ASTM D6743-11(2015)
(Test Method)Standard Test Method for Thermal Stability of Organic Heat Transfer Fluids
Standard Test Method for Thermal Stability of Organic Heat Transfer Fluids
SIGNIFICANCE AND USE
5.1 Heat transfer fluids degrade when exposed to sufficiently high temperatures. The amount of degradation increases as the temperature increases or the length of exposure increases, or both. Due to reactions and rearrangement, degradation products can be formed. Degradation products include high and low boiling components, gaseous decomposition products, and products that cannot be evaporated. The type and content of degradation products produced will change the performance characteristics of a heat transfer fluid. In order to evaluate thermal stability, it is necessary to quantitatively determine the mass percentages of high and low boiling components, as well as gaseous decomposition products and those that cannot be vaporized, in the thermally stressed heat transfer fluid.
5.2 This test method differentiates the relative stability of organic heat transfer fluids at elevated temperatures in the absence of oxygen and water under the conditions of the test.
5.3 The user shall determine to his own satisfaction whether the results of this test method correlate to field performance. Heat transfer fluids in industrial plants are exposed to a variety of additional influencing variables. Interaction with the plant's materials, impurities, heat build-up during impaired flow conditions, the temperature distribution in the heat transfer fluid circuit, and other factors can also lead to changes in the heat transfer fluid. The test method provides an indication of the relative thermal stability of a heat transfer fluid, and can be considered as one factor in the decision-making process for selection of a fluid.
5.4 The accuracy of the results depends very strongly on how closely the test conditions are followed.
5.5 This test method does not possess the capability to quantify or otherwise assess the formation and nature of thermal decomposition products within the unstressed fluid boiling range. Decomposition products within the unstressed fluid boiling range may ...
SCOPE
1.1 This test method covers the determination of the thermal stability of unused organic heat transfer fluids. The procedure is applicable to fluids used for the transfer of heat at temperatures both above and below their boiling point (refers to normal boiling point throughout the text unless otherwise stated). It is applicable to fluids with maximum bulk operating temperature between 260 °C (500 °F) and 454 °C (850 °F). The procedure shall not be used to test a fluid above its critical temperature. In this test method, the volatile decomposition products are in continuous contact with the fluid during the test. This test method will not measure the thermal stability threshold (the temperature at which volatile oil fragments begin to form), but instead will indicate bulk fragmentation occurring for a specified temperature and testing period. Because potential decomposition and generation of high pressure gas may occur at temperatures above 260 °C (500 °F), do not use this test method for aqueous fluids or other fluids which generate high-pressure gas at these temperatures.
1.2 DIN Norm 51528 covers a test method that is similar to this test method.
1.3 The applicability of this test method to siloxane-based heat transfer fluids has not been determined.
1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
1.5 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. For specific warning statements, see 7.2, 8.8, 8.9, and 8.10.
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Designation: D6743 − 11 (Reapproved 2015)
Standard Test Method for
Thermal Stability of Organic Heat Transfer Fluids
This standard is issued under the fixed designation D6743; 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
1.1 Thistestmethodcoversthedeterminationofthethermal 2.1 ASTM Standards:
stability of unused organic heat transfer fluids. The procedure D2887 Test Method for Boiling Range Distribution of Pe-
is applicable to fluids used for the transfer of heat at tempera- troleum Fractions by Gas Chromatography
turesbothaboveandbelowtheirboilingpoint(referstonormal D4175 Terminology Relating to Petroleum, Petroleum
boiling point throughout the text unless otherwise stated). It is Products, and Lubricants
applicable to fluids with maximum bulk operating temperature E691 Practice for Conducting an Interlaboratory Study to
between 260 °C (500 °F) and 454 °C (850 °F). The procedure Determine the Precision of a Test Method
shall not be used to test a fluid above its critical temperature. In 2.2 DIN Norms:
this test method, the volatile decomposition products are in 51528 Determination of the Thermal Stability of Unused
continuous contact with the fluid during the test. This test Heat Transfer Fluids
method will not measure the thermal stability threshold (the
3. Terminology
temperature at which volatile oil fragments begin to form), but
3.1 Definitions:
instead will indicate bulk fragmentation occurring for a speci-
3.1.1 thermal stability, n—the resistance to permanent
fied temperature and testing period. Because potential decom-
changes in properties caused solely by heat. D4175
position and generation of high pressure gas may occur at
temperatures above 260 °C (500 °F), do not use this test
3.2 Definitions of Terms Specific to This Standard:
method for aqueous fluids or other fluids which generate
3.2.1 decomposition products that cannot be vaporized,
high-pressure gas at these temperatures.
