Inserting The Plunger; Stuffing Box, Packing And Plunger Assemblies; General; Spring Loaded Packing - Pentair Myers Aplex Series Installation And Service Manual

energizing its lips. Apply oil lightly to the bore of the
box before pressing each seal into its counterbore.

INSERTING THE PLUNGER

Insert the extension rod through the wiper seals with
the tapered thread and entering first. Do not move the
extension rod through the seals with wrenching flats
entering first. The sharp corners on the wrenching
flats may damage the seal lips, resulting in oil leakage.
With extension rod inserted through the wiper box
seals, thread the tapered threads (must be clean!) into
the tapered crosshead female threads. Firmly tighten
and apply torque to the wrenching flats only. Never
damage the extension rod ground surfaces!
Then fasten the wiper box to the power frame by
tightening the cap screws. Oil leakage between frame
face and wiper box is prevented by use of an O-ring.
STUFFING BOX, PACKING
AND PLUNGER ASSEMBLIES

GENERAL

Myers Aplex Series pumps all feature field removable
and replaceable stuffing boxes with plungers
separable from the extension rods.
If desired, the boxes, plungers, and packing units
may be installed (or removed) as a unit assembly,
permitting service outside the pump. All boxes are
retained by four studs and nuts, and are centered in
the frame bore, ensuring correct alignment.
The plungers may also be removed separately (without
box removal) to facilitate repacking. With this option,
the necessary space required to remove plunger, it is
first necessary to remove the extension rod.

SPRING LOADED PACKING

Note that the gland is screwed tightly onto the box
and contacts its face. The spring is providing all of the
initial compression and adjustment. No adjustment is
provided by the gland.
Since the force exerted by the spring is contingent
on the space provided for it, the correct lengths of all
rings is essential for good tensioning.
Spring:
A stiff Inconel spring, which closely fits the bore of
®
the stuffing box, is used in this assembly. This spring is
compressed in a vise to the operating length required
plus 0.25" and tied with waxed nylon spot tie cord. The
cord is looped over the ends of the spring through the
coils and tied to maintain the length mention above.
Each spring is assembled into the stuffing box. Note
that the spring does not contact the plunger.
Spring-Guide Ring:
Plungers are heavy and the importance of a well-fitted
guide ring that carries this weight is often overlooked.
Discard any guide ring that becomes worn or scored,
as it will then not serve its purpose. It should fit snugly
in the box. Apply oil generously to this ring.
Spring Loaded Packing:
Three rings of chevron or compression packing are
installed next. For compression packing, install them
with the skive intersections 180º apart to discourage
leaking.
Gland Ring:
This ring also fits the plunger and helps support the
plunger weight. Discard it if bore is worn, rough or
out-of-round. Lightly oil the ring before insertion. The
gland ring fits all packing.
J-STYLE STUFFING BOX & PLUNGER
ASSEMBLY (STYLES 838 & 858)
Styles 838 and 858 packing correctly installed with all
packing lips facing toward the fluid pressure. Note that
two units of Styles 838 and 858 packing are positioned
ahead of the lantern ring, and one unit is positioned
behind it. Thus lubricant entering the lantern ring is
forced toward the pressure.
Throat Bushing:
Plungers are heavy and the importance of a well
fitted throat bushing that carries this weight is often
over- looked. Discard any throat bushing that becomes
worn or scored, as it will not then serve its purpose.
It should fit snugly in the bottom of the box. Apply oil
generously to this ring.
Styles 838 and 858 Packing:
Styles 838 and 858 are a non-adjustable type packing
which depends solely on hydraulic pressure to
energize the sealing lips. (Gland-tightening forces
do not energize the lips.) Tightening and hydraulic
end thrust loads are transmitted entirely through the
center support portions of each ring.
The flattened portions of the rings are large enough to
withstand overtightening. Do not attempt to adjust this
type packing. It should be kept thoroughly tightened at
all times. (Running it loose will ultimately ruin the bore
of the box.)
Running it loose will not usually cause it to drip at all,
but it can ruin the box in time.
Lightly oil each ring and the box bore and then lightly
tap in each ring separately with the rings facing
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