WIL-17100-E-03 6
CSA-Certified Pumps
SECTION 3
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
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.
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.
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 each stroke.
HOW IT WORKS – AIR-OPERATED DOUBLE-DIAPHRAGM PUMP
HOW IT WORKS – AIR DISTRIBUTION SYSTEM
