Thermal Conductivity of Insulating Powder

The apparatus consists of a copper sphere in which a mica heater is fitted. This small sphere is surrounded by another copper sphere and the insulating powder to be tested is filled in between these two spheres. The heat produced by heater is radially flows outwards in all directions through insulating powder. A digital temperature indicator is used to measure temperatures of Inner & Outer sphere. An ammeter & voltmeter is provided to measure heater input. By knowing heat input and temperatures, thermal conductivity of powder can be calculated. The unit is provided with asbestos powder, however any other powder can be tested with this unit.


  • Inner sphere - copper - 100 mm. dia.
  • Outer sphere - copper - 200 mm dia.
  • Heater – Mica heater placed in inner sphere.
  • Thermocouples on outer surface of inner sphere and inner surface of outer sphere.

Instrumentation & Controls :

  • Digital Voltmeter - 0 - 199.9 Volts.
  • Digital Ammeter - 0 - 1.999 Amp.
  • Multy channel Digital Temperature Indicator.
  • Heater Control.

Service Required :

  • 230 V.A.C. stabilised supply with earthing.
  • Floor space - 1.5m X 1.5 m at working height.


thermal conductivity test apparatus for insulating powder with copper sphere, thermocouples