ASTM D6595-00(2011)
(Test Method)Standard Test Method for Determination of Wear Metals and Contaminants in Used Lubricating Oils or Used Hydraulic Fluids by Rotating Disc Electrode Atomic Emission Spectrometry
Standard Test Method for Determination of Wear Metals and Contaminants in Used Lubricating Oils or Used Hydraulic Fluids by Rotating Disc Electrode Atomic Emission Spectrometry
SIGNIFICANCE AND USE
Used Lubricating Oil—The determination of debris in used oil is a key diagnostic method practiced in machine condition monitoring programs. The presence or increase in concentration of specific wear metals can be indicative of the early stages of wear if there are baseline concentration data for comparison. A marked increase in contaminant elements can be indicative of foreign materials in the lubricants, such as antifreeze or sand, which may lead to wear or lubricant degradation. The test method identifies the metals and their concentration so that trends relative to time or distance can be established and corrective action can be taken prior to more serious or catastrophic failure.
SCOPE
1.1 This test method covers the determination of wear metals and contaminants in used lubricating oils and used hydraulic fluids by rotating disc electrode atomic emission spectroscopy (RDE-AES).
1.2 This test method provides a quick indication for abnormal wear and the presence of contamination in new or used lubricants and hydraulic fluids.
1.3 This test method uses oil-soluble metals for calibration and does not purport to relate quantitatively the values determined as insoluble particles to the dissolved metals. Analytical results are particle size dependent and low results may be obtained for those elements present in used oil samples as large particles.
1.4 The test method is capable of detecting and quantifying elements resulting from wear and contamination ranging from dissolved materials to particles approximately 10 m in size.
1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. The preferred units are mg/kg (ppm by mass).
1.6 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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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D6595 − 00(Reapproved 2011)
Standard Test Method for
Determination of Wear Metals and Contaminants in Used
Lubricating Oils or Used Hydraulic Fluids by Rotating Disc
Electrode Atomic Emission Spectrometry
This standard is issued under the fixed designation D6595; 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 D4057 Practice for Manual Sampling of Petroleum and
Petroleum Products
1.1 This test method covers the determination of wear
metals and contaminants in used lubricating oils and used
3. Terminology
hydraulic fluids by rotating disc electrode atomic emission
3.1 Definitions:
spectroscopy (RDE-AES).
3.1.1 burn, vt—in emission spectroscopy, to vaporize and
1.2 This test method provides a quick indication for abnor-
excite a specimen with sufficient energy to generate spectral
mal wear and the presence of contamination in new or used
radiation.
lubricants and hydraulic fluids.
3.1.2 calibration, n—the determination of the values of the
1.3 This test method uses oil-soluble metals for calibration
significant parameters by comparison with values indicated by
and does not purport to relate quantitatively the values deter-
a set of reference standards.
mined as insoluble particles to the dissolved metals.Analytical
3.1.3 calibration curve, n—the graphical or mathematical
results are particle size dependent and low results may be
representation of a relationship between the assigned (known)
obtainedforthoseelementspresentinusedoilsamplesaslarge
values of standards and the measured responses from the
particles.
measurement system.
1.4 The test method is capable of detecting and quantifying
3.1.4 calibration standard, n—a standard having an ac-
elements resulting from wear and contamination ranging from
cepted value (reference value) for use in calibrating a measure-
dissolved materials to particles approximately 10 µm in size.
ment instrument or system.
1.5 The values stated in SI units are to be regarded as
3.1.5 emission spectroscopy, n—measurement of energy
standard. No other units of measurement are included in this
spectrum emitted by or from an object under some form of
standard.
energetic stimulation; for example, light, electrical discharge,
1.5.1 The preferred units are mg/kg (ppm by mass).
and so forth.
1.6 This standard does not purport to address all of the
3.2 Definitions of Terms Specific to This Standard:
safety concerns, if any, associated with its use. It is the
3.2.1 arc discharge, n—a self-sustaining, high current
responsibility of the user of this standard to establish appro-
density, high temperature discharge, uniquely characterized by
priate safety and health practices and determine the applica-
a cathode fall nearly equal to the ionization potential of the gas
bility of regulatory limitations prior to use.
or vapor in which it exists.
3.2.2 check sample, n—a reference material usually pre-
2. Referenced Documents
pared by a laboratory for its own use as a calibration standard,
2.1 ASTM Standards:
as a measurement control standard, or for the qualification of a
measurement method.
3.2.3 contaminant, n—material in an oil sample that may
This test method is under the jurisdiction of ASTM Committee D02 on
cause abnormal wear or lubricant degradation.
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.03 on Elemental Analysis.
3.2.4 counter electrode, n—either of two graphite electrodes
Current edition approved May 1, 2011. Published August 2011. Originally
in an atomic emission spectrometer across which an arc or
approved in 2000. Last previous edition approved in 2005 as D6595–00(2005).
spark is generated.
