BS EN ISO 7526:2020 pdf free.Ferronickels – Determination of sulfur content – Infrared absorption method after induction furnace combustion.
BS EN ISO 7526 Ceramic crucibles, containing the sample and any additions that can be necessary, are required for the combustion. They shall be of precise dimensions for the system and fit the supporting pedestal post so that the test portion in the crucible is positioned correctly within the induction coil for heating. Typical dimensions of combustion crucibles are: a height of 25 mm, an external diameter of 25 mm, an internal diameter of 20 mm, a wall thickness of 2,5 mm, and a thickness of base of 8 mm. The dimension of the hole of the lid should be larger than 10 mm.Crucibles and lids shall be as specified by the manufacturer of the instrumentation used and shall be capable of withstanding combustion in an induction furnace without evolving sulfur-containing chemicals so that achieving and maintaining blank values within specification is possible.In order to remove any sulfur contamination, pre-ignite the crucibles in air or oxygen in a furnace for not less than 1 h at 1100 °C and store in a desiccator or a closed container. A resistance furnace with a combustion tube through which a flow of oxygen passes may also be used.Crucible lids, used to help retain the solid oxidation products in the hot zone of the induction coil, shall be pre-ignited in a similar manner.WARNING一The risks related to combustion analysis are mainly burns in pre-igniting the ceramic crucibles and in the fusions. Use crucible tongs at all times and appropriate containers for the used crucibles. Normal precautions for handling oxygen cylinders shall be taken. Oxygen from the combustion process shall be removed effectively from the apparatus since a high concentration of oxygen in a confined space can present a fire hazard.Fourteen laboratories in four countries participated in an inter-laboratory validation test programme under the auspices of ISO/TC 155 involving three determinations of sulfur at seven content levels (samples).Each laboratory carried out two determinations under repeatability conditions as defined in ISO 5725-1,i.e. one operator, same apparatus, identical operating conditions, same calibration and a minimumperiod of time. The third determination was carried out at a different time using the same apparatus
with a different calibration.BS EN ISO 7526 pdf download.