wessmith said:Higher temps cause the air inside to expand so I'm told and that can affect the reading.
Wes
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Dreamboat, nearly all materials expand to some extent with heat so presumably there is some correction required for the expansion of the glass bulb.dreamboat said:Not saying that you are wrong on this... but it makes no sense to me at all. Unless the glass expands in some way due to a pressure increase inside the hydrometer, which moves the scale... which would have to be a very minor effect if at all.
The air can't go anywhere, so the mass can't change.....
Is it difficult to argue with someone who makes the things but the calibration tables that I am aware of simply adjust for the density of water at different temperatures which is a well established physical property of water. If the bulbs indeed are temperature stable (or much more so than water) then these tables *should* be accurate.wessmith said:Dreamboat, I am a little hazy on this and am trying to recall a long converation I had with the guru at Carlton in Brisbane who make the pro hydrometers. There is a HUGE difference in bulb diameters betwen different makes and that can lead to major differences in calibration. At the end of the day, any given hydrometer is only accurate at its rated temp and the various compensation tables can only apply to a particular type of hydrometer. When I asked Carlton for their comp tables he said they dont have any. Just cool the sample to the rated temp.
Simple I guess.
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Darren said:So nothing to do with the viscosity of the wort?
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