Your Hydrometer can lie. Calibrate it

CornyKegs 728
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Rhymenoceros

Rhymenoceros

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I thought that all 3 of my first batches had stuck fermentation, my gravities were around 1.02. It was frustrating, but I just calibrated the hydrometer, turns out it was 4 points off.

every one should calibrate their hydrometers with distilled water. If you get a reading for example of 1.002 (at the calibration temp., usually 60 deg.), subtract 2 from all future readings.

Edit:
For those of you who want to know the technical basis behind it read this BYO article:

http://***********/stories/projects...rate-your-hydrometer-and-fermenter-techniques

By only doing a single point calibration (i.e. if your hydrometer reads 1.004 in distilled water, you then subtract 4 from all future readings) we are assuming that the scale inside the hydrometer is correct (not elongated or compressed) if you want to get completely accurate about it read the a fore mentioned article.
 
Just to say...

Unless this is some sort of digital or electronic hydrometer, it cannot be calibrated. The typical glass hydrometers we use are made with all the calibration they will ever have.

What's being suggested here is to test how the hydrometer reads in distilled water at 60F or 68F, which ever it was made for.

There is no calibrating or changing a typical glass hydrometer. It is what it is.

:mug:
 
Zul'jin said:
Just to say...

Unless this is some sort of digital or electronic hydrometer, it cannot be calibrated. The typical glass hydrometers we use are made with all the calibration they will ever have.

What's being suggested here is to test how the hydrometer reads in distilled water at 60F or 68F, which ever it was made for.

There is no calibrating or changing a typical glass hydrometer. It is what it is.

:mug:
Click to expand...

Yes, you can't change anything, but you can take note of how off it is.

Test it in some distilled water and if it reads 1.002 at the right temp. then subtract 2 from any future readings.
 
There is no calibrating or changing a typical glass hydrometer. It is what it is.
Click to expand...

Calibration is the comparison to a standard and either adjusting OR noting an offset. As long as something is consistent, that is all it takes.
 
I used to do this everytime I bought a new hydrometer and I think last time I broke mine and got a new one I didn't bother. This thread reminded me to check. 4 points low. Explains why a lot of beers have been dropping to 1.010 when I was expecting 1.012 - 1.015
 
Rhymenoceros said:
Yes, you can't change anything, but you can take note of how off it is.

Test it in some distilled water and if it reads 1.002 at the right temp. then subtract 2 from any future readings.
Click to expand...

That is only true if the calibration is linear. Not sure whether or not that is the case but I think that it might be.
 
lmg95 said:
That is only true if the calibration is linear. Not sure whether or not that is the case but I think that it might be.
Click to expand...

No reason why it shouldn't be. The scale on the hydrometer has the same spacing between markings, it's just a matter of the paper strip not sitting at the right level in the glass.
 
lmg95 said:
That is only true if the calibration is linear. Not sure whether or not that is the case but I think that it might be.
Click to expand...

"Your hydrometer should read 1.000 at the specified temperature when in pure water. If it reads either higher (1.001 or more) or lower (0.9999 or less), simply subtract or add the amount of the difference from your readings in wort or beer. For example, if your hydrometer reads 0.998 in pure water at 60°F (its calibration temperature) it is reading two "points" low and means that two "points" need to be added to any reading taken in wort or beer. In other words, if your wort reads 1.050, your corrected reading would be 1.052. Conversely if it read 1.002 in water, it is reading two "points" high and you would need to subtract two points from your reading, e.g. a wort or beer reading of 1.052 should be adjusted to 1.050."

Using and Calibrating a Hydrometer
 
Until recently I had three hydrometers. Two read the same and one was significantly different. I just chucked the one that was off.
 
here is a more technical text about calibrating a hydrometer:

http://www.iop.org/EJ/article/0957-0233/17/10/005/mst6_10_005.pdf

it says to calibrate it at 3 or 4 graduations, but I'm guessing that that is over kill for our purposes.

Edit: sorry, I go to an engineering school... we like to get technical.
Edit again: By only using a single point calibration we are assuming that the scale printed inside the hydrometer is correct (i.e. not compressed or elongated)

here is a BYO article about it:

http://***********/stories/projects...rate-your-hydrometer-and-fermenter-techniques
 
Shouldn't we use our brew water to callibrate?
We want to know how much sugar is available.
If the brew water has minerals enough to bump the SG,
should that be taken into account?
 
lmg95 said:
i meant to say that it is probably linear and that simply adding or subtracting the value will work.
Click to expand...

if it was linear to the point that you can add or subtract what your reading is, why do they add or subtract due to temp as well? i dont think it will make much difference for what we do, but i think if we wanted an exact reading we would have to do some temp calcs along with this.
 
nvr2low said:
if it was linear to the point that you can add or subtract what your reading is, why do they add or subtract due to temp as well? i dont think it will make much difference for what we do, but i think if we wanted an exact reading we would have to do some temp calcs along with this.
Click to expand...