DOI: 10.1520/D6595-00R11.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.2.5 graphite disc electrode, n—a soft form of the element
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
carbon manufactured into the shape of a disc for use as a
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. counter electrode in arc/spark spectrometers for oil analysis.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6595 − 00 (2011)
3.2.6 graphite rod electrode, n—a soft form of the element ences of the instrument will compensate for a portion of the
carbon manufactured into the shape of a rod for use as a differences. In used oil applications, the hydrogen 486.10 nm
counter electrode in arc/spark spectrometers for oil analysis. spectral line has become the industry standard for use as an
internalreference.Withoutareference,trendeddataonusedoil
3.2.7 profiling, n—to set the actual position of the entrance
will be adversely affected if the sample base stock has a
slit to produce optimum measurement intensity.
different viscosity from the base line samples.
3.2.8 standardization, n—the process of reestablishing and
6.3 Particulate—When large particles over 10 µm in size
correcting a calibration curve through the analysis of at least
are detected, the analytical results will be lower than the actual
two known oil standards.
concentration they represent. Large particles may not be
3.2.9 uptake rate, n—the amount of oil sample that is
effectively transported by the rotating disk electrode sample
physically carried by the rotating disc electrode into the arc for
introduction system into the arc, nor will they be fully
analysis.
vaporized by the spark.
3.2.10 wear metal, n—material resulting from damage to a
solid surface due to relative motion between that surface and a
7. Apparatus
contacting substance or substances.
7.1 Electrode Sharpener—An electrode sharpener is neces-
sary to remove the contaminated portion of the rod electrode
4. Summary of Test Method
remainingfromthepreviousdetermination.Italsoformsanew
4.1 Wear metals and contaminants in a used oil test speci-
160° angle on the end of the electrode. Electrode sharpeners
men are evaporated and excited by a controlled arc discharge
are not required for instruments using a pre-shaped disc
using the rotating disk technique. The radiant energies of
electrode as the counter electrode.
selected analytical lines and one or more references are
7.2 Rotating Disc Electrode Atomic Emission Spectrometer,
collected and stored by way of photomultiplier tubes, charge
a simultaneous spectrometer consisting of excitation source,
coupled devices or other suitable detectors. A comparison is
polychromator optics, and a readout system. Suggested ele-
made of the emitted intensities of the elements in the used oil
ments and wavelengths are listed in Table 1. When multiple
test specimen against those measured with calibration stan-
wavelengths are listed, they are in the order of preference or
dards.The concentrations of the elements present in the oil test
desired analytical range.
specimen are calculated and displayed. They may also be
entered into a data base for processing.
7.3 Heated Ultrasonic Bath (Recommended), an ultrasonic
bathtoheatandhomogenizeusedoilsamplestobringparticles
5. Significance and Use
into homogeneous suspension. The ultrasonic bath shall be
5.1 Used Lubricating Oil—The determination of debris in used on samples containing large amount of debris and those
used oil is a key diagnostic method practiced in machine that have been in transit or stored for 48 hours or longer.
condition monitoring programs. The presence or increase in
8. Reagents and Materials
concentration of specific wear metals can be indicative of the
early stages of wear if there are baseline concentration data for
8.1 Base Oil, a 75 cSt base oil free of analyte to be used as
comparison.Amarkedincreaseincontaminantelementscanbe
a calibration blank or for blending calibration standards.
indicative of foreign materials in the lubricants, such as
8.2 Check Samples, An oil standard or sample of known
antifreeze or sand, which may lead to wear or lubricant
concentration which is periodically analyzed as a go/no go
degradation. The test method identifies the metals and their
sample to confirm the need for standardization based on an
concentration so that trends relative to time or distance can be
allowable 610 % accuracy limit.
established and corrective action can be taken prior to more
8.3 Cleaning Solution, An environmentally safe, non-
serious or catastrophic failure.
chlorinated,rapidevaporating,andnon-filmproducingsolvent,
6. Interferences
to remove spilled or splashed oil sample in the sample stand.
6.1 Spectral—Most spectral interferences can be avoided by
judicious choice of spectral lines. High concentrations of
additive elements can have an interfering influence on the
TABLE 1 Elements and Recommended Wavelengths
spectral lines used for determining wear metals. Instrument
Element Wavelength, nm Element Wavelength, nm
manufacturers usually compensate for spectral interferences
Aluminum 308.21 Nickel 341.48
during factory calibration. A background correction system,
Barium 230.48, 455.40 Phosphorus 255.32, 214.91
Boron 249.67 Potassium 766.49
which subtracts unwanted intensities on either side of the
Calcium 393.37, 445.48 Silicon 251.60
spectral line, shall also be used for this purpose. When spectral
Chromium 425.43 Silver 328.07, 243.78
interferencescannotbeavoidedwithspectrallineselectionand
Copper 324.75, 224.26 Sodium 588.89, 589.59
Iron 259.94 Tin 317.51
backgroundcorrection,thenecessarycorrectionsshallbemade
Lead 283.31 Titanium 334.94
using the computer software supplied by the instrument manu-
Lithium 670.78 Tungsten 400.87
facturer.
