Hydrometer? Refractometer? Or something better?

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chris2012
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Re: Hydrometer? Refractometer? Or something better?

Post by chris2012 » Sat May 09, 2020 1:29 pm

Re. the Mettler Toledo product, there's also https://shop.anton-paar.com/wwd-en/easydens.html still not cheap mind ;)

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Re: Hydrometer? Refractometer? Or something better?

Post by guypettigrew » Sat May 09, 2020 1:48 pm

Oh good grief. Have you seen the video? Embarrassing, and tells you nothing about the unit.

And what is that hanging out of the bloke's nose at 37 seconds?

I'll stay with the Miwaukee digital refractometer.

Guy

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Re: Hydrometer? Refractometer? Or something better?

Post by PeeBee » Sat May 09, 2020 7:01 pm

Looking back at this thread you will see I did make a few corrections 'cos I was mixing up weight and volume at different temperature. Nothing dramatic, 'cos errors on one side of the calculations were being cancelled by more errors on the other side. But very confusing if trying to follow the maths (some people do that!). So why didn't I make my life easier and cool things to 4°C when appropriate? Try it! I did! As soon as the cooled bottle is exposed to room air, condensation forms and messes up the weighing.

So I relied on my enormous mathematical abilities :^o with inevitable results.
Cask-conditioned style ale out of a keg/Cornie (the "treatise"): https://drive.google.com/file/d/0BwzEv5 ... rDKRMjcO1g
Water report demystified (the "Defuddler"; removes the nonsense!): https://drive.google.com/drive/folders/ ... sp=sharing

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Re: Hydrometer? Refractometer? Or something better?

Post by PeeBee » Wed May 13, 2020 8:35 pm

Next "real" application; I'm casking an "Usher's 1886 60/- Pale Ale" (a Durden Park Beer Club recreation). It was using a very heavy top cropping yeast (White Labs WLP028 "Edinburgh Ale"). After primary fermentation completed the Tilt hydrometer went haywire, reading were bouncing up and down, so its recordings were turned off about a week ago. The last reading from the Tilt was 1.011, but it was reading 1.015 at times. A refractometer provided 1.017 but the "line" was very foggy. A week later the refractometer had a slightly clearer line, suggesting 1.017-1.018. These higher readings are what I was expecting having used Chavallier barley malt (not renowned for finishing "dry") and Scottish Ale yeasts don't attenuate greatly. In fact it tasted a tad sweet too.

But this time I've a "pycnometer" :roll: . So, prepare my sample (which is delightfully quick and puts very little strain on eye function. But these things are beginning to worry me being small, roundish, slippery, and breakable.
20200513_192541_WEB.jpg
Quick bit of Maths, subtract weight of bottle and divide by weight of water the bottle holds at 20°C (although the sample was about 18°C which could be corrected for, but I can't be bothered). Which comes to … 1.019.




The purpose of all this chatter is to instil a bit of confidence in the technique for anyone else thinking of giving it ago.
Cask-conditioned style ale out of a keg/Cornie (the "treatise"): https://drive.google.com/file/d/0BwzEv5 ... rDKRMjcO1g
Water report demystified (the "Defuddler"; removes the nonsense!): https://drive.google.com/drive/folders/ ... sp=sharing

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Re: Hydrometer? Refractometer? Or something better?

Post by PeeBee » Fri Jul 03, 2020 4:56 pm

Just when you thought no-one will mention "pycnometer" again … I'm back! #-o

This time dealing with something well outside the ability of a home-brewing hydrometer. The SG of this liquid is very high and I'm switching to 4C water reference for this. It will show up one of the discrepancies in my earlier work and perhaps explain why I was getting muddled.

I created a solution of calcium chloride for water treatment. This is not a bad move because although we use calcium chloride (solid) quite a lot in water treatment, the stuff is so hygroscopic, however careful you weigh the stuff, what you think you're adding is likely to be out. Miles out! So adding a solution makes sense, and you know the concentration from the SG. I created some 1.079 solution which had a concentration of 7.9% calcium chloride. Some water treatment calculators (including Bru'n water) will work with calcium chloride solutions instead of solid.

So, I need more calcium chloride. I could make another solution, or else buy the stuff as a solution. It is used in cheese making so it actually has an "E" number. So I have 1L of solution ("E509") at 33% … plus or minus 1%. Hum, I can do better than that. So pycnometer is charged with the solution and weighed:

53.00gms, less weight of empty bottle (18.28gms) gives a 34.72g sample. Divide that by the volume of the bottle (26.37ml) gives 1.3166g/ml (or Kg/Litre) density.