n—materials from the thermally stressed heat transfer fluid,
from which those fractions that can be vaporized are removed
1.2 DIN Norm 51528 covers a test method that is similar to
by distillation procedures, that are quantitatively determined as
this test method.
residues in a bulb tube distillation apparatus.
1.3 The applicability of this test method to siloxane-based
3.2.2 fluid within the unstressed fluid boiling range, n—any
heat transfer fluids has not been determined.
fluid components with boiling point between the initial boiling
1.4 The values stated in SI units are to be regarded as
point and final boiling point of the unstressed fluid.
standard. The values given in parentheses are for information
3.2.3 gaseous decomposition products, n—materials with
only.
boiling points below room temperature, at normal pressure,
1.5 This standard does not purport to address all of the
such as hydrogen and methane, that escape upon opening the
safety concerns, if any, associated with its use. It is the
test cell and that can be determined by measuring the mass
responsibility of the user of this standard to establish appro-
immediately thereafter.
priate safety and health practices and determine the applica-
3.2.4 high boiling components, n—materials from the ther-
bility of regulatory limitations prior to use. For specific
mally stressed heat transfer fluid, with boiling points above the
warning statements, see 7.2, 8.8, 8.9, and 8.10.
final boiling point of the unstressed heat transfer fluid, but
1 2
This test method is under the jurisdiction of ASTM Committee D02 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Subcommittee D02.L0.06 on Non-Lubricating Process Fluids. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved July 1, 2015. Published July 2015. Originally approved the ASTM website.
in 2001. Last previous edition approved in 2011 as D6743 – 11. DOI: 10.1520/ AvailablefromDeutschesInstitutfurNormunge.V.(DIN),Burggrafenstrasse6,
D6743-11R15. 10787 Berlin, Germany, http://www.din.de.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6743 − 11 (2015)
which can still be separated by distillation from the heat 5.4 The accuracy of the results depends very strongly on
transfer fluid by means of classical separation procedures. how closely the test conditions are followed.
3.2.5 low boiling components, n—materials from the ther-
5.5 This test method does not possess the capability to
mally stressed heat transfer fluid, with boiling points below the
quantify or otherwise assess the formation and nature of
initial boiling point of the unstressed heat transfer fluid.
thermal decomposition products within the unstressed fluid
boiling range. Decomposition products within the unstressed
3.2.6 mass percentage of high boiling components, n—the
fluid boiling range may represent a significant portion of the
percentage of thermally stressed heat transfer fluid with a
total thermal degradation.
boiling point above the final boiling point of the unstressed
fluid.
6. Apparatus
3.2.7 mass percentage of low boiling components, n—the
6.1 Test Cell—The test cell shall be a new, clean ampoule
percentage of thermally stressed heat transfer fluid with a
made from ASTM A-269 grade 316L stainless steel tubing,
boiling point below the initial boiling point of the unstressed
25 mm (1 in.) outside diameter, 2 mm (0.083 in.) wall thick-
fluid.
ness. The test cell shall be 0.152 m 6 0.003 m (6 in. 6
3.2.8 test cell, n—an ampoule constructed from stainless
0.125 in.) in length and sealed with compression fittings at
steel tubing and sealed with compression fittings at each end.
each end.
3.2.9 thermally stressed, adj—subjected to heating, as de-
NOTE 1—Where tubing with SI dimensions is not readily available, the
scribed in this test method.
use of tubing with inch-pound dimensions is acceptable.
