ASTM E1652-00
(Specification)Standard Specification for Magnesium Oxide and Aluminum Oxide Powder and Crushable Insulators Used in the Manufacture of Metal-Sheathed Platinum Resistance Thermometers, Base Metal Thermocouples, and Noble Metal Thermocouples
Standard Specification for Magnesium Oxide and Aluminum Oxide Powder and Crushable Insulators Used in the Manufacture of Metal-Sheathed Platinum Resistance Thermometers, Base Metal Thermocouples, and Noble Metal Thermocouples
SCOPE
1.1 This specification covers the requirements for magnesium oxide (MgO) and aluminum oxide (Al2O3) powders and crushable insulators used to manufacture metal-sheathed cables of platinum resistance thermometers (PRTs) and noble metal thermocouples.
1.2 The values stated in SI 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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: E 1652 – 00
Standard Specification for
Magnesium Oxide and Aluminum Oxide Powder and
Crushable Insulators Used in the Manufacture of Metal-
Sheathed Platinum Resistance Thermometers, Base Metal
Thermocouples, and Noble Metal Thermocouples
This standard is issued under the fixed designation E 1652; 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 D 2858 Test Method for Thermal Conductivity of Electrical
Grade Magnesium Oxide
1.1 This specification covers the requirements for magne-
E 228 Test Method for Linear Thermal Expansion of Solid
sium oxide (MgO) and aluminum oxide (Al O ) powders and
2 3
Materials with a Vitreous Silica Dilatometer
crushable insulators used to manufacture metal-sheathed plati-
E 235 Specification for Thermocouples, Sheathed, Type K,
num resistance thermometers (PRTs), noble metal thermo-
for Nuclear or for Other High-Reliability Applications
couples, base metal thermocouples, and their respective cables.
E 344 Terminology Relating to Thermometry and Hydrom-
1.2 The values stated in SI units are to be regarded as the
etry
standard. The values given in parentheses are for information
E 585 Specification for Compacted Mineral-Insulated,
only.
Metal-Sheathed, Base Metal Thermocouple Cable
1.3 This standard does not purport to address all of the
E 1137 Specification for Industrial Platinum Resistance
safety concerns, if any, associated with its use. It is the
Thermometers
responsibility of the user of this standard to establish appro-
E 1225 Test Method for Thermal Conductivity of Solids by
priate safety and health practices and determine the applica-
Means of the Guarded-Comparative-Longitudinal Heat
bility of regulatory limitations prior to use.
Flow Technique
2. Referenced Documents
3. Terminology
2.1 ASTM Standards:
3.1 The definitions given in Terminology E 344 shall apply
B 329 Test Method for Apparent Density of Metal Powders
to this specification.
and Related Compounds Using the Scott Volumeter
C 573 Methods for Chemical Analysis of Fireclay and
4. Significance and Use
High-Alumina Refractories
4.1 Magnesium oxide and aluminum oxide are used to
C 574 Method for Chemical Analysis of Magnesite and
electrically isolate and mechanically support the thermoele-
Dolomite Refractories
ments of a thermocouple (see Specifications E 235 and E 585)
C 809 Test Method for Chemical, Mass Spectrometric, and
and the connecting wires of a PRT (see Specification E 1137)
Spectrochemical Analysis of Nuclear-Grade Aluminum
within a metal sheath. The metal sheath is typically reduced in
Oxide and Aluminum Oxide-Boron Carbide Composite
5 diameter to compact the oxide powder or crushable oxide
Pellets
insulators around the thermoelements or wires.
C 832 Test Method for Measuring the Thermal Expansion
6 4.2 In order to be suitable for this purpose, the materials
and Creep of Refractories Under Load
shall meet certain criteria for purity and for mechanical and
D 2766 Test Method for Specific Heat of Liquids and
7 dimensional characteristics. Material that does not meet the
Solids
purity criteria may cause premature failure of the sensor.
4.3 Use of this specification for the procurement of powder
and crushable insulators will help to ensure that the product
This specification is under the jurisdiction of ASTM Committee E20 on
Temperature Measurement and is the direct responsibility of Subcommittee E20.04 obtained is suitable for the intended purpose.
on Thermocouples.
