Waukesha Universal Series Pumps- Why They are the PD Pump of Choice for Making Wine

February 10, 2014
Waukesha U1 Pumps on Portable Bases

Waukesha U1 Pumps on Portable Bases

In the wine industry, low shear and gentle handling of grapes is essential. For viticulturists, gentle handling is important in early stages of wine making, as well as final fill and bottling. In wine making, damaged grapes, cracked skins, and crushed seeds can release unwanted elements into the juice, affecting the end product. While it is impossible to keep 100% of the grape clusters intact, certain pump designs are better than others for grape handling during common winery applications. While previous posts have focused the advantages of the Waukesha External Circumferential Piston pumps, the Universal 1 and Universal 2, this post will focus on a few specific wine applications where end users can benefit by employing rotary lobe pumps.

Must Pumping
At a vineyard, after grapes are harvested, they must be turned into must. Must is made up of crushed or cracked grapes, skins, seeds, and stems. Must can also contain other solids, such as small stones or even staples that are used to attached vines. A good must pump needs to be able to handle these entrained solids.

As we’ve detailed in past posts, ECP pumps are a great choice for handling entrained solids. Waukesha pumps are run at relatively low speeds and have large liquid cavities that make them ideal for drawing liquids with hard solids into the fluid head and gently displacing them.

The gentle, low shear nature of the Waukesha pump enables them to move the must through the pump without crushing the skins, stems, and seeds. Crushing of the skins, stems, and seeds can lead to the release of unwanted elements into the must which can negatively affect the final product.

Lees Removal
Lees are deposits of dead yeast or residual yeast and other particles that precipitate at the bottom of a vat of wine after fermentation and aging. This residual needs to be removed and is usually pumped into another bin or tank for disposal. Pumping lees is difficult because it has a high viscosity and solids content. Because it is a waste byproduct, gentle handling of lees is not essential. However, lees removal applications generally have low suction head available and require pumps that provide strong suction capabilities. The slow speeds and low suction head requirements of the Waukesha Universal pumps make them ideal for lees handling applications.

Pump Over
Maceration is the process where the phenolic components- largely responsible for the taste, color, and mouth feel of the wine- are leached from the grape skins, seeds, and stems into the must. To macerate is to soften by soaking, and maceration is the process by which the red wine receives it color. During the maceration process, rising carbon dioxide released from the must creates a cap of skins and solids at the top of the vat. Avoiding this cap layer is advantageous for many reasons that are outside the scope of this post. There are two traditional ways of removing this cap. The first uses a mechanical arm to “punch” the cap down into the must. Waukesha pumps don’t have a mechanical arm option and are not useful for this application. Waukesha pumps are, however, useful another way of avoiding cap layering- pump over.

In the pump over method, juice is pumped from the bottom of the tank onto the cap. The pumping over of the juice forces the cap back down into the must and maximizes maceration. Pump over requires circulating liquid over a long period of time. This means that the entire liquid contents of a batch may be circulated through the pump numerous times. Must is shear sensitive and choosing a pump that is as close to shear free as possible is essential. Because of their unique design, Waukesha pumps are able to produce a discharge head independent of rotational speed. This makes it possible to run the pump slowly, in a manner conducive to low shear, and still generate enough discharge pressure to pump the fluid back up and into the fermentation tank.

Pomace is solid remains of grapes, olives, or other fruits after pressing for juice or oils. It contains skins, pulp, seeds and stems. Pomace is left over after the wine making process and can be used to make grappa or brandy. It can also be composted and discarded altogether. Typically, pomace is washed or sluiced out of a tank and then pumped to its final destination. A pomace pump needs to be able to handle the thick viscous solids remaining after the winemaking process. Because the Universal 1 and Universal 2 pumps handle solids so well, only a minimal amount of must or water needs to be added to the pomace to make it pumpable. This, along with the low suction requirements previous noted, make ECP pumps ideal for pomace applications.

To conclude, the Universal 1 and Universal 2 pumps are Waukesha’s “Can Do” pumps. They have low suction requirements and can handle the thick, solid laden fluids often found in vineyards across the world. The ECP design is ultra-low shear and ideal for handling must and other shear sensitive fluids. The U1 and U2 are also light weight and Holland offers them pre-assembled to portable bases and extensive controls options that allows us to tailor their usage to any of many common wine making processing. Contact a Holland Sales Engineer today for more information about applying a Universal 1 or Universal 2 to your next pump application for making wine.