How accurate is your hydrometer?!!

[lancon]

I'm confused as to how you found a 2% abv difference. Did the calibrated hydrometer read a higher OG and a lower FG than your old hydrometer?

I think that only the FG might have been taken, the SR hydrometers suitable for HMRC purposes only have a narrow range, so you need 2, e.g. 1030-60 for OG and 1.005-015 for FG

 

[strange-steve]

I think that only the FG might have been taken, the SR hydrometers suitable for HMRC purposes only have a narrow range, so you need 2, e.g. 1030-60 for OG and 1.005-015 for FG

Ah ok, in which case then the OP can't say there was a 2% ABV difference, only that there was a difference of X gravity points in the measured FG.

 

[johncrobinson]

As others have pointed out its absolute accuracy is not essential only repeatability is and by the simple principle of operation this is guaranteed.
The only real worry is if the paper scale inside is loose and moves up or down during use.

Recently in my homebrew shop i was looking at thermometers despite all being clustered together on the shelf they were all reading different temperatures.
I chose one of the middle of the range ones.

 

[lancon]

It still means a 15 point difference, I've had a 3/4 point difference between the shop bought and a HMRC approved one, 15 points is something else

 

[Galena]

So today I received 2 more hydrometers through the post and now have three, the third by accident. I tested them all at 20 deg C The first reading made in France with no name was reading at 1.006, the second by Bevi Craft of New Zealand was just about spot on 1.000, the third was a Stevenson and read 1.004

 

[McMullan]

Hydrometers are a bit like tape measures The worse case would be HMRC insisting on Plaato's 'reinvented' airlock [Boycie]

 

[foxy]

Mines like that. It also has an 'about' function, i.e.

'how strong is that beer you are drinking!?!?!'

'about 3%, darling'

Been there done that, wives are a creature that can only be fooled so many times.
Coming home from a fishing comp at 10pm, wife, 'Why are you so late' me, 'It was a draw and we went into extra time' Wife, 'How strong is that beer you are drinking' me, ' Weak as water' wife, 'Then why are you swaying and slurring' me, ' I think our water has been nobbled'

 

[RichardM]

Does it really matter for the purposes of calculating abv? If my hydrometer reads the OG, say, 5 degrees to high and I use the same hydrometer to measure the FG, that'll also be 5 degrees too high. But the difference between the OG and the FG will be the same as if I used a finely tuned hydrometer so the abv calculation will also give the same result.

You are assuming that the error is linear, e.g. the same error at 1050 as at 1010. I have no idea if that would be the case or if the error may vary at different gravities. But, as others have said, does it really matter?

 

[An Ankoù]

You are assuming that the error is linear, e.g. the same error at 1050 as at 1010. I have no idea if that would be the case or if the error may vary at different gravities. But, as others have said, does it really matter?

I used to use a calculation which involved OG-FG x a constant which I can't remember so I reckon it's linear. Now I just bung it into Brewer's Fiend.

 

[lancon]

I used to use a calculation which involved OG-FG x a constant which I can't remember so I reckon it's linear. Now I just bung it into Brewer's Fiend.

0.13

 

[Edison]

After a disappointingly high FG today (1.015) I calibrated my hydrometer at 20C in RO water. 1.002!

I use a refractometer for twice daily readings during initial fermentation and despite calibrating the calculator at the beginning with unfermented wort and a hydrometer reading it's always been way out for FG, I wonder if this is why?

 

[RichardM]

After a disappointingly high FG today (1.015) I calibrated my hydrometer at 20C in RO water. 1.002!

I use a refractometer for twice daily readings during initial fermentation and despite calibrating the calculator at the beginning with unfermented wort and a hydrometer reading it's always been way out for FG, I wonder if this is why?

I doubt it, your hydrometer is not far out.
By the way, why are you taking twice daily readings? It won't help the wort ferment and greatly increases the chances of getting some nasty airborne yeasts or other undesirables in your wort.

 

[Edison]

I doubt it, your hydrometer is not far out.
By the way, why are you taking twice daily readings? It won't help the wort ferment and greatly increases the chances of getting some nasty airborne yeasts or other undesirables in your wort.

Curiosity. I’m interested to see how fast fermentation takes off and it’s convenient to take small (~30ml) samples, also for sensory evaluation.

With sufficient care of rehydration or starter health lately it seems within 6 hours fermentation has often begun and dropped several gravity points.

I have no concerns of contamination or oxidation as my FV is a SS Chronical so I sample from the racking port and sanitise the ball valve before and after.

 

[terrym]

After a disappointingly high FG today (1.015) I calibrated my hydrometer at 20C in RO water. 1.002!

I use a refractometer for twice daily readings during initial fermentation and despite calibrating the calculator at the beginning with unfermented wort and a hydrometer reading it's always been way out for FG, I wonder if this is why?

I assume you are adjusting your refractometer readings as soon as the fermentation is underway to allow for the presence of alcohol.
https://www.brewersfriend.com/refractometer-calculator/

 

[dalecek]

After a disappointingly high FG today (1.015) I calibrated my hydrometer at 20C in RO water. 1.002!

I use a refractometer for twice daily readings during initial fermentation and despite calibrating the calculator at the beginning with unfermented wort and a hydrometer reading it's always been way out for FG, I wonder if this is why?

I've noticed the similar with my hydrometer. 1.004 in water. OG seems to be about same as with refractometer but FG is higher with hydrometer. Refractometer reads 0.00 with water. Not quite sure what make of it?

 

[Edison]

I assume you are adjusting your refractometer readings as soon as the fermentation is underway to allow for the presence of alcohol.
https://www.brewersfriend.com/refractometer-calculator/

Oh yes! Thank you BeerSmith!

 

[Edison]

I've noticed the similar with my hydrometer. 1.004 in water. OG seems to be about same as with refractometer but FG is higher with hydrometer. Refractometer reads 0.00 with water. Not quite sure what make of it?

I think I may splash out on a high-accuracy hydrometer. I hate it when the numbers just don’t play nice, especially when trying to dial-in an equipment profile.

 

[Rogermort]

I think I may splash out on a high-accuracy hydrometer. I hate it when the numbers just don’t play nice, especially when trying to dial-in an equipment profile.

Trouble is the pro hydrometers are bigger than homebrew versions. Each sample means more lost!

 

[Edison]

Trouble is the pro hydrometers are bigger than homebrew versions. Each sample means more lost!

That’s not good! I only take three hydrometer readings, pre and post boil (OG) and FG. I can get away with a 100ml sample for my bog standard triple scale. During fermentation its just the refractometer to monitor process as an indication.

 

[Victor Churchill]

I use two hydrometers, one of which reads high and one low, and split the difference.

But I always find reading the thing pretty tricky because of the curve in the surface caused by surface tension, and the fact that there are often bubbles in the wort and/or a head in the jar.