Standard Test Methods for Residual Carbon, Apparent Residual Carbon, and Apparent Carbon Yield in Coked Carbon-Containing Brick and Shapes 

SIGNIFICANCE AND USE
3.1 These test methods are designed for use with carbon-containing products. The residual carbon content of a coked carbon-containing brick or shape is an indication of how much carbon may be available, in service, to resist slag attack on, or oxidation loss of, that body. Apparent carbon yield gives an estimate of the relative efficiency of the total carbonaceous matter to be retained as residual carbon.  
3.2 Residual carbon has a direct bearing on several properties of a pitch or resin containing refractory such as ignited porosity, density, strength, and thermal conductivity.  
3.3 These test methods are suitable for product development, manufacturing control, and specification acceptance.  
3.4 These test methods are very sensitive to specimen size, coking rates, etc.; therefore, strict compliance with these test methods is critical.  
3.5 Appreciable amounts of reducible components, such as Fe2O3, will have a noticeable effect on the results. Thus, values obtained by these test methods will be different when brick removed from service is tested. This must be kept in mind when attempting to use these test methods in an absolute sense.  
3.6 Oxidizable components such as metals and carbides can have a noticeable effect on the results. This must be kept in mind when using the second procedure, which is based on measuring weight loss after igniting the coked specimens.  
3.7 Testing of brick or shapes that contain magnesium metal presents special problems since this metal is highly volatile and substantial amounts of the magnesium can be lost from the sample during the coking procedure. This must be kept in mind when interpreting the results of testing of brick that contains magnesium. In addition, magnesium can react readily with atmospheric humidity. This must be kept in mind when storing brick that contains magnesium.
SCOPE
1.1 These test methods cover the determination of residual carbon content in carbon-bearing brick and shapes after a prescribed coking treatment. They provide two procedures. The first procedure is based on the combustion of carbon and its measurement as carbon dioxide. However, when using the first procedure for articles that contain silicon carbide or other carbides, no distinction will be made between carbon present in the form of a carbide and carbon present as elemental carbon. The second procedure provides a method for calculating apparent residual carbon (on the basis of weight loss after igniting the coked specimens), apparent carbonaceous material content, and apparent carbon yield. If the second procedure is used for brick or shapes that contain metallic additives or carbides, it must be recognized that there will be a weight gain associated with the oxidation of the metals, or carbides, or both. Such a weight gain can change the results substantially and this must be kept in mind when interpreting the data.  
1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: C831 − 98 (Reapproved 2017)
Standard Test Methods for
Residual Carbon, Apparent Residual Carbon, and Apparent
Carbon Yield in Coked Carbon-Containing Brick and
Shapes
This standard is issued under the fixed designation C831; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 These test methods cover the determination of residual
C571 Test Method for Chemical Analysis of Carbon and
carbon content in carbon-bearing brick and shapes after a
Carbon-Ceramic Refractories (Withdrawn 1995)
prescribed coking treatment. They provide two procedures.
D2906 Practice for Statements on Precision and Bias for
The first procedure is based on the combustion of carbon and
Textiles (Withdrawn 2008)
its measurement as carbon dioxide. However, when using the
E11 Specification for Woven Wire Test Sieve Cloth and Test
first procedure for articles that contain silicon carbide or other
Sieves
carbides,nodistinctionwillbemadebetweencarbonpresentin
the form of a carbide and carbon present as elemental carbon.
3. Significance and Use
The second procedure provides a method for calculating
3.1 These test methods are designed for use with carbon-
apparent residual carbon (on the basis of weight loss after
containing products. The residual carbon content of a coked
igniting the coked specimens), apparent carbonaceous material
carbon-containing brick or shape is an indication of how much
content, and apparent carbon yield. If the second procedure is
carbon may be available, in service, to resist slag attack on, or
used for brick or shapes that contain metallic additives or
oxidation loss of, that body. Apparent carbon yield gives an
carbides, it must be recognized that there will be a weight gain
estimate of the relative efficiency of the total carbonaceous
associated with the oxidation of the metals, or carbides, or
matter to be retained as residual carbon.
