1
2
3
1.
Stub sleeve
2.
ID pilot fit in stuffing box
3.
Standard flush gland with O-ring mounted stationary seat
Figure 30: S group pump — stub sleeve
The following figure illustrates a standard stepped sleeve used on the M group pumps to reduce the
mounting diameter down to the standard sleeve nut OD.
1
2
1.
Standard stuffing box bore
2.
Non-piloting gland requiring feeler gauge centering on the shaft
Figure 31: M group pump — stepped sleeve
Bellows-type mechanical seals are integrally balanced and do not require a step in the sleeve. They can
be mounted directly on the sleeveless S group shaft or on a standard, non-balanced M group sleeve.
Packing converted to a mechanical seal
Pumps that are supplied with packing boxes can be converted to mechanical seals in the field. This con-
version requires remachining the stuffing box to allow for the standard gland pilot feature or remachining
the standard gland to remove the pilot lip as shown in the following figures. In this case, a shimming op-
eration is required to center the gland on the shaft.
The following figure illustrates a single inside unbalanced mechanical seal mounted in the S group stand-
ard stuffing box. Note that the pilot lip has been machined off the gland since there is inadequate room in
the bore for the pilot. With this arrangement, it is necessary to use a feeler gauge or shims to center the
gland on the shaft.
5.10 Mechanical seal options
48
Model 3410 Installation, Operation, and Maintenance Manual
