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Our laboratories generate test data on the thermal properties of materials.
Air Over Layer
Bulk Powder (Diffusion Cell)
Aerated Cell
Differential Scanning Calorimetry (DSC)
Advanced Reactive System Screening Tool (ARSST)
Accelerating Rate Calorimetry (ARC)
Carius Tube
We also offer a range of Chemical Reaction Hazard Testing and Analysis services.
Thermal stability testing
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.
We offer a wide range of thermal stability testing services.
Discover our range of tests below and get in touch for a free consultation today.
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.
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.
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.
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.
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:
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.
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.
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.
Can’t find the tests you need?
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.
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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.
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