7
AD
since 1928
AD
since 1928
1.4 - OPERATING PRINCIPLE
The AODD pump is an air-powered, reciprocating positive displacement pump with two pumping chambers.
Two diaphragms, centrally located in the chambers, separate the compressed air (‘‘dry side’’) from the liquid
being pumped (‘‘wet side’’). A shaft connects the two diaphragms to each other.
A valve (air motor) distributes the air from one chamber to the other alternately, thus a reciprocating move-
ment of the diaphragms is created. At each stroke liquid is displaced by one of the diaphragms while the
opposite diaphragm sucks new liquid into the expanding chamber. Check valves, two on the discharge side
and two on the suction side, control and direct the liquid flow.
1.4.1 - OPERATING PRINCIPLE FOR THE AD PUMP
Compressed air enters the air chamber (
a) on the left side of the pump. The diaphragms are pushed to the
right and liquid is displaced from chamber (
A). Simultaneously pressure is reduced in chamber (B) and new
liquid enters. Used air is pushed out from the right air chamber (
b).
Note the short flow path through the centre of the pump and how the check valves are opening and closing.
In the AD pump the diaphragms are not fixed to the shaft. Thanks to this Flexible Diaphragm Suspension
(FDS-invention) and the spring at the shaft end, the diaphragms can move a short distance independently
of each other. At the end of each stroke both diaphragms are exposed to compressed air for a very short
period. When the left diaphragm has come to the end position, the right one has already started to move
back to the left and the spring is compressed. Thereafter the left diaphragm starts to move to the left and
the spring expands.
The two diaphragms are overlapping each other and thus there is no complete dead end at the same mo-
ment - pulsation is reduced.
This operating principle requires an extremely short reversing time of the compressed air.
The traditional sliding air valve could not be used and a new low friction air motor (FPV-invention - Friction-
less Pivoting Valve) with a rocking motion was developed. The new air motor is nothing less than a patented
sensation - extremely simple with very few parts and completely insensitive to the quality of the compressed
air.
The cycle is completed and the two diaphragms are now moving back to the left.
B
b
A
a
AD Instruction Manual-2011EE-GB.indd 7
25/07/11 09:45
