Valve Spring Options; Valve Disc Options; Pulling The Valve Seat; Salvage Of Worn Seats - Pentair Myers Aplex Series Installation And Service Manual

galling. Cleanliness of threads and other contacting
surfaces is of paramount importance in the assembly
of all valve elements.

VALVE SPRING OPTIONS

All Myers Aplex Series valve springs are made of
Inconel material, precisely designed and fabricated.
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Unless otherwise specified, the standard spring is
furnished. It provides excellent results in the great
majority of applications.
Pumps employed in marginally available NPSH
conditions may require a "softer" spring, to reduce the
required NPSH. For these special conditions, Myers
Aplex Series can supply "Light" valve springs which
exert lower pressure on the valve disc. The use of
"Light" valve springs may be limited by the choice of
plunger size and/or limited by the chosen speed of
the pump. "Light" valve springs may be impractical
for pump models fitted with their maximum plunger
size, or which operate near top speed rating as disc
bouncing and erratic seating may occur. Contact Myers
for more information.

VALVE DISC OPTIONS

Myers Aplex Series acetal resin discs are machined
flat and smooth to produce perfect sealing on the
lapped-flat face of the seat. Used successfully in
thousands of applications, these discs are light,
slightly flexible under load, and seal well, even at high
pump speeds, providing smooth pump action.
Acetal resins are very resistant to most corrodents, are
not usually suitable where fluid temperatures above
120 degrees are met. Nor do they afford long life at
extreme pressures. Pressure limitations depend on
valve size. But continuous valve operation at pressures
above 2,500 psi usually indicates the need of metal
valve discs.
For higher temperatures or pressures, Myers Aplex
Series offers lapped flat, hardened Type 17-4PH
stainless discs, or titanium alloy discs. These metal
discs are less tolerant of any fine grit in the liquid and
are noisier than the acetal resin disc.

PULLING THE VALVE SEAT

First drain the fluid end entirely. For abrasion resistant
valves, use the cage wrench to unscrew the cage from
the seat. For disc valves unscrew the stem from the
seat. Remove the cage, spring and valve from the fluid
end. Attach the Myers Aplex Series puller head to
the puller stem, tighten their tapered threads with a
pipe wrench applied to the knurled areas of the puller
stem and head. Lower the stem and head into the fluid
end and engage the threads of the head onto the seat
threads.
Using a 1/2" bar (or screwdriver), rotate the head
clockwise and thread it fully onto the seat. But do
not tighten.
Slide the bridge over the stem. Clean and oil the stem
threads. Oil the face of the wing nut. Thread wing nut
down onto the stem, seating it on the bridge top firmly.
Extract the seat from the pump by striking the wing
nut with a heavy hammer. A hydraulic ram may also
be used. Stand clear of the pump when applying heavy
tonnage, as the entire assembly will jump violently
upward when the pulling energy is suddenly released!
The Myers Aplex Series puller/setting tool and gauge
tool are custom designed and built for each specific
Myers Aplex Series pump model. The same puller
head is used on both suction and discharge seats.
The bridge is made to fit each model, and its proper
use will not damage the valve cover gasket machined
counterbore on the top of the fluid end.

SALVAGE OF WORN SEATS

Rough valve seat faces may often be renewed by
lapping or grinding, if not deeply fluid-cut.
Perfect flatness is required. A surface grind, followed
by lapping on a lapping plate, provides excellent
smoothness and the flatness needed for good sealing
and smooth running. Metal valve discs may sometimes
be salvaged by grinding or lapping, if not deeply cut
or cracked.
Acetal discs are relatively inexpensive and salvage is
seldom worthwhile. Replace the stem, if severely worn.
Inconel valve springs rarely require replacement.
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OTHER PUMP BRANDS

Myers Aplex Series Industries can provide its unique
(patented) valve to fit nearly all brands and models of
multiplex pumps. An Myers Aplex Series seat setting/
puller tool is available too.
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