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meerkat

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meerkat last won the day on July 7 2017

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  1. Lab distillation of very high-solids liqueurs

    @teh_pitts With a true ABV of around 13 % the lab distillations with 50 ml rinse water indicated 0.9 to 1.2 ABV % low.
  2. We have recently experienced some problems when using the standard TTB procedure for determining ABV by lab distillation of liqueurs containing above 30% solids, especially if we have milk solids present. If we start with 100 ml of sample, add 50 ml of rinsing water and then distill off the recommended 96 ml what is left in the boiling flask is so thick that it is impossible to deal with. The actual ABV of the sample is known because we know how much neutral spirit had been added and we know the total volume (from the total mass and measured density). This corresponded very closely with the ABV calculated by AlcoDens LQ, but the lab distillation always gave low results. I suspect this was due to carry over of solids. Even commercial lab results were quite far from the known ABV. We modified the lab distillation procedure and are now getting much more accurate and consistent results, and I would really appreciate your comments if you have experienced similar problems. In our modified procedure we still start with a 100 ml sample but we add 200 ml of water and then distill off 196 ml (which we make up to 200 ml), leaving approximately 100 ml in the boiling flask. This means that the initial solids are still in 100 ml and remain nicely in solution. My calculations show that for a sample containing 15 ABV this procedure will recover +99.99% of the alcohol. Since the alcohol that was initially in 100 ml is now in 200 ml the measured ABV has to be doubled. We understand that this halves the precision of the measurement but the results are so much closer to the known value and are much more consistent - and the glassware is much easier to clean afterwards! How have you gotten around this problem?
  3. Proofing Issues

    It would seem that your blending targeted at 95 proof was actually spot on (and not 95.6) because if you calculate 190 lb of 95 proof plus 1.65 lb of water you get 94.25 proof. I would guess that everything was correct, but your gauging after the first blend gave a slightly higher reading than it should have. Others have also mentioned that immediately after blending the measured proof can be slightly high and the most plausible theory I have come across for this is that micro bubbles of air are mixed into the spirit during blending lowering the density and making the proof appear high. It could of course also be caused by the exothermic blending raising the temperature and decreasing the density, but I presume that you would have corrected for the temperature. Whatever the cause, leaving the blend to settle for 12 hours or so will give the correct proof. What is strange in this case is that the second blending immediately gave the correct/expected proof. Was there any difference in the way you did the first and second blends? How soon after the first blend was completed did you do the gauging, and how long after the gauging did you add the extra water?
  4. How do you measure the spirits quantity ?

    @Still_Holler I am a bit confused about what exactly you are asking because in an earlier post you asked whether temperature corrections need to be applied if the quantity of spirit is measured by weight, but then in your example the quantity is given in volume. Let's look at both alternatives, as applied to your example. If you measure 1000 gallons at 76°F then you would have to use Table 7 to correct the volume to 60°F. As you showed before, the factor is 0.991 and there would be 991 wine gallons at 60°F. For reporting purposes you need the proof gallons and this is simply 991 x 190 / 100 = 1882.9 proof gallons. If you had weighed the same tank you would have got a weight of 6733 lbs. From Table 4 we get that 190 proof spirit has 0.27964 PG/lb so we can calculate the total proof gallons as 6733 x 0.27964 = 1882.8 PG. So in summary, if you have the weight and the proof you can go directly to the proof gallons using Table 4. If you have the volume and the proof then you also need the temperature at which the volume was measured so that you can obtain the volume at 60°F, and then obtain the proof gallons by correcting this volume by the ratio of the actual proof to 100 proof (190/100 in the example).
  5. Ethanol Water Contraction and Dilution

    Thanks to @John Bassett and @HedgeBird for the kind words. @PeteB - please will you make a screen shot of where the problem occurred. I guess it wasn't on the Hydrometer Correction calculator? If it was on one of the blending calculators then maybe I could lock the choice between Proof, ABV and Mass the way that the Standard Temperature can be locked. This would allow all the choices to be fixed for normal work, but leave the option open for the one weird day when you need to blend some European (or Aussie!) ABV spirit with some American Proof spirit.
  6. Pulsing Still

    @Hudson bay distillers If there is such a thing as a universal optimum temperature for the feed to a continuous column then I would say it is the boiling point corresponding to the composition of the feed. If it is colder than this it causes internal reflux in the bottom part of the column which does not do much towards providing a high strength top product. On the other hand if it is hotter than the boiling point you will find that you need to provide a higher reflux ratio from the condenser which increases the water requirements on the condenser but saves a bit of heat on the boiler. But I have seen feed temperatures from substantially below the boiling point all the way through to feeding the column with 100% vapour. If the feed is not a liquid at its boiling point then a change in diameter of the column at the feed point may be required.
  7. Pulsing Still

