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Hydrometer errors |
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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 which is fortunate because it is very difficult to calibrate for this.
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