ASTM D7752-11

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Designation: D7752 − 11
Standard Practice for
Evaluating Compatibility of Mixtures of Hydraulic Fluids
This standard is issued under the fixed designation D7752; 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 This practice covers the compatibility of mixtures of 2.1 ASTM Standards:
hydraulic fluids as defined by Specifications D6158, DIN D130 Test Method for Corrosiveness to Copper from Petro-
51524, ISO 11158, and ISO 15380. leum Products by Copper Strip Test
D445 Test Method for Kinematic Viscosity of Transparent
1.2 This practice can be used to evaluate new (unused)
and Opaque Liquids (and Calculation of Dynamic Viscos-
lubricant compatibility or the effects of combining new (re-
ity)
placement) lubricant with in-service (original) lubricant in the
D664 Test Method for Acid Number of Petroleum Products
system.
by Potentiometric Titration
1.3 Toevaluateprimarycompatibilityusingthismethod,the
D665 Test Method for Rust-Preventing Characteristics of
replacement fluid must pass the ISO 13357-1 Stage II filter-
Inhibited Mineral Oil in the Presence of Water
ability test. The original fluid is not required to pass ISO
D892 Test Method for Foaming Characteristics of Lubricat-
13357-1 filterability test, Stage I or II.
ing Oils
D974 Test Method for Acid and Base Number by Color-
1.4 Primary testing is conducted on fluid mixtures in 2:98,
10:90, and 50:50 ratios using the ISO 13357-1 Filterability Indicator Titration
D1401 TestMethodforWaterSeparabilityofPetroleumOils
Test, Stage II.
and Synthetic Fluids
1.5 Secondary testing is suggested when circumstances
D2270 Practice for Calculating Viscosity Index from Kine-
indicate the need for additional testing.
matic Viscosity at 40 °C and 100 °C
1.6 This practice does not evaluate the wear prevention
D3427 Test Method forAir Release Properties of Hydrocar-
characteristics, load carrying capacity, or the mechanical shear
bon Based Oils
stability of lubricant mixtures while in service. If anti-wear
D6158 Specification for Mineral Hydraulic Oils
(AW), extreme pressure (EP), or shear stability are to be
2.2 ISO Standards:
evaluated, further testing of these parameters may be required.
11158:1997 Lubricants, industrial oils and related products
1.7 This practice does not purport to cover all test methods
(class L)—Family H (hydraulic systems)—Specifications
that could be employed.
for categories HH, HL, HM, HR, HV and HG
13357-1:2002(E) PetroleumProducts—Determinationofthe
1.8 The values stated in SI units are to be regarded as
filterability of lubricating oils—Part 1: Procedure for oils
standard. No other units of measurement are included in this
in the presence of water
standard.
13357-2:2005(E) PetroleumProducts—Determinationofthe
1.9 This standard does not purport to address all of the
filterability of lubricating oils—Part 2: Procedure for dry
safety concerns, if any, associated with its use. It is the
oils
responsibility of the user of this standard to establish appro-
15380:2002 Lubricants, industrial oils and related products
priate safety and health practices and determine the applica-
(class L)—Family H (Hydraulic systems)—Specifications
bility of regulatory limitations prior to use.
for categories HETG, HEPG, HEES, and HEPR
4788 Laboratory glassware—Graduated measuring cylin-
ders
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This practice is under the jurisdiction ofASTM Committee D02 on Petroleum contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom- Standards volume information, refer to the standard’s Document Summary page on
mittee D02.N0 on Hydraulic Fluids. the ASTM website.
Current edition approved Oct. 1, 2011. Published November 2011. DOI: Available from International Organization for Standardization (ISO), 1, ch. de
10.1520/D7752–11. la Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland, http://www.iso.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7752 − 11
2.3 DIN Standards: 4.2 Option 2—Instead of testing mixtures in sequential
51524 Pressure fluids—Hydraulic oils—Parts 1–3 order, 50:50 and 10:90 mixtures are tested at the same time the
2:98 mixture is evaluated. Such tests can be run concurrently,
3. Terminology
ifdesired.IfallmixturespasstheprimaryISO13357-1test,no
further testing is required. If the 2:98 mixture does not pass, or
3.1 Definitions of Terms Specific to This Standard:
3.1.1 2:98 mixture, n—a uniform blend of2%by weight of the application requires the evaluation of specific properties,
secondary compatibility tests can be employed for further
original fluid with 98 % by weight of replacement fluid.
evaluation.
3.1.2 10:90 mixture, n—a uniform blend of 10 % by weight
of original fluid with 90 % by weight of replacement fluid.
