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IS0
ORGAN I Z AT I ON FOR STA N D AR D I Z AT I O N
I N T E R N AT I ON A L
IS0 RECOMMENDATION
R 349
AUDIBERT-ARNU DILATOMETER TEST FOR COAL
1st EDITION
December 1963
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 349, Audibert-Arm Dilatometer Test for Coal, was
drawn up by Technical Committee ISO/TC 27, Solid Mineral Fuels, the Secretariat of which
is held by the British Standards Institution (B.S.I.).
Work on this question by the Technical Committee began in 1951 and led, in 1957,
to the adoption of a Draft IS0 Recommendation.
In May 1958, this Draft IS0 Recommendation (No. 238) was circulated to all the IS0
Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial
nature, by the following Member Bodies:
Austria Greece Portugal
Belgium India Romania
Burma Italy Turkey
Canada Japan United Kingdom
Czechoslovakia Mexico U.S.S.R.
Denmark New Zealand Yugoslavia
Germany Poland
One Member Body opposed the approval of the Draft: Spain.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0
Council, which decided, in December 1963, to accept it as an IS0 RECOMMENDATION.
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Ref. No. : ISO/R 349-1963/A1-1971 (E)
UDC 662.6
Amendment 1 - November 1971 - to IS0 Recommendation R 349-1963
Amendment 1
to IS0 Recommendation R 349-1963
AUDIBERT-ARNU DILATOMETER TEST FOR COAL
Section 4, PROCEDURE, ciause 4.3
Replace the 1st paragraph by “The coal is heated at a rate of 3 “C per minute”.
In the 6th paragraph, 2nd line, replace “chosen” by “stated”.
BRIEF HISTORY
Amendment 1 to IS0 Recommendation U 349-1963, Audibert-Arnu dilatometer test for coal, was drawn up by
Technical Committee ISO/TC 27, Solid mineral fuels, the Secretariat of which is held by the British Standards
institution (BSI).
Draft IS0 Recommendation No. 1932 was drawn up on this subject, and was circulated to all the IS0 Member
Bodies for enquiry in April 1970. it was approved by the following Member Bodies :
Australia India Sweden
Belgium Iran Switzerland
.
Canada Italy Thailand
Chile Korea, Rep. of Turkey
Czechoslovakia Netherlands U.A.R.
Denmark New Zealand United Kingdom
France Poland U.S.A.
Germany Portugal U.S.S.R.
Greece South Africa, Rep. of Yugoslavia
No Member Body opposed the approval of the Draft.
This Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council, which decided to
accept it as AMENDMENT 1 to IS0 Recommendation R 349-1963.
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IS0 / R 349 - 1963 (E)
IS0 Recommendation R 349 Decem ber 1963
AUDIBERT-ARNU DILATOMETER TEST FOR COAL
1. OBJECT AND SCOPE
The Audibert-Arnu test is GiiC of the parameters adopted for the International Clüssiiication of
Hard Coals by Type of the United Nations Economic Commission for Europe. The object of
the test is to determine the coking properties of hard coal or hard coal blends on the laboratory
scale.
In principle, the test is not designed, nor can it be used, to indicate the pressures exertcd by
hard coals on the walls of industrial carbonization ovens.
2. PRINCIPLE AND TERMINOLOGY
A pencil made of powdered coal formed under pressure is inserted into a precisely calibrated
narrow tube and topped by a calibrated steel rod (piston) which slides in the bore of the tube.
The whole is heated at a constant and definite rate.
By making regular readings of the displacement of the piston as a function of the tcmperature
and expressing the displacements observed as percentages of the original length of the pencil,
a curve of the type shown in Figure 1 below can be plotted.
The following items are characteristic (see note below) :
% TI temperature at which the piston has moved down
0.5 mm * : softening temperature.
temperature at which the piston reaches its lowest
TI,
point: temperature of maximum contraction.
TI,, temperature at which the piston reaches its highest
point : temperature of maximum dilatation.
maximum contraction, of the length of the pencil per
a
cent.
maximum dilatation, of the length of the pencil per
b
FIG. 1 cent.
If, after contraction has taken place, the piston does not return to its original level, the dilatation,
equal, in absolute value, to the difference between the final level of the piston and the original
zero level, is reported as negative.
NOTE. - The principal factors capable of distorting the results of this empirical test are the
following:
(a) Deterioration of the coal, consequent on bad storage or faulty drying;
* Or 1 division, if the scale is calibrated in percentage of the standard length of pencil.
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IS0 / R 349 - 1963 (E)
(b) Deviation from the tolerances of
(1) the internal dimensions of the dilatometer tube,
(2) the clearance between tube and piston,
(3) the mass of the piston,
(4) the dimensions of the mould;
(c) Deviation from the specified mean rate and regularity of heating;
(d) Deviation from the specification for the preparation of the sample in respect of maximum
particle size, or for the pencil in respect of its length after tamping.