4.4 Useful information about alumina and magnesia is given
Current edition approved Oct. 10, 2000. Published December 2000. Originally
in the appendixes.
published as E 1652–95. Last previous edition E 1652–95.
Annual Book of ASTM Standards, Vol 02.05.
Discontinued. See 1993 Annual Book of ASTM Standards, Vol 03.05.
Discontinued. See 1995 Annual Book of ASTM Standards, Vol 03.06.
5 8
Annual Book of ASTM Standards, Vol 12.01. Annual Book of ASTM Standards, Vol 10.01.
6 9
Annual Book of ASTM Standards, Vol 15.01. Annual Book of ASTM Standards, Vol 14.02.
7 10
Annual Book of ASTM Standards, Vol 05.02. Annual Book of ASTM Standards, Vol 14.03.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E 1652
5. Ordering Information Specific density requirements, as well as the test method to be
used to determine density, shall be negotiated between the
5.1 The purchaser shall specify the following when order-
purchaser and manufacturer. See Appendix X3 for suggested
ing:
test methods.
5.1.1 Material—from 5.1.1.1 through 5.1.1.5 below:
7.2 Modulus of Rupture—In the past, a breaking force test
5.1.1.1 Al O Type 1 per Table 1.
2 3
has been used that is based on a relative modulus of rupture and
5.1.1.2 Al O Type 2 per Table 1 and Supplementary
2 3
is related to crushability. However, with variations in modulus
Requirement S1.
from 21 to 83 MPa (3000 to 12 000 lb/in. ) influenced by
5.1.1.3 MgO Type 1 per Table 1.
insulator configuration, number of holes, and cross-sectional
5.1.1.4 MgO Type 2 per Table 1 and Supplementary Re-
dimensions, specific modulus requirements cannot be listed for
quirement S1.
each configuration. The modulus of rupture is best used for lot
5.1.1.5 MgO Type 3 per Supplementary Requirement S2.
to lot comparison of a given insulator size and configuration.
5.1.2 Insulator Outside Diameter.
See Appendix X4 for a suggested test method.
5.1.3 Hole Diameter.
5.1.4 Number of Holes.
8. Dimensional Requirements
5.1.5 Hole Pattern.
8.1 Outside diameter and hole diameter tolerances for insu-
5.1.6 Length.
lators shall be as specified in Table 2 and Table 3, respectively,
5.1.7 Particle Size (if supplied as powder).
unless otherwise agreed to between purchaser and manufac-
5.1.8 Minimum Inside Diameter of Tubing, into which
turer.
insulators will be inserted.
8.2 Wall and web thicknesses (see Fig. 1) shall be equal
5.2 Consult the insulator manufacturer for limitations of
within outside diameter tolerance as specified in Table 2 unless
relationships between outside diameter, hole diameters, hole
otherwise agreed to between purchaser and manufacturer.
patterns, and length.
8.3 Camber shall not exceed 0.3 % of the length. Insulator
shall be capable of passing through a rigid straight tube longer
6. Chemical Requirements
than the insulator and with an inside diameter as specified in
6.1 The final product shall be chemically analyzed using
5.1.8.
appropriate methods listed in 9.1. Major impurities shall not
8.4 Helical twist of holes shall not exceed 2° per cm (5° per
exceed the limits indicated in Table 1 unless permitted by
in.) of length.
supplementary requirements. Any detected impurity with a
8.5 Length shall be as specified in 5.1.6 with a tolerance
concentration greater than 0.001 % (mass) shall be reported to
of +6/−0.00 mm ( +0.25/−0.00 in.).
the purchaser.
8.6 The ends of each insulator should be cut square and not
be chipped.
7. Physical Properties
7.1 Density—The density of crushable magnesium oxide
9. Test Methods
and aluminum oxide insulators typically ranges from 2060
9.1 Chemical Composition:
3 3 3 3
kg/m (0.074 lbm/in. ) to 3060 kg/m (0.111 lbm/in. ).
9.1.1 Wet chemical analysis, or fusion calorimetric analysis,
or both, can be used for quantitative determination of silicon
A
TABLE 1 Impurity Limits dioxide (SiO ), iron oxide (Fe O ), and zirconium oxide
2 2 3
(ZrO ) with gravimetric determination for SiO and Fe O .