6.2 Heating Oven—The oven shall be capable of being
4. Summary of Test Method
controlled within 61°C(61.8 °F) at test temperature.The test
4.1 Charge the test fluid in a thermal stability test cell
temperature selected will typically be between 260 °C (500 °F)
purgedwithnitrogenandtightlysealthetestcelltoremoveand
and 427 °C (800 °F), depending on the fluid being tested.
preclude introduction of oxygen and water from the atmo-
6.3 Bulb Tube Distillation Apparatus—This apparatus shall
sphere. Heat the fluid in an oven at a given temperature and for
be capable of heating to at least 250 °C (482 °F) and pressure
a given period of time. Determine the boiling range of the
down to at least 0.1 mm Hg.
heated fluid by gas chromatography (GC) analysis and com-
6.4 Dewar Flask—The flask is used to hold the test cells
pare it to the boiling range of pure, unused fluid.
during cooling after removal from the heating oven.
5. Significance and Use
6.5 Balance—The balance shall be capable of measuring
mass to the nearest 0.01 g.
5.1 Heat transfer fluids degrade when exposed to suffi-
ciently high temperatures. The amount of degradation in-
7. Preparation of Apparatus
creases as the temperature increases or the length of exposure
7.1 Test Cell—The test cell used shall always be a clean,
increases, or both. Due to reactions and rearrangement, degra-
new ampoule. Reuse of ampoules is not permitted.
dation products can be formed. Degradation products include
high and low boiling components, gaseous decomposition
7.2 Cleaning of Test Cell—A new test cell shall be cleaned
products, and products that cannot be evaporated.The type and
by washing with a suitable volatile solvent such as acetone and
content of degradation products produced will change the
dried. (Warning—Use adequate safety precautions with all
performance characteristics of a heat transfer fluid. In order to
solvents and cleaners.)
evaluate thermal stability, it is necessary to quantitatively
determine the mass percentages of high and low boiling 8. Procedure
components, as well as gaseous decomposition products and
8.1 Determine the initial boiling point (IBP) and final
those that cannot be vaporized, in the thermally stressed heat
boiling point (FBP) of the unstressed heat transfer fluid by GC,
transfer fluid.
in accordance with Test Method D2887 with the following
5.2 This test method differentiates the relative stability of requirements: the column shall be wall-coated open tubular
organic heat transfer fluids at elevated temperatures in the type of 7.5 m to 10 m length with a 100 % polydimethylsilox-
absence of oxygen and water under the conditions of the test. ane film thickness of 0.88 µm, the detector shall be flame
ionization type, the initial oven temperature shall be set to
5.3 The user shall determine to his own satisfaction whether
35 °C (95 °F) eliminating cryogenic cooling, the calibration
the results of this test method correlate to field performance.
mixture shall cover the boiling range from n-C to n-C . The
5 60
Heat transfer fluids in industrial plants are exposed to a variety
following GC parameters are recommended: oven temperature
of additional influencing variables. Interaction with the plant’s
rate 10 °C (18 °F) per minute, oven final temperature 375 °C
materials, impurities, heat build-up during impaired flow
(707 °F), time at oven final temperature 3 min, injector initial
conditions, the temperature distribution in the heat transfer
temperature 100 °C (212 °F), injector temperature rate 10 °C
fluid circuit, and other factors can also lead to changes in the
(18 °F) per minute, injector final temperature 375 °C (707 °F),
heat transfer fluid. The test method provides an indication of
detector temperature 375 °C (707 °F).
the relative thermal stability of a heat transfer fluid, and can be
considered as one factor in the decision-making process for 8.2 Measure the mass of a clean, dry test cell including
selection of a fluid. compression fittings to the nearest 0.01 g. Pour the unstressed
D6743 − 11 (2015)
heat transfer fluid into the clean, dry test cell in a vertical temperature to reduce the internal pressure. (Warning—
position. The quantity of heat transfer fluid transferred to the Pressure inside the test cell may reach several thousand kPa
test cell shall be 27 g 6 0.2 g. Invert the test cell in a vertical during the test.)
