Tank lids and wine pumps
When a pumping action is initiated on a tank with a closed lid, the tank can suck in and contract much like a Coke can pressed together. Preventing this from happening was identified by several winemakers consulted as the most important precautionary measure in a cellar. A good practical approach is to provide a checklist together with the job card when wine is pumped from one tank to another. The checklist can even be printed on the back of the job card. It is an easy way to remind cellar assistants about the importance of and accuracy required for the actions they execute. Cellar assistants then check off the items on the list as they complete them and sign at each action to confirm completion. Checklists can be especially helpful during harvest time when the work days are long and people become tired. Completed job cards and signed checklists serve as a record that each action was completed correctly. This is very important for traceability.
Example of a checklist:
- Ensure that the top lids of both the tank pumped from and the tank pumped to are open before the pump is switched on (most important point).
- Ensure that the correct tanks are worked with as specified on the job card.
- Ensure that the volume of each tank correlates with the volume indicated on the job card.
- Ensure that the receiving tank is properly cleaned before pumping wine into it.
- Ensure that the receiving tank’s lid is properly closed after the wine has been fully pumped in and that the lid seals well.
- Report any leakages observed on the tank the wine was pumped from, so these can be fixed before wine is pumped into the tank again.
Oxygen control in cellars
Excessive exposure to oxygen can cause oxidation and subsequent spoilage in wines. It is therefore critically important that high dissolved oxygen levels in wines are prevented. The saying ‘prevention is better than cure’ is apt in this regard. Here are a few tips:
- Use cylinders of carbon dioxide (CO2), nitrogen (N2) or dry ice to displace oxygen from tanks. Formulas and advice exist regarding the amount of dry ice to be used given the surface of your tank’s bottom, and how long to apply the gas.
- If you are just starting to fill the tank, the pump should initially be set to a slow speed. Where the wine enters the tank, there is usually a lot of turbulence and this can possibly lead to excessive oxygen uptake. If the wine level gets to approximately 20 to 30 cm above the bottom, the pump can be set faster.
- It is not desirable to leave a wine tank 100% full for a period of longer than a day or two. It does however occasionally happen that this cannot be avoided. The best practice in such cases is to apply a protective layer of CO2 or N2 on top of the tank. Equipment is available to help distribute the gas evenly across the tank. Even distribution is very important for the effectiveness of the protection.
- When bottling of a full tank is initiated, it is also a good practice to apply a protective layer of CO2 or N2 on the wine when the tank is approximately half full. This helps to ensure that even the last litre bottled out of such a tank cannot be spoiled by oxygen.
Cellar pumps
In the previous cellar mistakes article, pumps were also discussed. Here are a few more tips regarding pumps and their application:
- Make sure that the pump used is suitable for the type of product to be pumped. Different types of pumps are required for wine, wine lees, washing chemicals and grape concentrate. The lifespan of pumps can be extended and the quality of the cellar’s wine maintained by using the correct pump for each action and restricting its use to that action only.
- No pump is built and intended to be used at 100% of its capacity all the time. Neither the pump nor the wine benefit from a pump working too hard, hopping around frantically while the wine is pumped. This should be kept in mind when pumps are purchased. If the objective is to pump 30 000 litres within an hour, a pump should be purchased that can pump about 40 000 litres per hour at its maximum capacity.
- Pumps are manufactured and released with a certain size fitting. For example, a 65 mm fitting. Never use a pipe with a pump of this size that is smaller than 50 mm. In the case of a 100 mm pipe, nothing smaller than an 80 mm pipe. Using smaller pipes will only create unnecessary pressure on the pump, which is detrimental to its lifespan and wine quality.
- Suction pipes should be as short as possible and in good condition. If the pipe is damaged in any way, air can be sucked in. The weak spot can also cause the pipe itself to be sucked in and this can damage the pump.
In conclusion, it is the little foxes that spoil the vines. Regardless of how minor the mistakes highlighted here are, the more they are identified and prevented, the better it is for a cellar’s wine quality and economic sustainability.
For more information, contact Pieter Badenhorst at pieterb@fortheloveofwine.co.za.
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