Aluminum Oxide (Al O ) 99.65 % Magnesium Oxide (MgO) 99.40 % 2 2 2 3
2 3
(mass) min (mass) min
The SiO filtrate can be used for further calcium oxide (CaO)
determination.
Concentration, Concentration,
Impurity Impurity
% (mass) % (mass)
9.1.2 Test Method C 809 can be used for quantitative
B C
Fe O 0.04 max CaO 0.35 max
analysis of elemential impurities.
2 3
D C
SiO 0.08 max Al O 0.15 max
2 2 3
9.1.3 Methods C 573 can be used for quantitative analysis
B,C
CaO 0.08 max Fe O 0.04 max
2 3
C,D
of Fe O , SiO , CaO, MgO, and sodium monoxide (Na O) in
MgO 0.08 max SiO 0.13 max 2 3 2 2
ZrO 0.08 max C 0.02 max
Al O .
2 3
Na O 0.06 max S 0.005 max
9.1.4 Method C 574 can be used for quantitative analysis of
C 0.01 max B 0.0025 max
CaO, Al O ,Fe O , and SiO in MgO.
S 0.005 max Cd 0.001 max
2 3 2 3 2
Cd 0.001 max B + Cd 0.003 max
9.1.5 Any method used for quantitative determination
B 0.001 max
should have a detection sensitivity of at least 0.001 % (mass).
A
The total compositional analysis should equal 100 %.
B
The presence of Fe O can adversely affect the electrical resistivity of these
2 3
TABLE 2 Outside Diameter (O.D.) Tolerance
insulators. Moreover, changes in the thermometric properties of platinum and its
alloys that are exposed to Fe O concentrations above 0.04 % become more
2 3
O.D. Range O.D. Tolerance
pronounced when exposed to the higher service temperatures, for example, above
650 °C (1200 °F), for prolonged periods. However, at lower service temperatures, 0.25 to 1.48 mm (0.010 to 0.058 in.) 60.051 mm (60.002 in.)
1.49 to 2.27 mm (0.059 to 0.089 in.) 60.076 mm (60.003 in.)
purchaser may choose to allow Fe O concentrations of up to 0.1 % in Al O or
2 3 2 3
0.15 % in MgO. See Supplemental Requirement S1. 2.28 to 3.28 mm (0.090 to 0.129 in.) 60.076 mm (60.003 in.)
C
3.29 to 6.33 mm (0.130 to 0.249 in.) 60.076 mm (60.003 in.)
See Supplemental Requirement S2 for base-metal thermocouple applications.
D
The presence of SiO can, at elevated temperatures, lead to changes in the 6.34 to 9.51 mm (0.250 to 0.374 in.) 60.10 mm (60.004 in.)
electrical resistivity, thermoelectric characteristics, and mechanical properties of 9.52 mm (0.375 in.) and larger 60.15 mm (60.006 in.)
platinum and its alloys.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E 1652
TABLE 3 Hole Diameter Tolerance
10. Handling and Storage Precautions
Hole Diameter Range Hole Diameter Tolerance
10.1 Powders and crushable insulators shall be shipped and
0.05 to 0.26 mm (0.002 to 0.010 in.) 60.038 mm (60.0015 in.)
stored in containers that prevent contamination and breakage.
0.27 to 1.51 mm (0.011 to 0.059 in.) 60.051 mm (60.002 in.)
Powders and crushable insulators should be stored in a sealed
1.52 to 2.52 mm (0.060 to 0.099 in.) 60.076 mm (60.003 in.)
2.53 to 3.79 mm (0.100 to 0.149 in.) 604 %
container to prevent contamination by moisture absorption.
3.80 mm (0.150 in.) and larger 605 %
(See Appendix X2.)
11. Keywords
11.1 aluminum oxide; insulator; crushable; magnesium ox-
ide; mineral-insulated, metal-sheathed cable; platinum resis-
tance thermometer; thermocouple, base metal; thermocouple,
noble metal
FIG. 1 Wall and Web Thicknesses
9.2 Density (Powder)—Test Method B 329 can be used for
determining the density of Al O and MgO powders.
