ASTM D6546-00(2010)
(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 Table 1.
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.
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 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: D6546 − 00(Reapproved 2010)
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.Anumber 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:
D395Test Methods for Rubber Property—Compression Set
physical properties of elastomer seals in the form of O-rings
after exposure to industrial hydraulic fluids and thermal aging. D412TestMethodsforVulcanizedRubberandThermoplas-
tic Elastomers—Tension
The measured properties are then compared to the physical
properties of elastomer seals that have not been exposed to the D471Test Method for Rubber Property—Effect of Liquids
D1414Test Methods for Rubber O-Rings
industrial hydraulic fluids and thermal aging. The changes in
D2000Classification System for Rubber Products in Auto-
these properties form a basis for assessing compatibility when
motive Applications
these changes are compared against the suggested limits in
D2240TestMethodforRubberProperty—DurometerHard-
Table 1.
ness
1.2 While these test methods involve the use of O-rings,
D3677Test Methods for Rubber—Identification by Infrared
they can also be used to evaluate the compatibility of the
Spectrophotometry
elastomeric compounds of specialty seals with industrial hy-
D3767Practice for Rubber—Measurement of Dimensions
draulic fluids and their resistance to thermal aging. The
D5028Test Method for Curing Properties of Pultrusion
compounds can be molded into O-rings for evaluation pur-
Resins by Thermal Analysis
poses.
E1131Test Method for CompositionalAnalysis by Thermo-
1.3 These test methods provide procedures for exposing
gravimetry
O-ring test specimens to industrial hydraulic fluids under
2.2 SAE Standard:
definite conditions of temperature and time. The resulting
AS568AO-ring Sizes
deterioration of the O-ring material is determined by compar-
3. Terminology
ing the changes in work function, hardness, physical
properties, compression set, and seal volume after immersion
3.1 Definitions:
in the test fluid to the pre-immersion values.
3.1.1 batch—all the O-rings molded from the same lot of
material and presented for inspection at one time.
1.4 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are for information 3.1.2 compound—a fully formulated elastomer material
containing all fillers and cross-linking agents.
only.
3.1.3 fluid saturation effect—the absorption of fluid by the
1.5 This standard does not purport to address all of the
elastomer until an equilibrium swell value is reached at a
safety concerns, if any, associated with its use. It is the
particular temperature.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
3.1.4 O-ring—a rubber seal of homogeneous composition
bility of regulatory limitations prior to use.
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, 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.N0.09 on Compatibility. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Oct. 1, 2010. Published November 2010. Originally the ASTM website.
approved in 2000. Last previous edition approved in 2005 as D6546–00(2005). Available from Society of Automotive Engineers, 400 Commonwealth Drive,
DOI: 10.1520/D6546-00R10. Warrendale, PA 15096.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6546 − 00 (2010)
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 ±7 −20 −20 ±12 . . .
70 15 −3 ±7 −20 −20 ±12 20
100 15 −3 ±8 −20 −20 ±12 20
250 15 −4 ±8 −20 −20 ±12 25
500 20 −4 ±10 −25 −25 ±17 30
1000 20 −5 ±10 −30 −30 ±20 35
3.1.4.1 Discussion—O-rings are used as both dynamic and provisions of the test methods in Test Methods D6546, the
static seals. The size of the O-ring is normally designated by a latter shall take precedence.
dashnumbercorrespondingtothesizetableslistedinAS568A.
6. Test Conditions
The dimensions for the O-rings used in these test methods are
listed in Annex A2.
6.1 Temperature—The test temperature shall be the maxi-
mum sustained temperature anticipated in service.
3.1.5 ultimate elongation—the amount of stretch that the
O-ring is exposed to before breaking.
6.2 Immersion Periods—The following immersion periods
3.1.6 work function—workdoneonatestspecimentocause arerecommended:24h,72h,100h,250h,500h,and1000h.
The final immersion period will depend upon the results of the
20% deformation.
previous immersion period. If the changes in the physical
4. Significance and Use properties have deteriorated beyond the suggested limits, then
furthertestingisnotrequired.Thetoleranceforanyimmersion
4.1 When more than one elastomer seal material is tested,
period shall be 61% of the immersion period.
the test methods yield comparative data on which to base
judgementsastoexpectedservicequality.Suggestedin-service
7. Test Fluids
property change limits are provided. Property changes beyond
7.1 For reliable compatibility assessments, it is desirable to
these limits will indicate limited service life of the elastomer
use the fluid with which the elastomer will come in contact in
seal.
actualservice.Forcomparativetests,samplesoffluidfromthe
4.2 These test methods attempt to simulate service condi-
same drum or shipment shall be used.
tions through controlled aging and evaluation of property
changes but may not give any direct correlations with actual
8. Test Specimen
part performance since actual service conditions vary widely.
8.1 The test specimens shall be O-rings molded from the
These test methods yield comparative data and indications of
same compound batch from which the actual seals will be
property changes of the elastomeric seal material under ideal
molded.Thetestsamplesshouldapproximatethecrosssection
service conditions. These test methods can be used for quality
oftheactualsealtobeusedsothatthefluidsaturationeffectis
control purposes, for engineering assessments, for service
properly considered. The test samples should be either -021,
evaluation, and for manufacturing control. The information
-120, -214, or -320 O-rings, in accordance with AS568A.
from these test methods can be used to anticipate expected
These have an approximate inside diameter of 25.4 mm (1 in.)
service quality.
and represent the most popular cross sections of seals used in
industrial systems. The actual dimensions of each O-ring size
5. General Test Methods
are listed in Annex A2.
