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WILDEN PUMP & ENGINEERING, LLC
SECTION 2
THE WILDEN PUMP — HOW IT WORKS
The Wilden diaphragm pump is an air-operated, positive displacement, self-priming pump. These drawings show the flow
pattern through the pump upon its initial stroke. It is assumed the pump has no fluid in it prior to its initial stroke.
FIGURE 1 The air valve directs pressurized air to
the back side of diaphragm A. The compressed air is
applied directly to the liquid column separated by
elastomeric diaphragms. The diaphragm acts as a
separation membrane between the compressed air
and liquid, balancing the load and removing
mechanical stress from the diaphragm. The
compressed air moves the diaphragm away from the
center block of the pump. The opposite diaphragm
is pulled in by the shaft connected to the pressurized
diaphragm. Diaphragm B is on its suction stroke; air
behind the diaphragm has been forced out to the
atmosphere through the exhaust port of the pump.
The movement of diaphragm B toward the center
block of the pump creates a vacuum within chamber
B. Atmospheric pressure forces fluid into the inlet
manifold forcing the inlet valve ball off its seat. Liquid
is free to move past the inlet valve ball and fill the
liquid chamber (see shaded area).
FIGURE 2 When the pressurized diaphragm,
diaphragm A, reaches the limit of its discharge
stroke, the air valve redirects pressurized air to the
back side of diaphragm B. The pressurized air
forces diaphragm B away from the center block
while pulling diaphragm A to the center block.
Diaphragm B is now on its discharge stroke.
Diaphragm B forces the inlet valve ball onto its seat
due to the hydraulic forces developed in the liquid
chamber and manifold of the pump. These same
hydraulic forces lift the discharge valve ball off its
seat, while the opposite discharge valve ball is
forced onto its seat, forcing fluid to flow through the
pump discharge. The movement of diaphragm A
toward the center block of the pump creates a
vacuum within liquid chamber A. Atmospheric pres-
sure forces fluid into the inlet manifold of the pump.
The inlet valve ball is forced off its seat allowing the
fluid being pumped to fill the liquid chamber.
FIGURE 3 At completion of the stroke, the air
valve again redirects air to the back side of
diaphragm A, which starts diaphragm B on its
exhaust stroke. As the pump reaches its original
starting point, each diaphragm has gone through
one exhaust and one discharge stroke. This consti-
tutes one complete pumping cycle. The pump may
take several cycles to completely prime depending
on the conditions of the application.
PRO-FLO™AIR DISTRIBUTION SYSTEM
OPERATION —HOW IT WORKS
The Pro-Flo™patented air distribution
system incorporates three moving parts:
the air valve spool, the pilot spool, and the
main shaft/diaphragm assembly. The heart
of the system is the air valve spool and air
valve. As shown in Figure A, this valve
design incorporates an unbalanced spool.
The smaller end of the spool is pressurized
continuously, while the large end is alter-
nately pressurized then exhausted to
move the spool. The spool directs pres-
surized air to one air chamber while
exhausting the other. The air causes the
main shaft/diaphragm assembly to shift to
one side —discharging liquid on that side
and pulling liquid in on the other side.
When the shaft reaches the end of its
stroke, the inner piston actuates the pilot
spool, which pressurizes and exhausts the
large end of the air valve spool. The repo-
sitioning of the air valve spool routes the
air to the other air chamber.
Figure A
