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I've been having some real trouble understanding which hydrometers are necessary for operations. Does anyone know of a guide for the hydrometers needed for operation? I know we need to have NIST-certified equipment for proofing and gauging, but don't understand the ranges of SG for which we need. Can anyone share a list of ranges, use, quantity and whether NIST certified of your hydrometers?

We're ready to spend on these, but want to make sure we're spending correctly. I've seen a few posts on this, but there seems to be some variance on how many hydrometers most folks purchase and the number that are NIST certified vs. those that are not.

Thanks for your input. Any recommendations on where to buy (aside from Cole Parmer) are appreciated as well.

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Using the Gauger's Manual §30.22 Hydrometers and thermometers, you find a list of hydrometers and their precision letter and range. I would have 3 of each hydrometer on hand, except for the F, G, H. Maybe one of each to have on hand.

I use Davis Intruments. H-B Durac Ethyl Alcohol Glass Hydrometers are the best deal. You'll need to get at least one of each hydrometer precision level calibrated, that you use to determine tax liabilities. For us that's our K, P, Q, and R hydrometers. This will raise the price of the hydrometer significantly. Note that there is no precision letter with the Duracs. This is okay, because you will also note that they are "made according to the Bureau of Internal Revenue, US Treasure Department." but you'll need to pay attention to the proof range.

Good luck

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  • 3 weeks later...

Patrick, thanks for the insight. So the hydro meters you use don't have a NIST certification letter aside from the ones you have calibrated for proofing purposes?

One follow up - do you get your specific gravity hydro meters calibrated and provide letter of certification as noted in 30.24 of the gauging manual?

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Correct, they have a certificate of trace-ability from the manufacture but not calibration. Just means they can be calibrated if you wanted to send them out, or get them pre-calibrated.

For your follow up, we are a winery/distillery. All of our base material starts as grapes and is processed through the winery. Calibration of hydrometers are not required. When we transfer the wine from the BW to the DSP we must then have an accurate wine alcohol. And for that we use the FOSS oenofoss at the winery, pre-transfer. As far as I understand that covers our legal obligations. The FOSS is a very expensive, but it makes things very, very easy. Otherwise, we'd use the old school ebulliometer.

But back to the spirit of your question. If I were you, I would have one calibrated hydrometer for every range of SG you need. I would buy 2 or 3 extra un-calibrated hydrometers for actual use at each SG. I would then spend a bit of time cross referencing your calibrated with the uncalibrateds and note any deviation. Should by all pretty close, but this should allow you to confidently use your uncalibrated hydrometers. Same process for your proofing hydrometers, would be a good idea too.

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  • 4 weeks later...

Thanks for all the info. How often do the calibrated hydrometers get recertified? I worked with U.L. listed devices a long time ago so I think I'm confusing a lot of the requirements so wanted to clarify here.

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Our distillery has not been around long enough to give any advice on that question. I can't find anything in the regs regarding that and haven't heard anyone's advice related to the matter of re-calibration. Sorry

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What are some of the best options folks have found for having hydrometers certified?

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