3. APPARATUS
3.1 Apparatus for preparing the coal pencil
3.1.1 Mould, polished internally, with accessories, as shown in Figures 2 and 2 A, pages 10
and 11.
3.1.2 Gauge, as shown in Figure 2, page 10.
3.1.3 Ram, of which Figure 3, page 12, shows an example.
3.1.4 Press, of which Figure 4, page 13, shows an example.
3.2 Dilatometer and accessories
3.2.1 Dilutometer tubes andpistons, as shown in Figure 5, page 14.
3.3 Other apparatus
3.3.1
Electric furnace, of which Figure 6, page 15, shows an example, consisting of a block
of metal resistant to oxidation and of sufficiently high melting point. A suggested
material is aluminium bronze. The metal block is pierced by at least two holes of
15 mm diameter by 350 nim deep to take the dilatometer tubes and one hole 320 mm
deep to take a temperature-measuring device. The block is heated by a metallic winding,
suitably insulated. Control gear permits the use of any selected rate of heating up
to 5 deg per minute over a temperature range of 300 to 550 OC.
The furnace should be constructed so that the temperature conditions are uniform in
the dilatometer tubes placed in their normal position in each hole.
To verify this, the furnace is heated at a rate of 5 deg per minute. When the temperature
reaches about 450 OC, an exploration is made of the lower 180 mm of a dilatometer
tube placed in the furnace, by comparing the readings on the normal temperature
measuring device and a thermometric probe placed in the tube. The difference between
the probe temperatures and the mean temperature shown by the normal temperature
measuring device should be less than
f 2 deg in the lower 120 mm,
f 5 deg from 120 to 180 mm.
This verification is not to be confused with the later calibration of the temperature
measuring device; it is intended to measure only the temperature variation along the tube.
The furnace is equipped with an adjustable scale for each hole. The scale is preferably
engraved on a mirror in front of which the indicator pointer of the piston moves.
It is at least 180 mm in length and calibrated in millimetres or in percentages of the
standard length of the pencil (60 & 0.25 mm, see clause 4.2).
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iSO/ R 349 - 1963 (E)
If desired, the apparatus can be equipped with an automatic heating regulator and a
device for the automatic registration of the curve.
3.3.2 Temperature-measuring device, consisting of a mercury thermometer, or a thermocouple,
or a resistance thermometer, accurate to within f 1.0 per cent of the temperature
in degrees centigrade (Celsius) and capable of being read, if necessary by estimation,
to 1 deg.
3.3.3 Cleaning implements, consisting of the following :
3.3.3.1 Auger, diameter approximately 7.8 mm;
3.3.3.2 Reamer, consisting of a steel bar of semi-circular section of diameter 7.95 mm;
3.3.3.3 Brass wire brush, the diameter of which should slightly exceed 8 mm.
The total length of each of the cleaning implements should be 400 mm.
3.4 Calibration of apparatus
The apparatus is calibrated by comparing the temperature in a dilatometer tube in each
hole with the temperature indicated by the temperature-measuring device in its normal
position. The calibration is carried out at the desired rate of heating by using a thermocouple
with wires of diameter approximately 0.6 mm, the thermojunction touching the wall of the
tube 3 cm above the bottom. The temperatures read during the test are corrected by the
differences found during this calibration.
3.5 Inspection
3.5.1
Dilatometer. In order to inspect the wear of the tube and piston after a hundred determin-
ations have been carried out in one tube, the results of the next four determinations
using that tube should be compared with those obtained in a new tube. This com-
parison will thus be made successively on four coals.
The difference in percentage dilatation between the two tubes should be divided by
the " relative length " of the dilated pencil obtained with the new tube; the " relative
length " is here expressed as the ratio of the length of the dilated pencil to its original
length.
The figures so obtained from the four coals should be averaged. If the average is greater
than 3.5, irrespective of sign, the old tube should be discarded (see Appendix). If the tube
is still satisfactory, this comparison should be repeated after every subsequent 25 tests.
3.5.2
Mould. The wear of the mould is periodically checked with the gauge, which can also
be used to check new moulds.
If, when the gauge is inserted in the larger orifice of the mould,
(I) two lines can be seen on the gauge, the mould is too small and should be
reamed out;
(2) one line can be seen, the mould is satisfactory;
(3) no line can be seen, the mould is worn and should be replaced.
4. PROCEDURE
4.1 Sampling and treatment of sample
As certain types of hard coal are very susceptible to oxidation, it is necessary to minimize
the contact with air after reducing the gross sample.
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IS0 / R 349 - 1963 (E)
As a special precaution, therefore, the part sample after reduction is stored in an oxygen-free
nitrogen atmosphere or in freshly boiled water. In the latter c
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