Insane BIAB Efficiency after brewery revamp

[Lyrebird_Cycles]

I don't see that would work: I can't see a mechanism by which the sugar concentrates but the iso alpha acids don't.

I guess you could boil it for long enough to degrade the IAAs but that's a long time.

 

[Danscraftbeer]

So you've got something around 60 IBU, Pale, low carb. I'd go that. Before software one of my best pre all grain beers was with Sarochi Ace hops. After I got software I punched in that old brew and it turned out around 55IBU. I have to try it again all grain.

 

[mtb]

I don't see that would work: I can't see a mechanism by which the sugar concentrates but the iso alpha acids don't.

I guess you could boil it for long enough to degrade the IAAs but that's a long time.

My understanding of bittering hops (and their AAs) is that their bittering value plateaus after around 90min. So if I boil this 10L for a good few hours I'll increase its OG without increasing its IBUs at the same rate.

 

[MHB]

Actually in an open boil that is probably closer to 400 minutes, but it is going to depend on a lot of variables one of them being that if there are still any hops or un-isomerised Alpha aids in the wort you will still be making Iso-Alpha, as well as breaking down some of the Iso.
Even if you boiled for 2 hours and halved the volume and doubling the SG, you would still be concentrating the existing Iso-Alpha at pretty much the same rate (i.e. doubling it).

I cant understand how getting an accurate SG reading is so hard, I mean it isn't rocket science, probably easier than reverse parking a car!
Whether its in the kettle pre or post boil, or in the fermenter, make sure you stir thoroughly, run some off (more than the volume in the tap/any plumbing - other than in the fermenter just return the pre-run to the top) take your sample, adjust the temperature to close to 20oC (Measured Accurately), take your reading.

Just make sure your thermometer and hydrometer are accurate and develop a process that works and do it the same way every time, we are talking really basic brewing skills, something I would expect a kit brewer to be able to do accurately and consistently.
Mark

 

[Barge]

 

[mtb]

I cant understand how getting an accurate SG reading is so hard, I mean it isn't rocket science, probably easier than reverse parking a car!
Whether its in the kettle pre or post boil, or in the fermenter, make sure you stir thoroughly, run some off (more than the volume in the tap/any plumbing - other than in the fermenter just return the pre-run to the top) take your sample, adjust the temperature to close to 20oC (Measured Accurately), take your reading.

Just make sure your thermometer and hydrometer are accurate and develop a process that works and do it the same way every time, we are talking really basic brewing skills, something I would expect a kit brewer to be able to do accurately and consistently.
Mark

Have you seen some people try reverse parking a car..?
I'm doing this the same way I always have. Took my sample direct from the wort after giving it a good stir. Adjusted for temp via this handy calculator . I have to assume that my hydrometer is faulty - even though it reads 1.00 in tap water, it may mis-report a reading at higher gravities anyway.

 

[Lyrebird_Cycles]

My understanding of bittering hops (and their AAs) is that their bittering value plateaus after around 90min. So if I boil this 10L for a good few hours I'll increase its OG without increasing its IBUs at the same rate.

Actually in an open boil that is probably closer to 400 minutes, but it is going to depend on a lot of variables one of them being that if there are still any hops or un-isomerised Alpha aids in the wort you will still be making Iso-Alpha, as well as breaking down some of the Iso.

In normal conditions the peak utilisation occurs at around 4 hours. I wrote a calculator that allows you to work this out: aussiehomebrewer.com/topic/91684-improving-precision-in-ibu-calculations

 

[klangers]

I'd say that your issue is your adjustment for temperature.

 

[mtb]

I'd say that your issue is your adjustment for temperature.

Must've been. Next time I will be cooling my sample rather than adjusting with a calculator.
All in all though, final BH efficiency was 82%, so I got the increase I was looking for (I was around 62% before deciding to batch sparge).

 

[bradsbrew]

That is where a refractometer is handy.

 

[mtb]

That is where a refractometer is handy.

Yep, buying one next week.

 

[Lyrebird_Cycles]

I'd say that your issue is your adjustment for temperature.

I thought that too so I checked it and it's near enough.

I'm guessing MTB used the Brewer's friend calculator; it takes into account the variation in CTE with temperature rather than assuming a constant value of 200 PPM / oC.

 

[klangers]

Mmm, it is possible for the hydrometer, if cold, to reduce the temperature of the wort upon sampling, making the temperature to which one adjusts no longer relevant. That's the difficulty I've encountered personally anyhow.

