ASTM D7898-14(2020)
(Practice)Standard Practice for Lubrication and Hydraulic Filter Debris Analysis (FDA) for Condition Monitoring of Machinery
Standard Practice for Lubrication and Hydraulic Filter Debris Analysis (FDA) for Condition Monitoring of Machinery
SCOPE
1.1 This practice is intended to cover the extraction, analysis, and information management pertaining to visible wear debris collected from oil system filters or debris retention screens. Further, it is intended that this practice be a practical reference for those involved in FDA.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7898 − 14 (Reapproved 2020)
Standard Practice for
Lubrication and Hydraulic Filter Debris Analysis (FDA) for
Condition Monitoring of Machinery
This standard is issued under the fixed designation D7898; 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.
INTRODUCTION
Thepurposeofthispracticeistodescribebestpracticemethodsfortheanalysisoffilterdebrisfrom
machinery lubrication or hydraulic systems primarily for the purpose of machinery condition
monitoring. The purpose of Filter Debris Analysis (FDA) is to determine the health of oil-wetted
machinery by analyzing the size, quantity, morphology, and composition of debris trapped by the
system filter. FDA is emerging as an important condition monitoring technique as fine filtration
becomes more common and the associated reduction of metallic particulates makes traditional
elemental analysis of the lubricant less effective. System filters have an added advantage over
traditional sample-based techniques in that they capture a high percentage of the total system debris
(metallic, non-metallic, and organic particulate contamination) within the size range useful for
machinery condition monitoring.
1. Scope 2. Referenced Documents
1.1 This practice is intended to cover the extraction, 2.1 ASTM Standards:
analysis, and information management pertaining to visible D7684Guide for Microscopic Characterization of Particles
weardebriscollectedfromoilsystemfiltersordebrisretention
from In-Service Lubricants
screens. Further, it is intended that this practice be a practical
D7685Practice for In-Line, Full Flow, Inductive Sensor for
reference for those involved in FDA.
Ferromagnetic and Non-ferromagnetic Wear Debris De-
termination and Diagnostics forAero-Derivative andAir-
1.2 The values stated in SI units are to be regarded as
craft Gas Turbine Engine Bearings
standard. No other units of measurement are included in this
D7720Guide for Statistically Evaluating Measurand Alarm
standard.
Limits when Using Oil Analysis to Monitor Equipment
1.3 This standard does not purport to address all of the
and Oil for Fitness and Contamination
safety concerns, if any, associated with its use. It is the
D7690Practice for Microscopic Characterization of Par-
responsibility of the user of this standard to establish appro-
ticles from In-Service Lubricants by Analytical Ferrogra-
priate safety, health, and environmental practices and deter-
phy
mine the applicability of regulatory limitations prior to use.
F316Test Methods for Pore Size Characteristics of Mem-
1.4 This international standard was developed in accor-
brane Filters by Bubble Point and Mean Flow Pore Test
dance with internationally recognized principles on standard-
G40Terminology Relating to Wear and Erosion
ization established in the Decision on Principles for the
D4175Terminology Relating to Petroleum Products, Liquid
Development of International Standards, Guides and Recom-
Fuels, and Lubricants
mendations issued by the World Trade Organization Technical
2.2 Other Standards:
Barriers to Trade (TBT) Committee.
TTCP-AER-TP3-TR01-2010Guide for Filter DebrisAnaly-
sis
This practice is under the jurisdiction ofASTM Committee D02 on Petroleum
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-
mittee D02.96.06 on Practices and Techniques for Prediction and Determination of For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Microscopic Wear and Wear-related Properties. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved Nov. 1, 2020. Published December 2020. Originally Standards volume information, refer to the standard’s Document Summary page on
approved in 2014. Last previous edition approved in 2014 as D7898–14. DOI: the ASTM website.
10.1520/D7898-14R20. Published by the Technical Co-operation Program (TTCP), July 2010.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7898 − 14 (2020)
3. Terminology tached from a surface due to wear, corrosion, or erosion
process. D7684
3.1 Definitions:
3.1.7 debris, n—in internal combustion engines, solid con-
3.1.1 abrasive wear, n—wear due to hard particles or hard
protuberancesforcedagainstandmovingalongasolidsurface. taminant materials unintentionally introduced into the engine
or resulting from wear. D4175
D4175
3.1.8 filter debris analysis (FDA), n—intribology,aprocess
3.1.1.1 Discussion—Also called cutting wear in some in-
for extracting and inspecting debris accumulated on the filter
stances such as machining swarf.
media taken from an in-line circulating lubricating system.
