ASTM D7647-10

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D7647 − 10
Standard Test Method for
Automatic Particle Counting of Lubricating and Hydraulic
Fluids Using Dilution Techniques to Eliminate the
Contribution of Water and Interfering Soft Particles by Light
Extinction
This standard is issued under the fixed designation D7647; 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 priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
1.1 This test method covers the determination of particle
concentration and particle size distribution in new and in-
2. Referenced Documents
service oils used for lubrication and hydraulic purposes.
2.1 ASTM Standards:
1.2 Particlesconsideredareintherangefrom4µm to200
(c)
D4057 Practice for Manual Sampling of Petroleum and
µm with the upper limit being dependent on the specific
(c)
Petroleum Products
automatic particle counter being used.
D4177 Practice for Automatic Sampling of Petroleum and
NOTE1—Forthepurposeofthistestmethod,waterdropletsnotmasked
Petroleum Products
by the diluent procedure are detected as particles, and agglomerated
particles are detected and reported as a single larger particle.
D6786 Test Method for Particle Count in Mineral Insulating
NOTE 2—The subscript is used to denote that the apparatus has been
(c) Oil Using Automatic Optical Particle Counters
calibrated in accordance with ISO 11171. This subscript strictly only
(c)
2.2 ISO Standards:
applies to particles up to 50 µm.
ISO 3722 Hydraulic Fluid Power–Fluid Sample Containers
1.3 Lubricants that can be analyzed by this test method are
–Qualifying and Controlling Cleaning Methods
categorized as petroleum products or synthetic based products,
ISO 4406 Hydraulic Fluid Power–Fluids–Method for Cod-
such as: polyalpha olefin, polyalkylene glycol, or phosphate
ing Level of Contamination by Solid Particles
ester.Applicable viscosity range is up to 1000 mm /s @ 40°C.
ISO 11171 Hydraulic Fluid Power–Calibration ofAutomatic
This procedure may be appropriate for other petroleum and
Particle Counters for Liquids
synthetic based lubricants not included in the precision state-
ment.
3. Terminology
1.4 Samples containing visible particles may not be suitable
3.1 Definitions:
for analysis using this test method.
3.1.1 For the purposes of this test method, the following
1.5 Samples that are opaque after dilution are not suitable
definitions apply:
for analysis using this test method.
3.1.2 coincidence, n—thepresenceofmorethanoneparticle
in the sensing zone of a particle analyzer at the same time,
1.6 The test method is specific to automatic particle coun-
causing incorrect sizing and incorrect counting of the particle
ters that use the light extinction principle and are calibrated
present. The coincidence limit of the counter is determined by
according to the latest revision of ISO 11171.
the maximum acceptable concentration of particles in the
1.7 The values stated in SI units are to be regarded as
sensing zone and is supplied by the instrument manufacturer.
standard. No other units of measurement are included in this
Refer to Section 3.4 in ISO 11171.
standard.
3.1.3 diluent, n—a solvent listed in Annex A1, Table A1.1,
1.8 This test method does not purport to address all of the
having viscosity less than 10 mm /s at 40°C that is physically
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This test method is under the jurisdiction of ASTM Committee D02 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee Standards volume information, refer to the standard’s Document Summary page on
D02.96.05 on In-Service Lubricants Particle Counting Practices and Techniques. the ASTM website.
Current edition approved July 1, 2010. Published September 2010. DOI: Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
10.1520/D7647–10. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7647 − 10
and chemically compatible with the apparatus used and easily 4.9 Analyze data and conduct validity checks.
soluble at room temperature with the sample lubricant or
4.10 Report results.
hydraulic fluid.
3.1.4 emulsified water, n—water that exists in oil between
5. Significance and Use
the states of fully dissolved and phase-separated. An emulsi-
5.1 This test method is intended for use in analytical
fying agent in the oil causes the two immiscible liquids to
laboratories including onsite in-service oil analysis laborato-
coexist in a heterogeneous mixture.
ries.
