HydroMATE Petroleum hydrometers

The devices shown in the image are petroleum hydrometers (also known as densitometers), which are used to measure the specific gravity and density of liquid  like gasoline (petrol) and diesel.

Core Specifications & Ranges

 image outlines the specific gravity measurement ranges for different fuel types:

                (Gasoline / Petrol):

• 0.700 – 0.750
• 0.750 – 0.800
•              (Diesel):
  • 0.800 – 0.850
  • 0.850 – 0.900

How They Work

• Buoyancy Principle: These glass instruments float vertically in the liquid.
• Reading the Scale: The depth to which the stem sinks indicates the density of the fluid. Lower density liquids (like petrol) cause the hydrometer to sink deeper than higher density liquids (like diesel).
• Calibration: The faint text printed on the glass bulbs indicates they are calibrated for accuracy at a specific standard temperature (typically 20°C).