3.1.1.2 abrasive wear particles, n—long wire-like particles
D7684
in the form of loops or spirals that are generated due to hard,
abrasiveparticlespresentbetweenwearingsurfacesofunequal 3.1.9 non-ferrous metal particles, n—free metal particle
hardness; sometimes called cutting wear particles or ribbons.
composed of any metal except iron. All common nonferrous
D7684 metals behave nonmagnetically except nickel. D7690
3.1.1.3 three body abrasive wear, n—form of abrasive wear
3.1.10 nonmetallic particles, n—particles comprised of
in which wear is produced by loose particles introduced or
compounds, organic material, glasses, etc. that have bound
generated between the contacting surfaces. D7684
electrons in their atomic structure. D7690
3.1.1.4 two body abrasive wear, n—formofabrasivewearin
3.1.10.1 nonmetallic amorphous particles, n—particles
whichthehardparticlesorprotuberancesthatproducethewear
withoutlongrangeatomicorderthataretransparentandthatdo
ofonebodyarefixedonthesurfaceoftheopposingbody. G40
not appear bright in polarized light. D7690
3.1.2 adhesive wear, n—wear due to localized bonding
3.1.10.2 nonmetallic crystalline particles, n—particles with
between contacting solid surfaces leading to material transfer
long range atomic structure that appear bright in polarized
between the two surfaces or loss from either surface. G40
light. These may be single crystals but are most likely
3.1.2.1 Discussion—Also called sliding wear or rubbing
polycrystalline or polycrystalline agglomerates. D7690
wear.
3.1.11 rolling contact fatigue, n—damage process in a
3.1.2.1 rubbing wear particles, n—particles generated as a
triboelement subjected to repeated rolling contact loads, in-
result of sliding wear in a machine, sometimes called mild
volving the initiation and propagation of fatigue cracks in or
adhesive wear. Rubbing particles are free metal platelets with
under the contact surface, eventually culminating in surface
smooth surfaces, from approximately 0.5 to 15 µm in major
pits or spalls. G40
dimension and with major dimension-to-thickness ratios from
3.1.12 scoring, n—in tribology, a consequence of severe
about ten to one for larger particles to about three to one for
sliding wear characterized by formation of extensive grooves
smaller particles.Any free metal particle <5 µm is classified as
and scratches in the direction of sliding; also called striation.
a rubbing wear particle regardless of shape factor unless it is a
D7684
sphere. D7684
3.1.13 spalling, n—in tribology, the separation of macro-
3.1.2.1 Discussion—Rubbingparticlescanalsobeattributed
scopic particles from a surface in the form of flakes or chips,
tothebenignremovalofasperities(polishing)ofwearsurfaces
usuallyassociatedwithrollingelementbearingsandgearteeth,
during run-in of machine.
but also resulting from impact events. G40
3.1.2.2 severe sliding wear particles, n—intribology,severe
3.1.14 wear particles, n—particles generated from a wear-
slidingwearparticlesare>15µmandseveraltimeslongerthan
ing surface of a machine. D7684
theyarewide.Someoftheseparticleshavesurfacestriationsas
a result of sliding, and they frequently have straight edges.
3.2 Definitions of Terms Specific to This Standard:
Their major dimension-to-thickness ratio is approximately ten
3.2.1 debris, n—particulate recovered from a machine con-
to one. D7684
taining both wear-related, benign (for example, residual over-
3.1.2.1 Discussion—Severe Sliding Particles can be gener-
haul swarf), or organic material, or combinations thereof,
ated as a result of inadequate lubrication, wrong lubricant,
foreign to the system.
extreme loading, or no lubricant. Ferrous particles can often
3.2.2 Feret’s diameter, n—the largest distance between two
exhibitheattintingcolorationontheirsurfaceasaresultofthe
parallellinesthatjusttouchestheedgeofanirregularlyshaped
high frictional temperatures experienced during this process.
particle. Also known as calliper diameter.
3.1.3 asperity, n—a protuberance in the small-scale topo-
3.2.3 ferrous debris, n—metallicdebrisconsistingmainlyof
graphical irregularities of a solid surface. G40
iron (Fe) and exhibiting ferro-magnetic behavior (that is, the
3.1.4 contaminant particles, n—particles introduced from
material is attracted or repelled when exposed to a magnetic
anextraneoussourceintothelubricantofamachineorengine.
field). Recommended abbreviation: Fe.
