Carius Tube Testing

Recognised industry standard test, developed first at ICI and AstraZeneca hazard labs, and included in ABPI and IChemE publications on Chemical Reaction Hazard Assessment.

The Carius tube test is used as a small-scale screening tool for thermal stability. It is primarily undertaken to investigate exothermic activity and identify the pressure effects of permanent gas generation. Carius tube testing can also aid in the detection of exothermic activities such as onset temperatures.

The Carius tube test works by placing approximately 10 g of a test material in a heavy-walled sealed glass tube and then placing it in an oven. The oven temperature is then increased at a controlled rate (typically 0.5 °C/min). The temperature and pressure of the test cell are then detailed and recorded to assess the thermal stability of the sample upon heating.

A differential temperature reading between the sample and baseline of the oven can indicate and quantify energetic events, and whether they are exothermic or endothermic. A plot of Ln (pressure) versus the reciprocal of temperature can also indicate the onset temperature of gas generation.

The Carius Tube test can quickly identify thermal regions of interest (exothermic events, structural changes, permanent gas generation), which can then in turn be investigated in more detail using adiabatic or more precise techniques. It is often run as a screening test complimentary to DSC (Differential Scanning Calorimetry), as it provides the valuable pressure data not available from the DSC.