CLOSED
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FIGURE 1 The air valve directs pressuriz ed
air to the back side of diaphrag m A. The
compress ed air is applied directly to t he
liquid column separated by elastom e ri c
diaphrag ms. The diaphrag m acts as a
separatio n membrane betwee n t he
compres sed air and liquid; a balanc e d
load removes mechanic al stress from the
diaphrag m. The compress ed air mov es
the diaphrag m away f rom the center of
the pump. The opposite diaphrag m is
pulled in by the shaft connect ed to the
pressurized diaphrag m. Diaphrag m B is
on its suction stroke; air behind t he
diaphrag m has been f orced out to
atmosphe re through the exhaust port of
the pump. The movement of diaphrag m B
toward the center of the pump creates a
vacuum within chamber B. Atmosph e ri c
pressure forces fluid into the inlet
manifold forcing the inlet valve ball of f its
seat. Liquid is f ree to move past the inlet
valve ball and fill the liquid chamber (s ee
shaded area).
FIGURE 2 When the pressurized dia-
phragm, diaphragm A, reaches the limit of
its discharge stroke, the air valve redirect s
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 discharg e
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 lif t the discharge valve ball
of f its seat, while the opposite discharg e
valve ball is f orced onto its seat, forcing
fluid to f low through the pump discharge.
The movement of diaphragm A toward the
center of the pump creates a vacuum within
liquid chamber A. Atmospheric press ure
forces fluid into the inlet manifold of the
pump. The inlet valve ball is forced off its
seat allowing the f luid being pumped to f ill
the liquid chamber.
FIGURE 3 At completion of the stroke, the
air valve again redirects air to the bac k
side of diaphrag m A, whic h start s
diaphrag m B on its exhaust stroke. As the
pump reaches its original starting point,
each diaphrag m has gone through o ne
exhaust and one discharg e stroke. This
constitutes one complete pumping cyc le.
The pump may take several cycles to
completely prime depending on the
conditions of the applicatio n.
HOW IT WORKS —AIR DIST RIB UTION SYST EM
The Pro-Flo ®patented air distributio n system incorporat es t wo
moving parts: the air valve spool and the pilot spool. The hear t
of the system is the air valve spool and air valve. This valv e
design incorporat es an unbalanc ed spool. The smaller end of
the spool is pressurized continuo usly, while the large end is
alternately pressuriz ed then exhausted to move the spool. The
spool directs pressurized air to one air chamb er whil e
exhaust ing the other. The air causes the main shaft/diap h r ag m
assemb ly to shif t to one side —discharging liquid on that sid e
and pulling liquid in on the other side. When the shaft reac h e s
the end of its stroke, the inner piston actuates the pilot spool,
which pressurizes and exhaust s the large end of the air valve
spool. The repositio ning of the air valve spool routes the air to
the other air chamb er.
