SIST EN 27526:2009

SLOVENSKI STANDARD
SIST EN 27526:2009
01-november-2009
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Nickel, ferronickel and nickel alloys - Determination of sulphur content - Infra-red
absorption method after induction furnace combustion (ISO 7526:1985)
Nickel, Ferronickel und Nickellegierungen - Bestimmung des Schwefelgehaltes -
Verfahren der Infrarotabsorption nach Verbrennung im Induktionsofen (ISO 7526:1985)
Nickel, ferro-nickel et alliages de nickel - Dosage du soufre - Méthode par absorption
dans l'infrarouge après combustion dans un four à induction (ISO 7526:1985)
Ta slovenski standard je istoveten z: EN 27526:1991
ICS:
77.120.40 Nikelj, krom in njune zlitine Nickel, chromium and their
alloys
SIST EN 27526:2009 en,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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Foreword
ISO (the International Organization for Standardization) is a worldwide federation of
national Standards bodies (ISO member bedies). The work of preparing International
Standards is normally carried out through ISO technical committees. Esch member
body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, govern-
mental and non-governmental, in liaison with ISO, also take part in the work.
Draft International Standards adopted by the technical committees are circulated to
the member bodies for approval before their acceptance as International Standards by
the ISO Council. They are approved in accordance with ISO procedures requiring at
least 75 % approval by the member bodies voting.
International Standard ISO 7526 was prepared by Technical Committee ISO/TC 155,
Nickel and nicke/ alloys.
Users should note that all International Standards undergo revision from time to time
and that any reference made herein to any other International Standard implies its
latest edition, unless otherwise stated.
0
International Organkation for Standardization, 1985
Printed in Switzerland

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ISO 75264985 (E)
INTERNATIONAL STANDARD
Nickel, ferronickel and nicke1 alloys - Determination
of Sulfur content - Infra-red absorption method after
induction furnace combustion
4.5 Crucibles and lids.
1 Scope and field of application
This International Standard specifies an infra-red absorption
4.51 Ceramic crucibles shall be of precise dimensions so that
method after combustion for the determination of the Sulfur
the Sample is positioned correctly in the induction coil of the
content of nicke1 and ferronickel in the range 0,001 to 0,3 %
furnace (sec 9.1).
(mlm), and of nicke1 alloys in the range 0,001 to 0,l % (mlm).
Examples of compositions are given in annex A.
4.5.2 Pre-ignite the crucibles in air or Oxygen in a furnace for
not less than 1 h at 1 100 OC and store in a desiccator or closed
NOTE - lt may be possible to apply this method in the range 0,000 2
Container. A resistance furnace with a combustion tube
to 0,001 % (mlm). However, there were insuff icient laboratory test
data to support the inclusion of this lower level in the scope. through which a flow of Oxygen Passes may be used. Crucible
lids, used to help retain the solid Oxidation products in the hot
Zone, are pre-ignited in a similar manner.
2 References 4.6 Fluxes: Low Sulfur tin, topper plus tin, topper or
vanadium pentoxide (see 9.2).
ISO 5725, Precision of test methods - Determination of
repea tability and reproducibility b y in ter-labora tory tests.
4.7 Accelerators : Low Sulfur topper, iron, tungsten or
nicke1 (see 9.2).
Determination of Sulfur con ten t -
ISO 7525, Nickel -
Methylene blue molecular absorption spectrometric method
4.8 Nickel, low Sulfur of known value [ after genera tion of h ydrogen sulfide.
4.9 Standard reference steels, containing 0,l to
0,2 % (mlm) Sulfur.
3 Principle
Combustion of a test Portion in a flow of Oxygen at a high
temperature in a high frequency induction furnace in the
5 Apparatus
presence of fluxes and accelerators.
The apparatus required for combustion in a high frequency in-
Measurement of the Sulfur dioxide formed using an infra-red
duction furnace and the subsequent infra-red absorption
analyser and an integration procedure.
measurement of the evolved Sulfur dioxide may be obtained
commercially from a number of manufacturers. Follow the
manufacturer’s instructions for the Operation of the equipment.
A pressure regulator is required to control the Oxygen pressure
to the furnace according to the manufacturer’s specification
4 Reagents and materials
(usually 28 kN/m2). Features of commercial equipment are
given in annex B.
4.1 Oxygen (O$, 99,5 % Hrn) minimum.
4.2 Ascarite or soda lime, 0,7 to 1,2 mm (14 to 22 mesh).
6 Sampling and samples
4.3 Magnesium perchlorate [MgKl04)& 0,7 to 1,2 mm
(14 to 22 mesh).
6.1 Sampling and preparation of the laboratory Sample shall
be carried out by normal agreed procedures or, in case of
dispute, by the relevant International Standard.
4.4 Glass-wool.
1