both. Such a weight gain can change the results substantially
3.2 Residual carbon has a direct bearing on several proper-
and this must be kept in mind when interpreting the data.
ties of a pitch or resin containing refractory such as ignited
1.2 The values stated in inch-pound units are to be regarded
porosity, density, strength, and thermal conductivity.
as the standard. The values given in parentheses are for
3.3 These test methods are suitable for product
information only.
development, manufacturing control, and specification accep-
1.3 This standard does not purport to address all of the
tance.
safety concerns, if any, associated with its use. It is the
3.4 These test methods are very sensitive to specimen size,
responsibility of the user of this standard to establish appro-
coking rates, etc.; therefore, strict compliance with these test
priate safety, health, and environmental practices and deter-
methods is critical.
mine the applicability of regulatory limitations prior to use.
3.5 Appreciable amounts of reducible components, such as
1.4 This international standard was developed in accor-
Fe O , will have a noticeable effect on the results.Thus, values
2 3
dance with internationally recognized principles on standard-
obtained by these test methods will be different when brick
ization established in the Decision on Principles for the
removed from service is tested. This must be kept in mind
Development of International Standards, Guides and Recom-
when attempting to use these test methods in an absolute sense.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. 3.6 Oxidizable components such as metals and carbides can
have a noticeable effect on the results. This must be kept in
1 2
These test methods are under the jurisdiction of ASTM Committee C08 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Refractories and are the direct responsibility of Subcommittee C08.04 on Chemical contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Behaviors. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Nov. 1, 2017. Published November 2017. Originally the ASTM website.
approved in 1976. Last previous edition approved in 2013 as C831 – 98 (2013). The last approved version of this historical standard is referenced on
DOI: 10.1520/C0831-98R17. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C831 − 98 (2017)
mind when using the second procedure, which is based on 4.1.2 Inner and Outer Box, stainless steel (or equivalent
measuring weight loss after igniting the coked specimens. alloy), as shown in Figs. 1-3.
3.7 Testing of brick or shapes that contain magnesium metal 4.2 For CO Absorption:
presentsspecialproblemssincethismetalishighlyvolatileand 4.2.1 Laboratory Pulverizer, designed to provide a sealed,
substantial amounts of the magnesium can be lost from the dustproof grinding chamber, and having a capacity of at least
sample during the coking procedure.This must be kept in mind 50 g of sample.
when interpreting the results of testing of brick that contains 4.2.2 Combustion-Tube Furnace, capable of operating at
magnesium. In addition, magnesium can react readily with 183 °F (1000 °C)
atmospheric humidity. This must be kept in mind when storing 4.2.3 CO Absorption Train, as described in Fig. 4 and in
brick that contains magnesium. Test Method C571.
NOTE 2—Commercial automatic and semi-automatic carbon determi-
4. Apparatus
nators may replace the apparatus described in 4.2.2 and 4.2.3.
4.1 For Coking:
4.3 The precision obtained with these instruments shall
4.1.1 Gas or Electric Furnace, with heating chamber ca-
meet the requirements specified in Section 10.
pable of receiving the coking box shown in Fig. 1.
NOTE 1—Samples should not be subjected to thermal gradients greater
than 40 °F (22 °C) during heatup. In electric furnaces with silicon carbide
Typical grinders are: Blueler Mill, Applied Research Laboratories, Sunland,
heating elements, the length of the box should be parallel to these
CA; Laboratory Disc Mill, Angstrom, Inc., Bellville, MI; and Shatter Box, Spex
elements. Industries, Inc., Metuchen, NJ.
FIG. 1 Outer Coking Box (Dimensions are in Inches)
C831 − 98 (2017)
FIG. 2 Inner Coking Box
5. Preparation of Test Specimens 5.2 Although sample brick from either the 4 ⁄2-in. (114-mm)
or the 6-in. (152-mm) series may be tested, it is preferable to
5.1 This method assumes that the number of specimens
use the larger size for the test. Cut slices 1 6 ⁄32 in. (25 6
tested will be a statistically valid sample of the entire lot of
0.8 mm) in thickness perpendicular to the length at the mid-
brick or shapes being evaluated. The exact number is usually
section of each sample brick or shape.As shown in Fig. 5, the
arrived at by mutual agreement between parties concerned.
