All hydrometers are calibrated to be accurate at a given temperature. Most newer hydrometers are calibrated for 68 degrees (F). Because the density of fluids changes as their temperature changes if you don’t measure your specific gravity at your hydrometers calibration temperature you’re going to get an inaccurate reading.
While the correction may be small for a single reading if you don’t adjust, it becomes increasingly difficult to compare readings over time. For instance, if you take an original specific gravity reading at 75 degrees (F) and a final reading at 65 degrees (F) you can’t compare these readings because the fluid densities are different at the different temperatures. You must correct each of your readings for temperature differences before you can compare them. Continue reading “Specific Gravity Temperature Correction Calculator”
