The air pycnometer is supplied as a complete set, including a calibration block. The apparatus is suited for sample rings with a maximum diameter of 53 or 60 mm (max. height 51 resp. 40 mm). The instrument has a measuring range of 0-115 cm3. The time period of the measurement is approximately 1 minute. The maximum measuring accuracy equals 1%.
An under pressure is created in the vacuum bell in which the object to be measured is placed. Depending on the gas volume present in the bell, more or less air will be extracted. The quantity of the air present is independent of the volume taken by the object to be measured. After the under pressure has stabilized the volume of the object can be read from the calibrated scale.
The pycnometer is applied where there is an interest in knowing the specific weight.
Limitation: Temperature variations influence the measurements (can be prevented by climate control in the laboratory).