Temperature makes a big difference, thats why you should always take a reading at 60 (calibration temp.) or follow the hydrometer instructions for adjusting for temperature. The linear relationship is for the the SG through out different ranges of SG. For example, the difference between 1.002 and 1.000 (at 60 degrees) is the same as the difference between 1.052 and 1.050 (at 60*). This is visible by the graduations on your hydrometer (assuming they are correct). Where as the SG difference of distilled water at 60* and the SG of distilled water at 70* is not the same as the difference between 70* and 80*.
 
Rhymenoceros said:
Temperature makes a big difference, thats why you should always take a reading at 60 (calibration temp.) or follow the hydrometer instructions for adjusting for temperature. The linear relationship is for the the SG through out different ranges of SG. For example, the difference between 1.002 and 1.000 (at 60 degrees) is the same as the difference between 1.052 and 1.050 (at 60*). This is visible by the graduations on your hydrometer (assuming they are correct). Where as the SG difference of distilled water at 60* and the SG of distilled water at 70* is not the same as the difference between 70* and 80*.
Click to expand...

thats my point, if you are off by .02 at 60 you are not going to be off at .02 at 80. so if you do not make your adjusted readings at the exact same temp then there is no sense.

its probably not going to be a big enough difference to really matter for what we do with beer, but if you are looking for the most accurate measurement this type of calibration is not the way to go.
 
Interesting thread. I have collected 4 hydrometers over the years....everyone of them reading different!

Usually I just take readings with a couple of them and average the results.

I am gonna definitely check them out w/ distilled water at the proper temp....maybe then I can find out which one is the most accurate and just use that one in the future.
 
egolla said:
Shouldn't we use our brew water to callibrate?
We want to know how much sugar is available.
If the brew water has minerals enough to bump the SG,
should that be taken into account?
Click to expand...

I don't think so. What the OP was trying to say was you need a benchmark to calibrate from in which distilled water is used. Distilled water was determined to be 1.000. So you compare you reading to that and see if there is a difference. I think you are trying to compensate for minerals in the water that may add to the SG to know how much actual sugar is in the brew water. I don't believe hydrometer readings will give you the exact fermentable sugars for the reason you give, but close. But he is talking about calibration and you seem to be talking about adjusting to compensate for. Not sure that makes sense the way I explained it, sorry if it doesn't.
 
Down here at the plant, we do not accept documentation as calibration. We call that documentation in lieu of calibration and we reject it. I rejected 14 items of a point check last week because they were only documented as wrong instead of calibrated to be correct.

If an instrument cannot be calibrated to show a correct reading, that instrument must be replaced. That's how we do it in operations and that's how our engineers do it too.

Yes, one can document an instrument as being incorrect and still use it keeping in mind a paper or mental note of how incorrect it is. That's fine for us home brewers.
 
Zul'jin said:
Down here at the plant, we do not accept documentation as calibration. We call that documentation in lieu of calibration and we reject it. I rejected 14 items of a point check last week because they were only documented as wrong instead of calibrated to be correct.

If an instrument cannot be calibrated to show a correct reading, that instrument must be replaced. That's how we do it in operations and that's how our engineers do it too.

Yes, one can document an instrument as being incorrect and still use it keeping in mind a paper or mental note of how incorrect it is. That's fine for us home brewers.
Click to expand...

Until I read you last sentence I was going to say "Aw come on, this is just a simple fix to a simple problem in a pretty simple situation" :D
 
Zul'jin said:
Down here at the plant, we do not accept documentation as calibration. We call that documentation in lieu of calibration and we reject it.
Click to expand...

That's an okay jargon to use at work, but both in spoken English and in metrology science figuring out the correction factor is calibration (so in general, saying it's not calibration is wrong).

e.g. from Webster:

"calibrate: (3) to standardize (as a measuring instrument) by determining the deviation from a standard so as to ascertain the proper correction factors"
 
nvr2low said:
thats my point, if you are off by .02 at 60 you are not going to be off at .02 at 80. so if you do not make your adjusted readings at the exact same temp then there is no sense.

its probably not going to be a big enough difference to really matter for what we do with beer, but if you are looking for the most accurate measurement this type of calibration is not the way to go.
Click to expand...

While I'm not sure of the temperature relationship I don't think its terribly important for out purposes, and temp. ranges. I never get more than 15 degrees away from the calibration temp. and between 60 and 70 degrees is only 1 point difference, so I think we can neglect the error caused by a single point calibration. The way they calibrate hydrometers in labs is by adding weight untill it reads what they want ti to read, thats essentially what we're doing, only we're just making note of it.
 
The way they calibrate hydrometers in labs is by adding weight untill it reads what they want ti to read, thats essentially what we're doing, only we're just making note of it.
Click to expand...

