TM 5-3895-374-24-2
4.
Valve in suction line must be fully open at all
times. Close discharge valve before starting
pump to prevent motor over loading. Open
discharge valve only after pump reaches full
operating speed.
5.
Check pump speed and discharge head and
adjust where required. Check pump for
excessive vibrations.
B - During Operation
The following should be checked during pump operation:
1.
Discharge head
2.
Bearing temperature; 212°F (100°C) maximum.
3. Air flow from motor over bearing housing if a
TEFC motor is used.
4. Check pump for excessive vibration.
C - Shut Down
1. Close discharge valve. Do not run pump longer
than necessary against closed discharge valve.
2. Do not isolate pump by closing suction and
discharge valves.
SECTION IV - MAINTENANCE
A - Bearings
SIHI ZTN pump bearings consist of one outboard
grease lubricated ball bearing and one internal liquid
flushed carbon sleeve bearing. The ball bearing is
lubricated at the factory for initial operation. After
approximately every 1,000 hours of operation, the ball
bearings should be greased. After approximately 10,000
hours of continuous operation or after two (2) years of
intermittent operation, it is recommended to remove the
ball bearing and clean and regrease the bearing. Under
severe operating conditions, the above intervals should
be shortened. Use only high temperature grease with a
dropping point over 338°F (170°C) such as:
- Shell - Aero Grease No. 16
- Esso - Unirex N3
- Dow - Molykote BR2 - Plus
- Or equivalent
Mixing noncompatible types of grease may cause a
bearing lubrication problem resulting in a premature
failure The liquid lubricated sleeve bearing requires no
maintenance. Abrasives suspended in the liquid affect
the life of the sleeve bearing.
B - Shaft Sealing
The shaft sealing is obtained through the use of viton
seal rings. The shaft sealing does not require any
maintenance. Under normal operating conditions, the
shaft seal rings have a minimum expected life of one
year. Most pumps do not show inadmissable leakage
even after several years of operation, the maximum
admissible leakage is considered one drop per minute.
In the event of seal ring leakage, the medium
pumped will be confined in the drainage chamber
between the seal housing and ball bearing. Leakage, if
any, can be drained from this chamber through lower
tapped hole without any loss of liquid. DO NOT PLUG
LOWER TAPPED HOLE
The life of the shaft seal rings is affected by the
following factors:
1. Operation without initial venting, for venting
procedure refer to Section III, Paragraph A-3.
2. Failure to pack seal rings with high temperature
grease, refer to Section VI, Paragraph C-3.
3. Use of contaminated heat transfer oil.
4. Operation
above
maximum
recomended
temperature for extended periods.
5. Controlling pump operation from suction side.
6. An in-rush of air through the seal rings when
pump is subject to negative pressure. If this
occurs, pump must be vented before start-up
To prevent failure caused by an in-rush of air,
observe the following precautions:
1. When shutting down pumps, do not isolate the
pumps by closing both suction and discharge
isolating valves. As heat transfer oil cools, the
volume can be reduced up to 30%. The
reduction in volume causes an in-rush of air into
the pump through the seal rings.
2. For installations with constant negative suction
pressure, the cavity between the seal rings and
ball bearing may be flooded with oil to prevent air
from entering the pump. This is accomplished
by plugging the drain connection and installing a
constant oiler at the upper tapped connection.
C - Removal of Ball Bearing and/or Seal Rings
The removal of the ball bearing and/or seal rings will
necessitate the disassembly of the pump. Refer to
Section VI - Disassembly/Assembly Instructions for
complete details in the removal of these components.
The following paragraphs deal specifically with the
removal and installation of the ball bearing (230) and/or
seal rings (400).
Ball Bearing (Item 230)
Section VI, Paragraph A-1 to 6; B-1 to 7; D-1 to 7.
Seal Rings (Item 400)
Section VI, Paragraph A-1 to 6; B-1 to 7; C-2 to 4; D-3 to 7
D - Driver & Accessories
Maintenance
and
lubrication
for
driver
and
accessories shall be to the manfacturer's standard
procedures.
(page-3 - 1144)
