How to measure SG of a "lighter than water" liquid with your alcohol meter.
Quite often we get asked for hydrometers that can measure the SG (Secific Gravity) of liquids that is lighter than oil. Many of these requests concern the SG measurement of oils and other light petroleum products.
As an emergency measure, (or if you don't want to buy a "lighter than water" SG hydrometer it is quite possible to do this with an ordinary alcohol meter.
Take your alcohol meter and place it in the liquid to be measured and read the %alcohol reading. Also take note of the temperature of the liquid.
Now use the following table to do the conversion from %alcohol to SG as follows:
Say, for example the alcohol reading reads 31% and the liquid temerature is close to 25 Degree C.
No look at where the Temperature (The column with 25 Deg C) and the Alcohol percentage (31%) crosses and read off the approximate SG of the liquid (0.9489 in this example.)
There will be a very slight error as the table is for % alcohol by weght, and the alcohol meters are measuring %alcohol by volume. However, as an emergency backup, it does just fine!