5.1 Except as otherwise specified, the test methods for
8.2 Test specimens shall be wiped clean of external con-
rubberO-ringsreferredtoin5.1.1–5.1.6,whichareapplicable
taminants prior to testing by using a clean dry wipe.
in general to vulcanized rubber, shall be complied with as
required and are hereby made a part of these test methods.
9. Suggested Compatibility Test Limits
5.1.1 Tension Test—Test Methods D412 and D1414.
9.1 Foracriticalsealapplication,propertychangelimits,as
5.1.2 Compression Set—Test Methods D395 and D1414.
described in Table 1, should be observed.
5.1.3 Fluid Aging—Test Method D471 and Test Methods
D1414. 9.2 All values are in reference to soak time in the opera-
5.1.4 Hardness—Test Method D2240. tional fluid at the operating temperature of the application.
5.1.5 Compositional Analysis—Test Methods D3677 and Values reflect changes from the determined pre-immersion
Test Method E1131. original physical property values of the test specimens.
5.1.6 Degree of Cure—Test Method D5028.
9.3 If the changes are within these limits, the elastomer
5.2 In case of conflict between the provisions of theASTM shouldbeconsideredcompatible.Onceasealmaterialisfound
test methods referenced in 5.1.1 – 5.1.6 and the detailed tobecompatible,allsealsforthatsystemshouldbeorderedby
D6546 − 00 (2010)
specific compound or specification and not by Classification M 2 M 2 M 2 M
~ ! ~ !
3 4 1 2
∆V,% 5 3100 (1)
D2000 call out number or generic polymer designation. ~M 2 M !
1 2
where:
10. Procedure for Change in Volume
M = initial mass of specimen in air, g,
10.1 Apparatus:
M = initial mass of specimen in water, g,
10.1.1 Test Container, a Mason jar (quart size) fitted with a M = mass of specimen in air after immersion, g, and
M = mass of specimen in water after immersion, g.
lidtopreventliquidandvaporfromescaping.Thelidshallnot
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
61°C (1.8°F).
expected, the O-ring should not shrink beyond 5% of its
10.1.3 Test Specimen—Thetestspecimenshallconsistofan
previousvolumechangevaluesincethiscanaffectitsabilityto
entireO-ring.Thesamespecimenmaybeusedforalltestswith
beaneffectivesealwhenthesystemisrestarted.Inthosecases
hardnessandvolumedeterminationsmadepriortostress-strain
in which a positive volume change was obtained in 10.2 and
tests. Place the test specimen in the test liquid so that it is not
longsystemdowntimesareanticipated,itisrecommendedthat
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.
allowing a test specimen to be weighed whether in air or while Thespecimenmustfirstbesubmittedforthevolumeswelltest.
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 Placethetestspecimenfromthevolumeswelltestin
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
each specimen immersed in water, M .
small loops in the wire or by locating them in different
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
~M 2 M ! 2 ~M 2 M !
5 6 3 4
in.)oftestfluidisbetweenthelowerextremityofthespecimen
∆V,% 5 3100 (2)
M 2 M
~ !
3 4
andthebottomoftheapparatus.Addenoughtestfluidtocover
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,
removethespecimenfromtheapparatus.Coolthespecimento
M = mass of volume swell specimen in air after dry out, 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 out,
10.2.5 At the end of the cooling period, remove the speci- g.
men from the fluid, wipe with a cloth dipped in acetone, and
11. Changes in Tensile Strength, Work Function,
blot dry. Weigh each test specimen in air, M , and then weigh
Elongation, and Hardness
each specimen immersed in water, M .
11.1 Original Properties—The original tensile strength,
10.2.6 Someoilscanbeveryviscousandmaybedifficultto
work function, ultimate elongation, and hardness shall be
remove with an acetone wipe. Since these oils do not readily
determinedusingaduplicatesetofspecimensofO-ringsofthe
volatize, specimens exposed to these oils can be cooled by
same cross section as those that are to be immersed in the test
suspendingthemfor45mininairatroomtemperatureshielded
fluid.TheO-ringsshallbefromthesamebatchasthosethatare
fromdraft.Thiswillallowthemajorityoftheoiltodripoffthe
to be immersed in the test fluid.
surface of the specimen. Then proceed with the acetone wipe
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.
miningthetensilestrength,workfunction,ultimateelongation,
10.2.7 The change in volume is calculated as follows: and hardness of specimens after immersion in the test fluid at
D6546 − 00 (2010)
thetesttemperature.Attheendoftherequiredimmersiontime, T 5 F/A (4)
remove the specimens, and if necessary, cool them to room
where:
temperature in a fresh sample of the same fluid for 45 min.At
T = tensile strength, MPa (psi),
the end of the cooling period, remove the specimen from the
F = breaking force, N (lb), and
fluid, wipe it with a cloth dipped in acetone, and blot dry.
A = twice the cross-sectional area calculated from axial
Immediately determine the
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