SCLabGuy

@dwa336 There is an Anton Paar DMA 4500 M w/ refractometer for sale here: Not cheap...!

You could also use a thermowell to ensure only stainless comes into contact with product. Unless it says specifically that all the materials are compatible with high proof / pure ethanol, it is safe to assume that it is not intended for the use case you are proposing. I'd wager that you'll taste the plastic, and sooner rather than later, too.

Grain. Includes cereal grains and the seeds of the pseudocereals amaranth, buckwheat, and quinoa. https://www.ttb.gov/press/press-release-fy-22-5

Seconding: AODD pump (self prime & run dry) and lots of valves....valves everywhere.

Are you sure? The mash must be produced in the US (one proposed arm of the reg) and it must be distilled all in the same US distillery (another proposed arm). These two arms would not preclude the use of purchased domestic beer, by my reading.

In a perfect world? Money is no object? Copper bus bar throughout areas where you will store or process spirits. Permanent bonding of stationary tanks, pumps, scales, and tubing. At intervals, attach clamp-style coiled wires: https://www.grainger.com/product/9WN83 Use these clamps on drums, totes, barrels, and portable pumps, bottle fillers/lines, etc. What I've just described can easily be thousands of dollars of hardware...

It is common practice. It can be hard to achieve the flavor density that is typical of a distilled gin, though.

I also know of operators who misused citric with disastrous consequences. Seems like it's usually coming from wine production. It's like I always say. "different things are different."

Whatever I could scrounge up on Craigslist. I have a Beckman unit I like but quite a few brands make serviceable units. Thermo maybe? I look for a 5A+ compressor on the cooling side. I've also cobbled together something workable using a simple compressor-type chiller, pump & sous vide circulator wand in a plastic storage bin. You're heating and cooling and circulating all at once, which works surprisingly well, but isn't particularly energy efficient. Note that lab chillers will also heat and cool simultaneously to maintain temp.

Good questions, all. I have sent you a PM.

I'm sure someone with more chemistry knowledge will chime in here but copper oxide is composed of copper - right? It stands to reason that you are losing some pure copper to form the copper oxide layer. So when you blow away that layer, more copper will end up consumed in creating the next oxide layer. PBW is a caustic.

Yes, you need a water bath to get your sample to a target temp before & after distillation. I tried using a cheap heat-only bath, set for a couple degrees above ambient. I had measurable ethanol losses due to evaporation. I replaced the bath with a more expensive lab bath w/ recirculation & heating+cooling. It's set to 60F which also aids in hydrometer proofing. No more evap losses. YMMV. While the beginning and ending temperatures are not regulated, they do need to be the same before and after, which means you need an accurate thermometer to check your bath. My advice, don't skimp on your gauging tools too much.

TTB finally made a dedicated webpage for their list of approved density meters. https://www.ttb.gov/approvalalternatedevices The Label Modernization Act changes in allowed proofing tolerance did not change the required accuracy of your gauging instruments. You can be +/- 0.3% now, but, you must be as precise in your measurement as always. In other words, you are now allowed a variance, but you must still perform the measurement with a high degree of accuracy and precision.

As far as I can tell, the code of federal regulations is silent on the topic of exactly how frequently you have to recheck your instrument calibration. For the special case of a mass flow meter, it says "every 6 months". For Density Meters, you are supposed to zero on DI/distilled water every time you use it. But for Hydrometer & Thermometer, it is more vague: "... must have accurate instruments... for determining proof" and "Proprietors must frequently test their hydrometers and thermometers to ensure their accuracy". I really dislike wording like that. How often is "frequently"? Surely, it depends on how heavily they are used? I've heard that some TTB agents simply state that you must recertify annually. The question of "how long does a reference cert last" is therefore unanswerable. The certificate is just a piece of paper issued by a lab. It should satisfy a TTB agent for a period of time, but certainly not forever. It will last until the next instance of "frequently". My advice? Since the Reference Thermometer is out of stock, I'd just buy and use the single Reference Thermapen, as it also includes a calibration cert and has an RTD sensor with good accuracy. Take good care of the instrument and especially the probe, and it will easily last a year. After a year, buy a new one and use it to calibrate the old. Now the old is your "workhorse". This strategy balances cost & compliance to my personal satisfaction, but you have to make your own choice for your business. You can also hire a lab service to calibrate your existing instrument against their standard, but the cost of that usually exceeds the cost of buying a new one with a new calibration cert included. I recommend a similar strategy for Hydrometers. But, due to their cost & fragility, I would suggest buying a calibrated standard (~$200-300) and a workhorse upfront ($50-100). In a very simple case where you only bottle Vodka & Whiskey and you are a non distilling producer, you will still need to spend around $2k upfront for three pairs of hydrometers (75-95pf, 105-125pf, 185-206pf) and a reference thermometer. Then, you have an annual rebuy expense of around $1200. Considering that a used density meter can be had for around $8k, I really recommend thinking about that option, because it's so much faster and easier to use than hydrometer/thermometer. CFR citation follows. § 19.188 Measuring devices and proofing instruments. (a) General. A proprietor of a distilled spirits plant must have accurate instruments and equipment at the plant for determining the proof and volume of spirits. (b) Instruments. The hydrometers and thermometers that a proprietor uses to gauge spirits must show subdivisions or graduations of proof and temperature as specified in part 30 of this chapter. Proprietors must frequently test their hydrometers and thermometers to ensure their accuracy. If an instrument appears to be in error, the proprietor may not use the instrument until it is tested and certified as accurate by the manufacturer or another qualified person. (c) Meters. A proprietor may use an accurate mass flow meter to measure the volume of bulk spirits. A mass flow meter used for tax determination of bulk spirits must be certified by the manufacturer or other qualified person as accurate within a tolerance of plus or minus 0.1 percent. A mass flow meter used for all other required gauges of bulk spirits must be certified by the manufacturer or other qualified person as accurate within a tolerance of plus or minus 0.5 percent. The proprietor must make corrections for the temperature of the spirits being measured in conjunction with the volumetric measurement of spirits by mass flow meter. The proprietor must also test mass flow meters at least every 6 months to ensure that they are accurate within the required tolerances. https://www.ecfr.gov/current/title-27/chapter-I/subchapter-A/part-19/subpart-G/subject-group-ECFRe31d95ad7581d87/section-19.188

Here's a video on slow proofing from one of the distilleries (maybe THE distillery) that brought the slow proofing concept to light (brandy makers have been slow proofing for eons). https://www.youtube.com/watch?v=mFUdKxMN3BU You have the right idea to cut by weight. Personally I like to circulate the whiskey in a tote with a small-ish pump (just pump over itself) while a 1/4" ID R/O water supply flows into the tank. That takes minutes/hours instead of days. Proponents of slow proofing will tell you that fast cuts lead to cloudy whiskey and/or saponification, and also that the heat increase from cutting causes volatile aromas to be lost to the atmosphere. I think there's something to the first point and not much to the second point, unless your spirit and/or water are too warm to begin with. If you have multiple similar barrels, why not proof one down slowly (drip feed maybe?) and the other quickly and see if you can pick a difference in a triangle test. If you can't, maybe it's not worth the trouble.