APTAC 264 - Automatic Pressure Tracking Adiabatic Calorimeter

General

Technique

Accessories

 

APTAC 264 uses the patented “Heat–Wait–Search”™ mode of operation, coupled with adiabatic tracking of any detected exotherm. This allows standard analysis of the data for information on the activation energy, order of reaction, and heat of reaction. Data collected during cool-down measures the total amount of gas generated. A small tube can be inserted into the vessel to extract samples for analysis.

Other closed-vessel test options include:

• Linear heat ramps for scanning purposes

• Simulated fire exposure using heat ramps with exotherm detection followed by adiabatic operation

• Isothermal aging of the sample coupled with exotherm detection and followed by adiabatic operation

Reaction Calorimeter
Because APTAC 264 typically uses a larger sample size than the ARC, additional reagents may be added while the experiment is in progress. In this way, the instrument can simulate actual process operations for process development or evaluate the effectiveness of quenching agents in controlling runaway reactions. Samples can also be taken from APTAC 264 while an experiment is in progress.


Pressure Relief Analysis
APTAC 264 enables users to gather pressure relief data by
running a normal closed-cell test and then releasing sample pressure form the vessel into an external sample collection vessel. This test gives information about maximum rates of temperature, rise, gas production, and condensate vapors, which can be used for vent sizing using the DIERS simplified method. When the sample pressure is released, no chemicals vent directly into the calorimeter assembly. This important feature minimizes the safety and environmental hazards in the procedure and significantly reduces service and repair costs for the calorimeter. What’s more, releasing the sample into an external vessel allows engineers to further analyze the composition of the released material using direct links from APTAC 264 to gas chromatography and mass spectrometry instruments.


VariPhi:

VariPhi is a controlled variable DC heater used in ARC and APTAC calorimeters to provide the most accurate simulation of real-world thermal environment.
VariPhi’s sophisticated calibration software regulates and records the amount of energy supplied by the internal heater.
VariPhi enables precise measurement of heat, pressure, and activity within a sample, avoiding the need for complicated mathematical corrections.


VariPhi in ARC/APTAC Mode

The ARC and APTAC calorimeter heaters (acting as guard heaters) provide a well controlled near-adiabatic environment for the VariPhi, bomb, and sample system. This allows the sample to be tested in the standard ARC/APTAC operational modes such as Heat-Wait-Search™, Iso-fixed™, or Iso-Track™.


VariPhi’s key features in ARC/APTAC mode include:

• The internal heater compensates for the heat lost to the sample bomb during an exotherm.

• The user can define the thermal inertia or PHI (Φ) for the test. The heater returns all or part of the heat lost to the bomb wall to the sample. A user can define the exact thermal inertia at which to run the test.

• Tests can be run at the exact thermal inertia at which they will run in the plant or storage container.

• Sample heat capacity is measured as a function of temperature.

• Kinetics that are dependent on thermal inertia, such as competing reactions that cannot be compensated for mathematically, are no longer a problem.

• Thermal inertia can be corrected without having to extrapolate kinetics from overlapping and multiple reactions.

• Data obtained will directly correspond to actual run or storage conditions making it easier to relay the information to non-calorimetry specialists.

VariPhi in Scanning Mode

By using VariPhi as an additional heater, the user can run ramp tests with the ARC or APTAC that deliver improved information about the activity in a sample
By operating in scanning mode, VariPhi can measure exothermic and endothermic activity, heat capacity, and pressure within a sample, faster and more cost effectively than a standard differential scanning calorimeter.

In scanning mode, VariPhi provides the following key features:

• Faster data collection on exothermic activity than Heat-Wait-Search tests

• Heat capacity measured directly as a function of temperature

• Enhanced measurements and capabilities over traditional DSC analysis

• Endotherm activity

• Pressure data

• Ability to inject sample

• Ability to stir sample

• Ability to set thermal inertia for direct real-world comparison