Incorrect Hydrometer Readings

[BKBrews]

So I literally bought a new hydrometer and wide mouth boroscillate (sp?) test jar on the weekend to take my samples. In roughly 23 degree water it is reading between 1.004 and 1.006. The instructions say for 25 degree water, add 0.001 to the SG to compensate (it's calibrated for 20 degrees). Is it just the luck of the draw whether it reads 1.000 or should I be asking for a new one that reads true?

Stupid me forgot to check it in water prior to taking my beer samples, so I have been scratching my head as to why my beers are stuck at 1.016 and 1.014 respectively. This taken into account, they are at about 1.012 and 1.010 and likely done.

 

[Lyrebird_Cycles]

I'd send it back, an error of .005 is unacceptable IMO.


BTW it's borosilicate, as in silicate with boron in it (to reduce the CTE).

 

[Danscraftbeer]

Swap it if its easy to do so. Or not worry. If its out the calcs will still turn out the same for ABV.
I've never had two read exactly the same. Not that I've tested hundreds of them though.. -_-

 

[DJ_L3ThAL]

Also worth checking if it is a top or bottom meniscus read hydrometer, but that would only make 0.002 or so of a difference meaning it's still not that accurate.

 

[BKBrews]

It's a top meniscus, but I can't really see it?

This was tonight - yesterday it was definitely 1.004.

 

[Danscraftbeer]

That reads 1.008 to me. Is that in water? :huh:

 

[Lyrebird_Cycles]

If I were you I would toss that hydrometer in the bin and buy two better ones (or three if you like high alcohol beer).

It is very difficult (and therefore expensive) to make a hydrometer with adequate precision which ranges over say 10%. They are also usually quite long (over 300mm) so they are very fragile.

In practice, it is better to restrict the range of the hydrometer to less than 5% so they can be made smaller and thus cheaper.

As a rough guide, divide the length of the hydrometer in mm by the range in SG points, if the resulting number is under 5 it's no good.

 

[damoninja]

That reads 1.008 to me. Is that in water? :huh:

Seconded.

You need to read from the bottom of the meniscus.

 

[BKBrews]

I didn't know anything about hydrometers, so just picked this up from ibrew.

I won't be making beers over 1.075 I wouldn't think.

Dans - look at the water to the right of the hydrometer - the meniscus raises slightly to 1.006. Still out though! Yes it's water.

 

[S.E]

It's a top meniscus, but I can't really see it?

This was tonight - yesterday it was definitely 1.004.

ImageUploadedByAussie Home Brewer1474887902.311999.jpg

Did you spin it to dislodge bubbles before that photo? If not try and it should return to 1.004.

 

[BKBrews]

Yep tried everything! Have left it in there and will check it in the morning to see if it's settled.

 

[DJ_L3ThAL]

Looks like the same hydrometer as what I have (Made in France?)... it is OK. I've been eye-balling the Carlton glass type ones from Grain & Grape but they are exxy...

If it is the made in france type, it's definitely an UPPER meniscus reading and therefore 1.006 as you mentioned, still a problem though.

 

[Danscraftbeer]

I've never had one that bad before. In water it should be close to the dark black line that reads 1.000.

Plus or minus a tiny bit according to temp differentials. Eg. 0.099 to 1.001. Top or bottom of that thick black line is the variable range given untrained home brewers eyes. IMO.
Its a reject but it would still work but you have to record a zero level 1.000. Too annoying really. Its a dud and you have to refund etc.

 

[BKBrews]

Looks like the same hydrometer as what I have (Made in France?)... it is OK. I've been eye-balling the Carlton glass type ones from Grain & Grape but they are exxy...

If it is the made in france type, it's definitely an UPPER meniscus reading and therefore 1.006 as you mentioned, still a problem though.

Yes it's the one from France.

 

[BKBrews]

I've never had one that bad before. In water it should be close to the dark black line that reads 1.000.

Plus or minus a tiny bit according to temp differentials. Eg. 0.099 to 1.001. Top or bottom of that thick black line is the variable range given untrained home brewers eyes. IMO.
Its a reject but it would still work but you have to record a zero level 1.000. Too annoying really. Its a dud and you have to refund etc.

Yeah, it still works, I just have to remove 0.004 (or 0.006) from each reading. Annoying thing is I'll need to check it in water before each use to see what it's doing.

I think I'm going to ask for a new one.

 

[DJ_L3ThAL]

Recently I thought mine was reading -0.004. Just checked the two I have one Keg King the other the Made in France Ella type. Both actually read the same its just one is top and one is bottom meniscus. Both also 0.000 in water.

I suggest triple checking. Make sure your water temp is correct and it's mixed in the sample tube well. No bubbles from your hot water service etc

 

[nosco]

Do you test them in distilled water or is tap Melbourne tap water ok? I have 2 of the same kind but I mostly use the same one. I'll have to test them both.

Edit: I assumed that the manufacturer would test them before moving them on?

 

[DJ_L3ThAL]

Tap water in my above pics

 

[Lyrebird_Cycles]

Do you test them in distilled water or is tap Melbourne tap water ok? I have 2 of the same kind but I mostly use the same one. I'll have to test them both.

Edit: I assumed that the manufacturer would test them before moving them on?

Melbourne tap water is fine: it's currently around a TDS of 70*, which if it was all NaCl would be 50ppm and correspond to a density of 1.0001. Note the number of zeroes there.

Different ionic balances will change this slightly but it's not worth worrying about.

No, the manufacturer doesn't test each one before selling them, that would raise the price enormously. They will be using statistical quality control and the widest error band they think they can get away with.



* TDS 442 by my meter at my tap. YMMV etc.

 

[damoninja]

Looks like the same hydrometer as what I have (Made in France?)... it is OK. I've been eye-balling the Carlton glass type ones from Grain & Grape but they are exxy...

If it is the made in france type, it's definitely an UPPER meniscus reading and therefore 1.006 as you mentioned, still a problem though.

That's an awesome idea just goes against every other piece of lab kit which will be calibrated to read from the bottom middle

The height of a meniscus is affected by surface tension, get a dense liquid the tension's higher conversely a surfactant will reduce the surface tension. Negligible really considering the height difference with beer.

Though there's the container you use it in, some plastics will give no meniscus, some hold a strong static charge and affect the meniscus rise. Probably enough to be +/- 2 points depending on if the meniscus flattens out or is sucked upwards.