C831 − 98 (2017)
FIG. 3 Coking Box Arrangement
FIG. 4 CO Absorption Train
nominal size of each slice shall be 1 by 3 by 6 in. (25 by 76 by 5.4 Specimens that are cut wet must be dried immediately
152 mm). The two 1 by 3-in. faces and the two 1 by 6-in. faces with a paper or cloth towel and flash dried. For pitch-
must be original surfaces.
impregnated samples, flash drying should be done at a suffi-
ciently low temperature to avoid “weeping” of pitch from the
5.3 Test specimens may be cut wet or dry except for
pores of the brick. Drying can usually be done on a forced-air
products capable of hydration, such as dolomite brick, which
dryer at 220 °F (105 °C) by limiting exposure to 5 to 10 min.
must be cut dry and stored in a dry container prior to coking.
C831 − 98 (2017)
FIG. 5 Location of Test Specimen
Repeat if necessary. These drying procedures are especially 6.5 Place the coking box assembly (Fig. 3) into the furnace,
important for metal-containing brick because hydration of the and insert a calibrated thermocouple into the thermocouple
metals can occur. Specimens containing a coating of pitch on well.
uncut surfaces, as is typical of an impregnation process, must
6.6 Heatthefurnacesothatthethermocouplewithinthebox
be scraped clean prior to drying.
registers 250 °F (120 °C) after the first hour, then heat the
5.5 Weigh all specimens after drying to constant weight
furnace so that the box is heated at a rate of 400 6 20 °F (220
(60.2 g), recording weight to the nearest 0.1 g. This weight is 6 11 °C)⁄h to 1800 6 20 °F (980 6 11 °C).
“as-received weight, A.” (This step may be omitted if residual
6.7 Holdthetemperaturefor3 6 ⁄2h,startingfromthetime
carbon is to be determined by CO absorption, as indicated in
1780 °F (970 °C) is reached in the inner box.
1.1.)
6.8 After completing the hold period, shut off the furnace
6. Procedure for Coking
and allow the coking box to cool naturally within the furnace.
6.1 Place the test specimens randomly into the inner box,
6.9 Remove the samples from the coking box after the box
Fig. 2
has cooled sufficiently to handle. After removing specimens
from the inner box, clean by brushing carefully with a nylon or
NOTE 3—Burned pitch-impregnated magnesite brick should not be
naturalbristlebrushtoremoveclingingparticles.Thenproceed
coked with tempered, tar-bonded, or dolomite brick because of carbon
pickup by the impregnated samples and disruption of the bottom of
to either of the two alternatives for analyzing the specimens.
tempered samples. Pitch-bonded, pitch-bonded tempered magnesite brick,
NOTE 6—After each run, clean the muffle and the bottom carbon plate
and dolomite brick may be coked in the same box or coking run.
of any adhering coke breeze.
NOTE 4—The number of samples coked per run should be constant
within a laboratory. Dummy uncoked samples consistent with Note 3 may
6.10 Samples that contain dolomite or aluminum metal
be used to fill any empty positions in the inner box.
should be stored in a sealed container containing dessicant in
6.2 Place the inner box into the center of the outer box (Fig.
the time interval between coking and measurement of carbon
3), on the bottom of which has first been placed a ⁄2-in.
content. This is to prevent hydration of dolomite or aluminum
(13-mm) slab of carbon, covered with a thin layer of dust-free
carbide. The aluminum
...


