Operation and Maintenance Manual
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(7) Is the pump running with no abnormal noise and no vibration ?
2.3.2. Shaft seal
The shaft seal is available in two different types of gland packing and mechanical seal. The descriptions here under
covers the gland packing seal type. Refer to Chapter IV for the detailed instructions of the mechanical seal.
The gland packing insertion space in the casing cover is designed to be equivalent the either five packing rings
(4610) or three packing rings plus one lantern ring (4580).
The gland bush (4540) is of split type as to facilitate insertion of the packing rings.
(1) Gland packing without lantern ring
The seal type is applied to the suction pressure of 0,5 kgf / cm
2
G and over or the handling of odorous liquids
(e.g. ammonia water and benzine, benzol or lubricant for outdoor use, etc.). In such cases, self flushing or
external flushing is not applied to the gland packing.
(2) Gland packing with lantern ring
This seal type is applied to the following cases.
o
Clean liquid under suction pressure of 0.5 kgf/cm
2
G or under suction lift.
o
Pumping the liquid from vacuum tank.
o
The pump shaft and its gland packing must be protected from abrasion for handling liquid containing
abrasive component, (e.g. handling of sewage and the like).
In such cases, either self flushing or external flushing by proper liquid is applied to the gland packing as described
below.
(a) Self-flushing
In this case, flushing liquid is conducted into the lantern ring through a passage provided in the casing cover.
(b) External flushing
This flushing system is applied to such case that inclusion of external liquid in the pumping liquid is allowed.
In this case, same of the flushing liquid flows into the volute casing and the remaining is discharged into the
atmosphere through the clearance in the gland bush.
In the case of the gland packing shaft seal, packing ring (4610), lantern ring (4580) and gland bush (4540) are
inserted in the stuffing box. In this case, the outside surface of shaft protecting sleeve (5240) must keep smooth all
the times.
Any flaw on the shaft protecting sleeve surface or irregular tightening and over-tightening of the gland (4520)
would cause the shaft seal to be overheated and the packing rings to deteriorate earlier than expected.
When the packing rings are replaced with new ones, packing material highly resistant to pumping liquid and its
temperature must be used. Before replacement, clean the lantern ring, gland bush and gland and, cut the packing
material to the specified dimension with a proper cutter using the cutting jig illustrated in Fig. 4. Thereafter, insert the
packing rings, one by one into the stuffing box so that the butt ends of each ring are offset by 90° from each other on
the shaft protecting sleeve. (Refer to Fig. 5.)
Fig. 4
Fig. 5
Fig. 6
Set the gland bush to such extent that it fits a little in the stuffing box. Then, tighten the gland packing (packing
rings) lightly and put the pump in running-in operation for a meantime. Thereafter, re-tighten the gland packing to such
extent that leakage from the gland reaches 10 cc / min. ~ 20 cc / min. Refer to Fig. 6 and table 1 for the detailed
construction of the shaft seal and the number of packing rings.
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