position and allow it to drain until all free-flowing material has
8.10 Remove the test cell from the oven. (Warning— Use
been removed. More viscous fluids may require as long as
adequate safety precautions when removing the test cells from
15 min to drain completely. At the end of the draining period,
the oven in case some portion of the equipment is still hot.)
tapthetestcelltoremoveadropclingingtotheopenendofthe
8.11 Carefully measure the mass of the test cell to the
test cell—do not wipe away any fluid. Measure the mass of the
nearest 0.01 g. If the evaporation loss of gaseous decomposi-
test cell and its remaining contents including compression
tion products is calculated at greater than 0.5 mass %, the test
fittings to the nearest 0.01 g.
should be repeated since this would indicate tube leakage.
NOTE 2—The intent is to perform this step only once for each heat
8.12 PlacethetestcellinaDewarflaskcontainingacooling
transfer fluid being tested at this time.
mixture of acetone or isopropanol and dry ice. Allow the test
8.3 Measure the mass of a clean, dry test cell including
cell to cool to at least –55 °C (–67 °F). The duration of cooling
compressionfittingstothenearest0.01 g.Introducehighpurity
is approximately 5 min to 10 min. Stand the test cell in a
nitrogen using tubing at the bottom of the clean, dry test cell
vertical position and allow it to reach ambient temperature,
for 2 min at 60 mL⁄min to 70 mL⁄min.
then exercise care to remove any condensed water on the
exterior of the test cell. Stand the test cell in a vertical position
NOTE 3—To ensure accurate results, at least three test cells containing
and open the top of the test cell. Then measure the mass of the
samples of the same heat transfer fluid should be heated simultaneously.
test cell including compression fittings and its contents to the
8.4 Pour the thermally unstressed heat transfer fluid into the
nearest 0.01 g. Put a portion of the fluid into sample bottles for
clean, dry test cell. The quantity of heat transfer fluid trans-
analytical evaluation and store the remainder for additional
ferred to the test cell shall be 27 g 6 0.2 g.
measurementinaglassbottlethatishermeticallysealed.Invert
the test cell and allow it to drain until all free-flowing material
8.5 Completely displace the air remaining in the gas space
has been removed. More viscous fluids may require as long as
in the test cell by introducing high purity nitrogen using tubing
15 min to drain completely. At the end of the draining period,
just above the liquid surface of fluid inside the test cell at
tapthetestcelltoremoveadropclingingtotheopenendofthe
30 mL⁄min to 35 mL⁄min for 12 min at ambient temperature.
test cell—do not wipe away any fluid. Measure the mass of the
8.6 Carefully seal the test cell and measure its mass to the
test cell and its remaining contents including compression
nearest 0.01 g.
fittings to the nearest 0.01 g.
8.7 Insert the test cell vertically in the oven. Adjust the
8.13 Visually observe the appearance of the fluid sample for
heating oven to the proper test temperature. The time to
any insolubles, or other changes in the fluid. Examples include
achieve proper test temperature should be approximately 3 h.
high pressure upon opening the test cell, appearance of fouling
The test temperature shall be maintained throughout the entire
in the head space of the test cell and evidence of a leak from
test duration and controlled in such a way that the temperature
the test cell. Observations shall be noted in the report.
of the test liquid does not deviate by more than 61°C
8.14 Determinethemasspercentageoflowandhighboiling
(61.8 °F) at any location, including the heated wall. Tempera-
components in the thermally stressed sample, in accordance
ture shall be measured and recorded throughout the test at least
with Test Method D2887 using the same equipment and
once per day. If test cells containing different fluids are tested
requirements as specified in 8.1.
at the same time, the test cells shall be distributed symmetri-
8.15 The decomposi
...
