Differential Thermal Analysis DTA

Monitoring the exothermic behavior using DTA is critical for identifying potential runaway reactions or hazardous conditions within a process. Sudden and significant heat releases can result in a rise in temperature that exceeds the control capabilities of the process equipment, leading to thermal runaway, explosion, or other dangerous scenarios. In process safety, two commonly used DTA lab equipment are the Carius tube and the Rapid Screening Device (RSD) etc. These tools are particularly valuable as they allow for the measurement of pressure.

Principle of Operation

The principle of operation of DTA involves subjecting a small sample of a material to controlled heating while simultaneously measuring the temperature difference between the sample and an inert reference material. The heating is typically done at a constant rate. As the temperature increases, any exothermic reactions or decomposition reactions taking place within the sample will release heat. This heat release is reflected as deviations in the temperature difference recorded by the differential thermocouple. The purpose of this test is to offer an initial assessment of the thermal characteristics of a material. It provides a semi-quantitative evaluation of exothermic, endothermic, and gas generation events. Additionally, this test can be utilized on liquids, solids, or mixtures.

Test Method

In RSD or Carius tube test, a small amount of material (1 – 6 ml in RSD, 10-15ml in Carius tube) is placed inside the testing cell. The cell is then positioned in the center of a furnace and connected to a pressure transducer. The temperature is gradually increased at a fixed rate (0.5 K·min-1, for example) from the starting temperature to either 400°C or a cell pressure limit, whichever is reached first. Energetic events, such as exothermic or endothermic reactions, are detected by deviations from the baseline temperature difference between the sample and the oven. Additionally, it is possible to introduce reactive substances and stir the sample during this test.

Data Interpretation

The results of the test are presented in three graphs. Graph (a) displays the complete trace of temperature, pressure, and time. Graph (b) shows the relationship between temperature and the difference between the oven and sample temperatures. Graph (c) depicts the relationship between the natural logarithm of the pressure and the reciprocal of the absolute temperature. The point at which a deviation in the temperature difference is first observed is recorded as the onset of an event, with an upward deviation indicating an exothermic reaction and a downward deviation indicating an endothermic reaction. For safety purposes, the onset temperature is considered with a safety factor of approximately 50 K to account for heat losses from the test equipment. The height and width of the peak in the graphs provide a qualitative measurement of the event’s magnitude, although they are not directly scalable. A broader peak suggests a reaction controlled by mass transfer. Additionally, the deviation from linearity in the Antoine plot indicates the onset of gas generation, with the steepness of the rise reflecting the rate of gas generation. The residual pressure in the tube after cooling can provide a quantitative measure of the gases released. To determine the nature of the gas, mass spectrometry techniques can be utilized.

In summary, you may obtain:

  • Vapor-liquid phase equilibrium data – Antoine plot,
  • Quantify total gas generation,
  • Onset T of endo/exothermic reaction but with an appropriate safety factor,
  • Induction time of autocatalytic reaction but need expert guidance for testing procedure and data interpretation.

Why perform DTA test?

Performing Differential Thermal Analysis (DTA) in process safety is essential for a multitude of reasons. DTA enables the identification and characterization of thermal events, such as phase transitions, reactions, and decomposition processes, by measuring the temperature difference between the sample and an inert reference material. By analyzing these thermal events, potential hazards and risks associated with process conditions can be understood and mitigated. Furthermore, DTA provides valuable information on the thermal stability, thermal compatibility, and potential reactions of materials used in the process, allowing for the selection and optimization of parameters to ensure safety and enhance overall process performance.

Why use us?

  • Our team of experts has extensive knowledge and experience in performing differential thermal analysis, ensuring accurate and reliable results.
  • Our strict adherence to testing protocols and quality control measures ensures consistent and dependable test results.
  • We offer in-depth analysis and interpretation of the data obtained, providing valuable insights and recommendations for your specific application or research.
  • Our commitment to customer satisfaction guarantees prompt and efficient service, providing you with the information you need to make informed decisions for your materials or products.


1. What is Differential Thermal Analysis (DTA)?

Differential Thermal Analysis (DTA) is a technique used to measure the temperature difference between a sample and a reference material as they are heated or cooled. It provides information on the phase transitions, melting points, reactions, and thermal behavior of substances, making it useful in process safety evaluations.

2. How does DTA work?

In DTA, the temperature of the sample and a reference material are simultaneously measured as they undergo a controlled heating or cooling program. A temperature difference between the sample and the reference material indicates thermal events, such as phase transitions or reactions. DTA data provides insights into the heat flow associated with these events.

3. What are the applications of DTA in process safety?

DTA finds applications in process safety assessments by helping identify potential hazards related to thermal events in materials such as phase transitions, decomposition, or reaction-induced exothermic events. It aids in understanding the thermal behavior of materials and assists in designing safe operating conditions and selecting suitable mitigation measures.

4. What information can be obtained from DTA measurements?

DTA measurements can provide valuable information, including:

  • Identification of phase transitions, such as melting points, crystallization, and glass transitions, which are important in understanding material behavior and stability.
  • Detection of exothermic or endothermic reactions occurring during the temperature ramp, indicating potential hazards.
  • Quantification of gas generation.
  • Determination of thermal stability and decomposition temperature ranges.

5. Can DTA data be used for process optimization?

DTA data primarily focuses on understanding the thermal behavior and potential hazards of materials. However, the information obtained from DTA experiments, such as melting points or reaction temperatures, can be crucial in optimizing process conditions. By designing processes to operate below certain critical temperatures or avoiding conditions that induce reactions or phase changes, process safety can be improved.