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scale for weighing bulk spirit


daveflintstone

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For folks that are using floor scales for weighing spirits before bottling, what is the required accuracy? Is it permissible to use a scale for measuring before bottling?

In my opinion scales are the only practical way for small distillers to be accurate.

"what is the required accuracy?" I will attempt to explain.

I don't work under TTB rules but I think USA need to measure proof to 0.1 pr. If a bottle has say 100 proof then that is an accuracy of 0.1 in 100 or 1:1000

If you agree so far, then every other measurement on that 100 pr spirit needs to be of similar accuracy.

That means your scales need to be accurate to at least 1:1000

A bench top scale that you might measure a single bottle on, for ease of maths say it reads 1 Kg (1,000 g) would need to be accurate to 1 gram.

The scales to weigh a 1,000 Kg cube of spirit would need to be accurate to 1 Kg to get the 1:1,000 accuracy.

Most scales that weigh 1,000 Kg are useless at measuring one gram in a bottle.

A roughly symmetrical (height to width) tank that holds 1,000 litres would be nearly impossible to measure with a dipstick to a 1 litre accuracy. That is 1 millimeter. The temperature needs to be at 60F or 20C depending on how THE tank was calibrated. Also, how do you read at the bottom of the meniscus. (put on goggles and stick your head under the spirit then subtract the volume of your head ;=)

Jessica Jewel's scale that has 1000 lb capacity and measures in increments of .2 lbs. is accurate to 1:5,000 at 1000 lb but if weighing only 200 lb it is accurate to 1:1000, the same as a good hydrometer.

If weighing only 100 lb then it is only half as accurate as the hydrometer, probably not good enough for TTB

There is also a difference between "sensitivity" and "accuracy"

For example a cheap digital scale may be quite sensitive and read out in 1 g increments, but it may be 3 or 4 grams off the true mass = inaccurate.

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I like mixing in a cube container, the ones around 300 gallons. Has anyone found a large, accurate scale to weigh 2500 lbs + ? I consider accurate to be 1/10th lb. The floor scales I've seen are accurate only to 1/2 to 1 lb.

Dave, if your floor scales are accurate to 1 lb in 2,500 that is much more accurate than a hydrometer at 1:1000

It will be accurate enough down to 1000 lb. I assume from your mention of 1/2 lb that it becomes more sensitive at lower weights, that means it should be accurate enough down to 500 lbs

Could someone tell me quickly if I have stuffed up the 1:1000 accuracy of a hydrometer at 100 proof !!

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