Water volume by weight

[MuddyBrown]

We do have to watch our terminology. We understand what the OP means, but it is more nuanced. It comes down to accuracy, precision, and resolution. https://phidgets.wordpress.com/2014/05/20/accuracy-precision-and-resolution-theyre-not-the-same/

However, that is just fun reading and just some clarification on terminology.

It is safe to assume that a common digital weight scale will be mostly accurate and precise. This assumes you are not measuring at the very low end, or at the high of the scale capacity, as this is common limitation of load cells. Scales can not measure accurately at these points. It is also safe to assume that the weight measurements are going to be repeatable within some small margin of error. Lets say 5 to 10g?

If making multiple water measurements to fill a kettle, that might add up to a total error of 100g corresponds to 100mL of water, a very small amount of liquid. OP will have to determine the acceptable amount of measurement error. That is just For filling up the kettle in batches if needed.

It would be trivial to design an series of weight based measurements, record the results, take the mean and standard deviation of the results to see if the scale was an appropriate measurement device. I suspect the measurement error would be around 50mL or less. But I'm just taking a guess.

You could attempt to find a calibration weight to double check your scale. The scale is going to be close enough. Personally I would't care as it wouldn't actually matter. All that matters is repeatable, accurate, precise measurements for every batch. If your scale was off by anything more than 10g (ie 10mL), you need a new scale.

Perhaps the OP could report back on how the weight based measurements are going?

 

[Oginme]

Not the OP, but in my system I have +/- 10 ml in 11 liter end of boil volume (room temp measurements). My scales are calibrated using class 'S' weights. I have a milk scale for official DHIA use which also needs calibration and keep traceable calibration weights up to 20 KG.

If I get a differential in volumes from my process, I can pretty much chase it back to where it originated. This has also come into use when I suddenly had a step change downward in my efficiency and was able to trace it back to a set of "precision" hydrometers which i had received as a gift. They were certainly precise, just not accurate.

For my purposes, the effort is one of predictability. I can easily predict when a change in my process occurs and tackle it immediately. This has also led to vastly reproducible results.

I fully understand that what I may do is not what everyone must or should follow. Each person has their own way of doing things and following what is important for them. If you feel that using weight for water measurement is too much work, then more power to you. Just don't project your desires not to add one step as "too much work" but recognize that we each have different goals.

 

[shredthrash]

One of your reasons for wanting to do this is accuracy, but do you know how accurate your scale is at 20kg (44 lbs)? The accuracy of your volumes are only going to be as good as the scale. Unless you have a 20kg calibration weight, how are you supposed to know how good the scale is?

I work in a large brewery that - among other things - calibrates all scales with standardized weights. I have access to use this for calibrating my anvil scale at home. Good point!

 

[shredthrash]

That's the fourth time that you said it's not worth it. I agree with you, but that's not the point of the thread.

Exactly and to the point of that comment, the objective should be to eliminate variables that are simple to have more control over. This has the benefit of not only accurately measuring your initial strike water, etc, but also to make every single volume calculations downstream of the mash more simple and accurate. Everything from cast out volume, trub loss, and ferm full.

 

[shredthrash]

We do have to watch our terminology. We understand what the OP means, but it is more nuanced. It comes down to accuracy, precision, and resolution. https://phidgets.wordpress.com/2014/05/20/accuracy-precision-and-resolution-theyre-not-the-same/

However, that is just fun reading and just some clarification on terminology.

It is safe to assume that a common digital weight scale will be mostly accurate and precise. This assumes you are not measuring at the very low end, or at the high of the scale capacity, as this is common limitation of load cells. Scales can not measure accurately at these points. It is also safe to assume that the weight measurements are going to be repeatable within some small margin of error. Lets say 5 to 10g?

If making multiple water measurements to fill a kettle, that might add up to a total error of 100g corresponds to 100mL of water, a very small amount of liquid. OP will have to determine the acceptable amount of measurement error. That is just For filling up the kettle in batches if needed.

It would be trivial to design an series of weight based measurements, record the results, take the mean and standard deviation of the results to see if the scale was an appropriate measurement device. I suspect the measurement error would be around 50mL or less. But I'm just taking a guess.

You could attempt to find a calibration weight to double check your scale. The scale is going to be close enough. Personally I would't care as it wouldn't actually matter. All that matters is repeatable, accurate, precise measurements for every batch. If your scale was off by anything more than 10g (ie 10mL), you need a new scale.

Perhaps the OP could report back on how the weight based measurements are going?

You make a great point by reminding us to be careful about terminology with our thoughts, but yes I used the term accuracy in it's common use, ie "being as close as possible to a true representation of something", not in the technical way that one would describe instruments of measure, etc.

Great conversation, all! Thanks for all of the contributions! I will need to actually grab the calibration weights from work and see how accurate everything is down to the gram.

PS I use the anvil brewing grain scale for my water weighing.

 

[shredthrash]

Not the OP, but in my system I have +/- 10 ml in 11 liter end of boil volume (room temp measurements). My scales are calibrated using class 'S' weights. I have a milk scale for official DHIA use which also needs calibration and keep traceable calibration weights up to 20 KG.

If I get a differential in volumes from my process, I can pretty much chase it back to where it originated. This has also come into use when I suddenly had a step change downward in my efficiency and was able to trace it back to a set of "precision" hydrometers which i had received as a gift. They were certainly precise, just not accurate.

For my purposes, the effort is one of predictability. I can easily predict when a change in my process occurs and tackle it immediately. This has also led to vastly reproducible results.

I fully understand that what I may do is not what everyone must or should follow. Each person has their own way of doing things and following what is important for them. If you feel that using weight for water measurement is too much work, then more power to you. Just don't project your desires not to add one step as "too much work" but recognize that we each have different goals.

That is a very encouraging post. As I've only just started playing around with a scale for water, I'll have to revisit your process as a benchmark for dialing mine in.

Thanks!