What effect does temperature have on the specific gravity measured by a hydrometer?

A hydrometer measures the specific gravity of a liquid, which is defined as the ratio of the density of the liquid to the density of a reference substance (typically water). The temperature of a liquid significantly influences its density because, as temperature increases, most liquids expand and their density decreases.

Thus, when a hydrometer is immersed in a liquid at a higher temperature, the density of that liquid is lower compared to the same liquid at a lower temperature. As a result, the specific gravity measured by the hydrometer would be lower at elevated temperatures since it's a comparison of the liquid's density to that of water, which remains stable at a given temperature.

This relationship indicates that as temperature increases, specific gravity decreases, because the hydrometer floats higher in less dense liquids. Understanding how temperature affects density and consequently specific gravity is crucial for accurate readings in various refrigeration and air conditioning applications, ensuring that technicians can assess fluid characteristics effectively for maintenance and troubleshooting.