How to calibrate gallons of volume or several lbs weight

[SpeedYellow]

Has anyone found a good way to accurately calibrate their volumes or weights? A small scale for hops and minerals is easy: just buy a 100-gram calibration weight for $3 on amazon. But how to calibrate 1 gallon or 5-10 lbs?

One possibility is buy a 1-gal jug of water (should be 8.35 lbs), but my scale says that's not 1-gal. But maybe the scale is off...

 

[Xpertskir]

Dumbells.


Also, a nickel weighs exactly 5 grams for your small scale

 

[blizz81]

One possibility is buy a 1-gal jug of water (should be 8.35 lbs), but my scale says that's not 1-gal. But maybe the scale is off...

This. I suppose if you really want to be anal, you could measure up from smaller volumes if you have something that has a line for a pint, etc. For me, "good enough" was buying a sturdy 1gal jug of Ocean Spray, marking their fill line, and weighing that with water after enjoying 1gal of sugary juice. They have probably paid for expensive calibration equipment, I reckon.

 

[Brickman]

This is what I use for volume. I tried the water jug and it became a pain as the SWMBO kept recycling them. I am very happy with it. I may pick up a big scale as I am trying to force transfer into sealed corny kegs and would have to go off of weight.

1 Gallon Pitcher

 

[dyqik]

If you really aren't sure about your scale, then calibrate everything against a single reference weight, and use your scale to measure both weights and volumes - e.g. using a 50 lb limit scale that you will use to measure your grain, calibrate volume by weighing the volume of water (and taking its temperature). Everything is then referred to a single standard, and any systematic errors will cancel out - e.g. adding your measured 10lb of grain to your measured 15 quarts of strike water using your calibrated scale and volume will still result in the correct ratio, even if your scale is quite far out in absolute calibration.

Then you just need to check that your calibration isn't varying with time. For the kind of accuracies required for brewing, just take a dumbbell weight (or two), mark it and weigh them whenever you want to check the calibration of your scale. Using two weights would let you check for zero point errors and linear calibration errors.

 

[SpeedYellow]

This. I suppose if you really want to be anal, you could measure up from smaller volumes if you have something that has a line for a pint, etc. For me, "good enough" was buying a sturdy 1gal jug of Ocean Spray, marking their fill line, and weighing that with water after enjoying 1gal of sugary juice. They have probably paid for expensive calibration equipment, I reckon.

Surely any 1-gal drink would be intentionally overfilled, because under-filling would invite class action lawsuits and/or fines. Same goes when we buy grains online. When I buy 1-gal jugs of water, they weigh around 4% high! But I suspect like 2% is my scale reading high and 2% is intentional overfilling. But that's just a guess, since I can't figure out how to calibrate a 10-lb scale.

 

[SpeedYellow]

Dumbells.


Also, a nickel weighs exactly 5 grams for your small scale

LOL. Dumbells aren't usually even close to their stated weight.

And although a nickel's spec weight is 5 grams, their actual weight varies quite a bit, at least a couple %, making them unsuitable to calibrate. The $3 calibration weight on amazon is a no-brainer.

 

[philjohnwilliams]

As long as your measurements are consistent, there really is no need for super precise calibration. Your scale /jug may off by a few percent, but as long as they are off by the same amount every time it really doesn't matter. Just make sure to use the same measuring tools every time and you will be fine.

 

[SpeedYellow]

If you really aren't sure about your scale, then calibrate everything against a single reference weight, and use your scale to measure both weights and volumes - e.g. using a 50 lb limit scale that you will use to measure your grain, calibrate volume by weighing the volume of water (and taking its temperature). Everything is then referred to a single standard, and any systematic errors will cancel out - e.g. adding your measured 10lb of grain to your measured 15 quarts of strike water using your calibrated scale and volume will still result in the correct ratio, even if your scale is quite far out in absolute calibration.

Then you just need to check that your calibration isn't varying with time. For the kind of accuracies required for brewing, just take a dumbbell weight (or two), mark it and weigh them whenever you want to check the calibration of your scale. Using two weights would let you check for zero point errors and linear calibration errors.

Great point there. I've been using my (inaccurate) scale for both weights and volume, and it never occurred to me that this works out. Even if the scale is off like 10%, that's probably fine as long as you adjust your other parameters to get the needed volumes.

 

[Rivenin]

thats what i do... for the most part i weigh everything against my one scale.
no ones scale is going to be EXACT... which is unfortunate but with the sizes of things we are dealing with, it's not going to matter much. just learn your system