ASTM D6546-00(2005)
(Test Method)Standard Test Methods for and Suggested Limits for Determining Compatibility of Elastomer Seals for Industrial Hydraulic Fluid Applications
Standard Test Methods for and Suggested Limits for Determining Compatibility of Elastomer Seals for Industrial Hydraulic Fluid Applications
SIGNIFICANCE AND USE
When more than one elastomer seal material is tested, the test methods yield comparative data on which to base judgements as to expected service quality. Suggested in-service property change limits are provided. Property changes beyond these limits will indicate limited service life of the elastomer seal.
These test methods attempt to simulate service conditions through controlled aging and evaluation of property changes but may not give any direct correlations with actual part performance since actual service conditions vary widely. These test methods yield comparative data and indications of property changes of the elastomeric seal material under ideal service conditions. These test methods can be used for quality control purposes, for engineering assessments, for service evaluation, and for manufacturing control. The information from these test methods can be used to anticipate expected service quality.
SCOPE
1.1 These test methods cover the procedure for measuring physical properties of elastomer seals in the form of O-rings after exposure to industrial hydraulic fluids and thermal aging. The measured properties are then compared to the physical properties of elastomer seals that have not been exposed to the industrial hydraulic fluids and thermal aging. The changes in these properties form a basis for assessing compatibility when these changes are compared against the suggested limits in .
1.2 While these test methods involve the use of O-rings, they can also be used to evaluate the compatibility of the elastomeric compounds of specialty seals with industrial hydraulic fluids and their resistance to thermal aging. The compounds can be molded into O-rings for evaluation purposes.
1.3 These test methods provide procedures for exposing O-ring test specimens to industrial hydraulic fluids under definite conditions of temperature and time. The resulting deterioration of the O-ring material is determined by comparing the changes in work function, hardness, physical properties, compression set, and seal volume after immersion in the test fluid to the pre-immersion values.
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.
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.5 This test method covers the determination of the cure state of elastomers by DSC. It is based on Test Method D 5028. This test method is applicable to elastomers with adequate vulcanizers. The normal operating temperature range is from room temperature to 250C (482F), but not limited to such. All elastomers should be fully cured.
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Designation:D6546–00 (Reapproved 2005)
Standard Test Methods for
and Suggested Limits for Determining Compatibility of
Elastomer Seals for Industrial Hydraulic Fluid Applications
This standard is issued under the fixed designation D6546; 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 These test methods cover the procedure for measuring 2.1 ASTM Standards:
physical properties of elastomer seals in the form of O-rings D395 Test Methods for Rubber Property—Compression Set
after exposure to industrial hydraulic fluids and thermal aging. D412 Test Methods for Vulcanized Rubber and Thermo-
The measured properties are then compared to the physical plastic Elastomers—Tension
properties of elastomer seals that have not been exposed to the D471 Test Method for Rubber Property—Effect of Liquids
industrial hydraulic fluids and thermal aging. The changes in D1414 Test Methods for Rubber O-Rings
these properties form a basis for assessing compatibility when D2000 Classification System for Rubber Products in Auto-
these changes are compared against the suggested limits in motive Applications
Table 1. D2240 Test Method for Rubber Property—Durometer
1.2 While these test methods involve the use of O-rings, Hardness
they can also be used to evaluate the compatibility of the D3677 TestMethodsforRubber—IdentificationbyInfrared
elastomeric compounds of specialty seals with industrial hy- Spectrophotometry
draulic fluids and their resistance to thermal aging. The D3767 Practice for Rubber—Measurement of Dimensions
compounds can be molded into O-rings for evaluation pur- D5028 Test Method for Curing Properties of Pultrusion
poses. Resins by Thermal Analysis
1.3 These test methods provide procedures for exposing E1131 TestMethodforCompositionalAnalysisbyThermo-
O-ring test specimens to industrial hydraulic fluids under gravimetry
definite conditions of temperature and time. The resulting 2.2 SAE Standard:
deterioration of the O-ring material is determined by compar- AS568A O-ring Sizes
ing the changes in work function, hardness, physical proper-
3. Terminology
ties, compression set, and seal volume after immersion in the
test fluid to the pre-immersion values. 3.1 Definitions:
3.1.1 batch—all the O-rings molded from the same lot of
1.4 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are for information material and presented for inspection at one time.
3.1.2 compound—a fully formulated elastomer material
only.
1.5 This standard does not purport to address all of the containing all fillers and cross-linking agents.
3.1.3 fluid saturation effect—the absorption of fluid by the
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- elastomer until an equilibrium swell value is reached at a
particular temperature.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. 3.1.4 O-ring—a rubber seal of homogeneous composition
moldedinonepiecetotheconfigurationofatoruswithcircular
cross section.