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ISO 75264985 (E)
7.3 Calibration
6.2 The laboratory Sample normally is in the form of a
powder, granules, millings or drillings and no further prep-
aration of the Sample is necessary.
7.3.1 Select a certified Standard reference steel (4.9).
6.3 If it is suspected that the laboratory Sample is con-
NOTE - For ferronickel, reference materials with a higher Sulfur
taminated with oil or grease from the milling or drilling process, content are used.
it shall be cleaned by washing with high purity acetone and
drying in air.
7.3.2 Use the certified Standard reference steel in conjunction
with pure nicke1 of low Sulfur content [ ~0,001 % (mlm)]
6.4 If the laboratory Sample contains particles or pieces of
which is known or has been determined by ISO 7525.
widely varying sires, the test Portion should be obtained by
riffling .
7.3.3 Weigh appropriate proportions of the two materials
(7.3.1 and 7.3.2) into a pre-ignited crucible, to cover the high
end of the calibration range. Add the preselected amounts of
7 Procedure
flux and accelerator and combust as in 7.2.2. Note the instru-
ment reading.
WARNING - 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 suitable
7.3.4 Adjust the instrument reading to correspond to the cor-
Containers for the used crucibles. Normal precautions for
rect level of Sulfur in the mixture (7.3.3) according to the
handling Oxygen cylinders shall be taken. Oxygen from
manufacturer’s operating instructions.
the combustion process shall be removed effectively
from the apparatus since a high concentration of Oxygen
7.3.5 Repeat 7.3.3 to check the repeatability of the reading.
in a confined space tan present a fire hazard.
7.3.6 Repeat 7.3.3 with different ratios of the reference
7.1 Stabilizing the equipment
Sample and pure nicke1 to provide a calibration check over the
required range.
7.1.1 Condition and stabilize the equipment by combusting
several samples, similar to those to be analysed (7.4), using ap-
propriate fluxes and accelerators.
7.3.7 Table 1 illustrates the use of the calibration technique
using a certified Standard reference steel containing,
NOTE - It is not necessary to use pre-ignited crucibles.
0,100 % (mlm) S and a reference nicke1 Sample containing
0,001 % b7lm) s.
7.12 Allow the instrument to cycle several times with Oxygen
flowing and adjust the instrument Zero.
Table 1 - Calibration example
7.2 Blank test and zero adjustment
Sulfur content
Mass of steel Mass of nicke1
in composite
I I I
7.2.1 Charge a pre-ignited crucible (4.5) with the quantity of
% b7lm)
Cl
flux and accelerator to be used in the determination (7.4) and
0,500 0,500 0,050 + 0,000 5
add 1,00 g of pure nicke1 of known low Sulfur content (4.8).
0,300 0,700 0,030 + 0,000 7
0,100 0,900 0,010 + 0,000 9
7.2.2 Place the crucible and contents on the pedestal post of
0 1,000 0,001 0
the furnace, raise to the combustion Position and leck the
System. Operate the furnace in accordance with the manufac-
turer’s instructions. See 9.3 and annex B.
7.4 Determination
NOTES
1 The reading obtained corresponds to the blank due to the crucible,
7.4.1 Weigh, to the nearest 0,001 g, 0,9 to 1,l g of the test
flux, accelerator and Sulfur in the pure nickel.
Sample, and transfer to a pre-ignited crucible (4.5) containing a
suitable amount of the preferred flux (4.6). Add the appropriate .
2 The blank should not exceed 0,001 % (mlm) Sulfur.
quantity of accelerator (4.7), if required. The flux and ac-
3 If the blank reading is abnormally high, investigate and eliminate
celerator used will depend on the individual characteristics of
the Source of contamination.
the equipment and the type of material being analysed. Typical
additions to a 1,0 g test Portion are 2 g of topper, 1 g of topper
7.2.3 Adjust the instrument reading using the zero adjust or,
plus 1 g of iron, 2 to 3 g of tungsten, or 1 g of vanadium
on some instruments, the blank offset control, to read the
pentoxide plus 1 g of iron powder. Place the crucible lid in
Sulfur value of the nicke1 (4.8).
Position.
7.2.4 Repeat 7.2.1 to 7.2.3 to obtain a reproducible reading
7.4.2 Place the crucible and contents on the pedestal post of
within the precision limits of the instrument.
the furnace, raise to the combustion Position and leck the
System. Operate the furnace in accordance with the manufac-
NOTE - An alternative procedure is to record the reading of the blank
turer’s instructions. See 9.3 and annex B.
test and make the correction using a calibration graph.
2

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ISO 7526-1985 (El
14 laboratories in six countries. Eleven samples were analysed
7.4.3 Record the analyser reading and repeat the deter-
in duplicate, according to the procedure, on two different days.
mination.
Repeatability and reproducibility were calculated according to
NOTES
ISO 5725 with the results given in table 2.
1 lt is important that a high temperature be maintained after the
Sample is fused to ensure complete transfer of the Sulfur dioxide from
the furnace to the infra-red analyser.
2 A quiescent combustion is necessary to avoid splashing on to the
9 Notes on procedure and equipment
crucible lid where the fused mass may be removed from the induction
heating Zone.
9.1
...