Thermal Stability Testing Equipment

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Thermal Stability Testing & Analysis

Our laboratories generate test data on the thermal properties of materials.

We also offer a range of Chemical Reaction Hazard Testing and Analysis services. 

Thermal stability testing

Test the thermal properties of your materials

The safe management, handling and elimination of the dangers posed by uncontrolled exothermic activity is of vital importance to the protection of your business, people, workplace and the environment. Sigma-HSE’s thermal stability testing lab offer comprehensive standard and custom testing packages to aid you in the identification of the oxidation, combustion or molecular decomposition of materials in your workplace.

Discover our range of tests

We offer a wide range of thermal stability testing services to ISO/IEC 17025:2017 standards, globally.
Discover our range of tests below and get in touch for a free consultation today.

Air Over Layer

The air over layer test is conducted to establish the onset temperature of exothermic activity on thin layers of materials when exposed to elevated atmospheric temperatures. It replicates thin layer (up to 15 mm) deposits in a drying situation i.e. drier walls or roofs where hot air may rush over the surface.

Using a small tray test cell, a sample is placed inside a cell and thermocouples are placed into the material at three locations. This assembly is then placed into a digitally controlled horizontal laboratory tube oven with a controlled heated air supply.

Either of the below tests can be performed using a data acquisition system to monitor, detect and record any exothermic activity.

An environmental temperature is digitally increased from ambient conditions up to 400°C at 0.5°C.min-1. This test configuration is used for estimating exothermic activity for onset temperature.

The loaded test cell is placed into a heated oven and set to a specified temperature for a duration of 24 hours. The temperature selected can be based on working or proposed process conditions, plus factors for safety. Alternatively, full determination can be undertaken, whereby several isothermal tests can be conducted to establish a definitive ignition temperature.

Not only is the air over layer test a necessity in evaluating whether current or proposed drying and process temperatures are safe, it can also confirm the possibility of using higher temperatures to increase productivity.

Bulk Powder (Diffusion Cell)

The bulk powder diffusion cell test is conducted to establish the onset temperature of the potential exothermic activity of a material when exposed to elevated atmospheric temperatures. It replicates small bulk deposits in any drying situation where air is naturally available.

Using an open cylindrical glass test cell with a sintered glass bottom and a sample is placed inside the cell. Thermocouples are then inserted through the wall into the material at four locations from the bottom upwards. This assembly is placed into a digitally controlled laboratory oven and either of the below tests are performed using a data acquisition system to monitor, detect and record any exothermic activity.

An environmental temperature is digitally increased from ambient conditions up to 400°C at 0.5°C.min-1. This test configuration is used for estimating exothermic activity for onset temperature.

The loaded test cell is placed into a heated oven and set to a specified temperature for a duration of 24 hours. The temperature selected can be based on working or proposed process conditions, plus factors for safety. Alternatively, full determination can be undertaken, whereby several isothermal tests can be conducted to establish a definitive ignition temperature.

Not only is the bulk powder diffusion cell test a necessity in evaluating whether current or proposed drying and process temperatures are safe, it can also confirm the possibility of using higher temperatures to increase productivity.

Aerated Cell

The aerated bulk powder diffusion cell test is conducted to establish the onset temperature of the exothermic activity of a material when exposed to elevated atmospheric temperatures. It replicates small bulk deposits in any drying situation where heated air is percolated through a material i.e. fluid bed driers.

Using a cylindrical glass test cell with a sintered glass bottom, the sample is placed inside the cell. Thermocouples are then inserted through its wall into the material at four locations from the bottom upwards. A glass lid is applied, and a regulated hot air supply that pushes air through the test material is connected. The assembly is placed into a digitally controlled laboratory oven and either of the below tests are performed using a data acquisition system to monitor, detect and record any exothermic activity.

An environmental temperature is digitally increased from ambient conditions up to 400°C at 0.5°C.min-1. This test configuration is used for estimating exothermic activity for onset temperature.

The loaded test cell is placed into a heated oven and set to a specified temperature for a duration of 24 hours. The temperature selected can be based on working or proposed process conditions, plus factors for safety. Alternatively, full determination can be undertaken, whereby several isothermal tests can be conducted to establish a definitive ignition temperature.

Not only is the aerated bulk powder diffusion cell test a necessity in evaluating whether current or proposed drying and process temperatures are safe, it can also confirm the possibility of using higher temperatures to increase productivity.

Differential Scanning Calorimetry (DSC)

ASTM E 537-12

The Differential Scanning Calorimetry test is conducted to assess the presence of enthalpic changes and to approximate both the temperature of initiation and enthalpies (heats) of solids, liquids or slurries.