1 2
These test methods are under the jurisdiction of ASTM Committee D02 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
D02.N0 on Hydraulic Fluids. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved May 1, 2005. Published June 2005. Originally the ASTM website.
approved in 2000. Last previous edition approved in 2000 as D6546–00. DOI: Available from Society of Automotive Engineers, 400 Commonwealth Drive,
10.1520/D6546-00R05. Warrendale, PA 15096.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6546–00 (2005)
TABLE 1 Property Change Limits
Time, h Maximum Maximum Hardness Maximum Maximum Maximum Maximum
Volume Volume Change, Tensile Elongation Work Compression
Swell, Shrinkage, Shore A Strength Change, Function Set, %
% % Points Change, % Change,
% %
24 15 −3 67 −20 −20 612 .
70 15 −3 67 −20 −20 612 20
100 15 −3 68 −20 −20 612 20
250 15 −4 68 −20 −20 612 25
500 20 −4 610 −25 −25 617 30
1000 20 −5 610 −30 −30 620 35
3.1.4.1 Discussion—O-rings are used as both dynamic and 6. Test Conditions
static seals. The size of the O-ring is normally designated by a
6.1 Temperature—The test temperature shall be the maxi-
dashnumbercorrespondingtothesizetableslistedinAS568A.
mum sustained temperature anticipated in service.
The dimensions for the O-rings used in these test methods are
6.2 Immersion Periods—The following immersion periods
listed in Annex A2.
are recommended: 24 h, 72 h, 100 h, 250 h, 500 h, and 1000 h.
3.1.5 ultimate elongation—the amount of stretch that the
The final immersion period will depend upon the results of the
O-ring is exposed to before breaking.
previous immersion period. If the changes in the physical
3.1.6 work function—workdoneonatestspecimentocause
properties have deteriorated beyond the suggested limits, then
20 % deformation.
further testing is not required.The tolerance for any immersion
period shall be 61 % of the immersion period.
4. Significance and Use
7. Test Fluids
4.1 When more than one elastomer seal material is tested,
the test methods yield comparative data on which to base
7.1 For reliable compatibility assessments, it is desirable to
judgementsastoexpectedservicequality.Suggestedin-service
use the fluid with which the elastomer will come in contact in
property change limits are provided. Property changes beyond
actual service. For comparative tests, samples of fluid from the
these limits will indicate limited service life of the elastomer
same drum or shipment shall be used.
seal.
8. Test Specimen
4.2 These test methods attempt to simulate service condi-
tions through controlled aging and evaluation of property
8.1 The test specimens shall be O-rings molded from the
changes but may not give any direct correlations with actual
same compound batch from which the actual seals will be
part performance since actual service conditions vary widely.
molded.The test samples should approximate the cross section
These test methods yield comparative data and indications of
of the actual seal to be used so that the fluid saturation effect is
property changes of the elastomeric seal material under ideal
properly considered. The test samples should be either -021,
service conditions. These test methods can be used for quality
-120, -214, or -320 O-rings, in accordance with AS568A.
control purposes, for engineering assessments, for service
These have an approximate inside diameter of 25.4 mm (1 in.)
evaluation, and for manufacturing control. The information
and represent the most popular cross sections of seals used in
from these test methods can be used to anticipate expected
industrial systems. The actual dimensions of each O-ring size
service quality.
are listed in Annex A2.
8.2 Test specimens shall be wiped clean of external con-
5. General Test Methods
taminants prior to testing by using a clean dry wipe.
5.1 Except as otherwise specified, the test methods for
9. Suggested Compatibility Test Limits
rubber O-rings referred to in 5.1.1-5.1.6, which are applicable
in general to vulcanized rubber, shall be complied with as 9.1 For a critical seal application, property change limits, as
required and are hereby made a part of these test methods. described in Table 1, should be observed.
9.2 All values are in reference to soak time in the opera-
5.1.1 Tension Test—Test Methods D412 and D1414.
5.1.2 Compression Set—Test Methods D395 and D1414. tional fluid at the operating temperature of the application.
Values reflect changes from the determined pre-immersion
5.1.3 Fluid Aging—Test Method D471 and Test Methods
D1414. original physical property values of the test specimens.
9.3 If the changes are within these limits, the elastomer
5.1.4 Hardness—Test Method D2240.
5.1.5 Compositional Analysis—Test Methods D3677 and should be considered compatible. Once a seal material is found
to be compatible, all seals for that system should be ordered by
Test Method E1131.
5.1.6 Degree of Cure—Test Method D5028. specific compound or specification and not by Classification
D2000 call out number or generic polymer designation.
5.2 In case of conflict between the provisions of theASTM
test methods referenced in 5.1.1-5.1.6 and the detailed provi-
10. Procedure for Change in Volume
sions of the test methods in Test Methods D6546, the latter
shall take precedence. 10.1 Apparatus:
D6546–00 (2005)
10.1.1 Test Container, a Mason jar (quart size) fitted with a
M = mass of specimen in air after immersion, g, and
lid to prevent liquid and vapor from escaping. The lid shall not
M = mass of specimen in water after immersion, g.
contaminate the test liquid. Cover the lid with aluminum foil.
