WIL-10131-E-01
3
WILDEN PUMP & ENGINEERING, LLC
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 1, this valve
design incorporates an unbalanced spool.
The smaller end of the spool is pressur-
ized continuously, while the large end is
alternately pressurized and exhausted to
move the spool. The spool directs pressur-
ized air to one chamber while exhausting
the other. The air causes the main shaft/
diaphragm assembly to shift to one side
— discharging liquid on one side and
pulling liquid in on the other side. When
the shaft reaches the end of its stroke, it
actuates the pilot spool, which pressur-
izes and exhausts the large end of the
air valve spool. The pump then changes
direction and the same process occurs in
the opposite direction, thus reciprocating
the pump.
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
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 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.
RIGHT STROKE
MID STROKE
LEFT STROKE
S e c t i o n 3
H O W I T W O R K S
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