This will be looked up on a table presumably created using a scientific hydrometer, so a 4C (3.98C to be really exact) water reference will be used. Water at 4C has a density of 1.000. So, divide my sample density by the reference density (easy, it's 1!) gives SG 1.317. Yeap, SG is the same as density (in g/ml or kg/litre) in this case!

So look this up on the tables found here: https://www.oxy.com/OurBusinesses/Chemi ... -01791.pdf and …

SG and density columns do not match! The SG provided is using a water reference at 25C not 4C. I was using this table as a reference in my early work, no wonder I was getting muddled (America do not go by ISO recommendations, they beat their own path). Fortunately the table does list density, so 1.3166kg/litre is a tiny bit less than a 32% solution (not in the specified limits of 32-34%; was I done?).


Eee, you can have so much fun with these pycnometers! :? You won't get the SG of isopropyl alcohol or strong CaCl2 solutions with just one hydrometer. And use the same instrument for beer brewing.
Last edited by PeeBee on Fri Jul 03, 2020 7:08 pm, edited 1 time in total.
Cask-conditioned style ale out of a keg/Cornie (the "treatise"): https://drive.google.com/file/d/0BwzEv5 ... rDKRMjcO1g
Water report demystified (the "Defuddler"; removes the nonsense!): https://drive.google.com/drive/folders/ ... sp=sharing

guypettigrew
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Re: Hydrometer? Refractometer? Or something better?

Post by guypettigrew » Fri Jul 03, 2020 6:06 pm

Goodness-have you ever thought about getting counselling, PeeBee? Or just drinking more beer to fill your time!

Guy

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Re: Hydrometer? Refractometer? Or something better?

Post by PeeBee » Fri Jul 03, 2020 6:53 pm

guypettigrew wrote:
Fri Jul 03, 2020 6:06 pm
Goodness-have you ever thought about getting counselling, PeeBee?
Don't be silly. The counselling sessions came to an abrupt stop in March. Probably because half the nation suddenly needed counselling. The nett result being everyone on this forum gets me in the raw. And I guess I'll just be getting rawer?

As for drinking more beer: These tablets say I should avoid alcohol. What the hell, ay …
Cask-conditioned style ale out of a keg/Cornie (the "treatise"): https://drive.google.com/file/d/0BwzEv5 ... rDKRMjcO1g
Water report demystified (the "Defuddler"; removes the nonsense!): https://drive.google.com/drive/folders/ ... sp=sharing

guypettigrew
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Re: Hydrometer? Refractometer? Or something better?

Post by guypettigrew » Fri Jul 03, 2020 7:47 pm

PeeBee wrote:
Fri Jul 03, 2020 6:53 pm
As for drinking more beer: These tablets say I should avoid alcohol. What the hell, ay …
That probably means 'avoid' as in 'don't trip over it'.

Guy

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Re: Hydrometer? Refractometer? Or something better?

Post by Kev888 » Fri Jul 03, 2020 8:17 pm

The issue I've had with refractometers is not the brix scale or even the effect of alcohol, but how massively they have been affected by wort colour. They're fine with most pale worts of course, but it seems like a different correction factor is needed for almost every shade once getting to things like dark milds, porters and stouts - they can read several points different to pale wort of the same gravity (i.e. even before any alcohol is present).

My bad luck and/or choice in buying cheapo chinese ones possibly, since other people don't seem to find it quite such a problem. Though with half the world brewing only pales and considering bitter to be dark these days, it is a bit hard to get a handle on what is typical for these cheapo things, and i've only had two. Not that I'd be without them for a moment, so convenient are they, but i can't let the hydrometers go as yet - for when more decent accuracy is wanted.

At least the weight/volume measuring Pycnometer wouldn't care or even know about the colour. It is though quite reliant on weight and temperature measurements made on other devices, as well as volume, so hard to judge in and of itself. In terms of use, it seems more similar to a hydrometer - if the trial jar is sized appropriately the volumes, and requirements for cooling them, aren't so very different (compared to a refractometer).

Though with a pycnometer the volume must be got correct, the weight must be measured accurately and so must the temperature; a hydrometer also relies on temperature but then lets one read it directly, to within half a point fairly easily with mine (which isn't a wide range beer+wine type). So I'm not immediately convinced that the pycnometer is an obvious step forward, though certainly interesting and quite fun.
Kev

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Re: Hydrometer? Refractometer? Or something better?