Manganese 403.07, 294.92 Vanadium 290.88, 437.92
Magnesium 280.20, 518.36 Zinc 213.86
6.2 Viscosity Effects—Differences in viscosity of used oil
Molybdenum 281.60
samples will cause differences in uptake rates. Internal refer-
D6595 − 00 (2011)
TABLE 2 Repeatability
10. Preparation of Test Specimen
Element Range, mg/kg Repeatability, mg/kg
10.1 Homogenization—Used oil samples may contain par-
0.45
Aluminum 0.23–101 0.5419(X+0.57)
ticulate matter and, in order to be representative, must always
1.18
Barium 28–115 0.0694X
0.56
be vigorously shaken prior to pouring a test specimen for
Boron 0.14–120 0.4280(X+0.1028)
Calcium 3.7–11460 0.1106(X+2.184)
analysis.
0.41
Chromium 0.18–152 0.7285(X+0.0557)
0.85
Copper 0.47–100 0.1631(X+0.3459) 10.2 Ultrasonic Homogenization—Samples that have been
0.73
Iron 4.8–210 0.3159 (X+0.0141)
in transit for several days, idle in storage or very viscous, shall
0.34
Lead 0.43–101 1.062(X+0.6015)
be placed in a heated ultrasonic bath to break up clusters of
Magnesium 4.9–1360 0.1049X
0.34
Manganese 0.3–117 0.7017(X+0.3534) particles and to bring them back into suspension. The samples
0.34
Molybdenum 0.21–100 0.9978(X+0.4795)
shall be vigorously shaken after being in the ultrasonic bath
0.40
Nickel 0.35–100 0.7142(X+0.3238)
and prior to pouring a test specimen for analysis. The bath
Phosphorus 52–2572 0.0761(X+14.76)
0.63
Potassium 0.35–247 0.4075(X+0.1154) temperature shall be at least 60°C and the total agitation time
0.63
Silicon 3.2–142 0.4015(X+0.1692)
at least 2 min.
0.88
Silver 31–102 0.1523(X+1.2)
Sodium 3.6–99.6 0.1231(X−2.674)
10.3 Specimen Holders—Used oil samples and oil standards
0.45
Tin 30–139 0.6777(X+0.6578)
shallbepouredintoaspecimenholderofatleast1mLcapacity
0.5
Titanium 6.8–103 0.5831(X+0.9304)
0.41
prior to analysis. Exercise care to pour the sample consistently
Vanadium 2.1–101 0.6389(X+0.8418)
0.87
Zinc 5.3–1345 0.2031(X+1.553)
to the same level in the specimen holders to maintain good
X = mean concentration in mg/kg
repeatability of analysis.
10.4 Specimen Table—The specimen table shall be adjusted
so that when it is in the fully raised position, at least one-third
8.4 Disc Electrode, a graphite disc electrode of high-purity
of the disc electrode is immersed in the oil test specimen.
graphite (spectroscopic grade). Dimensions of the electrodes
shall conform to those shown in Fig. 1. 11. Preparation of Apparatus
8.5 Glass Cleaning Solution, capable of cleaning and re- 11.1 Warm-up Burns—If the instrument has been idle for
moving splashed oil sample from the quartz window that several hours, it may be necessary to conduct at least three
warm-up burns to stabilize the excitation source. The warm-up
protects the entrance lens and fiber optic. Isopropyl rubbing
alcohol or ammonia based window cleaner has been found to procedure can be performed with any oil sample or standard.
Consult the manufacturer’s instructions for specific warm-up
be suitable for this purpose.
requirements.
8.6 Organometallic Standards, single or multi-element
11.2 Optical Profile—Perform the normal optical profile
blended standards for use as the high concentration standard
for instrument standardization purposes or for use as a check procedure called for in the operation manual of the instrument.
An optical profile shall also be performed if the instrument has
sample to confirm calibration. Typical concentrations in the
upper calibration point standard for used oil applications is 100 been inoperative for an extended period of time or if the
temperature has shifted more than 10°C since the last calibra-
mg/kg for wear metals and contaminants, and 900 mg/kg for
additive elements. tion check.
8.6.1 Standards have a shelf-life and shall not be used to
11.3 Validation Check—A go/no go standardization check
standardize an instrument if they have exceeded the expiration
can be performed with one or more check samples to confirm
date.
calibration prior to the analysis of routine samples. A calibra-
8.7 Counter Electrode—The counter electrode can be either tion standard or known oil sample can be used for this purpose.
a rod or a disc. The counter electrode must be high-purity The optical profile and standardization routine recommended
graphite (spectroscopic grade). Dimensions of the counter by the instrument manufacturer shall be performed if the
electrodes shall conform to those shown in Fig. 2. validation check fails to meet the 610 % accuracy guidelines
for each element of interest.
8.8 Specimen Holders—A variety of specimen holders can
be used for the analysis of used oil samples. Disposable
12. Calibration
specimen holders must be discarded after each analysis and
12.1 Factory Calibration—The analytical range for each
reusable specimen holders must be cleaned after each analysis.
element is established through the analysis of organometallic
All specimen holders must be free of contamin
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