Dover Wilden Original P1 Engineering, Operation & Maintenance Download Page 5

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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 mechan-

ical 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 move-

ment of diaphragm B toward the center block of the

pump creates a vacuum within chamber B. Atmo-

spheric 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 pull-

ing 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 mani-

fold 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.

The Pro-Flo

patented air distribution system

incorporates three moving parts: the air valve
spool, the pilot spool, and the main shaft/dia-
phragm 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 alternately pressurized then exhausted to
move the spool. The spool directs pressurized
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 repositioning of
the air valve spool routes the air to the other air
chamber.