Post by Haydnexport » Sat Jul 04, 2020 10:10 am

I find refractometers wildly inaccurate for fg , they are bang on for sg , and even better at on the fly runnings readings, so I have one for that reason. And a hydrometer for the fg. They are the easiest ways of taking readings IMO.

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Re: Hydrometer? Refractometer? Or something better?

Post by PeeBee » Sat Jul 04, 2020 11:37 am

Kev888 wrote:
Fri Jul 03, 2020 8:17 pm
The issue I've had with refractometers is not the brix scale or even the effect of alcohol, but how massively they have been affected by wort colour. They're fine with most pale worts of course, but it seems like a different correction factor is needed for almost every shade once getting to things like dark milds, porters and stouts - they can read several points different to pale wort of the same gravity (i.e. even before any alcohol is present).

My bad luck and/or choice in buying cheapo chinese ones possibly, since other people don't seem to find it quite such a problem. Though with half the world brewing only pales and considering bitter to be dark these days, it is a bit hard to get a handle on what is typical for these cheapo things, and i've only had two. Not that I'd be without them for a moment, so convenient are they, but i can't let the hydrometers go as yet - for when more decent accuracy is wanted.

At least the weight/volume measuring Pycnometer wouldn't care or even know about the colour. It is though quite reliant on weight and temperature measurements made on other devices, as well as volume, so hard to judge in and of itself. In terms of use, it seems more similar to a hydrometer - if the trial jar is sized appropriately the volumes, and requirements for cooling them, aren't so very different (compared to a refractometer).

Though with a pycnometer the volume must be got correct, the weight must be measured accurately and so must the temperature; a hydrometer also relies on temperature but then lets one read it directly, to within half a point fairly easily with mine (which isn't a wide range beer+wine type). So I'm not immediately convinced that the pycnometer is an obvious step forward, though certainly interesting and quite fun.
Cheers Kev88. :)

The volume of a pycnometer must be determined beforehand, or it can't work. But it is only done once per bottle and isn't difficult. But weight is an issue. And decent scales getting cheaper (mine were about £30, you can still pay about £130!) is the only "step forward" making any difference (pycnometers have been around for eons). Temperature isn't a major concern, the same as for a hydrometer, but you're already having to use a calculator for using a pycnometer so corrections could be made if wished. I do still use a refractometer while doing the pre-ferment stuff.

The bottle is 25ml (I tried 10ml but it was too "random"). You could use 50 or 100ml to cover up for naff weighing scales, but even that isn't near the volume of a hydrometer trial jar.

But, my reason for meddling with pycnometers is hydrometers are near impossible to use with my kooky eyes, as I said in the OP. But people now refrain from telling me hydrometers are a better choice. Don't they?
Cask-conditioned style ale out of a keg/Cornie (the "treatise"): https://drive.google.com/file/d/0BwzEv5 ... rDKRMjcO1g
Water report demystified (the "Defuddler"; removes the nonsense!): https://drive.google.com/drive/folders/ ... sp=sharing

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Kev888
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Re: Hydrometer? Refractometer? Or something better?

Post by Kev888 » Sat Jul 04, 2020 12:25 pm

Yes, 'better' usually depends on circumstances and objectives, which aren't the same for everyone. Some don't get that but i think most of us do if we actually notice the underlying reasons (which I don't always, so reasserting is rarely a bad thing).

The pycnometer is certainly a well proven approach, to put it mildly, and unlikely to have any tricky surprises. In using it for wort measurement, not sure how much the weight might be affected by any gas; of course hydrometers can be affected by bubbles but the mechanism is a bit different, a pycnometer might be less affected.

Also not sure if there would be both density and something equivalent to apparent density when alcohol is present; the medium having changed in nature, not just the density of it.. I'm not confident either way without much more head-scratching. Though either way, if you convert mathematically to conventional gravity then probably important to distinguish which gravity (apparent or true) when you do so.

Otherwise I can't think of any pit-falls, so if it suits you then it sounds like quite a decent method to me, quite interesting too.
Kev

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Re: Hydrometer? Refractometer? Or something better?

Post by PeeBee » Sun Jul 05, 2020 9:15 am

For anyone else's benefit (I guess this is a geek only zone now?) …

I'm not trying to emulate a hydrometer messing with pycnometers. Hydrometers emulate what a pycnometer can do!

