The densities of three biodiesel fuels at temperatures up to 300 °C

In order to obtain the densities of biodiesel fuels at temperatures up to 300 °C, a capacitance type liquid level meter was designed to measure the increase in volume of 50 ml of three commercial biodiesel fuels over the temperature range of 20–300 °C. Densities were measured for methyl esters of canola and soy and ethyl esters of fish-oil. The frequency output from the meter was linear with temperature and liquid level. Frequencies were recorded in kHz to within three decimal places and had sensitivities of 0.040 kHz/°C and −2.740 kHz/cm for temperature and submergence depth, respectively. Derived densities were found to be linear with temperature over the measured range. Used in this fashion, the level meter can be considered a precise densitometer with a repeatability of 1%.