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meerkat last won the day on May 3

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  1. In the US the TTB distillation method is the only officially acceptable method of proofing. But as PeteB has pointed out, if you have two separate measurements of two independent properties (i.e. density and RI in the case of the Rudolph machine) you can combine them with the applicable math and get to an accurate, but unofficial result. You can do a similar procedure using much cheaper, but also much slower, equipment than the Rudolph AlcoTest. With a simple drying oven and an accurate weighing scale you can measure the solids content after the infusion. Once the sugar content is known it
  2. I think @PeteB is correct regarding the reactions being faster in the liquid phase. I have seen large continuous vodka columns which were made of stainless steel, but the reflux was passed through a bed of copper raschig rings before returning to the column.
  3. I have been supplying engineering software (including a units conversion program) to the US for 30 years, and alcohol blending software for 15 years. Over this period I have seen a gradual shift towards metric units in the US and the eventual total switch over is inevitable. You have already switched to 750 ml bottles to match the rest of the world, and the other changes will not be much more difficult. I think that being proactive about it is the right way to go. Apart from the actual units, the basis of the ABV measurement will have to be changed from 60 °F to 20 °C as the reference t
  4. Check the regulations CFR 30.31 "Determination of Proof" and CFR 30.32 "Determination of Proof Obscuration". Unless you are doing an extreme maceration there is a good chance your solids will be below the 600 mg per 100 milliliter limit. You only need to do an evaporation test to confirm the solids levels. If you are below the limit then you do not need the fancy lab distillation setup or the expensive electronic meters, and the proof determination is basically the same as for a normal vodka.
  5. To move the apparent ABV from a true value of 42.52% down to the 41.97% that you are reading would require only 0.26 mass % of sugar/solids. The only way to be sure of what is happening is to do as Silk City has recommended and do the evaporation test. This will tell you the quantity of solids present. If your column was sufficiently overloaded to carry over that quantity of sugar you would not achieve any rectification at all, so I believe you can rule out sugar from distillation being the cause. If there are solids present they would have to be leached out from the maturation barrel
  6. There is not enough information to comment meaningfully. Was the external lab's ABV higher or lower than yours? Have you given any other samples to this lab where their readings match yours? (in other words - do you trust this lab? if so, why?). What analysis method did the external lab use? If they were compensating for obscuration by solids, did they report any solids levels? If the SNAP 50 does not compensate adequately for temperature, a high temperature sample would have the opposite effect to dissolved solids. High temperature decreases the density of the sample, while dissolv
  7. @Birster If each column has its own drain line with the discharge end below the liquid surface in the pot then the siphon-break holes are not required. This arrangement will prevent vapor traveling between the column bases and the U-bend seals are therefore also not required. Without the U-bend seals there is nothing to siphon out. Doing away with the seals also makes the piping easier to flush and drain. The extra expense of the separate lines does make for a nicer system.
  8. ViolentBlue and I were replying at the same time so I did not see his reply before I hit "submit". It is true that for optimum energy efficiency the bottoms from a column should be pumped as reflux to the top of the previous column. It is always done this way in large commercial distilleries. However, it is common in craft distilleries to drain the bottoms from each column directly back to the pot and each column generates its own reflux by using a deflegmator built into the top of the column. This works just fine, and maybe even adds a bit of flexibility, even if it is a bit less energy e
  9. It is very common for them to share a common return line. However, it is important that vapor cannot travel from one column to another via this line. This seal can be made by using a U bend or a P-trap (but not an S trap). The return line must also not cause a siphon which would pull all the liquid from the return line. The siphon is usually prevented by making sure that the return line is big enough to never run full and by drilling a small (approx 3 mm) hole in the return line inside the pot above the bulk liquid level.
  10. I accept that the time taken for water addition can affect the taste and appearance of the product, but I doubt that this is because of any chemical reactions taking place with the water. I know through personal experience, as well as from studying the theory, that some of the cogeners are not soluble in water. If you add the water too quickly there will be zones in the mixing vessel where the cogeners are in contact with high concentrations of water and very little alcohol. The oils can form emulsions that cause haze and taste concentrations, and these emulsions are extremely difficult to get
  11. It is important to remember that the temperature is not an independent variable that we can set arbitrarily. The temperatures in the table I posted earlier are boiling point temperatures and are fixed by the composition of the boiling liquid. The only way to change the boiling point for a given concentration is to change the pressure, but I am assuming here that everything is being done at normal atmospheric pressure. Let me take the data from the 4th row in the table as an example and assume you have material from a previous stripping run at 32.26 %ABV. If you put this in a pot still an
  12. In general, mixtures of two liquids will boil at temperatures between the boiling points of the two pure liquids and the boiling point will vary with the concentration. The ethanol-water mixture is a bit different in that it forms an azeotrope. From the first sentence above we would expect the boiling point (at atmospheric pressure) of a mixture of ethanol and water to be between 100°C (boiling point of pure water) and 78.37°C (boiling point of pure ethanol). In most cases this is true. However, a mixture containing 95.58 mass % ethanol will boil at 78.15°C, which is lower than the boiling p
  13. For a column of 300 mm ID you definitely do not want to go for the split flow design you have shown. It is unnecessarily complex and restricts the bubbling area. I have seen single pass trays of 2 m diameter working very well, even back in the days of bubble caps. I have never seen a downcomer with perforations at the bottom. You want the flow down the downcomer to be as unimpeded as possible, especially if the liquid is not totally clear. I would leave the bottom of the DC totally open. The residence time is calculated as DC volume divided by volumetric flowrate. Your flowrate of 48
  14. @Modernity I would be wary of using perforated trays if you are going to be distilling grain in. If you are going to make the trays into a removable cassette then that could work if you need to clean them. Maybe wait for @PeteB to post his photos and diagrams to see how he did it. He and I discussed using very simple splash trays before he built his first column, and he came up with a very innovative way of installing the trays but I have not seen what he finally built. If you do go with the perforated trays be generous with your downcomer sizing. I like to allow a downcomer residenc
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