AIR OPERATED DOUBLE DIAPHRAGM PUMPS
FUNCTIONALITY AND FLOW PATTERN
Figure 1: Air valve directs
pressurized air to the back side
of diaphragm A. 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
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. 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 the 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.
These same hydraulic forces
lift the discharge valve ball off
its seat, while the opposite
discharge valve ball is forced
ontoitsseat,forcingfluidtoflow
through the pump discharge.
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.
NTG50
NOMAD TRANS-FLO™
3
