From Vine to Wine with Air-Operated Double-Diaphragm (AODD) Pumps
AODD Technologies in Winemaking
Today, various pump technologies are used for winemaking and transfer. While many offer the applicable features to meet the demands of the wine industry, some of those technologies can also come with deficiencies:
- Progressive Cavity: Progressive cavity pumps can be used in the juice-extraction process, but can be susceptible to damage during dry-run conditions. When a pump “runs dry,” it continues to operate even after the wine has been processed in order to clear the lines. As a result, the pump’s components can burn and seize, damaging the pump internals. The wine industry generally relies on manual-batch production operation that can lend themselves to dry-running conditions. One other possible disadvantage of progressive cavity pumps in wine applications is that stator/rotor wear can impact the quality and taste, if rubber shavings penetrate the product stream.
- Lobe: Lobe pumps are commonly used for wine due to their portability and low shear. One concern, however, is the presence of a rotary seal, which increases the possibility of leaks and contamination. A seal fail can lead to expensive downtime and maintenance along with loss of product. Even one lobe pump advantage — portability — can be a disadvantage as lobe pumps are traditionally heavier in nature, hindering the ease of transfer in wineries. Because of the inefficiencies of lobe (or ECP) pumps at low viscosity, they are also prone to impart shear into the wine and degrade the end product.
- Eccentric Disc: Eccentric disc pumps are used in several wineries around the world, consisting of a cylinder and pumping element mounted on an eccentric shaft. As the eccentric shaft is rotated, the pumping element forms chambers within the cylinder, which increase in size at the intake port, drawing fluid into the pumping chamber. The fluid is transported to the discharge port where the pumping chamber size is decreased. This action squeezes the fluid out into the discharge piping. Eccentric disc pumps are seal-less, self-priming and can run dry, while also providing shear-sensitivity and gentle transfer of products. They are exceptional at clearing tanks and piping. In wineries, they are ideal for transfer from storage tanks to tangential filters, or to bottling tanks.
- Centrifugal: Centrifugal pumps are commonly used in large wineries for tank-to-tank transfers, although, due to the absence of self-priming capabilities, they are most effective if placed below the level of the tank outlet. Another concern with centrifugal pumps is that they tend to homogenize air in wine and trap the oxygen, producing oxidation that adversely affects the taste.
- Peristaltic (Hose): Peristaltic pumps boast some advantages in wine applications as they can effectively transfer the most delicate or abrasive media or fluids containing solids, can run dry and handle higher capacities. Peristaltic pumps are also self-priming, have high suction-lift capabilities and can run in forward or reverse. Unfortunately, these positives can be outweighed by a few operational negatives: their mode of operation creates pulsation within the transferred product; hoses must be changed regularly, which increases downtime; and the rubber hose can shed or spall, which can lead to product contamination.
- Diaphragm: Another pump technology that has been gaining greater acceptance in wineries: diaphragm pumps, which account for approximately 25% of the pumps used in the wine industry worldwide, are easy to clean and maintain, offering the gentle handling required in winemaking and transfer. Diaphragm pumps can also move large volumes of fluid and can be set up to automatically stop when pumping against a closed valve due to the back pressure in the hose. Diaphragm pumps are portable and have no seals, which allows them to keep outside air from compromising the integrity of the wine.