How do you measure the spirits quantity ?

[Silk City Distillers]

I've seen others making reference to this "stick" for measuring volume.  Don't forget about TTB table 27.  Expansion coefficient by temperature and liquid absorption for each wood species.  You need to adjust for growth and shrinkage of the stick based on the temp and how much liquid it's absorbed in the process.

Never a day so freeing as the day you stop thinking in volumetric measurement.  I've had lots of commercial bakers tell me this as well.  It's hard to give it up, but once you do, woooo wee you don't look back.

 

[dhdunbar]

There is a simple bottom line here.  Silk City said it. 

22 hours ago, Silk City Distillers said:

The weight stays the same regardless of the temperature.  Just to be very clear, when gauging with a hydrometer, you always need to adjust for temperature.  But the weight of the distillate being gauged, that's static.

Once you have determined the proof to whatever degree of accuracy your vision, your instruments, and the five decimal conversion factors of TTB's tables will allow, just apply the factors in Table 4 and enter the result, properly rounded, into your records.  That is what TTB tells you to do and it is also what makes sense.  

Meerkat's variance is illustrative.  I've not checked his calculations, I'll just accept them.  His variance is 0.1 proof gallons on a total of 1882 proof gallons, or 0.0053%.  But the "actual" corrected volume of the liquid does not change with temperature.  I'm forced to use quotation marks around actual because we have no way of determining the "actual" quantity.  All of our measurements are estimates.  The he calculated, 0.1 pg  difference arises  from the accuracy of the five decimal place, more than likely irrational, conversion factors  in the table.  With each decimal place added to the conversion factors, to the limits of our ability to calculate them, the variance shrinks.   Meerkat's variance says,  by its election to use five decimal conversion factors, TTB expresses the intrinsic  difference it is willing to accept when the variables, volume and proof, are held to be spot on accurate.  In practice,  of course, TTB is willing to accept a lot greater variance than that,  since we cannot measure apparent proof to anything like PeteB's 1:1000 as we stare at the meniscus of the spirits in the flask or at the apparent temperature reading on the thermometer.  Nor is any instrument certified to such accuracy.    

[dhdunbar]

Regarding sticks.  It seems we used to use a long wooden stick at a vinegar plant to measure the volume of alcohol in a large tank.  We also used a stick - wood again, and again as I recall - when measuring the depth of the alcohol in tank trucks.  I don't recall making any adjustments for the absorption factor of the wood, but we did have to watch how it would seep up the stick by a process for which Silk City probably has a name. As I recall, the measurements were not critical to anything. 

But all tax determination gauges were made by weight.  Period.  That is still the requirement.  See 19.284.  Because cutting to proof is essentially a tax determination gauge, although it is not called that, since the tax determination gauge for packaged spirits is made based on the label claims and number of bottles per case, I would conjecture that TTB would like the gauge in the bottling tank made by weight.  However, the regulations allow all other required gauges to be made by volume (19.284 (c)), so the reduction to proof before bottling, which is a required gauge (19.283(g)) may be done by volume.   That said,  Silk City's reference to bakers would seem to apply.  You run the real risk of missing the cut, if you measure your spirits by volume.

 

[Dehner Distillery]

If you know the weight and the proof you are set. 

If you go by volume well if its 72f the spirit may show x amount of volume, if it is 92 it will show y amount of volume...... but the weight will always be the same.

Weight , weight, weight, weight!!!! always weight.

We have many scales and an Anton Parr