ASTM D923-15(2023)
(Practice)Standard Practices for Sampling Electrical Insulating Liquids
Standard Practices for Sampling Electrical Insulating Liquids
SIGNIFICANCE AND USE
4.1 Accurate sampling, whether of the complete contents or only parts thereof, is extremely important from the standpoint of evaluating the quality of the liquid insulant sampled. Obviously, examination of a test specimen that, because of careless sampling procedure or contamination in sampling equipment, is not directly representative, leads to erroneous conclusions concerning quality and in addition results in a loss of time, effort, and expense in securing, transporting, and testing the sample.
4.2 A study of gases and moisture contained in insulating oils from transformers and other electrical power apparatus can frequently give an early indication of abnormal behavior of the apparatus, and may indicate appropriate action be taken on the equipment before it suffers greater damage. Specific gas and moisture content can be determined from oil sampled for this purpose.
SCOPE
1.1 These practices cover sampling of new electrical insulating liquids including oils, askarels, silicones, synthetic liquids, and natural ester insulating liquids as well as those insulating liquids in service or subsequent to service in cables, transformers, circuit breakers, and other electrical apparatus. These practices apply to liquids having a viscosity of less than 6.476 × 10-4 m2/s (540 cSt) at 40 °C (104 °F).
1.2 Representative samples of electrical insulating liquids are taken for test specimens so that the quality pertinent to their use may be determined. The quality in different portions of a given container, or the average quality of the whole bulk may be ascertained if desired.
1.3 The values stated in SI units are regarded as the standard where applicable. Inch pound units are used where there is no SI equivalent.
1.4 These practices also include special techniques and devices for sampling for dissolved gases-in-oil (DGA) (D3612), water (D1533) and particles (D6786).
1.5 For ease of use, this document has been indexed as follows:
Section Title
Section/Paragraph
Mandatory Conditions and General Information
Section 5
Description of Sampling Devices and Containers
Section 6, Annex A1, Appendix X2
Most Frequently Used Sampling Techniques for Electrical Apparatus
Collecting Samples from Electrical Equipment Using Bottles and Cans
Section 7, Appendix X1, Appendix X2
Collecting Samples from Electrical Equipment Using Glass Syringes (DGA and Water Analysis)
Section 8
Collecting Samples from Electrical Equipment Using Stainless Steel Cylinders (DGA and Water Analysis)
Section 9
Sampling of Cans, Drums, Tank Cars, Tank Trucks and Small Electrical Equipment
Sampling Using the Dip-Type Device (drum thief)
Section 10
Sampling Using the Pressure-Type Device
Section 11, Annex A1.1
Sampling Using the Tank Car-Type Device
Section 12, Annex A1.2
Sampling Cable Feeders
Mandatory Conditions
Section 13
General Considerations
Section 14
Sampling Using the Manifold-Type Device
Section 15, Annex A1.3
Cleaning, Preparation, Storage, and Handling of Sampling Containers
Section 16
Storage, Packaging and Shipping of Samples
Section 17
Cleaning and Storage of Sampling Devices
Section 18
Sample Information
Section 19
Mandatory Information—Construction of Sampling Devices
Annex A1
Determination of Electrical Apparatus Temperature
Appendix X1
Sample Container Types
Appendix X2
1.6 Handle askarels containing polychlorinated biphenyls (PCBs) according to federal and local regulations existing for that country. For example, the federal regulations concerning PCBs in the United States can be found in 40 CFR Part 761.
1.7 Properly contain, package and dispose of any liquid or material resulting from the use of these practices in a manner that is in accordance with local and state regulations specific to the country in w...
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: D923 − 15 (Reapproved 2023)
Standard Practices for
Sampling Electrical Insulating Liquids
This standard is issued under the fixed designation D923; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
Section/
Section Title
Paragraph
1.1 These practices cover sampling of new electrical insu-
lating liquids including oils, askarels, silicones, synthetic Sampling of Cans, Drums, Tank Cars, Tank Trucks and
Small Electrical Equipment
liquids, and natural ester insulating liquids as well as those
Sampling Using the Dip-Type Device (drum thief) Section 10
insulating liquids in service or subsequent to service in cables,
Sampling Using the Pressure-Type Device Section 11,
transformers, circuit breakers, and other electrical apparatus. Annex A1.1
Sampling Using the Tank Car-Type Device Section 12,
These practices apply to liquids having a viscosity of less than
Annex A1.2
-4 2
6.476 × 10 m /s (540 cSt) at 40 °C (104 °F).
Sampling Cable Feeders
Mandatory Conditions Section 13
1.2 Representative samples of electrical insulating liquids
General Considerations Section 14
are taken for test specimens so that the quality pertinent to their
Sampling Using the Manifold-Type Device Section 15,
Annex A1.3
use may be determined. The quality in different portions of a
Cleaning, Preparation, Storage, and Handling of Section 16
given container, or the average quality of the whole bulk may
Sampling Containers
be ascertained if desired. Storage, Packaging and Shipping of Samples Section 17
Cleaning and Storage of Sampling Devices Section 18
1.3 The values stated in SI units are regarded as the standard
Sample Information Section 19
where applicable. Inch pound units are used where there is no
Mandatory Information—Construction of Sampling Devices Annex A1
SI equivalent.