3.1.5 free water, n—water that exists in a separate phase in
5.2 Hardparticlesinlubricatingorfluidpowersystemshave
an oil sample. This occurs when the water content of the oil
a detrimental effect on the system as they cause operating
exceeds the water holding capacity of the oil.
components to wear and also accelerate the degradation of the
3.1.6 interfering soft particles, n—anundissolved,dispersed
oil. Hard particles in the oil originate from a variety of sources
material (such as an additive) within an oil blend or substance
including generation from within an operating fluid system or
that is formed during the service life of an oil blend.
contamination, which may occur during the storage and han-
3.1.6.1 Discussion—When these substances are present in a
dling of new oils or via ingress into an operating fluid system.
sample and not completely solubilized, they are likely to be
5.3 High levels of contaminants can cause filter blockages
counted by an optical particle counter in a similar manner to
and hard particles can have a serious impact on the life of
dirt and wear metal particles, air bubbles, and free water
pumps, pistons, gears, bearings, and other moving parts by
droplets.
accelerating wear and erosion.
3.1.7 ISO Codes, n—a standard classification for coding the
5.4 Particle count results can be used to aid in assessing the
level of contamination by solid particles.
capability of the filtration system responsible for cleaning the
3.1.7.1 Discussion—This code simplifies the reporting of
fluid, determining if off-line recirculating filtration is needed to
particle count data by converting the number of particles per
clean up the fluid system, or aiding in the decision of whether
mL into three classes covering ≥4µm , ≥6µm and ≥14
(c) (c)
or not a fluid change is required.
µm . ISO 4406 classifications are used as an option to report
(c)
results for this test method.
5.5 To accurately measure hard particle contamination
levels, it is necessary to negate the particle counts contributed
3.1.8 particle size, µm ,n—diameter of a circle with an
(c)
by the presence of small levels of free water. This method
area equivalent to the projected area of a particle passing
includes a process by which this can be accomplished using a
through the detecting cell in accordance with ISO 11171.
water-masking diluent technique whereby water droplets of a
3.1.9 particle size cumulative count, n—total number of
size below the target level are finely distributed.
particles with sizes greater than a specified particle size (for
5.6 Certain additives or additive by-products that are semi-
example, ≥4µm , ≥6µm , ≥10 µm , ≥14 µm , ≥21
(c) (c) (c) (c)
insoluble or insoluble in oil, namely the polydimethylsiloxane
µm , ≥38 µm , etc.).
(c) (c)
defoamant additive and oxidation by-products, are known to
NOTE 3—All particle counts are expressed on per 1 mL basis.
cause light scattering in automatic particle counters, which in
3.1.10 soot-in-oil, n—a sub-micron particulate product of
turn causes falsely high counts.These and similar materials are
incomplete combustion commonly found in in-service diesel
commonly termed “soft particles” (see 3.1.6) and are not
engine crankcase oil.
known to directly increase wear and erosion within an operat-
ing system. The contribution of these particles to the particle
3.1.11 water-masking diluent, n—a particular kind of di-
size cumulative count is negated with this method.
luent capable of dissolving otherwise immiscible substances
such as water or soft particles in the sample lubricant or
5.7 The use of dilution in this test method counteracts
hydraulic fluid. See Annex A1, Table A1.1.
viscosity effects for highly viscous oils that impact the accu-
racy of automatic optical particle counting results.
4. Summary of Test Method
6. Interferences
4.1 Inspect sample.
NOTE 4—This section is consistent with the interferences described in
4.2 Agitate sample.
Test Method D6786.
4.3 Obtainaliquotfromhomogeneoussampleifnotdiluting
6.1 Dirty environmental conditions and poor handling tech-
in original container.
niques can easily contaminate the sample or test specimen, or
both.Careshallbetakentoensuretestresultsarenotbiasedby
4.4 Dilute with appropriate diluent for the sample type.
introduced particles.
4.5 Agitate diluted sample.
6.2 Air bubbles in the oil may be counted as particles giving
4.6 Degas sample.
false positive readings. Mixing or agitating the sample intro-
4.7 Begin testing within 90 s (or repeat agitation and duces bubbles into the oil, but these readily dissipate with
degassing). sonication or vacuum degassing.
4.8 Obtain particle counts in triplicate (for sample and 6.3 Suspended or free water in the oil will generally be
method blank). counted as particles.
