A new term heat transfer index (HTI) has been introduced to avoid confusion with the thermal protective index (TPI) or other terms used in previous versions of this test. HTI calculated from the mean time in seconds to achieve a temperature rise of 24±0.2℃ when testing by this method using a copper disc and a starting temperature of 25±5℃. The heat transfer index provides a method of grading materials which does not imply that the material tested will give any precise protective time under actual use conditions.
The Heat Transfer Index Test Equipment is designed and manufactured according to EN 367 and ISO9151 standards.
The apparatus consists of the burner, the cover sheet and the specimen holder with copper calorimeter.
The cover sheet and the specimen holder are controlled via pneumatic transmission which is automatically controlled by software.
A horizontally oriented test specimen subjected to an incident heat flux of 80KW/㎡from the flame of a Meker burner beneath it.
The heat passing through the specimen is measured by means of a small copper calorimeter on top of and contact with the specimen.
The time to record a temperature rise of 12 or 24℃ in the calorimeter is recorded in seconds.
The calorimeter cooling device shorten the test time.
The mean result for the three test specimens is calculated as the HTI.
The calibration of heat flow density of 80 kW/㎡is performed automatically by software.