D7690
3.2.4 filter bypass system, n—a system by which circulating
3.1.5 debris, n—in tribology, particles that have become
fluid can bypass the filter element if the differential pressure
detached in a wear or erosion process. G40
across the filter becomes excessive due to blockage by con-
3.1.6 debris, n—in tribology, solid or semi-solid particulate tamination. Under bypass conditions, fluid can continue to
matter introduced to lubricant through contamination or de- circulate but will be unfiltered.
D7898 − 14 (2020)
3.2.5 filter debris, n—any matter captured in a system filter 4. Summary of Practice
element.
4.1 Lubrication and hydraulic system filters are a rich
3.2.6 filter patch, n—a piece of filter material of known
source of information about system health that are seldom
permeability (mesh opening dimension) used to capture debris
exploited for machinery condition monitoring purposes. This
sized greater than the rated mesh opening; usually specified in
practiceseekstodefinesomeproceduresthatensureconsistent
µm. Also known as membrane patch.
extractionandanalysisoffilterdebrisinordertoassesssystem
3.2.7 filter patch mesh size, n—the diameter of the largest health.
sphere that can pass through the filter patch mesh opening.
5. Significance of Use
3.2.8 fine filtration, n—filtration applied to a lubrication or
hydraulic system that meets or exceeds a Beta ratio of 200 for
5.1 The objective of FDA is to diagnose the operational
5 µm (c) particles (that is, β ≥ 200).
5(c) condition of oil-wetted machinery systems in order to identify
3.2.9 graticule, n—fine lines of known spacing used to
abnormal wear or incipient component failures. Oil system
determine the scaling of microscopic images. filters (typically lubrication system or hydraulic systems)
capture the vast majority of metallic and non-metallic debris
3.2.10 metal map, n—alistofcomponentswithinamachine
generated or contained within a system. The exploitation of
bypartnumberorfunctiontogetherwiththecomponent’salloy
this potential source of information for machinery condition
specificationandcomposition.Alsoknownasmaterialsatlasor
monitoring purposes has been difficult in the past due to the
component material specification list.
absence of a clear automated or manual method for extracting,
3.2.11 parent system, n—themechanicalsystemfromwhich
analyzing, reporting, and archiving the debris. This practice is
the debris sample originated from, for example, helicopter
provided to enable a consistent approach to the analysis of
main rotor gearbox.
in-service debris captured in filters and is intended primarily
3.2.12 particle areas, n—this measurement is used by some
for lubrication or hydraulic systems.
aircraftmanufacturerstodefinethecriticalityofweardebris.It
5.2 Caution shall be exercised when drawing conclusions
is not recommended since it is almost impossible to obtain an
based on particle quantity, composition, and morphology.Any
accurate measurement of an individual particle in the field
maintenance or operational actions shall be carefully consid-
without using appropriate particle image processing software.
ered and take into consideration any extant limits provided by
3.2.13 particle aspect ratio, n—the length of a predomi-
the manufacturer as well as any historical information known
nantly two-dimensional particle divided by its width.
about the subject system.
3.2.14 rolling contact fatigue particles, n—these particles
are generated in a load/unload (cyclic) environment and is a
6. Filter Elements
typical failure mode for rolling element bearings and gears.
6.1 Filter elements may be broadly classified as either
Particles are generated when subsurface cracks, generated by
reusable or disposable. Prior to processing a filter element, it
thesignificantsub-surfaceshearstressassociatedwithHertzian
should be understood whether the element is disposable or
contact stresses, propagate to a point where a spall is liberated
reusable so that appropriate processing techniques can be
fromtheloadsurface.Theseparticlescanbetensofmicronsup
applied.
to millimetres in length. Particles may show evidence of the
machined load-bearing surface on one face and a rough
6.2 This is to ensure disposable elements are not inadver-
crystallinesurface(wherethecrackpropagated)onthereverse.
tently reused following extraction of debris.
Particles may be rolled and reworked by subsequent rolling
6.3 Reusable filter elements are typically made from sin-
elements or gear teeth and may then appear as a flattened flake
tered metal or woven metal fiber (mesh), but can also employ
with characteristic radial cracking from the edges and a
other media types.
fissured or crazed edge. Particles are hard and brittle, not
6.3.1 If a reusable filter is to be reinstalled into a machine,
deformable without cracking when load is applied.
then the filter element should be treated as a serviceable part,
3.2.15 scale bar, n—a reference measurement embedded
and as such the following observed:
into or applied on an image to enable scaling of other objects
6.3.1.1 Anyprocess,solvent,etc.usedtoextractweardebris
present in that image. The units of measurement must be
mustbeinaccordancewiththeapprovedmaintenancemanual.
clearly presented with the scale bar.
This will typically include a predefined c
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