This test in conducted by measuring the heat flow (Δq) associated with the change of enthalpy. An absolute temperature (T) of the test material or reference to the average temperature of elapsed time is also taken. The test sample is examined before the test is undertaken. The material and a thermally inert reference material are then placed into isolated containers.

Both the testing sample and the reference material are then simultaneously heated at a controlled rate of 2 K/min to 20 K/min under an equilibrated atmosphere. A record of heat flow as a function of temperature is then established. When the sample experiences a transformation that involves a change of enthalpy indicated by a departure from the established baseline. These temperature changes are then detailed and recorded.

The Differential Scanning Calorimetry (DSC) test can detect potentially hazardous reactions from volatile chemicals while estimating the time at which a hazardous reaction may occur. The DSC can also be used as an early-stage test for detecting the potentially hazardous thermal components of uncharacterised materials.

Advanced Reactive System Screening Tool (ARSST)

The Advanced Reactive System Screening Tool (ARSST) is an adiabatic calorimeter batch reactor tool that is used to quickly identify potential chemical hazards in processes.

It consists of a well instrumented pressure vessel that holds a spherical glass test cell that can heat a 10ml sample at a uniform rate of up to 400°C. The reaction mixture, magnetic stirrer and thermocouple are then introduced to this cell. The pressure inside the vessel is then measured by a pressure transducer. Due to the unique heating method by a wraparound heater, the sample is kept in a quasi-adiabatic mode and no heat is lost to surroundings occurs. Typical data outputs can include the following:

  • Rate of pressure rise
  • Heat of reaction
  • Heat of mixing
  • Total adiabatic temperature rise
  • Onset temperature
  • Tempering temperature
  • Self-accelerating decomposition temperature
  • Time to maximum rate (induction time profile)

ARSST data yields critical experimental knowledge of the rates of temperature and pressure rises during runaway reactions. This, in turn, provides reliable energy and gas release data that can be applied directly to full scale process conditions. Potential deviations and worst-case scenarios can also be explored with the ARSST and the information generated can be used to design future safeguards.

Accelerating Rate Calorimetry (ARC)

ASTM E 1981-98

The Accelerating Rate Calorimetry test is conducted to assess the time, temperature and pressure data of a material as it undergoes a physicochemical change under near adiabatic conditions.

A sample is placed in a reaction container and positioned in the calorimeter. This is then heated to an optimum environmental temperature until the test sample has reached an equilibrium. During this time, evidence of an exothermic reaction is monitored. If the environmental rate of temperature rise is first exceeded, then an exotherm has usually occurred. If not, the system temperature is raised slightly, and the test begins again. This cycle is repeated until an exotherm has been detected or the upper temperature limit of the test has been reached.

Time, temperature, and pressure data are recorded at temperature intervals as a function of time. This data can then be used to the time rates of changes of pressure and temperature. This data can be used to calculate a time-to-maximum rate, obtain kinetic parameters for nonautocatalytic exothermic reactions and to calculate an adiabatic temperature rise / heat of reaction.

The Accelerating Rate Calorimetry (ARC) test can directly simulate and predict thermal and pressure events in the processing, storage, and shipping of potentially hazardous chemicals. The ARC can also be used to investigate the effects of catalyst, inhibitors, initiators, reaction atmospheres, materials of construction and agitation.

Carius Tube

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

The Carius tube apparatus works by placing approximately 10 grams 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 K/min). The temperature and pressure of the test cell are then detailed and recorded to assess the thermal stability of the sample upon heating.

The Carius tube apparatus can be used to detect the onset temperature of an exotherm and any concurrent gas evolution, while simultaneously obtaining an estimate of their energy and volume. It can also be used to examine the delayed onset of reactions and to estimate the rate at which gas evolution has been detected. 

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The Sigma-HSE Advantage

From exothermic effects to flashpoint testing, Sigma-HSE is your single solution provider for a range of thermal stability testing. Our dedicated team of experts are committed to helping you ensure and maintain compliance.

How to test the thermal properties of your materials

Receive quick and accurate data in just a few simple steps

Contact us

Get in touch with one of our experts so we can learn more about your specific requirements. We’ll then generate and send you a customised quote.

Prepare & ship

Prepare your samples and ship them to one of our global laboratories.

Test, analyse & report

Once we’ve received your samples, we’ll begin testing and analysing. We’ll then create and send you a custom in-depth report with actionable insights.

Post-Project Support

If you need support after receiving your report, our after-sales support team will be on hand to assist you with any questions you may have.

Understand the thermal properties
of your materials

Testing for the thermal properties of your facilities materials is an important
aspect of safety compliance. Learn more about how we can assist you today.