Wilden Saniflo PS4 Hygienic Series, Engineering, Operation & Maintenance, Page: 6 / 36

WIL-12610-E-04
Wilden ®
6
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. 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.
HOW IT WORKS — AIR DISTRIBUTION SYSTEM
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.
Section 3
HOW IT WORKS — PUMP