    From one physics nerd to another.... I believe you are on the right track with your interpretation that it is the boiling that stops and starts. I have seen a similar phenomenon in continuous columns that have significantly oversized external reboilers. These get into a similar cycle of pulsing and the accepted interpretation was always that boiling was stopping and starting. With the very oversized reboiler, heat can be passed through the tubes into the liquid so fast that a vapor blanket is formed on the inside of the tubes. The heat transfer through vapor is much slower than through liquid and suddenly the heat transfer stops. The bouyancy of the vapor gradually causes the vapor to rise out of the reboiler and colder liquid flows in from the bottom of the column. Heat transfer picks up because of the higher thermal conductivity of the liquid and the cycle repeats.
  8. Violent bubbling in the parrot

    To eliminate the liquid U-seal formed by the tapered section below the condenser and the parrot itself you can either lower the parrot or raise the entire condenser. Once you have the levels changed so that the section of pipe coming out of the condenser stand no longer stays flooded with liquid you can install a vent as suggested by Dehner. It probably sounds like a lot of hassle to do, but if you don't this setup will always be awkward to operate.
  9. Violent bubbling in the parrot

    It appears that the stainless vessel to the right of the parrot in the photo is the condenser. If that is so, then you will have a problem installing a vent. In order for the condensed liquid to develop sufficient head to flow over the top edge of the parrot the level of liquid in the condenser will have to build up to slightly higher than the top edge of the parrot. This will create a liquid seal at the bottom of the condenser and gas will not be able to get to the outlet. If you were only concerned with flushing trapped air at startup then the suggestion by PeteB to open the bypass would be adequate. But there will also be dissolved air and CO2 in the fermented beer and this could continue to come out during operation. There will also be light ends (aldehydes etc) that some operators allow to escape from the vent by setting the cooling water flow to get a fairly high temperature for the condensate. Colder isn't always better. By creating a seal at the bottom of the condenser you will force the pressure in the still and condenser to gradually build up (due to incondensible gases) to the point where the seal is blown and you get the surging you are seeing now. In my experience the outlet from the condenser either flows to a small vented pot and then drains from the bottom of the pot to the parrot, or else the vent is mounted on the body of the condenser itself. This second option is common when the condenser is mounted at floor level. We cannot see the other side of the condenser in the photo - perhaps there is already a vent mounted there?
  10. Violent bubbling in the parrot

    When I have seen this in the past it has always been because the product line from the condenser down to the parrot (or flow meter) has been too small and the liquid flowing down entrains air sucked in via the condenser vent. The solution is just to use a larger diameter drain pipe from the condenser. But it seems this is not the reason in your case. If you genuinely do not have a vent after the condenser there is nowhere for the air that is in the system at startup to escape - except via the parrot. As the water is turned to steam and displaces the air, the air will be forced out via the parrot. Seeing that it stops after 10-20 minutes I suspect this is the cause rather than the small drain pipe I mentioned above.
  11. Bottle Filling Calibration

    ReadeHud, your math is correct. There are two reasons why the mass you have calculated for 750 ml is different from the values calculated by PeteB and Silk City earlier. The first reason is that the values calculated by Pete and Silk were for 750 ml at 60°F but you are working at 20°C. 20°C is a bit hotter than 60°F and the spirit expands and for the same volume you have less mass. The second reason is that although 80 Proof is equal to 40 Vol% at 60°F it is not the same as 40 Vol% at 20°C. Alcohol and water have different rates of thermal expansion and as the spirit is warmed from 60°F to 20°C the alcohol portion expands (very slightly) more than the water. This changes the volumetric ratio between the alcohol and the water. 80 Proof is equal to 40.07 ABV at 20°C, so when you buy equal volumes of spirit at 40 ABV from US and European suppliers you actually get a bit more alcohol from your US supplier. A large part of the confusion between weights and masses in air and in vacuum is our loose use of the terms weight and mass. We use the terms weight and mass interchangeably, but they are really two entirely different physical quantities. Weight is actually a force, and is related to mass by Newton's second law ( F = m x a ). The most common way to determine mass is to actually measure the weight (i.e. force of gravitational attraction to the earth measured on a balance or scale) and then infer the mass from the second law. Of course we don't actually do the math every time and the "a" term is built into the calibration of the scale and we simply read out the result as a mass in pounds or kilograms. The mass of an object is not affected by the presence of surrounding air, water or other fluid. Nor is it affected by the force of gravity. But weight is obviously affected by both. Using gravity to measure weight and inferring the mass is not the only way to measure mass. When astronauts spend extended periods in space it is very important for them to know how their mass is changing (for health reasons) but because they are weightless in space a normal scale will not work. They measure their "inertial mass", which is actually the same as the "gravitational mass". If all this is not sufficiently confusing, try using the Canadian alcohol tables which measure ABV using the "in vacuum" density value, and then use the "in air" density value to determine the volume of the spirit.
  12. Ethanol Water Contraction and Dilution

