ARC 244 - Accelerating Rate Calorimeter

General

Technique

Applications

Accessories

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