Calibrating your own hydrometers?

[H-D]

I'm a little suspicious of the NIST Traceable hydrometers I've purchased, as the values listed in the calibration reports don't exactly match up when calibrating the hydrometers to each other.

Does anyone here do their own calibrations? Are there any companies that sell certified ethanol reference solutions? I've searched, but have only found calibration solutions for breathalizers (my next step should probably be to just call one of those companies to inquire about getting custom solutions).

Another option would be to mix my own ethanol solutions by weight, using a certified analytical grade ethanol, but I don't think my scale is certified to a high enough tolerance.

Any other ideas?

[Sherman]

Everclear or Golden grain 190 proof is 190 proof to .05 abv.

First I have to ask did you get the IRS certification with your hydrometer? If it is one of those 0-200 proof homebrew hydrometers it is definately wrong. I buy mine from Novatech International and they are always right on. If I need ones for proofing and gauging then I pay the additional $300 for the certificate. I have never had issues with these hydrometers. Often I'll carry a case with 4 of these in 20 proof rages to a new distiller in a custom aluminum case. For accounting for storage and bottling these are a real value compared to the Anton Paar desktop and more accurate than the hand held.

[H-D]

I'm using H-B instrument 75-95 proof hydrometers with 0.2 proof divisions for eveyday use, as well a high precision 79-90 proof hydrometer with 0.1 proof divisions that I was hoping to use for my own calibrations. The outside calibrations I had done were completed by a company called INNOCAL.

Here's another question- does anyone know if the TTB requires a specific calibration procedure?

[bluestar]

Here's another question- does anyone know if the TTB requires a specific calibration procedure?

What is in the CFR seems unclear to me. The whole issue of calibration seems unclear. We really should push the TTB to get up to date with the state-of-the-art in densitometry, and set new standards for using electronic densitometers at accuracy to MEET LEGAL REQUIREMENT as opposed to simply matching what they use in their analytical laboratories, which are complete overkill. JMO.

[jeffw]

I don't remember where I saw it on the TTB site, but somewhere on there it states that only 62% of distilled spirits labels are in compliance which I imagine was a reference purely to proofing.

[H-D]

I don't remember where I saw it on the TTB site, but somewhere on there it states that only 62% of distilled spirits labels are in compliance which I imagine was a reference purely to proofing.

This doesn't surprise me much, considering that the TTB Gauging tables and procedures are inexact, as well as the fact that measuring temperature is just as important as specific gravity. It's hard to make a a truly accurate measurement if your thermometer is only accurate to 0.1 degrees F

[Sorghumrunner]

So, I will be producing products in several different proof ranges (fortified wines - 36-40proof, bottled spirits 75-90 proof, high proof brandy for fortifying wine 140-165 proof, and then I have spirits that will be barrel aged around 110-125 proof)

So that is at least four different hydrometers, plus a wide range one for the still parrot. Should I be purchasing a $300 calibration for each of the four hydrometers, or is it acceptable to just calibrate the final spirits bottling hydrometer (75-90 proof)?

Chris

Everclear or Golden grain 190 proof is 190 proof to .05 abv.
First I have to ask did you get the IRS certification with your hydrometer? If it is one of those 0-200 proof homebrew hydrometers it is definately wrong. I buy mine from Novatech International and they are always right on. If I need ones for proofing and gauging then I pay the additional $300 for the certificate. I have never had issues with these hydrometers. Often I'll carry a case with 4 of these in 20 proof rages to a new distiller in a custom aluminum case. For accounting for storage and bottling these are a real value compared to the Anton Paar desktop and more accurate than the hand held.

[PeteB]

This doesn't surprise me much, considering that the TTB Gauging tables and procedures are inexact, as well as the fact that measuring temperature is just as important as specific gravity. It's hard to make a a truly accurate measurement if your thermometer is only accurate to 0.1 degrees F

I don't work under TTB rules but as some of you may have noticed I do enjoy a bit of mathematical stimulation.

At bottleing proof is where you need to be the most accurate.

80 proof reading at 60 F = 80 proof

80 proof reading at 60.1 F=79.95 proof @ 60 F, only 0.05 wrong

What is the tolerance allowed by TTB? I thought it was 0.2 proof. Don't take my word for it, check for yourself.

So if the hydrometers have 0.1 divisions and TTB says you need to read to 0.2 pr, then a thermometer accurate to 0.1F is four times as accurate at TTB requires.

[JohninWV]

The tolerance is .15% ABV, or .3 proof.

The question comes in when there's a tolerance error on the thermometer and the hydrometer and general human capabilities. Add all of those together, and I think it's very likely that it exceeds the tolerance allowed by the TTB.

We have a DMA5000M (digital density meter), which is the same one the TTB uses. We still regularly send samples to TTB certified labs to check our proof. I also check everyone else's stuff I bring into my office. Nearly every sample I test is outside the allowable tolerance.

[H-D]

We have a DMA5000M (digital density meter), which is the same one the TTB uses. We still regularly send samples to TTB certified labs to check our proof. I also check everyone else's stuff I bring into my office. Nearly every sample I test is outside the allowable tolerance.

How close are your own measurements compared to the values from the TTB lab? Just curious, what's the calibration procedure and frequency for a DMA5000M?

[nabtastic]

IS the DMA5000M more accurate than using scales? (weights)?

[JohninWV]

How close are your own measurements compared to the values from the TTB lab? Just curious, what's the calibration procedure and frequency for a DMA5000M?

Very close. We were off .05 proof from our DMA to the TTB certified lab. That's pretty damn close. What does through us off from time to time is obscuration. We get different numbers from the lab. We recently sent samples to two different TTB certified labs and got two different proofs from the same sample set. The variance was in the amount of obscuration measured.

nabtastic...

You can't measure proof with a scale. You can measure proof gallons once you have the proof.

[JohninWV]

Oh...and to calibrate, we just run distilled water into the machine every day. It runs a test off of pure water to zero itself. It also reads barometric pressure, but we don't calibrate that.

[meerkat]

Perhaps the original intention of TTB Table 6 was to allow the determination of proof using scales, but it is very difficult to do sufficiently accurately. If you used a 1 liter measuring flask you could weigh the contents but you would have to achieve an accuracy of 0.23 gram (0.024%) to be within 0.3 proof at 80 proof. There is also the volume tolerance of the flask to take into account so you really need to be able to measure the volume and the mass to within 0.01% each. It's much easier to get this accuracy with a high grade hydrometer, and even easier (though more expensive) with the DMA machine.

[nabtastic]

I'm a bit embarrassed now. Thanks for clearing things up - I'll stick to the hydrometer. DMA 5000m is pushing $25k though. I can go through a lot of hydrometers and potential tax loss for that. Pardon, while I remove the foot from my mouth..

[JohninWV]

meerkat....

I think that's above my "smarts" level.

[meerkat]

There's nothing to be embarrassed about. I have the "book learning" but I have very little knowledge of the practical side of running a distillery. I'm not embarrassed that I lack that knowledge - just very grateful that the generous people here offer their help so freely. And if I can give any help in return I feel that maybe I am at least contributing something.

[Rich Morgan]

Hydros (of any sort) should be calibrated against purpose designed SG calibration fluids, not ethanol reference solutions. The calibration fluids are temperature stable, and usually NIST certified. You buy them at the nominated SG. You'll have to calculate the ABV to SG of course.