Many companies ignore their pumps until they fail. And when they
do fail, the main concern is how to get them up and running –
fast. That’s why it’s so important to ask proactive questions
like: How long are pumps supposed to last? How can a pump reach
its best efficiency point? How can I prevent a pump from failing
again? What is the proper way to repair a pump? Answering these
questions can save thousands of dollars a year - maybe even a
month. In short, effective pump maintenance will ensure your
pumps never leave you high and dry.
The first task in repairing
pumps is to note the condition of each component when
disassembling the pump. Proper and complete records are one of
the most commonly overlooked procedures necessary for
maintaining good pump repair. Also often overlooked is the need
to keep the surrounding environment clean when reassembling a
pump. Bearing contamination introduced during the pump rebuild
will shorten the life of the seals, the lubricant and will lead
to bearing damage and bearing failure.
During a rebuild,
measuring the bearings seats' diameters on the shaft and the
housing with a micrometer, rather than callipers, is also
advised, as improper sizes are a common cause of pump bearing
failures. Ensuring that the shaft is straight is also important.
The proper way to do this is to set the bearing seats on the
shaft on V blocks. Then, using a dial indicator at several
points on the shaft, you can determine if the shaft is bent.
When reassembling the pump bearings be sure the snap ring on the
held bearing does not cover any bearing lubrication groove. Also
note that the word 'top' in the casting is reassembled on the
top to ensure that the bearing is not deprived of lubrication
and that the labyrinth seal drain slot is down. After both the
motor and pump are reattached to the bedplate (base plate) and
before connecting their shafts, ensure that the two shafts are
aligned. This can be done with either laser aligning equipment
or with a pair of dial indicators and magnetic bases. While some
feel that a straight edge will suffice when checking the
alignment, this isn't advisable because a straight edge cannot
detect less than 0.01”.
With your reassembly completed, be sure
that all bolts are tightened to the proper torque values and
your pump is ready for service! To keep your newly maintained
pumps working at peak levels, be sure to maintain proper bearing
lubrication: If grease is used to lubricate the bearings, use
either a sodium or lithium based grease with an NLGI rating of
2. If temperatures are greater than 200°F, choose a rating of 3.
Bearing grease re-lubrication intervals should be once every 3
months, under normal operating conditions. If the temperature
exceeds 200°F, the intervals should be more frequent. When it
comes to ensuring your pumps run longer and more efficiently,
think high quality bearings that need less bearing maintenance
and increase productivity. Think training and technical service
support. Think NSK.
About the author:
NSK Corporation is
a world-class producer of ball and roller bearings. Established
in 1916, NSK is one of the leaders in the bearing industry due
to our intense commitment to engineering research, dedication to
modern manufacturing processes and an obsession with quality.
