In many industrial practices, liquids are stored in airtight containers that can only be accessed through a small round hole. Often these liquids are placed in the containers over a period of time which allows solids to settle from the liquid suspension. The clear liquid needs to be recovered without contamination of the settled solids in a process called racking.
The most common usage of racking is in the wine industry. Newly made wine is aged in wooden barrels. Over time, sediment, or lees, settles to the bottom of the barrels. Winemakers need to remove the clear wine from the lees to process the wine.
A simple instrument for racking is a racking wand. A racking wand is a rigid, hollow tube that is often attached to a rubber hose so that fluid can be siphoned from the container. This method has several disadvantages. The wand must be supported manually so that the tube inlet is above the lees. Suction must be created in the rubber hose (often by mouth suction) which is not only unsanitary, but generally requires another person. Most importantly, as the racking wand is inserted into a small hole in the barrel (called a bung hole), the wine is exposed to the atmosphere, which can oxidize the wine, turning it into vinegar.
U.S. patent 2007/0199,199 to Lake et al. (2007) added magnets to the end of the wand to keep the inlet tube above the lees. However, this device can only work in metallic containers which can hold an adjoining magnet and does not solve the problem of wine oxidation.
Some nonpatented racking wands insert the wand through a plastic corklike device called a bung—which fits snugly into the bung hole. Now the racking wand is suspended above the lees. However, every barrel has a different level of lees, so the racking wand has to be laboriously adjusted within the bung. Additionally, in order to seal the bung snugly into the bung hole, the bung must be pounded in with a hammer. Removal of the bung and racking wand is difficult, and must be hammered out again. If the bung isn't hammered in tightly enough, the racking wand loosens the bung and falls out.
Other nonpatented racking assemblies use gas to displace wine from the barrels. Inert gas, such as nitrogen, prevents wine oxidation. Current gas pressure racking systems still have several disadvantages.
A system manufactured by TCW has an adjustable wand through a bung that pushes wine with an external gas. However, the bung still needs to be hammered into the barrel.
One system (marketed as the Gentle Giant) uses screw tightening mechanism to expand the bung so that is compressed against the bunghole. This method requires a great deal of strength from the operator to get an airtight seal and also is time consuming.
Another system that has been used since 1986 (marketed as the Bulldog Pup) uses a lever lock mechanism to expand the bung into the bung hole. Although less strength is needed to push the levers down and to release them when finished racking, the seal is not airtight and much of the inert gas used to push the wine escapes, which not only is costly, but increases the time needed to rack the wine. Additionally, the lever lock mechanism does not stabilize the wand securely, so that it rotates with the bung as the fulcrum. Therefore, this mechanism requires a person to stabilize the wand manually. The Bulldog pup has attempted to solve the problem of a clear separation of the lees and liquid by adding a brass adjustor with a single bevel compression ferrule to allow vertical lees height adjustment. However, in practice, the wand still tends to slide down into the lees, thus preventing a clean wine racking. Finally, on the occasion when a completely airtight seal is achieved, the bung can still be pushed out of the barrel with high gas pressure. If the system is not watched closely, wine is spilled.