gauging of spirits

[Werner Distilling]

After receiving my permit, this week has been the first batch I've run. I ran three days of stripping runs and I am beginning the spirit run today. I weighed my daily production, and I have 184lb of 98.6 proof rum. That's corrected for temp. If I know the weight and the proof, what's the formula for volume? I'd like to know how much water to add, not just for getting below 40% to do this run, but I'm going to need that basic knowledge to make the final cut to 40% with the finished product.

[PeteB]

You can do it the long way by looking up TTB tables and doing a lot of maths,

or the easy way

Find a free trial version of AlcoDens on line, it will calculate almost any spirit calculations in any units and mixtures of units

[meerkat]

Disclaimer - I am the author of the AlcoDens program mentioned by PeteB above

When converting between mass and volume you have to use the density (or specific volume). Sometimes it is confusing whether you should multiply or divide, and the trick is to look at the units. TTB Table 4 will tell you that the specific volume of 98.6 proof spirit is 0.12835 gallon/lb. To convert your 184 lbs to gallons you must multiply by the 0.12835 gallon/lb because if you multiply lb x gallon/lb the lbs cancel out and you are left with the gallons that you want. Multiplying these two together tells you that you will have 23.62 gallons at 60 °F. You can then use Table 7 to correct to your actual temperature.

If you download the trial version of AlcoDens ( http://www.katmarsof...om/alcodens.htm ) it will tell you that the volume at 60 °F is 23.59 gallons. The trial version will work for 15 runs, so rather leave it running until you switch your computer off at the end of the day or you will use up the trial runs very quickly.

The layout of the TTB Tables is specifically designed to enable you to do the dilution calculation you want. The procedure required was very well described by Will in another thread so I won't try to do it again here. See http://adiforums.com...owtopic=769&hl=

While you are learning to do the TTB calculations you can test yourself by doing them in AlcoDens as well to check that you get the same answers. You will also find several online (i.e. web based) dilution calculators, but so far the ones I have found all use the Pearson Square method which is not accurate for spirits. Its fine for blending wines of similar strengths, but it does not take into account the volume changes that occur when ethanol and water are mixed. The TTB Tables (and AlcoDens) do take the volume changes into account properly.

[Werner Distilling]

Thanks! The link was a great read and I found the charts.