This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: C831 − 98 (Reapproved 2013) C831 − 98 (Reapproved 2017)
Standard Test Methods for
Residual Carbon, Apparent Residual Carbon, and Apparent
Carbon Yield in Coked Carbon-Containing Brick and
Shapes
This standard is issued under the fixed designation C831; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 These test methods cover the determination of residual carbon content in carbon-bearing brick and shapes after a prescribed
coking treatment. They provide two procedures. The first procedure is based on the combustion of carbon and its measurement as
carbon dioxide. However, when using the first procedure for articles that contain silicon carbide or other carbides, no distinction
will be made between carbon present in the form of a carbide and carbon present as elemental carbon. The second procedure
provides a method for calculating apparent residual carbon (on the basis of weight loss after igniting the coked specimens),
apparent carbonaceous material content, and apparent carbon yield. If the second procedure is used for brick or shapes that contain
metallic additives or carbides, it must be recognized that there will be a weight gain associated with the oxidation of the metals,
or carbides, or both. Such a weight gain can change the results substantially and this must be kept in mind when interpreting the
data.
1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information
only.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
C571 Methods Test Method for Chemical Analysis of Carbon and Carbon-Ceramic Refractories (Withdrawn 1995) (Withdrawn
1995)
D2906 Practice for Statements on Precision and Bias for Textiles (Withdrawn 2008)
E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves
3. Significance and Use
3.1 These test methods are designed for use with carbon-containing products. The residual carbon content of a coked carbon
containing carbon-containing brick or shape is an indication of how much carbon may be available, in service, to resist slag attack
on, or oxidation loss of, that body. Apparent carbon yield gives an estimate of the relative efficiency of the total carbonaceous
matter to be retained as residual carbon.
3.2 Residual carbon has a direct bearing on several properties of a pitch or resin containing refractory such as ignited porosity,
density, strength, and thermal conductivity.
3.3 These test methods are suitable for product development, manufacturing control, and specification acceptance.
These test methods are under the jurisdiction of ASTM Committee C08 on Refractories and are the direct responsibility of Subcommittee C08.04 on Chemical Behaviors.
Current edition approved April 1, 2013Nov. 1, 2017. Published August 2013November 2017. Originally approved in 1976. Last previous edition approved in 20082013
as C831 – 98 (2008).(2013). DOI: 10.1520/C0831-98R13.10.1520/C0831-98R17.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C831 − 98 (2017)
3.4 These test methods are very sensitive to specimen size, coking rates, etc.; therefore, strict compliance with these test
methods is critical.
3.5 Appreciable amounts of reducible components, such as Fe O , will have a noticeable effect on the results. Thus, values
2 3
obtained by these test methods will be different when brick removed from service is tested. This must be kept in mind when
attempting to use these test methods in an absolute sense.
3.6 Oxidizable components such as metals and carbides can have a noticeable effect on the results. This must be kept in mind
when using the second procedure, which is based on measuring weight loss after igniting the coked specimens.
3.7 Testing of brick or shapes that contain magnesium metal presents special problems since this metal is highly volatile and
substantial amounts of the magnesium can be lost from the sample during the coking procedure. This must be kept in mind when
interpreting the results of testing of brick that containcontains magnesium. In addition, magnesium can react readily with
atmospheric humidity. This must be kept in mind when storing brick that containcontains magnesium.
4. Apparatus
4.1 For Coking:
4.1.1 Gas or Electric Furnace, with heating chamber capable of receiving the coking box shown in Fig. 1.
NOTE 1—Samples should not be subjected to thermal gradients greater than 40°F (22°C)40 °F (22 °C) during heatup. In electric furnaces with silicon
carbide heating elements, the length of the box should be parallel to these elements.
4.1.2 Inner and Outer Box, stainless steel (or equivalent alloy), as shown in Figs. 1-3.
FIG. 1 Outer Coking Box (Dimensions are in Inches)
C831 − 98 (2017)
FIG. 2 Inner Coking Box
4.2 For CO Absorption:
4.2.1 Laboratory Pulverizer, designed designed to provide a sealed, dustproof grinding chamber, and having a capacity of at
least 50 g of sample.
