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HDT/Vicat Allround

Test methods
  • HDT
  • Vicat
Heat transfer
  • Via heat transfer fluid

The All-Round Instrument for Convenient Testing

ZwickRoell's HDT/Vicat Allround instruments determine the heat deflection temperature (HDT), and are designed to enable convenient testing in research and development, goods inwards checks and production monitoring as well as for educational and training purposes.

The instruments are available in various versions with up to six testing stations according to requirements. Test-sequence parameterization and display of measured values are conveniently handled via ZwickRoell testing software.

Advantages & Features

Advantages & Features

Functions, elements and interfaces
Automatic test sequence
Re-cooling the heat-transfer fluid


  • Measuring station lowered automatically
  • Optionally available automatic lowering of the test weights
  • Testing to ISO 306, ASTM D1525, ISO 75 and ASTM D648.


Determination of heat deflection temperature (HDT)

  • as per ISO 75, Parts 1 to 3, and ASTM D648, Method B, on thermoplastics, hard rubber and fiber-reinforced and filled thermosets.

Determination of Vicat softening temperature (VST)

  • of thermoplastics as per ISO 306 and ASTM D1525 .

Determination of creep behavior

  • under flexural load

Functions, elements and interfaces

  • Built-in programmable logic controller (PLC) for temperature control and measured-value acquisition
  • Re-cooling controlled by solenoid valve
  • Motorized lowering of measuring stations
  • Safety thermostat
  • Electronic level-monitoring
  • Test control and data acquisition via PC with ZwickRoell testing software (RS232 interface in PC required)
  • Integrated compensation for heat expansion

Automatic test sequence

As soon as the heat-transfer fluid has reached the starting temperature, the specimens are inserted into the measuring stations and lowered (motor-driven) into the oil bath. In the next step the test weight specified in the standards is applied manually and the test sequence is started by the PC software.

On completion of preconditioning under the influence of force, the displacement signals are zeroed (program-controlled) and heating of the heat transfer fluid at the previously set rate is started. As soon as the required deflection, outer-fiber strain or penetration is attained, the heating is switched off and the test is ended.

Re-cooling of the heat-transfer fluid is started automatically via a solenoid valve. Afterwards, the specimens can be removed.

Re-cooling the heat-transfer fluid

Cooling for Type A1 HDT/Vicat instruments is by means of a cooling coil located in the oil-bath. Coolant can be pumped in via a connection located on the left-hand side of the instrument. Cooling is started automatically via a solenoid valve, however only at 130°C or above. For faster re-cooling a connection for an external re-cooling unit is available (option).

Technical Overview

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Learn more about HDT & Vicat

Determination of HDT VST plastics
ISO 306, ASTM D1525, ISO 75, ASTM D648
Determination of heat deflection temperature (HDT) and Vicat softening temperature (VST)
to Determination of HDT VST plastics
HDT and Vicat Testing Instruments
Standard-compliant testing to ISO 75, ISO 306, ASTM D1215 and ASTM D648.
The thermal resistance of plastics in many ranges of application is measured via heat deflection temperature (ISO 75 and ISO 306).
to HDT and Vicat Testing Instruments


Name Type Size Download
  • Product information: HDT/Vicat Allround PDF 529 KB
  • Product information: HDT/Vicat Allround with integrated recooling unit PDF 357 KB