5. Significance and Use
3.1.3 50:50 mixture, n—a uniform blend of 50 % by weight
5.1 Hydraulic fluid compatibility is important to hydraulic
of each of two component fluids.
equipment users because a mixture of incompatible fluids may
3.1.4 compatibility, n—of hydraulic fluids, the ability of
produce a substance that is markedly inferior to its constitu-
hydraulicfluidstomixtogetherwithoutsignificantdegradation ents. Even in identical base stocks, the formation of a precipi-
of properties or performance.
tate may occur as a result of additive interactions. In this
3.1.4.1 Discussion—Compatibility will be determined using
practice, compatibility will be determined using ISO 13357-1
the ISO 13357-1 filterability test. When a mixture passes the
filterability test method. Since hydraulic systems utilize fine-
Stage II filterability designation as specified in the ISO
filtration to protect components from wear, incompatibility
13357-1 test, the mixture is considered compatible at the tested
often exhibits itself as premature filter plugging.
ratio by the primary testing procedure. If this practice is to be
5.2 Because of such occurrences, suppliers recommend
used for adding new (replacement) to in-service (original) and
evaluatingthecompatibilityofhydraulicfluidspriortomixing.
the system is not drained (for example, top-up), two additional
Aflowchart is provided in AnnexA1 to aid in interpretation of
ratioswillberequired,10:90and2:98.Dependingontheratios
the test results and hydraulic system conversion.
that have passed the test, flush quantities are given in Annex
5.3 Although new hydraulic fluids may be compatible,
A1.
in-service fluid of the same type may be degraded or contami-
3.1.5 fail,n—insecondarycompatibilitytestingofhydraulic
nated to such an extent that the new fluid added may not be
fluid mixtures, a test result that is inferior to that of the poorer
compatible with the system fluid. In-service fluid compatibility
of the two constituent fluids.
with new fluid additions should be evaluated on a case by case
3.1.6 original fluid, n—fluid that the system is being con-
basis.
verted from.
5.4 Theoxidationresistanceandwearprotectionofdifferent
3.1.7 pass, n—in secondary compatibility testing of hydrau-
fluids of the same type can vary widely, and compatibility does
lic fluid mixtures, a test result that is equal to or better than that
not imply equivalent performance.
of the poorer of the two constituent fluids.
6. Apparatus
3.1.8 primary testing, n—Two constituent fluids are com-
bined at 2:98, 10:90, and 50:50 ratios by weight. The fluid 6.1 The equipment and materials required for this practice
mixtures are prepared, aged, and evaluated for changes in shall be those required by the test methods used to evaluate
filterability using the procedure described in ISO 13357-1. compatibility.
6.1.1 Laboratory Oven, static-air or stirred-air type, capable
3.1.9 replacement fluid, n—fluid that the system is being
ofmaintainingthetesttemperaturewithin 62 °Candequipped
converted to.
with one or more grill-type wire shelves.
3.1.10 secondary testing, n—Mixtures of the fluids are
6.1.2 Filtration Apparatus, stainless steel, consisting of a
prepared following ISO 13357-1 samples and sampling section
lidded funnel of at least 350 mL capacity and a funnel base
and evaluated for changes in the parameters detailed in 7.4.
with filter support, such that a membrane filter (6.1.3) can be
3.1.11 type, n—type refers to lubricant base stock and
clamped between the sealing surfaces of the funnel and the
additive composition. For example, Rust and Oxidation Inhib-
base by means of a metal clamp or other suitable gas-tight
ited fluid (R & O) versus antiwear (AW).
closure. The apparatus shall be grounded (earthed), and suit-
able electrical bonding of the parts shall be provided. The
4. Summary of Practice
2 2
effective filtration area shall be 1130 mm 6 60 mm.A
4.1 Option 1—Prepare a 2:98 mixture of two fluids to be
suitable schematic may be found in the ISO 13357 standard.
evaluated for compatibility. This mixture and the two neat,
6.1.3 Membrane Filters, of mixed cellulose esters, diameter
constituent fluids are tested using the primary compatibility
47 mm and mean pore size 0.8 µm. Membranes of an equiva-
test. If the 2:98 does not pass ISO 13357-1 Stage II
lent specification to Millipore filter membranes, catalogue
requirement, secondary tests may be run or a different replace-
number AAWP 04700, have been found satisfactory.
mentfluidshouldbeconsidered.Ifthe2:98mixturepasses,the
6.1.4 Measuring Cylinders, of 250 mLcapacity, of borosili-
10:90 and 50:50 ratios should be tested.
cate glass, conforming to the requirements of ISO 4788. This
cylinder shall be permanently marked with further graduation
marks at 10 mL and 300 mL. A second c
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