4.2.2 Combustion-Tube Furnace, capable of operating at 183°F (1000°C)183 °F (1000 °C)
4.2.3 CO -Absorption Train Absorption Train, as described in Fig. 4 and in Test Method C571.
NOTE 2—Commercial automatic and semi-automatic carbon determinators may replace the apparatus described in 4.2.2 and 4.2.3.
Typical grinders are: Blueler Mill, Applied Research Laboratories, Sunland, CA; Laboratory Disc Mill, Angstrom, Inc., Bellville, MI; and Shatter Box, Spex Industries,
Inc., Metuchen, NJ.
C831 − 98 (2017)
FIG. 3 Coking Box Arrangement
FIG. 4 CO -Absorption Absorption Train
4.3 The precision obtained with these instruments shall meet the requirements specified in Section 10.
5. Preparation of Test Specimens
5.1 This method assumes that the number of specimens tested will be a statistically valid sample of the entire lot of brick or
shapes being evaluated. The exact number is usually arrived at by mutual agreement between parties concerned.
C831 − 98 (2017)
5.2 Although sample brick from either the 4 ⁄2-in. (114-mm) or the 6-in. (152-mm) series may be tested, it is preferable to use
the larger size for the test. Cut slices 1 6 ⁄32 in. (25 6 0.8 mm) 0.8 mm) in thickness perpendicular to the length at the mid-section
of each sample brick or shape. As shown in Fig. 5, the nominal size of each slice shall be 1 by 3 by 6 in. (25 by 76 by 152 mm).
The two 1 by 3-in. faces and the two 1 by 6-in. faces must be original surfaces.
5.3 Test specimens may be cut wet or dry except for products capable of hydration, such as dolomite brick, which must be cut
dry and stored in a dry container prior to coking.
5.4 Specimens that are cut wet must be dried immediately with a paper or cloth towel and flash dried. For pitch-impregnated
samples, flash drying should be done at a sufficiently low temperature to avoid “weeping” of pitch from the pores of the brick.
Drying can usually be done on a forced-air dryer at 220°F (105°C)220 °F (105 °C) by limiting exposure to 5 to 10 min. Repeat
if necessary. These drying procedures are especially important for metal-containing brick because hydration of the metals can
occur. Specimens containing a coating of pitch on uncut surfaces, as is typical of an impregnation process, must be scraped clean
prior to drying.
5.5 Weigh all specimens after drying to constant weight (60.2g),(60.2 g), recording weight to the nearest 0.1 g. This weight
is “as-received weight, A,A.” (This step may be omitted if residual carbon is to be determined by CO absorption, as indicated in
1.1.)
6. Procedure for Coking
6.1 Place the test specimens randomly into the inner box, Fig. 2
NOTE 3—Burned pitch-impregnated magnesite brick should not be coked with tempered, tar-bonded, or dolomite brick because of carbon pickup by
the impregnated samples and disruption of the bottom of tempered samples. Pitch-bonded, pitch-bonded tempered magnesite brick, and dolomite brick
may be coked in the same box or coking run.
NOTE 4—The number of samples coked per run should be constant within a laboratory. Dummy uncoked samples consistent with Note 3 may be used
to fill any empty positions in the inner box.
6.2 Place the inner box into the center of the outer box (Fig. 3), on the bottom of which has first been placed a ⁄2-in. (13-mm)
slab of carbon, covered with a thin layer of dust-free metallurgical-grade coke breeze (No. 14 (1.40–mm)(1.40-mm) sieve size)
(Note 5). To ensure that the coke breeze is free of moisture which could oxidize carbon during cooking, dry the coke at 400°F
(205°C)400 °F (205 °C) for 24 h, and keep in a closed container at room temperature until needed.
NOTE 5—Detailed requirements for sieves are given in Specification E11.
6.3 Place the thermocouple well into the center of the inner box and put the lid on the inner box. The thermocouple well must
be long enough to extend above the cover of the outer box.
6.4 Cover the inner box with metallurgical-grade coke breeze retained on a No. 14 sieve and place a loose-fitting lid over the
coke breeze (see Fig. 3). Pack the coke breeze between the edges of the lid and box.
