location is
named "Front," the "Back" and "Side" locations
become apparent. Make sure you use the same
reference for future measurements.