ISO 1762 pdf download.Paper, board and pulps — Determination of residue (ash) on ignition at 525 °C
1 Scope
This International Standard describes the determination of the residue (ash) on ignition of paper, board and pulp at . It is applicable to all types of paper, board and pulp samples. The ash may consist of a) mineral matter in the pulp and various residues from chemicals used in its manufacture, b) metallic matter from piping and machinery, and c) fillers, pigments, coatings or residues from various additives. In samples containing calcium carbonate, there is practically no decomposition of carbonate by ashing at . Other fillers and pigments such as clay and titanium dioxide are also unaffected by ashing at . Accordingly, the residue on ignition as determined by this International Standard provides a good estimate of the total inorganic matter in the sample, provided that the sample does not contain other minerals which decompose at or below this temperature. For example, magnesium carbonate and calcium sulfate may, at least partly, decompose at temperatures below 525 °C
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 1 86:— 1 ) , Paper and board— Sampling to determine average quality ISO 287:1 985, Paper and board— Determination of moisture content— Oven-drying method ISO 638:1 978, Pulps — Determination of dry matter content ISO 721 3:1 981 , Pulps — Sampling for testing
3 Term and definition
For the purposes of this International Standard, the following term and definition applies. 3.1 residue on ignition ash on ignition mass of the residue remaining after a sample of paper, board or pulp is ignited in a furnace at as specified in this International Standard
4 Principle
A test specimen is weighed in a heat-resistant crucible and ignited in a muffle furnace at . The moisture content of a separate test specimen is also measured. The percentage ash is then determined, on a moisture-free basis, from the weight of residue after ignition and the moisture content of the sample.
5 Apparatus
5.1 Heat-resistant crucibles, made of platinum, porcelain, or silica, with a capacity of to . 5.2 Muffle furnace, capable of maintaining a temperature of . It is recommended to place the furnace in a hood or to provide means for evacuating smoke and fumes. 5.3 Analytical balance, accurate to . 5.4 Desiccator.
6 Sampling and preparation of sample
If the analysis is being done to evaluate a lot, obtain a representative sample of paper, board or pulp as described in ISO 1 86 or ISO 721 3, as relevant. Sufficient sample must be collected to allow for at least duplicate determinations and for determination of moisture content. Take a test specimen consisting of small pieces, not larger than , taken from various parts of the sample in such a manner as to be thoroughly representative of it. The total mass shall be at least moisture free and shall yield a weight of ash not less than and preferably over . See the note in clause 7. In a similar manner, obtain a moisture specimen from the sample.
7 Procedure
Carry out the procedure in duplicate. Air-dry the test and moisture specimens in the laboratory atmosphere until they reach equilibrium moisture. Determine the moisture content on the moisture specimen as described in ISO 287 or ISO 638, as relevant. Weigh this specimen at the same time as the specimen used for ash determination. Heat the empty crucible (5.1 ) for to in the muffle furnace (5.2) at . Cool it to room temperature in a desiccator. Weigh the empty crucible to the nearest . Add the test specimen and immediately weigh again. Place the crucible containing the test specimen in the furnace at room temperature and gradually raise the temperature to (about ) in order to burn the sample without it bursting into flames, and to ensure that no material is lost in the form of flying particles. Maintain the ignition temperature of for at least in the case of pulp and board samples and at least for paper samples. The specimen shall be completely charred as indicated by the absence of black particles.