13
DEPA
®
Air Operated Diaphragm Pumps
1.3.1 Functionality
DEPA Air Operated Diaphragm
Pumps are oscillating positive
displacement pumps with two
pump chambers arranged
opposite each other. Both
of these are separated by a
diaphragm each into an air and a
fluid section.
Both diaphragms are linked by
a piston rod, so that with every
stroke product is displaced to
the outside from the one pump
chamber and product is drawn
into the opposite pump chamber.
The four drawings opposite
describe the sequence of a
complete cycle consisting of a
suction and pressure stroke, an
empty and a filled pump chamber.
In order to explain the function
the product to be pumped was
highlighted in colour.
By filling the right hand air chamber
(dark grey) the right hand diaphragm
is pressed towards the outside. The
piston rod thereby pulls the left hand
diaphragm to initial position. Valve ball
(1) is pulled out of its position, product
(grey) flows into the left hand pump
chamber. At the same time valve
ball (2) is fixed in end position by the
vacuum. The left hand pump chamber
is thus completely filled with product
(grey).
After switching of the control valve air
flows into the left hand air chamber
(dark grey), the right hand air chamber
is vented. The suction process (see
A) now takes place in the right hand
pump chamber. Product (dark grey)
is drawn in , product (light grey) in the
left hand pump chamber is displaced
to the outside. Valve ball (1) presses
down, closes and valve ball (2) opens
the flow path for product to the
pressure outlet port.
The suction process “A” is repeated
with the only difference, that the right
hand pump chamber is already filled
with product (light grey). By switching
of the control valve the right hand air
chamber (dark grey) is filled, product
(red) is drawn into the left hand pump
chamber and the product from the
right hand pump chamber (light gery)
is displaced.
This sequence is repeated in reverse
order as shown under C. The left
hand air chamber (dark grey) fills up,
vacuum draws product (dark grey)
into the right hand pump chamber,
while product (green) from the left
hand pump chamber is displaced
through the pressure port.
A
B
C
D
