IOM/GK(P)/CONICAL ISSUE DATE: 10.11.2015
Page 65 LAST REV. DATE: 01.08.2019
from being drawn in to the pump or choking the foot-valve and for this purpose an
efficient strainer should be provided.
STUFFING BOXES AND PACKING (only for gland packed pump)
Stuffing boxes should be carefully cleaned and packing placed in them. Be sure that
sufficient packing is placed at the back of the water seal cage. If the water to be
pumped is dirty or gritty, sealing water should be piped to the stuffing boxes from
clean outside source of supply in order to prevent damage to the packing and shaft.
In placing the packing, each packing ring should be cut to the proper length so that
ends come together but don’t overlap. The succeeding rings of packing should not
be pressed too tight, as it may result in burning the packing and cutting the shaft. If
the stuffing box is not properly packed, friction in stuffing box prevents turning the
rotor by hand. On starting the pump, it is well to have the packing slightly loose
without causing an air leak, and if it seems to leak, instead of putting too much
pressure on the gland, put some heavy oil in the stuffing box until the pump works
properly and then gradually tighten up the gland. The packing should be
occasionally changed.
BALL BEARINGS
Correct maintenance of ball bearings is essential. The bearing manufacturers give
the following as a guide to re-lubrication periods under normal condition for Grease
lubricated bearings.
Three monthly when on continuous duty.
Six monthly when on eight hour per day duty.
The bearings and housings should be completely cleaned and recharged with fresh
grease after 2500 hrs. or the nearest pump overhaul time.
PRIMING
No pumping action occurs unless the pump casing is filled with the liquid. Pump
casing and suction pipe must therefore be completely filled with liquid and thus all
air removed before the pump is started. Several different priming methods can be
used depending on the kind of installation and service involved.
1)
Liquid level above pump level.
Pump is set below liquid level of source of supply, so that liquid always
flows to pump under positive head.
2)
Priming with foot-valve.
a.
When pump is installed on suction lift with foot valve at the end of
suction line, fill pump with water from some outside source till all air is
expelled and water flows through the air vent.
b.
When there is liquid under some pressure in the discharge pipe, priming
can be effected by bypassing the pressured liquid around the check and
gate valve. Of course, the initial priming must be effected from some
outside source.
Note:
In this case, the foot-valve must be capable of withstanding pump
pressure and possible surge.