2 3
9.3 Appendix X5 lists other optional test methods.
SUPPLEMENTARY REQUIREMENTS
The following supplementary requirement shall apply only when specified by the purchaser in the
inquiry, contract, or order.
A
TABLE S2.1 Impurity Limits
S1. Iron Oxide (Fe O ) Concentration
2 3
Magnesium Oxide (MgO) 97.00 % (mass) min
S1.1 Insulators used in service at temperatures 650 °C
Impurity Concentration, % (mass)
(1200 °F) and below shall conform to the chemical require-
ments of 6.1 except that the impurity Fe O may have a CaO 0.80 max
2 3
Al O 1.00 max
2 3
maximum concentration of 0.10 % for Al O or 0.15 % for
2 3
Fe O 0.08 max
2 3
MgO. These oxide compositions shall be designated Al O
2 3
SiO 1.20 max
Type 2 and MgO Type 2, respectively. Fe 0.02 max
C 0.02 max
S 0.005 max
S2. Insulators for Base Metal Thermocouples
B 0.0025 max
S2.1 Calcium oxide, aluminum oxide, and silicon oxide are
Cd 0.001 max
B + Cd 0.003 max
no more likely than is magnesium oxide to react deleteriously
MgO + CaO + Al O + SiO 99.50 min
2 3 2
with the thermoelement alloys of base metal thermocouples at
A
The total compositional analysis should equal 100 %.
temperatures that are recommended for the operation of those
thermoelement alloys. Therefore, optionally, for base metal
thermocouples only, MgO insulators shall conform to the
chemical requirements of 6.1 and Table S2.1 instead of Table
1. This oxide composition shall be designated MgO Type 3.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E 1652
APPENDIXES
(Nonmandatory Information)
X1. MATERIALS AND MANUFACTURE
X1.1 Alumina (Al O ) X1.1.2.4 Dielectric Strength—5600 kV/m (142 000 V/in.).
2 3
X1.1.2.5 Hardness (MOHS)—9.
X1.1.1 Sources:
X1.1.2.6 Softening Temperature—1750 °C (3182 °F).
X1.1.1.1 Bauxite is the principal source of alumina. Gibb-
X1.1.2.7 Melting Temperature—2050 °C (3722 °F).
site, Al(OH) , is the most stable phase. Boehmite, AlO(OH),
X1.1.2.8 Molecular Weight—101.94.
also occurs in nature. High grade bauxite is low in iron and
X1.1.2.9 Typical Electrical Resistivity—See Table X1.1.
silica content. The major use of purified alumina is in the
X1.1.2.10 Specific Heat— 8.8 3 10 J/kg·K@ 20 °C (0.21
production of aluminum metal.
Btu/lbm °F @ 68 °F). 1.2 3 10 J/kg·K @ 1000 °C (0.28
X1.1.1.2 Depending upon the application, the economics,
Btu/lbm °F @ 1832 °F).
and the purity of the bauxite, the purification process could be
X1.1.2.11 Typical Thermal Conductivity—See Table X1.2.
wet alkaline, wet acid, alkaline furnace, carbothermic furnace,
X1.1.2.12 Macroscopic Thermal Neutron Absorption Cross
or electrolytic processes.
−1 −1
Section—1.0 m (0.03 in. ).
X1.1.1.3 The wet alkaline processes are most economical.
Gibbsite bauxite is easier to dissolve. It is digested in sodium
X1.2 Magnesia (MgO)
hydroxide (NaOH) solution at about 150 °C (302 °F) at 345
2 X1.2.1 Sources:
kPa (50 lb/in. ). Boehmitic bauxite, AlO(OH), is more difficult
X1.2.1.1 Magnesia can be made by the oxidation of mag-
to dissolve. It requires a higher concentration of NaOH
2 nesium metal or by heating easily decomposed oxy-compounds
solution, a pressure of 1930 to 4826 kPa (280 to 700 lb/in. ),
of magnesium, such as the hydroxide, Mg(OH) , the oxalate,
and a temperature of about 238 °C (545 °F).
MgC O , or the naturally occurring carbonate (magnesite),
2 4
X1.1.1.4 Wh
...
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