Chapter 22

Wine Tanks

Wine Tank Accessories

There are many types of tanks used in winemaking and winemakers have a variety of options available to them such as aspect ratio, cooling jackets (dimple or channel style), tank control systems (e.g., temperature, cap management, etc.), tank bottoms (flat sloped, dished, or conical), ports, manways (round, oval, or rectangular), gas vents, and fittings and valves of all common types and sizes.

Aspect Ratio

Aspect ratio is the ratio of liquid height to the tank diameter. The ratio of a fermentor's liquid height to diameter can impact its heat-transfer surface area, blend time, and required agitator power. What is the optimum aspect ratio (or height/diameter ratio) for a fermentor? The best answer is it depends on the type of wine.

Red Wine Fermentors

Most producers use stainless-steel fermentors with relatively small height-to-diameter ratios of 1.0 to 1.3. It is believed that such dimensions produce a cap which is relatively easy to manage.

White Wine Fermentors

With regard to tanks typically used to make white wines, these are usually tall in height and small in diameter. White fermentors height-to-diameter ratios tend to range from three times as tall as they are in diameter (3:1 ratio) to as much as eight times as tall as they are in diameter (8:1 ratio).

Cooling Jackets

The excess heat being created must be removed from the fermentor if the temperature of fermentation is to be controlled, which means the fermentor must be equipped with a cooling jacket(s) to remove heat generated during that exothermic reaction and other ambient temperature factors (Figure 22.8). For winemakers, high-quality, lowpressure, dimpled cooling and heating jackets using glycol and water is the most popular option.

Ports

Tanks have two ports at the base of the tank, one for racking and one for total drainage. Typically, a winemaker will rack out of the higher port (appropriately called a racking port) and then drain all the lees and other sediment out of the bottom port (called the drainage port).

Tank Bottoms

Tank bottom configurations can either be flat sloped, dished, or conical. Sloped bottom tanks have, as the name suggests, a sloped bottom. It slopes down at an angle (45°slope) to one side, and this slope leads down to a large door that allows for easy access. A dish bottom tank makes mixing simple due to its construction. Most fermentors have an inclined floor sloping toward the front, while others have hemispherical or dished bases.

Tank Control Systems

Control systems for wine tanks most commonly focus on temperature control for management of wine fermentations, wine storage, and cold stabilization. Tank control systems offer options to monitor and adjust parameters remotely by computer, the internet, or wireless technology. Controller systems can operate tank-stirring devices that reduce temperature stratification. Control systems can be used to automate pump-overs and cap irrigations too.

Temperature Control

Tank control options include basic single-tank thermostats with manual entry and adjustment of temperature set points. These are often used by small wineries with a small number of tanks but can sometimes be integrated into a larger, more complex winery control system as production expands.

Manholes

Other typical components include manholes for winemaking operations which allow access to the interior of the tank for maintenance such as periodic cleaning, inspection, and servicing. Rectangular doors are often used on red wine tanks to speed the removal of cap or must from the bottom of the tank. The rectangular shape better accommodates shovels so that the cleaning process can be accomplished quickly.

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