 

[Lyrebird_Cycles]

Unlikely: weird factoid, the volumetric heat capacities of most solids are within 20% of a value of 3 MJ/m3, water is anomalously high at almost 4.2, glass is a bit low at 2.1. Combined with density, this means the specific heat capacity of glass is about one fifth that of water.

The mass of the hydrometer is by definition equal to the volume of fluid displaced, in a normal scenario with adequate clearance between hydrometer and bulb the hydrometer represents about one quarter of the combined mass of the system. Accordingly, a 40 degree difference in temperature between glass and sample would equilibrate out to a temperature drop of about 2.5 degrees.

Before anybody asks: the linear CTE of borosilicate glass is about 3 ppm and more or less linear with temperature so the resultant expansion of the hydrometer is not material.

 

[klangers]

Yes I am aware of that, but you forget the lead mass at the bottom of the bulb.

Unlikely, but has happened to me before - possibly a combination of multiple errors - error in temperature, error in calculator, some temperature loss upon sampling, temperature loss as the hydrometer equalises and slowly disspates heat.

Possible to all add up to the error experience by the OP.

 

[n87]

Before anybody asks: the linear CTE of borosilicate glass is about 3 ppm and more or less linear with temperature so the resultant expansion of the hydrometer is not material.

Lucky you mention that... otherwise i may have pulled you up on it :unsure:

 

[mtb]

I'm guessing MTB used the Brewer's friend calculator; it takes into account the variation in CTE with temperature rather than assuming a constant value of 200 PPM / oC.

Correct, I used Brewer's Friend.

Mmm, it is possible for the hydrometer, if cold, to reduce the temperature of the wort upon sampling

I took wort temp from the hydrometer tube itself via an STC-1000 probe

Unlikely: weird factoid, the volumetric heat capacities of most solids are within 20% of a value of 3 MJ/m3, water is anomalously high at almost 4.2, glass is a bit low at 2.1. Combined with density, this means the specific heat capacity of glass is about one fifth that of water.

The mass of the hydrometer is by definition equal to the volume of fluid displaced, in a normal scneario with adequate clearance between hydrometer and bulb the hydrometer reresents about one quarter of the combined mass of the system. Accordingly, a 40 degree difference in temperature between glass and sample would equilibrate out to a temperature drop of about 2.5 degrees.

Before anybody asks: the linear CTE of borosilicate glass is about 3 ppm and more or less linear with temperature so the resultant expansion of the hydrometer is not material.

Great bit of knowledge there mate - I'm always sure to watch out for your posts..

 

[Lyrebird_Cycles]

Yes I am aware of that, but you forget the lead mass at the bottom of the bulb.

The specific heat capacities of lead and bismuth are around 1/40th the value for water so including them in the calculation reduces the error. If the intention is to show that the error is small it is usual to go with the largest possible error (worst case scenario).

That's why I mentioned the volumetric heat capacities all being in a narrow range: this means the specific heat capacities of dense materials tend to be very low.

 

[Rocker1986]

I just stick my pre-boil sample in the fridge as soon as I take it, it's down to around 20C in a couple of hours or less depending on what temp it started at. I have borosilicate glass testing jars which makes it easier I suppose.

The post boil sample I take into a 500mL pyrex jug after transferring the wort to the cube and just leave to sit on the bench for a few hours to cool down before taking a reading. It's usually full of hot break so this allows that to settle and get a clear wort sample too.

 

[klangers]

The specific heat capacities of lead and bismuth are around 1/40th the value for water so including them in the calculation reduces the error. If the intention is to show that the error is small it is usual to go with the largest possible error (worst case scenario).

That's why I mentioned the volumetric heat capacities all being in a narrow range: this means the specific heat capacities of dense materials tend to be very low.

I agree with you on that. I was more trying to be a smart arse splitting hairs with your very thorough post.

I think we both know there's more to it than specific heat capacity differences. There's definitely more to it than simply the thermal mass of the submerged hydrometer. How the wort gets poured into the hydrometer and sample jar means that it can mix with the air, contacts the side of the jar which the brewer might be holding etc etc.

We can be going to and fro about the details, but at the end of the day if all other inputs check out,the most obvious thing to me is that the temperature that was plugged into the calculator was wrong or at least not representative of reality at that point in time.