10.3 Volume Shrinkage-Simulated Dry Out (Optional Test
10.1.2 Heating Device, a forced air oven, aluminum block
Method)—Test three specimens.
heater, or oil bath heater. Maintain the temperature within
10.3.1 In some situations when long downtimes are ex-
61°C (1.8°F).
pected,theO-ringshouldnotshrinkbeyond5 %ofitsprevious
10.1.3 Test Specimen—The test specimen shall consist of an
volume change value since this can affect its ability to be an
entireO-ring.Thesamespecimenmaybeusedforalltestswith effective seal when the system is restarted. In those cases in
hardnessandvolumedeterminationsmadepriortostress-strain
which a positive volume change was obtained in 10.2 and long
tests. Place the test specimen in the test liquid so that it is not system down times are anticipated, it is recommended that
distorted or in contact with the sides of the test container or
volume shrinkage be determined. To perform this optional test
with the other test specimens. Test a minimum of three test method,additionalO-ringswillhavetobetestedinaccordance
specimens at one time. It is also important that only O-rings of
with 10.2 and then tested in accordance with 10.3 since the
one size and one material compound be placed in the test normal test for volume change is immediately followed by the
container. destructive tensile test.
10.1.4 Analytical Balance, an analytical balance capable of 10.3.2 The test specimen shall consist on an entire O-ring.
Thespecimenmustfirstbesubmittedforthevolumeswelltest.
allowing a test specimen to be weighed whether in air or while
submerged in water. This specimen is only to be used for this test sequence and not
for any other testing.
10.2 Volume Change—Test three specimens.
10.3.3 Place the test specimen from the volume swell test in
10.2.1 Weigh each test specimen in air, M , to the nearest 1
a forced-air oven that allows air circulation around the test
mg, and then weigh each specimen immersed in water, M,at
specimen, and maintain the oven at a test temperature of 23 6
room temperature. It is important that all air bubbles clinging
1°C (73.4 6 1.8°F) for 22 6 0.25 h.At the end of the required
to the test specimen be removed before reading the weight in
period, remove the specimen from the oven and allow it to air
water. Blot the specimen dry.
cool.
10.2.2 Suspend the specimens in the glass jar by the use of
10.3.4 Weigh each test specimen in air, M , and then weigh
corrosion-resistant wire. Separate the specimens by bending 5
each specimen immersed in water, M .
small loops in the wire or by locating them in different 6
10.3.5 The change in volume or shrinkage is calculated as
locations so that they do not contact each other.
follows:
10.2.3 Suspend the specimen vertically so that 25.4 mm (1
in.) of test fluid is between the lower extremity of the specimen ~M 2 M ! 2 ~M 2 M !
5 6 3 4
DV,% 5 3 100 (2)
and the bottom of the apparatus.Add enough test fluid to cover ~M 2 M !
3 4
the specimen to a depth of 25.4 mm (1 in.) over the upper
where:
extremity of the specimen.
M = initial mass of volume swell specimen in air after
10.2.4 Placethetestapparatusintheheatingdeviceadjusted
immersion, g,
to maintain the sample at the test temperature for the required
M = initial mass of volume swell specimen in water after
length of time. At the end of the required immersion period,
immersion, g,
remove the specimen from the apparatus. Cool the specimen to
M = massofvolumeswellspecimeninairafterdryout,g,
room temperature by immersing it in a cool, fresh amount of
and
the test fluid for 45 min.
M = mass of volume swell specimen in water after dry
10.2.5 At the end of the cooling period, remove the speci-
out, g.
men from the fluid, wipe with a cloth dipped in acetone, and
blot dry. Weigh each test specimen in air, M , and then weigh
11. Changes in Tensile Strength, Work Function,
each specimen immersed in water, M .
Elongation, and Hardness
10.2.6 Some oils can be very viscous and may be difficult to
11.1 Original Properties—The original tensile strength,
remove with an acetone wipe. Since these oils do not readily
work function, ultimate elongation, and hardness shall be
volatize, specimens exposed to these oils can be cooled by
determined using a duplicate set of specimens of O-rings of the
suspendingthemfor45mininairatroomtemperatureshielded
same cross section as those that are to be immersed in the test
from draft.This will allow the majority of the oil to drip off the
fluid.TheO-ringsshallbefromthesamebatchasthosethatare
surface of the specimen. Then proceed with the acetone wipe
to be immersed in the test fluid.
and weighing process described in 10.2.5. Report when this
11.2 Properties After Exposure to the Test Fluid, for deter-
alternate method of specimen cooling is used.
mining the tensile strength, work function, ultimate elongation,
10.2.7 The change in volume is calculated as follows:
and hardness of specimens after immersion in the test fluid at
thetesttemperature.Attheendoftherequiredimmersiontime,
~M 2 M ! 2 ~M 2 M !
3 4 1 2
DV,% 5 3 100 (1)
remove the specimens, and if necessary, cool them to room
~M 2 M !
1 2
temperature in a fresh sample of the same fluid for 45 min. At
where:
the end of the cooling period, remove the specimen from the
M = initial mass of specimen in air, g,
fluid, wipe it with a cloth dipped in acetone, and blot dry.
M = initial mass of specimen in water, g,
Immediately determine the hardness, tensile strength, work
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