IEC 60695-11-11-2021 pdf Fire hazard testing – Part 11-11: Test flames – Determination of the characteristic heat flux for ignition from a non-contacting flame source

5.2 Burner and test flame The burner shall conform to IEC 60695-11-4. The flame size and the gas flow rate will differ from that specified in IEC 60695-11-4 in order to obtain the heat flux necessary for the test. The test flame used for each test shall be kept unchanged throughout the test. The fuel gas shall be methane gas having a purity of 98 % or greater. 5.3 Heat flux meter The heat flux meter shall be of a water-cooled thermopile type (see ISO/TS 14934-4) which determines the incident heat flux, Q, applied to the test specimen. When incident heat flux measurements are made, the heat flux meter shall be placed in the centre of a heat flux meter mounting board, and the heat flux meter shall not have any optical filter in-line with the sensor. NOTE 1 The incident heat flux measurement is of critical importance to the test results. ISO 14934-3 [5] provides the calibration method for the heat flux meter. NOTE 2 A heat flux meter of Schmidt-Boelter type with a thermopile, which has a measurement range of up to 100 kW/m 2 and a target diameter of approximately 12,5 mm, has been found to be suitable for the purpose of this international standard. 5.4 Data acquisition system The voltmeter for measuring the output of the heat flux meter shall have a resolution of 0,01 % or better for the maximum output range. NOTE The usual output level of the heat flux meter is several tens of millivolts. 5.5 Heat flux meter mounting board The heat flux meter mounting board shall be approximately 75 mm × 75 mm × 12 mm with a centrally located hole whose diameter is slightly larger than the outside diameter of the heat flux meter. The board shall be made from a heat-resistant non-combustible rigid board. The heat flux meter mounting board is used, together with the heat flux meter (see Figure 2), for the determination of incident heat flux, Q (see 8.1).