Xylem AC2008B Series HSC3 Base Mounted Centrifugal Pump - Manual (Page 15)

15
MAINTENANCE
1. General Maintenance
Operating conditions vary so widely that to recommend one
schedule of preventative maintenance for all centrifugal
pumps is not possible. Yet some sort of regular inspection
must be planned and followed. We suggest a permanent
record be kept of the periodic inspections and maintenance
performed on your pump. This recognition of maintenance
procedure will keep your pump in good working condition, and
prevent costly breakdown.
One of the best rules to follow in the proper maintenance of
your centrifugal pump is to keep a record of actual operating
hours. Then, after a predetermined period of operation has
elapsed, the pump should be given a thorough inspection. The
length of this operating period will vary with different applica-
tions, and can only be determined from experience. New
equipment, however, should be examined after a relatively
short period of operation. The next inspection period can be
lengthened somewhat. This system can be followed until a
maximum period of operation is reached which should be con-
sidered the operating schedule between inspections.
2. Maintenance of Pump Due to Flood Damage
The servicing of centrifugal pumps after a flooded condition is
a comparatively simple matter under normal conditions.
Bearings are a primary concern on pumping units. First, dis-
mantle the bearings; clean and inspect them for any rusted or
badly worn surfaces. If bearings are free from rust and wear,
reassemble and relubricate them with one of the recommend-
ed pump lubricants. Depending on the length of time the
pump has remained in the flooded area, it is unlikely that bear-
ing replacement is necessary; however, in the event that rust
or worn surfaces appear, it may be necessary to replace the
bearings.
Next, inspect the stuffing box, and clean out any foreign mat-
ter that might clog the box. Mechanical seals should be
cleaned and thoroughly flushed.
Couplings should be dismantled and thoroughly cleaned.
Any pump that is properly sealed at all joints and connected to
both the suction and discharge should exclude outside liquid.
Therefore, it should not be necessary to go beyond the bear-
ings, stuffing box, and coupling when servicing the pump.
3. Bearing Lubrication – Grease
Grease lubricated ball bearings are packed with grease at the
factory and ordinarily will require no attention before starting,
provided the pump has been stored in a clean, dry place prior
to its first operation. The bearings should be watched the first
hour or so after the pump has been started to see that they
are operating properly.
The importance of proper lubrication cannot be over empha-
sized. It is difficult to say how often a bearing should be
greased, since that depends on the conditions of operation. It
is well to add one ounce of grease at regular intervals, but it is
equally important to avoid adding too much grease. For aver-
age operating conditions, it is recommended that 1 oz. of
grease be added at intervals of three to six months, and only
clean grease be used. It is always best if unit can be stopped
while grease is added to avoid overloading.
NOTE: Excess grease is the most common cause of
overheating.
A lithium based NLGI-2 grade grease should be used for lubri-
cating bearings where the ambient temperature is above
-20°F. Grease lubricated bearings are packed at the factory
with Shell Alvania No. 2. Other recommended greases are
Texaco Multifak No. 2 and Mobilux No. 2 grease.
Greases made from animal or vegetable oils are not recom-
mended due to the danger of deterioration and forming of
acid. Do not use graphite. Use of an ISO VG 100 mineral base
oil with rust and oxidation inhibitors is recommended.
The maximum desirable operating temperature for ball bear-
ings is 180°F. Should the temperature of the bearing frame rise
above 180°F, the pump should be shut down to determine the
cause.
4. Mechanical Seals
a. Mechanical seals are precision products and should be
treated with care. Use special care when handling seals.
Clean parts are essential to prevent scratching the finely
lapped sealing faces. Even light scratches on these faces
could result in leaky seals.
b. Normally, mechanical seals require no adjustment or
maintenance, except routine replacement of worn, or
broken parts.
c. A mechanical seal which has been used should not be put
back into service until the sealing faces have been replaced
or relapped. (Relapping is generally economical only in
seals two inches in size and above.)
5. Cleaning Without Dismantling Pump
A short section of pipe, so designed that it can be readily
dropped out of the line, can be installed adjacent to the suc-
tion flange. With this arrangement, any matter clogging the
impeller is accessible by removing the pipe section.
If the pump cannot be freed of clogging after the above
methods have been tried, dismantle the unit as previously
described to locate the trouble.