Density Gradient Column Floats



February 4, 2015

What is a Density Gradient Column?

Density gradient columns can be used to determine the density of solid samples which are too small to be measured by pyknometry or hydrostatic weighing. A density gradient column is normally made in a glass tube between 750 and 1500 mm long and 35 to 60 mm diameter. It is mounted vertically in a water bath, and held at a constant temperature. The gradient is filled by mixing two miscible liquids, in constantly varying proportions as the column is filled.
Density Gradient Column Floats

Once the gradient has been formed, calibrated floats are lowered into the column. These will slowly sink until each reaches liquid of its own density. This allows a relationship for height up the column against density to be determined.
Quality Calibrated Glass Floats

H&D Fitzgerald’s calibrated Glass Floats are manufactured to the highest specifications and are calibrated traceably to recognised national standards of mass, density and temperature.

• Density range 700 to 2300 kg/m3 at 23°c. You specify the density, we make the float!
• Unique identification number fused inside the glass to allow floats to be easily distinguished from each other.
• Standard uncertainty of the density value is ±0.15 kg/m3 at k=2. However our accredited Calibration and Measurement Capability (cmc) is ±0.1 kg/m3 at k=2 and, if necessary, we can calibrate floats with this uncertainty.
• Recalibration service available for both our own floats and floats made by other manufacturers.

Analytical Techniques

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