ASTM D6786-08
(Test Method)Standard Test Method for Particle Count in Mineral Insulating Oil Using Automatic Optical Particle Counters
Standard Test Method for Particle Count in Mineral Insulating Oil Using Automatic Optical Particle Counters
SIGNIFICANCE AND USE
Particles in insulating oil can have a detrimental effect on the dielectric properties of the fluid, depending on the size, concentration, and nature of the particles. The source of these particles can be external contaminants, oil degradation by-products, or internal materials such as metals, carbon, or cellulose fibers.
Particle counts provide a general degree of contamination level and may be useful in accessing the condition of specific types of electrical equipment. Particle counts can also be used to determine filtering effectiveness when processing oil.
If more specific knowledge of the nature of the particles is needed, other tests such as metals analysis or fiber identification and counting must be performed.
SCOPE
1.1 This test method covers the determination of particle concentration and particle size distribution in mineral insulating oil. It is suitable for testing oils having a viscosity of 6 to 20 cSt at 40°C. The test method is specific to liquid automatic particle analyzers that use the light extinction principle.
1.2 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: D6786 − 08
StandardTest Method for
Particle Count in Mineral Insulating Oil Using Automatic
1
Optical Particle Counters
This standard is issued under the fixed designation D6786; 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 is determined by the maximum acceptable concentration of
particles in the given sample and is supplied by the instrument
1.1 This test method covers the determination of particle
manufacturer.
concentration and particle size distribution in mineral insulat-
ing oil. It is suitable for testing oils having a viscosity of 6 to 3.1.3 electronic saturation level—particle concentration at
20 cSt at 40°C. The test method is specific to liquid automatic whichtheelectroniccircuitryoftheanalyzerceasestofunction
particle analyzers that use the light extinction principle. properly due to excessive counting rates.
1.2 This standard does not purport to address all of the
3.1.4 light extinction—the reduction in intensity of a light
safety concerns, if any, associated with its use. It is the
beam passing through the sensing zone of a particle analyzer,
responsibility of the user of this standard to establish appro-
caused by the absorption and/or scattering of the light by
priate safety and health practices and determine the applica-
particles. Synonyms: light obscuration, light interruption, light
bility of regulatory limitations prior to use.
blockage.
2. Referenced Documents
4. Summary of Test Method
2
2.1 ASTM Standards:
4.1 Samples are taken in particle-clean bottles that are
D923 Practices for Sampling Electrical Insulating Liquids
suitable for particle analysis. The sample bottle is agitated to
2.2 ISO Standards:
redistribute particles in the oil, then the oil is placed in an
4406:1999 Hydraulic Fluid Power—Fluids—Method for
automatic particle counter, where the number of particles and
3
Coding the Level of Contamination by Solid Particles
their size distribution are determined by the light extinction
11171:1999 Hydraulic Fluid Power—Calibration of Auto-
principle.
3
matic Particle Counters for Liquids
4.2 As particles pass through the sensing zone of the
3. Terminology
instrument, the quantity of light reaching the detector is
obscured. This signal is translated to an equivalent projected
3.1 Definitions:
area diameter based on calibration with a NIST-traceable fluid
3.1.1 coincidence—the presence of more than one particle
(ISO Medium Test Dust suspension).
in the sensing zone of a particle analyzer at the same time,
causing mis-sizing and mis-counting of the particle present.
The coincidence limit of the counter is determined by the 5. Significance and Use
maximum acceptable concentration of particles in the sensing
5.1 Particles in insulating oil can have a detrimental effect
zone and is supplied by the instrument manufacturer.
on the dielectric properties of the fluid, depending on the size,
3.1.2 concentration limit—a direct function of coincidence
concentration, and nature of the particles. The source of these
and electronic saturation.The concentration limit of the system
particles can be external contaminants, oil degradation by-
products, or internal materials such as metals, carbon, or
cellulose fibers.