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: D6743 − 11 D6743 − 11 (Reapproved 2015)
Standard Test Method for
Thermal Stability of Organic Heat Transfer Fluids
This standard is issued under the fixed designation D6743; 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*Scope
1.1 This test method covers the determination of the thermal stability of unused organic heat transfer fluids. The procedure is
applicable to fluids used for the transfer of heat at temperatures both above and below their boiling point (refers to normal boiling
point throughout the text unless otherwise stated). It is applicable to fluids with maximum bulk operating temperature between
260°C (500°F) and 454°C (850°F).260 °C (500 °F) and 454 °C (850 °F). The procedure shall not be used to test a fluid above its
critical temperature. In this test method, the volatile decomposition products are in continuous contact with the fluid during the
test. This test method will not measure the thermal stability threshold (the temperature at which volatile oil fragments begin to
form), but instead will indicate bulk fragmentation occurring for a specified temperature and testing period. Because potential
decomposition and generation of high pressure gas may occur at temperatures above 260°C (500°F),260 °C (500 °F), do not use
this test method for aqueous fluids or other fluids which generate high-pressure gas at these temperatures.
1.2 DIN Norm 51528 covers a test method that is similar to this test method.
1.3 The applicability of this test method to siloxane-based heat transfer fluids has not been determined.
1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
1.5 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. For specific warning statements, see 7.2, 8.8, 8.9, and 8.10.
2. Referenced Documents
2.1 ASTM Standards:
D2887 Test Method for Boiling Range Distribution of Petroleum Fractions by Gas Chromatography
D4175 Terminology Relating to Petroleum, Petroleum Products, and Lubricants
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
2.2 DIN Norms:
51528 Determination of the Thermal Stability of Unused Heat Transfer Fluids
3. Terminology
3.1 Definitions:
3.1.1 thermal stability, n—the resistance to permanent changes in properties caused solely by heat. D4175
3.2 Definitions of Terms Specific to This Standard:
3.2.1 decomposition products that cannot be vaporized, n—materials from the thermally stressed heat transfer fluid, from which
those fractions that can be vaporized are removed by distillation procedures, that are quantitatively determined as residues in a bulb
tube distillation apparatus.
3.2.2 fluid within the unstressed fluid boiling range, n—any fluid components with boiling point between the initial boiling point
and final boiling point of the unstressed fluid.
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.L0.06 on Non-Lubricating Process Fluids.
Current edition approved Dec. 1, 2011July 1, 2015. Published February 2012July 2015. Originally approved in 2001. Last previous edition approved in 2011 as
D6743–06(2011).D6743 – 11. DOI: 10.1520/D6743-11.10.1520/D6743-11R15.
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.
Available from Deutsches Institut fur Normung e.V.(DIN), Burggrafenstrasse 6, 10787 Berlin, Germany, http://www.din.de.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6743 − 11 (2015)
3.2.3 gaseous decomposition products, n—materials with boiling points below room temperature, at normal pressure, such as
hydrogen and methane, that escape upon opening the test cell and that can be determined by measuring the mass immediately
thereafter.
3.2.4 high boiling components, n—materials from the thermally stressed heat transfer fluid, with boiling points above the final
boiling point of the unstressed heat transfer fluid, but which can still be separated by distillation from the heat transfer fluid by
means of classical separation procedures.
3.2.5 low boiling components, n—materials from the thermally stressed heat transfer fluid, with boiling points below the initial
boiling point of the unstressed heat transfer fluid.
3.2.6 mass percentage of high boiling components, n—the percentage of thermally stressed heat transfer fluid with a boiling
point above the final boiling point of the unstressed fluid.
3.2.7 mass percentage of low boiling components, n—the percentage of thermally stressed heat transfer fluid with a boiling point
below the initial boiling point of the unstressed fluid.
3.2.8 test cell, n—an ampoule constructed from stainless steel tubing and sealed with compression fittings at each end.
3.2.9 thermally stressed, adj—subjected to heating, as described in this test method.
4. Summary of Test Method
4.1 Charge the test fluid in a thermal stability test cell purged with nitrogen and tightly seal the test cell to remove and preclude
introduction of oxygen and water from the atmosphere. Heat the fluid in an oven at a given temperature and for a given period
of time. Determine the boiling range of the heated fluid by gas chromatography (GC) analysis and compare it to the boiling range
of pure, unused fluid.
