DIN EN ISO 14720-1:2013-06

This document defines a method for the determination of sulfur in powdered and granular nonoxidic ceramic raw materials and materials such as silicon carbides, silicon nitrides, graphites, carbon blacks, cokes, carbon powders. If proved by the recovery rate, this method can also be applied for other non-metallic powdered and granular materials, for example, silicon dioxide. This document is applicable for materials with mass fractions of sulfur from 0,005 % to 2 %. This document can also be applied for materials with higher mass fractions of sulfur after verification of the particular case. The sample and added combustion accelerators (mostly tungsten- or iron-granules) are heated in an inductive furnace under oxygen atmosphere. The high-frequency field of the furnace couples with electrically conductive components of sample and combustion accelerators. The sample is heated to temperatures above 1 800 °C and the total sulfur content of the sample is released as sulfur dioxide. The reaction gas is transferred to the infrared absorption cell of the analyser. The molecular absorption of sulfur dioxide is measured by using a narrow-band optical filter which is translucent for the wavelength of the characteristic infrared absorption of sulfur dioxide. The mass fraction of sulfur dioxide in the reaction gas is proportional to peak-height and peak-area, respectively, of the transient absorption signal. The mass fraction of sulfur in the sample is calculated by using a calibration function established by suitable calibration standards measured under comparable conditions. This document (EN ISO 14720-1:2013) has been prepared by Technical Committee ISO/TC 33 "Refractories", in collaboration with Technical Committee CEN/TC 187 "Refractory products and materials", the secretariat of which is held by BSI (United Kingdom). The responsible German committee is Working Committee NA 062-02-64 AA "Chemische Analyse von nichtoxidischen keramischen Roh- und Werkstoffen" ("Chemical analysis of non-oxidic ceramic raw and basic materials") at the Materials Testing Standards Committee (NMP) at DIN.