Installation and Maintenance
AODD pumps are very reliable since they have very few moving parts or components that can wear.
They are easily dismantled for maintenance or diaphragm replacement. They can be mounted wherever there is physical space for them, even submerged if the material of the pump is compatible with the fluid and the exhaust is ported out of the liquid.
Their simple mode of operation means that there is no need for bypass piping or pressure relief valves. If vibrations and surges cause problems in the piping systems, pulsation dampeners can be fitted.
The AODD pump uses compressed air as its power source and therefore can be used in areas either where electricity simply isn’t available, or in hazardous areas where electrical supplies are forbidden.
Compressed air is explosion-proof and there are no electrical or heat-generating components to spark and cause product flashing. This gives AODD pumps greater versatility than centrifugal or positive displacement pumps and offers pollution-free operation.
Most AODD pumps use oil-free compressed air, which has environmental benefits since no oil mist is vented into the atmosphere, and also there can be no oil contamination of the pumped fluid. In addition, there are no costs associated with oil consumption or lubrication.
Life cycle costs
Assessing the cost of ownership of a pump is actually a function of the overall installation as much as the costs associated with purchasing and running the pump itself. If the plant is not appropriately designed for the application, the pump may well cost more to run than it should. In terms of the pump itself, costs can be broken down into purchase and installation costs, maintenance costs (labour and spares), energy costs and removal/disposal costs.
The main consumable items in an AODD pump are valves, valve seats and diaphragms. In general, spares are low cost, but it is important to use the most appropriate components. For example, Neoprene is excellent for general-purpose, low cost diaphragms giving the highest flex life. Buna-N® (also known as nitrile) is approximately 70% more expensive than neoprene, while Nordel® (also known as EPDM) is approximately 40% more expensive than neoprene. Viton® is highly resistant but is approximately nine times more expensive than neoprene. Teflon diaphragms are typically ten times more expensive than polyurethane.
Thus choice of the most suitable diaphragm for the application can significantly affect maintenance costs. Compressed air is a relatively costly utility in many plants, requiring compressors and air distribution systems and higher energy costs, so engineers must weigh up the cost benefits.
However, the sheer versatility of the AODD pump has a value that is almost impossible to calculate. The AODD pump offers a real alternative to centrifugal and positive displacement pumps and should not be overlooked in the pump selection process.
This article was first published in World Pumps.