5. Significance and Use
5.1 Heat transfer fluids degrade when exposed to sufficiently high temperatures. The amount of degradation increases as the
temperature increases or the length of exposure increases, or both. Due to reactions and rearrangement, degradation products can
be formed. Degradation products include high and low boiling components, gaseous decomposition products, and products that
cannot be evaporated. The type and content of degradation products produced will change the performance characteristics of a heat
transfer fluid. In order to evaluate thermal stability, it is necessary to quantitatively determine the mass percentages of high and
low boiling components, as well as gaseous decomposition products and those that cannot be vaporized, in the thermally stressed
heat transfer fluid.
5.2 This test method differentiates the relative stability of organic heat transfer fluids at elevated temperatures in the absence
of oxygen and water under the conditions of the test.
5.3 The user shall determine to his own satisfaction whether the results of this test method correlate to field performance. Heat
transfer fluids in industrial plants are exposed to a variety of additional influencing variables. Interaction with the plant’s materials,
impurities, heat build-up during impaired flow conditions, the temperature distribution in the heat transfer fluid circuit, and other
factors can also lead to changes in the heat transfer fluid. The test method provides an indication of the relative thermal stability
of a heat transfer fluid, and can be considered as one factor in the decision-making process for selection of a fluid.
5.4 The accuracy of the results depends very strongly on how closely the test conditions are followed.
5.5 This test method does not possess the capability to quantify or otherwise assess the formation and nature of thermal
decomposition products within the unstressed fluid boiling range. Decomposition products within the unstressed fluid boiling range
may represent a significant portion of the total thermal degradation.
6. Apparatus
6.1 Test Cell—The test cell shall be a new, clean ampoule made from ASTM A-269 grade 316L stainless steel tubing, 25 mm
(1 in.) outside diameter, 2 mm (0.083 in.) 25 mm (1 in.) outside diameter, 2 mm (0.083 in.) wall thickness. The test cell shall be
0.152 6 0.003 m (6 6 0.125 in.) 0.152 m 6 0.003 m (6 in. 6 0.125 in.) in length and sealed with compression fittings at each
end.
NOTE 1—Where tubing with SI dimensions is not readily available, the use of tubing with inch-pound dimensions is acceptable.
6.2 Heating Oven—The oven shall be capable of being controlled within 6 1°C (6 1.8°F) 61 °C (61.8 °F) at test temperature.
The test temperature selected will typically be between 260°C (500°F) and 427°C (800°F),260 °C (500 °F) and 427 °C (800 °F),
depending on the fluid being tested.
6.3 Bulb Tube Distillation Apparatus—This apparatus shall be capable of heating to at least 250°C (482°F)250 °C (482 °F) and
pressure down to at least 0.1 mm 0.1 mm Hg.
6.4 Dewar Flask—The flask is used to hold the test cells during cooling after removal from the heating oven.
6.5 Balance—The balance shall be capable of measuring mass to the nearest 0.01 g.0.01 g.
D6743 − 11 (2015)
7. Preparation of Apparatus
7.1 Test Cell—The test cell used shall always be a clean, new ampoule. Reuse of ampoules is not permitted.
7.2 Cleaning of Test Cell—A new test cell shall be cleaned by washing with a suitable volatile solvent such as acetone and dried.
(Warning—Use adequate safety precautions with all solvents and cleaners.)
