First, I must confess that I have been lazy and neglectful as a brewer because I have never actually calibrated my hydrometer ... as far as I can recall. Oh, I'm sure I must have dropped it in some faucet water when I first got the thing many years ago, and it probably came close enough to 1.000 that I never gave it another thought.
Anyway, my real question/comment has to do with the 'S.G.' tab in the BTP calculator -- selecting "Hydrometer" (I don't know anything about refractometers other than what they are used for). On that panel, the user enters "Calibration Temp", "Sample Temp", and "Hydrometer Reading", and then BTP provides the "Corrected" gravity. Should there be a place to indicate how much the hydrometer may have been 'off' during calibration? For instance, if I use distilled water at 60F, and it is supposed to read 1.000 but instead reads 1.005, shouldn't there be a way for me to tell BTP? Or are we supposed to be searching for the exact temp at which the reading is actually 1.000, and then use that as our calibration temp? ... or should the hydrometer just be thrown in the trash?
Cheers.
Bill Velek
Question re BTP S.G. Calculator and hydrometer calibration
Bill, personally I'd dump a hydrometer that read 5 points off in the trash! However, that's not all that useful in taking care of your problem since many hydrometers that homebrewers use will be off by a point or two. So yes, I agree with you -- there should be a hydrometer correction factor built in.
A potentially bigger problem lies in the way a particular hydrometer is showing error. I've heard about hydrometers that are fine at 1.000 but are off at 1.060, for example. For those (admittedly extreme) cases, building in a correction factor is going to be a major pain in the butt -- but most likely those hydrometers deserve death by garbage disposal rather than being used in our precious beer.
A potentially bigger problem lies in the way a particular hydrometer is showing error. I've heard about hydrometers that are fine at 1.000 but are off at 1.060, for example. For those (admittedly extreme) cases, building in a correction factor is going to be a major pain in the butt -- but most likely those hydrometers deserve death by garbage disposal rather than being used in our precious beer.
Here is an article from BYO that shows how...slothrob wrote:Bill, I like this idea.
CJ, do you calibrate your hydrometer in a solution other than 1.000?
http://byo.com/departments/1464.html
cheers!
Fermenting : Ordinary Bitter, Hefe
Bottled : Too many bottles
WinXP PentiumIV Res:1920x1200 120DPI
Blog: http://hobbybrau.blogspot.com
Bottled : Too many bottles
WinXP PentiumIV Res:1920x1200 120DPI
Blog: http://hobbybrau.blogspot.com
Short answer -- no. Longer answer -- I have several hydrometers and occasionally checked the OG used all of them. At one time, I had four and found out that two were always in total agreement, one was off by 1.002, and one was off by 1.004 -- both at zero and when measuring wort. Now I use a digital refractometer and occasionally compare it with my hydrometer to make sure I'm measuring the same thing.slothrob wrote:Bill, I like this idea.
CJ, do you calibrate your hydrometer in a solution other than 1.000?
Totally off topic but the digital refractometer rocks! Expensive as hell, but man is that thing cool.