b'4Equipment 4.1Furnace Thefurnacehadanominalopeningof3000-mmx3000-mmfortheattachmentofvertical specimens. The furnace was lined with refractory bricks and materials with the thermal properties as specified in AS 1530.4:2014 and was heated by combustion of a mixture of natural gas and air. 4.2Temperature ThetemperatureinthefurnacechamberwasmeasuredbyeighttypeK,3-mmdiameter,and310stainlesssteelMineralInsulatedMetalSheathed(MIMS)thermocouples.Each thermocouple was housed in high-nickel steel tubes opened at the exposed end. 4.3Radiant heat source The radiant heat source consisted of a 3-mm thick mild steel sheet mounted into a refractory frame in two sections with a vertical joint at its centre. The frame housing the steel sheet was positioned and sealed up against the front of the furnace aperture. 4.4Radiant heat flux calibration Prior to the test, the positions of the specimen (relative to the radiant heat source) were established that corresponded to the required radiant heat flux levels. Radiation distribution was also established by measuring radiant heat flux levels at the centre and the centre of each quarter section of the specimen in a plane approximating the intended position of the specimen such that the central value will be approximately equal to the rest of the radiant heat flux. 4.5Measurement system Theprimarymeasurementsystemcomprisedmultiple-channeldataloggers,scanningatfive second intervals during the test.5Ambient temperature The temperature of the test area was 21C at the commencement of the test.6Departure from standard There were no departures from the requirements of AS 1530.8.1-2018.FSZ 2411 | page8 of 40'