Timeline for Hydrometer reading interference
Current License: CC BY-SA 3.0
14 events
| when toggle format | what | by | license | comment | |
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| Mar 7, 2013 at 13:16 | comment | added | GHP | While this answer is very detailed and informational, I think its FAR more likely that this is just another case of the extract and top-off water not mixing properly. | |
| Mar 6, 2013 at 20:26 | vote | accept | Hock | ||
| Mar 6, 2013 at 20:25 | vote | accept | Hock | ||
| Mar 6, 2013 at 20:26 | |||||
| Mar 6, 2013 at 0:52 | comment | added | mdma | That's a nice link. We in agreement - under normal circumstances the impact is negligible. Let's just hope the OP's sample was normal and not full of break material. | |
| Mar 6, 2013 at 0:32 | comment | added | MalFet | Definitely. I understand how hydrometers work, and certainly suspended solids can have a measurable impact on displacement. They're often used, for example, to measure particle size in soil samples. However, I'm not convinced it matters at the level of precision we work with (I've edited my answer to make that more clear). For example, ajdelange used some of his fancy equipment to compare trubbed & yeasted beer to centrifuged beer. He found densities of 1.053140 and 1.053037 respectively. That's a mighty small difference. (thebrewingnetwork.com/forum/viewtopic.php?f=&t=20854) | |
| Mar 5, 2013 at 23:25 | history | edited | mdma | CC BY-SA 3.0 |
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| Mar 5, 2013 at 23:11 | history | edited | mdma | CC BY-SA 3.0 |
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| Mar 5, 2013 at 22:41 | comment | added | mdma | The hydrometer works by displacement - the weight of the hydrometer equals the weight of the volume displaced. If there are solids present in the liquid being displaced these are also part of the displacement, adding to the total weight of displacement. When we are talking 1 part in 1000 being significant (1 gravity point) then suspended solids should be avoided if they are of any appreciable weight - protein and yeast don't have any appreciable weight so their affect is not significant. | |
| Mar 5, 2013 at 22:39 | comment | added | mdma | Yes, there's no way 50 points difference comes from suspended solids. More likely an uneven mixture of extract. But suspended solids do make a difference to the reading and should be avoided as much as possible. I frequently hear people say that suspended solids don't affect the reading, which is a fallacy. What I do agree with is that the affect will typically be small. I should have put that in my answer. | |
| Mar 5, 2013 at 22:04 | comment | added | MalFet | That's a very interesting link. I'm not the one who voted this down, and I agree that it's not helpful for someone to have done so without comment. That said, I'm still skeptical that particle suspension is relevant to brewers, especially to the extent that the OP seems to be experiencing. I can't run the numbers on the equations you linked because I don't know all of the constants, but just playing around I'm struck by how quickly larger particles fall. If we were talking about a point or two, I'd believe it, but 50 points? I've just never seen anything like it, even in my muckiest beers. | |
| Mar 5, 2013 at 19:01 | comment | added | FishesCycle | Downvote with no comment? This is not helpful. | |
| Mar 5, 2013 at 17:27 | history | edited | mdma | CC BY-SA 3.0 |
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| Mar 5, 2013 at 17:17 | history | edited | mdma | CC BY-SA 3.0 |
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| Mar 5, 2013 at 17:10 | history | answered | mdma | CC BY-SA 3.0 |