WIL-12620-E-03
3
WILDEN PUMP & ENGINEERING, LLC
The Wilden diaphragm pump is an air-operated, positive displacement, self-priming pump. These drawings show 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; a balanced
load removes mechanical stress from the
diaphragm. The compressed air moves
the diaphragm away from the center 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 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 while pulling diaphragm A
to the center. 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 of the pump creates a
vacuum within liquid chamber A. Atmos-
pheric pressure 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 constitutes one complete pumping
cycle. The pump may take several cycles
to completely prime depending on the
conditions of the application.
OUTLET
CLOSED
CLOSED
OPEN
OPEN
INLET
B
A
OUTLET
OPEN
OPEN
CLOSED
CLOSED
INLET
B
A
OUTLET
CLOSED
CLOSED
OPEN
OPEN
INLET
B
A
S e c t i o n 3
H O W I T W O R K S — P U M P
H O W I T W O R K S — A I R D I S T R I B U T I O N S Y S T E M
The heart of the patented Pro-Flo
®
SHIFT Air Distribution
System (ADS) is the air valve assembly. The air valve design
incorporates an unbalanced spool with the small end of the
spool being pressurized continuously while the large end of
the spool is alternately pressurized, then exhausted to move
the spool. The air valve spool directs pressurized air to one
chamber while exhausting the other. The air forces the main
shaft/diaphragm assembly to move to one side – discharging
liquid on that side and pulling liquid in on the other side. When
the shaft reaches the end of the stroke, the inner piston actuates
the pilot spool, which controls the air to the large end of the air
valve spool. The repositioning of the air valve spool routes the
air to the other air chamber. The air control spool allows air to
flow freely into the air chamber for the majority of each pump
stroke, but it significantly restricts the flow of air into the air
chamber when activated by the inner piston near the end of the
each stroke.
