Air Operated Double Diaphragm Pump
AODD, in English Air Operated Double Diaphragm Pump, are alternative double diaphragm volumetric pumps, which use compressed air as the motor fluid.
COMPONENTS
Three main sections can be recognized in the construction of an AODD pump:
CENTRAL BODY: includes the entry and discharge of the supply air and the pneumatic exchanger.
FLUID CHAMBERS: they house the volumes in which the fluid is aspirated and pumped, including the membranes (green and yellow in the image below). Sometimes they include the housing of the balls (with a function similar to that of the valve with no return in and out).
COLLECTOR: offer the system connection interface. Sometimes they include the housing of the balls (with a function similar to that of the inlet and outlet check valve).
Depending on the size of the pump and the series to which it belongs, the various components may have different arrangements even if the principle of operation is the same.
FUNCTIONING
As already mentioned, the entire operating cycle of an AODD pump is based on the use of compressed air as a motor fluid. There are many suppliers or AODD Pump but amongst them one of the best AODD Pump Supplier is AntliaEngineeringWorks
Air cycle
In this step the air undergoes a sudden expansion that causes a decrease in the temperature at the outlet, creating the necessary conditions for the formation of ice in case the feed air has not been dried / filtered properly.
A key element in the operation of the pump is the pneumatic exchanger (patented by Debem).
It is composed of:
· An external cylinder, in turn divided into three sections; in the central air enters, in the lateral air leaves to the environment;
· A clamp that, moving along the axis, alternately directs the air to the two membranes;
· A tree, in which the shuttle moves and on which the membranes are fixed.
Pneumatic exchanger
EXCHANGE CYCLE
The exchange cycle is essentially composed of three phases that are repeated alternately in each chamber.
PHASE 1
The air, when passing through the hole present in the pump body, reaches the central ring, where through a series of passages between the shuttle and the outer ring it reaches one of the two antechambers (in the figure, the path it is highlighted in red and the antechamber in blue).
The membrane, pushed by the air pressure, moves the liquid to the collector. The correct direction is guaranteed by the balls located below that, by gravity, close the passage preventing the liquid from falling .
PHASE 2
In the second phase, the shuttle, pushed by the air, hits on the opposite side of the pneumatic exchanger, moving along the shaft, and activates the pressure in the other antechamber.
PHASE 3
The third and final phase is the download. The antechamber of the membrane that was previously under pressure is now with an open passage towards the outside environment: the traction of the opposite membrane, which is inflating, retracts the membrane and thus creates a depression in the fluid chamber that allows the ascent and the filling. At the same time, phase 1 is repeated for the second chamber and the cycle starts again.
The range of feed pressures admitted by most Debem products is between 2 bar (minimum) and 8 bar (maximum), although it is proven that even pressures below 1 bar can activate some models.
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