UNITHERM™ MODEL 6000 GUARDED HOT PLATE THERMAL CONDUCTIVITY SYSTEM
- SALIENT FEATURES

(Technical Note #102)

The Unitherm™ Guarded Hot Plate (GHP) family of instruments is designed with the most up-to-date technology in mind. First and foremost in producing these instruments is to assure that their performance is the best level one can expect from a commercially produced device of its kind. While accuracy and reproducibility for these machines is generally better than one can get from most other types of thermal conductivity measuring systems, commercially produced devices should not be confused with GHP instruments used in national standards laboratories built after years of painstaking development by highly skilled personnel at costs many times the prices these devices command.

There are four GHP Systems in the Unitherm™ product line.

Most of the underlying technology used applies to all systems, but some features may not be used with all models.
Salient features are:

• Pneumatically actuated plate lifter for smooth operation.
• Gimbaled stack plate to accommodate slight thickness variations in the sample.
• Counterbalanced cover box. ( 6010 and 6021 only).
• Single sided system, requiring only one sample, rather than two (double sided systems optional).
• RTD temperature sensors throughout. These are superior to thermocouples, especially in the cryogenic range.
• Pulse width modulated DC heater power supplies for very fine and accurate heat adjustment.
• Proprietary sectional film heaters (for below 250°C) with individual power balance to provide best available heating uniformity.
• Sectioned "cold plate" with center and ring section mirroring the main heater to aid in attaining uniaxial heat flow.
• Bifilar wound heater sections for high temperature applications.
• Sample sizes 300 X 300 mm square or custom 150 X 150 mm square.
• Flowing (dynamic) liquid nitrogen cooling for subambient operation, using proprietary bifilar path heat
  sink design.
• Single sided design for 50% LN2 consumption.
• Water cooling for elevated temperature operation using proprietary bifilar path heat sink design.

All Unitherm™ GHP Systems are fully computer controlled using current model PC’s and Windows™ operating platform. Each unit comes with extensive operating software.