1
This test method is under the jurisdiction of ASTM Committee D27 on
Electrical Insulating Liquids and Gases and is the direct responsibility of Subcom-
5.2 Particle counts provide a general degree of contamina-
mittee D27.07 on Physical Test.
tion level and may be useful in assessing the condition of
Current edition approved Jan. 1, 2008. Published February 2008. Originally
approved in 2002. Last previous edition approved in 2007 as D6786–07. DOI:
specific types of electrical equipment. Particle counts can also
10.1520/D6786-08.
be used to determine filtering effectiveness when processing
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
oil.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
5.3 If more specific knowledge of the nature of the particles
the ASTM website.
3
is needed, other tests such as metals analysis or fiber identifi-
Available from American National Standards Institute, 11 West 42nd Street,
New York, NY 10036. cation and counting must be performed.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D6786 − 08
6. Interferences 9. Sampling
6.1 Dirty environmental conditions and poor handling tech-
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:D6786–07 Designation:D6786–08
Standard Test Method for
Particle Count in Mineral Insulating Oil Using Automatic
1
Optical Particle Counters
This standard is issued under the fixed designation D 6786; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the determination of particle concentration and particle size distribution in mineral insulating oil.
It is suitable for testing oils having a viscosity of 6 to 20 cSt at 40°C. The test method is specific to liquid automatic particle
analyzers that use the light extinction principle.
1.2 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.
2. Referenced Documents
2
2.1 ASTM Standards:
D 923 Practices for Sampling Electrical Insulating Liquids
2.2 ISO Standards:
3
4406:1999 Hydraulic Fluid Power—Fluids—Method for Coding the Level of Contamination by Solid Particles
3
11171:1999 Hydraulic Fluid Power—Calibration of Automatic Particle Counters for Liquids
3. Terminology
3.1 Definitions:
3.1.1 coincidence—the presence of more than one particle in the sensing zone of a particle analyzer at the same time, causing
mis-sizingandmis-countingoftheparticlepresent.Thecoincidencelimitofthecounterisdeterminedbythemaximumacceptable
concentration of particles in the sensing zone and is supplied by the instrument manufacturer.
3.1.2 concentration limit—a direct function of coincidence and electronic saturation. The concentration limit of the system is
determined by the maximum acceptable concentration of particles in the given sample and is supplied by the instrument
manufacturer.
3.1.3 electronic saturation level—particle concentration at which the electronic circuitry of the analyzer ceases to function
properly due to excessive counting rates.
3.1.4 light extinction—the reduction in intensity of a light beam passing through the sensing zone of a particle analyzer, caused
by the absorption and/or scattering of the light by particles. Synonyms: light obscuration, light interruption, light blockage.
4. Summary of Test Method
4.1 Samples are taken in particle-clean bottles that are suitable for particle analysis.The sample bottle is agitated to redistribute
particles in the oil, then the oil is placed in an automatic particle counter, where the number of particles and their size distribution
are determined by the light extinction principle.
4.2 As particles pass through the sensing zone of the instrument, the quantity of light reaching the detector is obscured. This
signal is translated to an equivalent projected area diameter based on calibration with a NIST-traceable fluid (ISO Medium Test
Dust suspension).
5. Significance and Use
5.1 Particles in insulating oil can have a detrimental effect on the dielectric properties of the fluid, depending on the size,
1
This test method is under the jurisdiction ofASTM Committee D27 on Electrical Insulating Liquids and Gases and is the direct responsibility of Subcommittee D27.07
on Physical Test.
Current edition approved Dec.Jan. 1, 2007.2008. Published JanuaryFebruary 2008. Originally approved in 2002. Last previous edition approved in 20022007 as
D 6786–027.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
Available from American National Standards Institute, 11 West 42nd Street, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
---------------------- Page: 1 ----------------------
D6786–08
concentration, and nature of the particles. The source of these particles can be external contaminants, oil degradation by-products,
or internal materials such as metals, carbon, or cellulose fibers.
5.2 Particle counts provide a general degree of contamination level and may be useful in accessing the condition of specific
types of electrical equipment. Particle counts can also be used to determine filtering effectiveness
...
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