    PeteB - The calculation for the quantity of water required to dilute to a target proof is illustrated in the article I referenced before. The example is based on volumes, but it could easily be converted to weights using a similar method to what I showed above when using Tom's suggestion to use Table 4. whiskeytango - The questions you are asking are exactly those AlcoDens was designed to answer. The formulas are way too complex to use in manual calculations. They are freely available from the OIML site if you want to see just how involved they are. The AlcoDens calculator for doing this can convert back and forth between Mass (Weight) %, Density, Volume % (ABV), Proof and Molar % As an example assume there is an unknown quantity of 150 proof spirit to which we add 100 lbs of water. After mixing the proof is 100 proof. What was the unknown volume of 150 proof spirit and what volume of 100 proof spirit has been produced? In the example shown below Source 2 is the pure water (Proof = 0). I have set the Source 2 quantity to mass and given the weight as 100 lbs, but you could equally well give the quantity as volume. In the bottom right panel you tell the program that the quantity of Source 2 is the known quantity. Set the Source 1 and Final Blend quantities to Volume and it will calculate how much 150 proof spirit was used and how much 100 proof has been produced. THis could be solved using Tom's Table 4 method provided all quantities are in weight terms by starting off with the classic "Let X be the mass of 150 proof spirit" and noting that the number of proof gallons does not change when you add pure water. Once the answers have been calculated in weight terms they can easily be converted to volumes.
  13. Ethanol Water Contraction and Dilution

    Thanks Tom, using Table 4 is a bit easier because it provides data for every 0.1 proof and it is probably easier to understand. For comparison with my earlier calculation here is the Table 4 method. 160 pf spirit has 0.13903 WG/lb. Table 4 only starts at 1 proof and from standard engineering tables the specific volume of water at 60 degrees F is 0.12008 WG/lb. The weight of the spirit is therefore 100/0.13903 = 719.27 lbs and the weight of the water is 100/0.12008 = 832.78 lbs The total weight is 719.27+832.78 = 1552.05 lbs. This contains the same 160 PGs that were in the original spirit so we have 160/1552.05 = 0.10309 PG/lb Table 4 shows (without interpolation) that this is 81.6 proof and the specific volume is 0.12633 WG/lb Total volume is 1552.05 x 0.12633 = 196.07 gallons This is definitely shorter and more direct than my earlier calculation. But AlcoDens still wins, especially if the temperature is not 60 F and the calculated PG/lb requires interpolation.
  14. Ethanol Water Contraction and Dilution

    Disclaimer: I am the author of the AlcoDens blending app mentioned below, so I am probably biased. This question of how to do blending calculations comes up fairly often, so I wrote this article to compare 3 of the methods. I have not seen any really comprehensive guide to performing calculations using the TTB Tables, but I am aware of two distillers who are in the process of preparing books that will cover this. Hopefully early next year (2018) things will be better. The theoretical blend proposed by whiskeytango is unfortunately not in the form for which the TTB Tables were structured. The tables are designed to easily answer the question of how much water to add to dilute the 100 gallons of 160 proof down to 80 proof. But it can be done. I will show my solution but perhaps someone who actually uses the TTB tables can show an easier way. From Table 6, 160 proof spirit contains 80 parts of alcohol and 22.87 parts of water. BTW, the fact that these add up to 102.87 shows how the tables do include the effect of contraction. If we now add 100 gallons of water to 100 gallons of 160 proof spirit we still have 80 parts (gallons) of alcohol but we now have 122.87 parts of water. The ratio of parts of alcohol to parts of water is 80/122.87 = 0.6511. Now we have to scan through Table 6 to find what proof corresponds to this ratio. As I said, the tables are not structured to make this easy. At 81 proof the ratio is 40.5/62.95 = 0.6434 At 82 proof the ratio is 41.0/62.47 = 0.6563 By interpolation we see that a ratio of 0.6511 corresponds to a strength of 81.6 proof. This diluted spirit obviously contains 81.6/2 = 40.8 parts of alcohol. This came from the original 80 gallons of alcohol in the 160 proof spirit. If 80 gallons is 40.8 parts then the total parts (i.e. 100) must be 80x(100/40.8)= 196.08 gallons. Naturally, I checked this with AlcoDens to make sure I had the correct answers. Because I do not do these calculations using the TTB Tables very often I did make a few mistakes along the way, but the values above compare well with the AlcoDens answer shown below.
  15. Proofing using Gauging Manual Table 6

    Yes, the interpolation in Table 6 is very similar to that for Table 1. In fact it is a bit easier because you only have two parameters to deal with (proof vs parts of water) while in Table 1 you have three parameters (apparent proof, true proof and temperature). I have not seen the TTB data in the form of an equation - only as the Tables. There must be an equation because the Tables could not have been generated from experiments at every published point, and must have been generated from an equation. I just have not seen it. The data that is openly available as a formula is the European OIML alcohol-water density data. This is the data that forms the basis of my AlcoDens program. The OIML and TTB data are based on much of the same original experimental data but they are presented in different terms. The TTB data is (mostly) presented as densities and masses measured in air but the OIML data is presented as absolute or "in vacuum" values. Fortunately it is possible to convert between "in air" and "in vacuum" data so it is possible to select in AlcoDens whether you want to match the TTB or OIML tables.
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