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PostPosted: Wed Dec 20, 2017 9:29 pm 
Hophead

Joined: Sat Feb 11, 2017 9:29 am
Posts: 51
Location: Evansville indiana
To begin this new year and makeing great beer we often for get some little things like calibrating our equipment. How to calibrate a hydrometer - the easy way

A hydrometer used in homebrew and in professional wine making needs either very precise factory calibration (expensive!) or you need to calibrate it every time you use it. Fortunately, this is very simple so you can turn your standard homebrew hydrometer into a precision instrument with minimum hassle.

wine making hydrometer You can easily calibrate for most errors and use a low cost hydrometer to get a high quality reading using the following procedure:

Keep a trial jar with water near your brew. The idea is that this water have the same temperature as your brew so leave it there all the time.

Before using your hydrometer (every time!): Check the reading of the water. It should be around 1000 s.g. (0 on hydrometers showing oechsle degrees) but it will vary depending on temperature and scale errors.

If your hydrometer shows, say 1002 (+2) you obviously need to take your reading minus 2 to get it right. Then simply take all your wine/beer readings minus 2 and thats it!

Similarly of course, if your hydrometer shows 997 (-3) on the water - just add 3 to all your readings.

Remember that you have to check the water reading every time because temperature might have changed and/or your hydrometer scale might have moved inside the hydrometer. The beauty with this procedure is that it compensates for both temperature and scale moving errors at the same time so no need any more to make sure that the wine has a certain temperature before measuring the specific gravity.

Why do you need to calibrate the hydrometer?

There are many sources of errors when you use a hydrometer, either it is a cheap one or an expensive lab quality one.

Temperature: The same liquid will show different readings at different temperatures. High temperature means lower reading. Your hydrometer usually states what temperature to use it at (normally 15-20 C). If you have a liquid with another temperature there are formulas to calculate the correct value. But then of course you need an accurate thermometer as well.
Scale movement: The scale inside your hydrometer is usually glued inside to the glass and quite often the glue is not good enough which means it slides up or down.
Scale misplacement: In production, especially on cheap hydrometers, the scale might have been fitted in the wrong position. A more expensive hydrometer would probably have been tested in water before approval so you are less likely to have this problem the more money you spend on your hydrometer.
You can easily calibrate your hydrometer for all the above problems which means that you can use a low cost hydrometer and still get a high quality reading. Calibrating your hydrometer - here is how you do it.

Scale distortion: Scales are often photocopied from previous production run and eventually this might distort the scale. This is a less common problem and if it is there, it us usually very small, which is fortunate because we can not calibrate this error away (since it is 
There are two methods for calibrating thermometers:

Ice point. Fill an insulated glass with crushed ice and then add a little water. Let it sit for at least five minutes and then insert the sensing part of the thermometer into the cup. Make sure the sensor is in the middle of the glass and at least an inch from the sides, bottom, and top of the glass. Hold it there for 30 seconds or until the dial stops moving or the digital thermometer beeps. Your thermometer should be reading 32 degrees Fahrenheit after 30 seconds. If it’s not, it needs to be recalibrated. The ice point method is the most accurate way to calibrate a thermometer.

Boiling point. Boil at least six inches of water. Once the water has reached a rolling boil, stick the sensor part of the thermometer into the middle of the water, taking care to keep it at least two inches from the sides, top, and bottom. After 30 seconds, the thermometer should read 212 degrees Fahrenheit if you’re at 1,000 feet or less of elevation. See below if you are at a higher altitude. If it doesn’t read 212, your thermometer needs to be recalibrated.

Changes in boiling point temperature by elevation:

Sea Level: 212 degrees Fahrenheit
1,000 feet: 210 degrees Fahrenheit
2,000 feet: 208 degrees Fahrenheit
3,000 feet: 206.4 degrees Fahrenheit
4,000 feet: 204.5 degrees Fahrenheit
5,000 feet: 202.75 degrees Fahrenheit
8,000 feet: 197.5 degrees Fahrenheit

How To Calibrate A Thermometer

Dial thermometers have a little screw or nut that adjusts the dial to the correct temperature. Simply turn the adjuster until the dial reads the correct temperature according to the method you’re using to calibrate.

Digital thermometers have a reset button. Simply push that button when you’re at the temperature point and your thermometer is ready to go.

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PostPosted: Fri Dec 22, 2017 9:12 am 
Brewmaster

Joined: Sun Feb 15, 2009 12:08 pm
Posts: 400
Location: Evansville, IN
That reminds me I need to calibrate the thermometer on my mash tun.

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