8. Procedure
8.1 Determine the initial boiling point (IBP) and final boiling point (FBP) of the unstressed heat transfer fluid by GC, in
accordance with Test Method D2887 with the following requirements: the column shall be wall-coated open tubular type of
7.57.5 m to 10 m 10 m length with a 100 % polydimethylsiloxane film thickness of 0.88 μm, 0.88 μm, the detector shall be flame
ionization type, the initial oven temperature shall be set to 35°C (95°F)35 °C (95 °F) eliminating cryogenic cooling, the calibration
mixture shall cover the boiling range from n-C to n-C . The following GC parameters are recommended: oven temperature rate
5 60
10°C (18°F)10 °C (18 °F) per minute, oven final temperature 375°C (707°F),375 °C (707 °F), time at oven final temperature 3 min,
injector initial temperature 100°C (212°F),100 °C (212 °F), injector temperature rate 10°C (18°F)10 °C (18 °F) per minute, injector
final temperature 375°C (707°F),375 °C (707 °F), detector temperature 375°C (707°F).375 °C (707 °F).
8.2 Measure the mass of a clean, dry test cell including compression fittings to the nearest 0.01 g. 0.01 g. Pour the unstressed
heat transfer fluid into the clean, dry test cell in a vertical position. The quantity of heat transfer fluid transferred to the test cell
shall be 27 g 6 0.2 g. 27 g 6 0.2 g. Invert the test cell in a vertical position and allow it to drain until all free-flowing material
has been removed. More viscous fluids may require as long as 15 min 15 min to drain completely. At the end of the draining period,
tap the test cell to remove a drop clinging to the open end of the test cell – do cell—do not wipe away any fluid. Measure the mass
of the test cell and its remaining contents including compression fittings to the nearest 0.01 g.0.01 g.
NOTE 2—The intent is to perform this step only once for each heat transfer fluid being tested at this time.
8.3 Measure the mass of a clean, dry test cell including compression fittings to the nearest 0.01 g. 0.01 g. Introduce high purity
nitrogen using tubing at the bottom of the clean, dry test cell for 2 2 min at 60 mL ⁄min at 60 to 70 70 mL mL/min.⁄min.
NOTE 3—To ensure accurate results, at least three test cells containing samples of the same heat transfer fluid should be heated simultaneously.
8.4 Pour the thermally unstressed heat transfer fluid into the clean, dry test cell. The quantity of heat transfer fluid transferred
to the test cell shall be 27 g 6 0.2 g.27 g 6 0.2 g.
8.5 Completely displace the air remaining in the gas space in the test cell by introducing high purity nitrogen using tubing just
above the liquid surface of fluid inside the test cell at 3030 mL ⁄min to 3535 mL ⁄ mL/min for 12 min min for 12 min at ambient
temperature.
8.6 Carefully seal the test cell and measure its mass to the nearest 0.01 g.0.01 g.
8.7 Insert the test cell vertically in the oven. Adjust the heating oven to the proper test temperature. The time to achieve proper
test temperature should be approximately 3 h. 3 h. The test temperature shall be maintained throughout the entire test duration and
controlled in such a way that the temperature of the test liquid does not deviate by more than 61°C (61.8°F)61 °C (61.8 °F) at
any location, including the heated wall. Temperature shall be measured and recorded throughout the test at least once per day. If
test cells containing different fluids are tested at the same time, the test cells shall be distributed symmetrically inside the oven to
minimize the effect of oven temperature variation on the results. The test duration shall be the time from attaining the test
temperature to the time the heat supply is cut off. The test duration at the specified test temperature shall be a minimum of 500
h. 500 h. The preferred test duration is 500500 h 6 1 h, 1 h, however, a longer test duration may be used. Thermal degradation
cannot be assumed to be linear with time. Therefore, the stability of two fluids can only be compared at the same test temperature
and test duration.
8.8 Protect the oven from heat transfer fluid that may spill in case of damage by placing a collecting pan under the test cell.
(Warning—If fluid leaks out due to improper sealing of the test cell, there may be the potential of flammable vapors inside the
oven. The oven design and installation should consider this possibility. )
8.9 At the conclusion of the heating period, shut off the oven. Do not immediately remove the test cell. Leave the oven closed
and allow the oven and the test cell to cool to ambient temperature to reduce the internal pressure. (Warning—Pressure inside the
test cell may reach several thousand kPa during the test.)
8.10 Remove the test cell from the oven. (Warning— Use adequate safety precautions when removing the test cell
...
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