Hydrometers are more convenient for most people (not me) and hide away concerns about "reference densities". But as a result hydrometers are very inflexible and not being aware of "reference densities" a source of confusion (it keeps confusing me, although some will believe "reference density" is a source of confusion in itself!). Remember, the other (and preferred) name for "specific gravity" is "relative density", and so SG must relative to something; and it is that "reference density".
Cask-conditioned style ale out of a keg/Cornie (the "treatise"): https://drive.google.com/file/d/0BwzEv5 ... rDKRMjcO1g
Water report demystified (the "Defuddler"; removes the nonsense!): https://drive.google.com/drive/folders/ ... sp=sharing

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Reference Density

Post by PeeBee » Sun Jul 05, 2020 11:48 am

I'll list a few water reference densities you might come across (so I can refer to this record too!):

Pure water @ 4°C (3.98°C) is 1.000g/ml (the default for laboratory or "scientific" hydrometers).
Pure water @ 60°F (15.55 or 16°C) is 0.999g/ml (older and perhaps some country "default" hydrometers).
Pure water @ 20°C is 0.998g/ml (most British brewing hydrometers).
Pure water @ 77°F (25°C) is 0.997g/ml (some US hydrometers).

The reference does not have to be the same temperature required of the sample (laboratory hydrometers, by default, require the sample to be 20C and uses a water reference at 4°C).

No concern of yours? But most common UK brewing hydrometers are calibrated for a 20°C sample and a 20°C water reference sample. They read about 2 gravity point higher than a scientific hydrometer (so water at 20°C is 1.000).


For example, a brewing hydrometer in water at 20°C: The water has a density of 0.998g/ml. The reference is also water at 0.998g/ml. So, 0.998 divided by 0.998 gives an SG of 1.000 which is what the hydrometer indicates. Well, you wouldn't want it to be anything else would you.


EDIT: Hydrometers with a reference of 4°C more often get described as "density hydrometers" (BS718:1991 which is generally aligned with ISO 387 and ISO 649) for the obvious reason that they read off "density" (in g/ml) directly. While I describe these hydrometers as the "default" the old 60°F water reference hydrometers remain very much prevalent.
Last edited by PeeBee on Sun Jul 12, 2020 7:30 am, edited 2 times in total.
Cask-conditioned style ale out of a keg/Cornie (the "treatise"): https://drive.google.com/file/d/0BwzEv5 ... rDKRMjcO1g
Water report demystified (the "Defuddler"; removes the nonsense!): https://drive.google.com/drive/folders/ ... sp=sharing

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Reference Density (Part 2)

Post by PeeBee » Tue Jul 07, 2020 9:39 am

Just to expand on this subject of "reference density" to help you (and me!) understand it, here's some real-life examples of it applying. And yes it is applied to your hydrometer! But a hydrometer may be stuck with a scale using one reference density (e.g. home-brewing hydrometers).

As a key: My pycnometer has an empty weight of 18.28g (need this to get "tare" weight, using the weighing scale's tare function is often inconvenient). My pycnometer's volume is 26.37ml. Sample temperature in each case was 20°C (although the last example should ideally have been 25°C).

I've a beer wort (made just a few days ago). Fill pycnometer with wort …
45.50g - 18.28g = 27.22g (weight of wort sample)
27.22g / 26.37ml = 1.032g/ml (the density of the wort, not the SG!)
1.032g/ml / 0.998g/ml = 1.034 (the relative density or SG; 0.998 was the reference density which is water's density at 20°C)

I've some "99.9%" isopropyl alcohol (IPA) of uncertain concentration. The SG tables I can compare against are to ISO specs.
38.01g - 18.28g = 20.73g
20.73g / 26.37ml = 0.786g/ml
0.786g/ml / 1.000g/ml = 0.786 (SG of pure IPA; 1.000 reference density which is water's density at 4°C)

I've some "33%" calcium chloride solution. The SG tables I can compare against are from USA.
55.00g - 18.38g = 34.72g
34.72g / 26.37ml = 1.317g/ml
1.317g/ml / 0.997g/ml = 1.321 (the SG of 32% solution; 0.997 was the reference density which is water's density at 25°C)

Lots of phaff, but you can't avoid seeing the obvious versatility of a pycnometer.
Cask-conditioned style ale out of a keg/Cornie (the "treatise"): https://drive.google.com/file/d/0BwzEv5 ... rDKRMjcO1g
Water report demystified (the "Defuddler"; removes the nonsense!): https://drive.google.com/drive/folders/ ... sp=sharing

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