What is an AODD Pump?
Air operated double diaphragm (AODD) pumps are positive displacement pumps that use a combination of the reciprocating action of two flexible diaphragms, two inlet and two outlet ball check valves to pump a fluid. There are two pump chambers which are divided by the diaphragms into air and fluid regions. The two diaphragms are connected to a common shaft located in the centre section. This creates the effect that during a cycle one side is pumping fluid while the other side is filling.
Why use an AODD Pump?
AODD pumps have many benefits over other pump technologies:
| • Simple installation | • Easy to operate and run | • Portable |
| • Self-priming | • Submersible | • Dry running |
| • Can pump dirty liquids or liquids with particles | • Abrasive liquid handling | • Viscous liquid pumping |
| • Can pump shear sensitive liquids | • Affordable compared to other positive displacement technologies | • Low maintenance and running cost |
Selecting a pump
step 1: Determine application requirements:
It is important to determine how the pump is going to be used before you can select the appropriate pump size and construction.
Required head and flow
Most AODD pump applications are simple transfer but some require higher flow rates (for use in flooding or quickly emptying sumps) or higher head (pressure) capabilities (transferring liquids to the top of a machine, to a second floor or to pump higher viscosity fluids).
Chemical name or type
This is very important information and is required to ensure that the wetted materials of the AODD are compatible with the fluid being pumped. In addition, it is important to determine if the fluid is a flammable or combustible liquid. The pumps on our online shop can be filtered to only include ATEX rated models.
Temperature of the fluid being pumped
On the useful info section of this website there is a temperature guide for the materials used in the AODD pumps. This should be used in conjunction with the chemical compatibility guide as the effect of most corrosive chemicals is exacerbated by increased temperature.
Specific gravity and viscosity
This will affect the actual flow rate that an AODD pump can deliver. The useful info section also contains a viscosity correction curve which shows how pump capacity is affected by viscosity.
step 2: Select the correct wetted Material
Once you have established the application requirements, you can select the correct AODD for the application.
Choose compatible pump body material
Use a chemical resistance guide to select a pump material that is resistant to the material being pumped. AODD pumps are available in the following materials:
| Aluminium | |
| Conductive Polypropylene - Carbon filled Polypropylene, a thermoplastic that is resistant to alkali and strong acids and conductive. | |
| Polypropylene - Thermoplastic that is resistant to alkali and strong acids. | |
| PVDF - Strong fluoropolymer with excellent chemical resistance | |
| Stainless steel |
Choose compatible diaphragm material
Use a chemical resistance guide to select a diaphragm material that is resistant to the material being pumped. Diaphragms are available in the following materials
| Buna | |
| EPDM | |
| FKM | |
| PTFE (with Neoprene) | |
| PTFE (with Santoprene) | |
| Santoprene |
Note: Each pump contains other materials that will be in contact with the fluid being pumped in addition to the diaphragm material. Information on the materials of construction can be found on the individual series datasheet. If you have any questions concerning compatibility, contact our sales office on 0800 3167891
Santoprene is a registered tradename of Exxon Mobil Corp.