No way, Jose. Not essentially. Not practically. Not any way even like it. No matter the definition of calibrate, changing a device to read as it should compared to noting its discrepancy is not same, essentially or otherwise. One either changes the device or they do not. We cannot say "essentially" when one method is to add weight and the other method is to document instead of adding weight. The two actions are physically and essentially different.

The great folly in accepting documentation as calibration is that it leads to ever more documentation. Documentation will get distorted by every increase in documentation. Each time documentation of a wrong answer from an instrument is accepted as calibration, it must be documented and the next calibration made off of that document as well as what it should read if it were reading correctly. And so on, and so on, and so on. It doesn't take long for all that documentation to become a jumbled mess. "Stephen has a watermelon in his pumpkin patch." can become "Stephanie grows watermelons instead of pumpkins now. We will not be celebrating Halloween this year." This happens because documentation is misinterpreted, lost and questioned. Questions lead to people rationalizing toward the answer they believe is wanted or makes the most sense to them.

Really, I believe documentation has been accepted as calibration because some engineers (not saying Rhymenoceros), vendors, manufacturers, contractors and installers wanted a way around doing the job right. I see it all the time. We have several flow meters that the contractors want us to accept based on documentation of their consistent false readings being sufficient for us to figure out what the true flow really is. Their allotted time to finish the job and the money they allotted to pay their workers is coming to a close and they don't want to be fined for going over. In the words of my plant manager, and even our plant engineers, "Well, they better make it right." Not documented as wrong.

The work place is the place where it matters the most. In the work place, we cannot chance an instrument being misread because it is wrong and only documented as wrong. For us, that could result in a catastrophic failure. The type of failure that gets our licenses pulled, our permit revoked, fines and even jail time. It could also very well result in an environmental catastrophe and loss of human life.

Text book answers can be correct. Yours are. Work place answers earn results and paychecks. I'll stick to the answers that keep me paid, licensed in my field and my plant in permit.

As for the original intent of this thread, us home brewers getting the most out of our hydrometers, yes, testing and documentation of discrepancies is fine. It is the most practical means for us. It will still make mighty fine beer. And I'm gonna go have one. :mug:
 
So does everyone need to attach more weight or remove weight so their hydrometer is calibrated correctly?

I think the point of this post was to give people the idea that your hydrometer could be a little off and to give it a test. I dont see why we need to elaborate on the differences between mentally noting the difference and correctly calibrating a cheap $3 device. Having an incorrectly calibrated hydrometer is not going to cause a "catastrophic failure" when brewing.

But really, what does it do for us? Tells us our efficiency, tells us when the beer is done fermenting and helps calculate the ABV. Is it essential that we precisely know all of these? Not really...but that's just me. I'm more of a relaxed brewer!

:mug:
 
Zul'jin said:
No way, Jose. Not essentially. Not practically. Not any way even like it. No matter the definition of calibrate, changing a device to read as it should compared to noting its discrepancy is not same, essentially or otherwise. One either changes the device or they do not. We cannot say "essentially" when one method is to add weight and the other method is to document instead of adding weight. The two actions are physically and essentially different.

The great folly in accepting documentation as calibration is that it leads to ever more documentation. Documentation will get distorted by every increase in documentation. Each time documentation of a wrong answer from an instrument is accepted as calibration, it must be documented and the next calibration made off of that document as well as what it should read if it were reading correctly. And so on, and so on, and so on. It doesn't take long for all that documentation to become a jumbled mess. "Stephen has a watermelon in his pumpkin patch." can become "Stephanie grows watermelons instead of pumpkins now. We will not be celebrating Halloween this year." This happens because documentation is misinterpreted, lost and questioned. Questions lead to people rationalizing toward the answer they believe is wanted or makes the most sense to them.

Really, I believe documentation has been accepted as calibration because some engineers (not saying Rhymenoceros), vendors, manufacturers, contractors and installers wanted a way around doing the job right. I see it all the time. We have several flow meters that the contractors want us to accept based on documentation of their consistent false readings being sufficient for us to figure out what the true flow really is. Their allotted time to finish the job and the money they allotted to pay their workers is coming to a close and they don't want to be fined for going over. In the words of my plant manager, and even our plant engineers, "Well, they better make it right." Not documented as wrong.

The work place is the place where it matters the most. In the work place, we cannot chance an instrument being misread because it is wrong and only documented as wrong. For us, that could result in a catastrophic failure. The type of failure that gets our licenses pulled, our permit revoked, fines and even jail time. It could also very well result in an environmental catastrophe and loss of human life.

Text book answers can be correct. Yours are. Work place answers earn results and paychecks. I'll stick to the answers that keep me paid, licensed in my field and my plant in permit.

As for the original intent of this thread, us home brewers getting the most out of our hydrometers, yes, testing and documentation of discrepancies is fine. It is the most practical means for us. It will still make mighty fine beer. And I'm gonna go have one. :mug:
Click to expand...

I wasn't trying to argue with you, merely create a analogy to make it easier to understand what the "documentation" was accomplishing. The work place and home brewery are 2 completely different things.
 

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