6.5 Place the coking-box coking box assembly (Fig. 3) into the furnace, and insert a calibrated thermocouple into the
thermocouple well.
6.6 Heat the furnace so that the thermocouple within the box registers 250°F (120°C)250 °F (120 °C) after the first hour, then
heat the furnace so that the box is heated at a rate of 400 6 20°F (2206 11°C)/h 20 °F (220 6 11 °C) ⁄h to 1800 6 20°F20 °F
(980 6 11°C).11 °C).
6.7 Hold the temperature for 3 6 ⁄2 h, starting from the time 1780°F (970°C)1780 °F (970 °C) is reached in the inner box.
FIG. 5 Location of Test Specimen
C831 − 98 (2017)
6.8 After completing the hold period, shut off the furnace and allow the coking box to cool naturally within the furnace.
6.9 Remove the samples from the coking box after the box has cooled sufficiently to handle. After removing specimens from
the inner box, clean by brushing carefully with a nylon or natural bristle brush to remove clinging particles. Then proceed to either
of the two alternatives for analyzing the specimens.
NOTE 6—After each run, clean the muffle and the bottom carbon plate of any adhering coke breeze.
6.10 Samples that contain dolomite or aluminum metal should be stored in a sealed container containing dessicant in the time
interval between coking and measurement of carbon content. This is to prevent hydration of dolomite or aluminum carbide. The
aluminum carbide is formed by reaction between aluminum and carbon in the shape during the coking operation. Aluminum
carbide can react with a water source such as atmospheric humidity to form methane. Care should be taken since methane can be
an explosion hazard.
CO ABSORPTION (FIRST ALTERNATIVE PROCEDURE)
7. Preparation of Sample
7.1 A sample consists of a single slice or multiple specimens of brick prepared as described in Sections 5 and 6.
7.2 Crush the sample in a laboratory jaw crusher, or other impact-type crusher, to pass a No. 4 (4.75-mm) sieve (Note 5).
Thoroughly mix the crushed sample and reduce to approximately 50 g by quartering or riffling.
7.3 Place the sample in the laboratory pulverizer and grind to 100 % passing a No. 100 (150 μm) (150-μm) sieve. This takes
approximately 90 to 100 s. Promptly transfer the ground sample to a suitable airtight container.
NOTE 7—Extreme care must be taken during the entire sample preparation to avoid loss of carbon by segregation or dusting. About 60 % of the variance
in this procedure is in this step.
8. Procedure
8.1 With the furnace at operating temperature, pass oxygen through the absorption train until the CO -absorption absorption
bulb attains constant weight (usually 15 to 30 min). Adjust the oxygen pressure and flow rate to provide 120 to 150 bubbles per
minute through the bubbling tower. Close the stopcock, remove the absorption bulb from the train, cool to room temperature, and
weigh to the nearest 0.1 mg.
8.2 Into a previously ignited combustion boat, weigh a 0.1 to 1.0 g sample to the nearest 0.1 mg. Return the weighed CO
absorption bulb to the train and open the stopcock. Then place the combustion boat with sample in the combustion tube and
immediately reseal the train. Adjust the flow of oxygen as before (8.1), heat the furnace to 1740 to 1830°F1830 °F (950 to
1000°C),1000 °C), and maintain until the CO adsorption bulb attains constant weight (usually 45 to 60 min).
8.3 Remove the absorption bulb from the train, close the stopcock, cool to room temperature, and reweigh. The increase in
weight is the CO won from the sample by combustion of the carbon.
9. Calculation and Report
9.1 Calculate the percentage of residual carbon in the sample as follows:
wt of CO 30.2729 3100
Residual carbon, %5 (1)
wt of sample
9.2 Run the determinations in duplicate. Results shall not vary by more than 60.05 % stated in terms of the whole sample as
100 %. If satisfactory checks are not obtained, repeat the analysis in duplicate. Report at least two individual analyses per slice.
10. Precision and Bias
10.1 An interla
...

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