IEC 60754-2:2011 pdf free download – Test on gases evolved during combustion of materials from cables
7.3 Heating procedure
The air flow shall be adjusted by means of a needle valve to the value specified in 5.6 andshall be kept constant during the test.
The temperature shall be measured by a thermocouple suitably protected against corrosionand placed inside the quartz glass tube.The heating system shall be adjusted such that thetemperature at the designated position for the boat shall be not less than 935 C and notmore than 965 ℃.The temperature at a position 300 mm from the designated position inthe direction of the air flow shall be not less than 900 ℃.
The boat containing the test specimen shall be quickly inserted into the heating zone of thetube to the designated position determined by the thermocouple measurement and the timershall be started. The combustion boat shail be placed in ‘such a way that the distancebetween the boat and the exit end of the effective heating zone is at least 300 mm. Theeffective heating zone is that zone where a temperature of not less than 900 C has beendetermined by the thermocouple measurement.
The combustion procedure,under the air flow condition, shall be continued for (30 ±1) min inthe furnace.
WARNING The operator should take precautions， e.g. the wearing of eye protection and suitable protectiveclothing, because certain materials ignite quickly,and can cause “blow back” of hot gases.Care should also betaken to avoid over-pressurization of the system, and to allow for venting of exhaust gases. Guidance on theavoidance of”blow back” is given in NOTE 2 of 5.1.
7.4 Washing procedure
Following the heating procedure, all the bottles used shall be disconnected,and the contentswashed into a 1 000 ml volumetric flask.Using water with the properties given in 5.5, thebottles, the connecting links and, after cooling, the end of the quartz glass tube including thesilica wool (if used) shall also be washed into the flask,and the contents made up to1000ml.
8.1 General method
From the three test determinations undertaken，the mean value，standard deviation andcoefficient of variation shall be calculated for both pH and conductivity.
lf the coefficient of variation is higher than 5 %，a further three tests shall be carried out andthe mean value, standard deviation and coefficient of variation shall be recalculated using thesix values.
8.2 Simplified method
From the two test determinations undertaken, the sample shall be considered to have met theperformance requirement if both pH values are greater than or equal to the specified valueand both conductivity values are less than or equal to the specified value.
lf one test specimen fails to meet this requirement, the test procedure and determination shallbe repeated on two further test specimens taken from the same sample of material.Bothrepeat test specimens shall comply with specified values for pH and conductivity.