D7647 − 10
NOTE 5—Free or emulsified water interference presented can be
7.5 Liquid Dispensers, fitted with 0.8 µm or finer filter.
negated by using the water-masking diluent as described in this test
7.6 Volumetric Pipette and Bulb, if volumetric dilution or
method.
fluid transfer with a pipette is desired. Pipettes made of
6.4 Excessive concentrations of particles in the oil will
graduated glass or disposable polyethylene. Any glassware
cause coincidence or electronic saturation errors, or both.
used shall be cleaned and verified in accordance with ISO
LimitsaredeterminedbyISO11171andaregenerallysupplied
3722.
by the instrument manufacturer. These errors may be avoided
7.7 Density Meter, with an accuracy of 0.01 g/cm,ifthe
by increasing the dilution ratio with the diluent used in this test
mass dilution method is used.
method.
7.8 Filter Apparatus, for filtering the diluent. There is no
6.5 Odd-shaped particles and fibers may be classified with
requirement for the apparatus itself but it shall be capable of
incorrect calculated particle size, depending on their orienta-
producing acceptably clean diluent as necessary. Take appro-
tion as they pass through the sensing zone of the instrument.
priate safety precautions in handling low flash materials.
6.6 Dye-in-oil is used by some lubricant manufacturers to
distinguish certain lubricant types or brands. It is unusual for 7.9 Vacuum Degassing Apparatus, capable of pulling full
vacuum on the sample container in a vacuum chamber (per
that dye to have a discernible impact on particle count data.
Nonetheless, it is worthwhile to evaluate possible interferences 12.4.1) or syringe degassing port (per 12.4.3) within time limit
specified.
for dye-in-oil by testing a sample of filtered, dyed, lubricant. If
the automatic particle counter yields unusual results or if it
7.10 Glassware, any glassware used shall be cleaned and
reports an optical warning message, then this may be an
verified in accordance with ISO 3722.
indication of this type of interference.
7.11 Sample Container, a container used for collecting the
6.7 Excessive soot-in-oil is an interference that makes it
neat sample per 9.1 and 9.2, or for diluting sample specimens.
impractical to test in-service diesel engine lubricants, espe-
7.11.1 Sample containers shall not be reused.
cially when soot level exceeds 1 %. This is not normally a
7.11.2 Recommended containers are cylindrical specimen
problem for natural gas and gasoline engine oils. However
bottles (or jars) typically made of polypropylene, polystyrene,
heavy duty diesel engine oils typically produce excessive soot
PET, or glass with nominally flat bottoms, fitted with a suitable
for most automatic particle counters. The coincident, opaque,
non-shedding threaded cap.
soot particles reduce light transmission and produce very high
7.11.3 The dimensions and capacity of sample containers
false particle counts.
depends on specimen requirements and APC design. Sample
6.8 Solid lubricants, such as molybdenum disulfide or containers often have an approximate capacity of 125 mL.
graphite are used in some lubricating oils, especially for However individual specimen requirements and APC design
extreme pressure applications. These materials are typically may call for substantially smaller or much larger sample
used at levels high enough to render the fluid opaque or to containers.
cause coincidence errors due to high particle concentrations in
7.11.4 After performing any cleaning procedures, the
the detector. Even if these factors can be overcome with
sample containers shall meet the cleanliness criteria of contrib-
sufficient dilution, increases in particle counts are difficult to
uting less than 1 % of the total particles expected in the
determine with adequate precision due to the inherently high
cleanest sample.
particle counts in these fluids.
7.11.5 Sample containers shall be compatible with fluid and
able to withstand the temperature of the fluid when collecting
6.9 Specimen bottles shall not be reused. This is a source of
the sample. Sample containers with certified cleanliness levels
cross-contamination interference.
(for example, “ultra clean”) may be used to collect samples for
particle counting.
7. Apparatus
7.12 Specimen Bottle, or sample specimen bottle, a sample
7.1 Liquid Automatic Particle Counter (APC), liquid optical
container used for diluting at least a portion of a sample. A
particle counter based on the light extinction principle. The
specimen bottle shall meet the same criteria as the sample
instrumentshallbecapableofrecordingthesizeandnumberof
container (7.11.1-7.11.5).
particles as they pass across the detector. The particle counter
shall include a sampling apparatus that automatically delivers
7.13 Filters, to be used with filter apparatus (see 7.8).
a predetermined volume of specimen at a controlled flow rate
Recommended filters are cellulose o
...