ASTM C767-93(1998)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: C 767 – 93 (Reapproved 1998)
Standard Test Method for
Thermal Conductivity of Carbon Refractories
This standard is issued under the fixed designation C 767; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.4 The use of these data requires consideration of the actual
application environment and conditions.
1.1 This test method supplements Test Method C 201, and
shall be used in conjunction with that procedure to determine
4. Apparatus
the thermal conductivity of carbon or carbon-bearing refracto-
4.1 The apparatus shall be in accordance with Test Method
ries. This test method is designed for refractories having a
C 201 with the addition of thermocouples, back-up insulation,
conductivity factor of not more than 200 Btu·in./h·ft ·°F (28.8
and refractory fiber paper as described in Section 5 of this test
W/m·K).
method.
1.2 The values stated in inch-pound units are to be regarded
as the standard.
5. Test Specimen and Preparation
1.3 This standard does not purport to address all of the
5.1 Select the test specimen and prepare in accordance with
safety concerns, if any, associated with its use. It is the
Test Method C 201.
responsibility of the user of this standard to establish appro-
5.2 Thermocouples—Embed calibrated thermocouples in
priate safety and health practices and determine the applica-
the test specimen at two points for measuring temperature.
bility of regulatory limitations prior to use.
Thermocouples sheathed with material having low reactivity
with carbon must be used. Use the top thermocouple for one
2. Referenced Documents
test only.
2.1 ASTM Standards:
2 5.3 Installation of Thermocouples— Place the hot junction
C 155 Classification of Insulating Firebrick
of the thermocouples in the center of each 9 by 4 ⁄2-in. (228 by
C 201 Test Method for Thermal Conductivity of Refracto-
2 114-mm) face and just below the surface of the test specimen.
ries
Cut grooves to receive the wire in each 9 by 4 ⁄2-in. face of the
E 220 Method for Calibration of Thermocouples by Com-
3 brick to a depth necessary to embed the thermocouple just
parison Techniques
beneath the surface by means of an abrasive wheel. The layout
3. Significance and Use for the grooves allows all of the cold-junction ends of the wires
to extend from one end of the brick. Cut a groove in the center
3.1 The thermal conductivity of carbon refractories is a
1 1
of each 9 by 4 ⁄2-in. face along the 9-in. dimension and end ⁄4
property required for selecting their thermal transmission
in. (6 mm) beyond the center. Before cementing the thermo-
characteristics. Users select carbon refractories to provide
couples in place, take measurements to obtain, within 60.01
specified conditions of heat loss and cold face temperature,
in. (60.3 mm), the eventual distance between the center lines
without exceeding the temperature limitation of the carbon
of the thermocouple junctions. Do this by measuring the
refractory. This test method establishes placement of thermo-
2 ⁄2-in. (64-mm) dimension of the brick at the location for the
couples and positioning of test specimens in the calorimeter.
hot junctions and deducting the distance between the center
3.2 This procedure must be used with Test Method C 201
line of each junction in its embedded position and the surface
and requires a large thermal gradient and steady state condi-
of the brick.
tions. The results are based upon a mean temperature.
5.4 Cover the calorimeter and inner and outer guards with a
3.3 The data from this test method is suitable for specifica-
0.50-in. (12.7-mm) thick layer of Group 20 insulating firebrick
tion acceptance, estimating heat loss and surface temperature,
(see Classification C 155) for the purpose of obtaining a higher
and the design of multi-layer refractory construction.
mean temperature in the test sample than would result by
placing the sample directly over the calorimeter area. Cut and
This test method is under the jurisdiction of ASTM Committee C-8 on
Refractories and is the direct responsibility of Subcommittee C08.02 on Thermal
Properties. Method E 220 specifies calibration procedures for thermocouples.
Current edition approved Dec. 15, 1993. Published February 1994. Originally Claud S. Gordon Co., 5710 Kenosha St., Richmond, IL 60071, 1 16 -in.
/
e1
published as C 767 – 73. Last previous edition C 767 – 86 (1993) . (2-mm) sheathed Xactpak thermocouple, Cat. No. 401-2104 or equivalent.
2 6
Annual Book of ASTM Standards, Vol 15.01. Alundum Cement RA 562 supplied by the Norton Co., One New Bond St.,
Annual Book of ASTM Standards, Vol 14.03. Worcester, MA 01606, is satisfactory for this purpose.
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C 767 – 93 (1998)
grind the back-up insulation so as to provide surfaces that are duction of argon under slight positive pressure as measured by
plane and do not vary from parallel by more than 60.01 in. a draft gage. In addition, place several pieces of carbon
(0.3 mm). Grind the sides of the pieces that are to be placed in refractory around the edges of the furnace on top of the outer
contact plane and at right angles to the horizontal faces. Make guard brick to react with any oxygen that may enter the furnace
the joints between the pieces tight without the use of any chamber. The argon should not impinge on the test s
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