Determination of Electrical Apparatus Temperature Appendix X1
Sample Container Types Appendix X2
1.4 These practices also include special techniques and
devices for sampling for dissolved gases-in-oil (DGA)
1.6 Handle askarels containing polychlorinated biphenyls
(D3612), water (D1533) and particles (D6786).
(PCBs) according to federal and local regulations existing for
that country. For example, the federal regulations concerning
1.5 For ease of use, this document has been indexed as
PCBs in the United States can be found in 40 CFR Part 761.
follows:
Section/
1.7 Properly contain, package and dispose of any liquid or
Section Title
Paragraph
material resulting from the use of these practices in a manner
Mandatory Conditions and General Information Section 5 that is in accordance with local and state regulations specific to
Description of Sampling Devices and Containers Section 6,
the country in which the samples are taken.
Annex A1,
Appendix X2
1.8 This standard does not purport to address all of the
Most Frequently Used Sampling Techniques for
safety concerns, if any, associated with its use. It is the
Electrical Apparatus
Collecting Samples from Electrical Equipment Using Bottles Section 7,
responsibility of the user of this standard to establish appro-
and Cans Appendix X1,
priate safety, health, and environmental practices and deter-
Appendix X2
mine the applicability of regulatory limitations prior to use.
Collecting Samples from Electrical Equipment Using Glass Section 8
Syringes (DGA and Water Analysis)
Specific warning statements are given in 1.6, 1.7, Section 5,
Collecting Samples from Electrical Equipment Using Section 9
10.1, 13.2, 15.2.3, Section 16, and 18.2. These practices
Stainless Steel Cylinders (DGA and Water Analysis)
involve close contact with the electrical insulating liquids
being sampled as well as liquids and other materials used to
clean the sampling tools and devices. When required, or as a
matter of diligence to personal safety, use personal protective
These practices are under the jurisdiction of ASTM Committee D27 on
equipment (PPE).
Electrical Insulating Liquids and Gases and are the direct responsibility of
Subcommittee D27.07 on Physical Test.
1.9 This international standard was developed in accor-
Current edition approved Dec. 1, 2023. Published December 2023. Originally
dance with internationally recognized principles on standard-
approved in 1947. Last previous edition approved in 2015 as D923 – 15. DOI:
10.1520/D0923-15R23. ization established in the Decision on Principles for the
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D923 − 15 (2023)
Development of International Standards, Guides and Recom- 5. Mandatory Conditions and General Information
mendations issued by the World Trade Organization Technical
5.1 Mandatory Conditions when Sampling Electrical Appa-
Barriers to Trade (TBT) Committee.
ratus:
5.1.1 Energized electrical apparatus being sampled must
2. Referenced Documents
have a positive pressure at the sampling outlet, so as not to
2.1 ASTM Standards: introduce an air bubble into the apparatus during the sampling
process. Refer to 7.2.
D1533 Test Method for Water in Insulating Liquids by
Coulometric Karl Fischer Titration 5.1.2 Do not draw samples from any energized electrical
D1933 Specification for Nitrogen Gas as an Electrical Insu- equipment with a small volume of oil, especially those that
lating Material require the addition of oil to maintain the electric strength of
D3612 Test Method for Analysis of Gases Dissolved in the insulation system. If the proper level or existing level can
Electrical Insulating Oil by Gas Chromatography not be accurately determined do not proceed.
D4057 Practice for Manual Sampling of Petroleum and 5.1.3 Maintain the insulating fluid within the electrical
Petroleum Products
apparatus being sampled at a level that will not reduce the
D6786 Test Method for Particle Count in Mineral Insulating electric strength of the insulation system.
Oil Using Automatic Optical Particle Counters
5.1.4 Do not sample electrical apparatus if only a drain plug
is provided, as it would be difficult to control the flow.
3. Terminology
5.1.5 Do not draw samples from energized instrument
transformers such as CTs and PTs.
3.1 Definitions:
5.1.6 Do not draw samples from an energized switch or the
3.1.1 sampling, v—the obtaining of that amount of a mate-
cable termination compartment of network transformers.
rial which is adequate for making the required tests and which
is representative of that portion of the material from which it is
5.2 General Information:
taken.
5.2.1 Take and handle samples or test specimens in such a
3.1.1.1 Discussion—In most cases the detection of contami-
manner as to avoid the loss or gain of properties for which they
nants that are not ordinarily dispersed uniformly through the are being tested. Some tests are greatly affected by minute
liquid being sampled, such as water or solid particles, neces-
traces of impurities, and it is imperative that utmost precau-
sitates taking samples at specific locations where the contami- tions be taken to prevent contamination when obtaining
nants are likely to be found. For a liquid having a relative samples. Due to the hygroscopic tendency of insulating liquids,
density (specific gravity) less than one, water and some other it is important to minimize exposure to the atmosphere of the
impurities are most likely to be found on or near the bottom. In sample being taken.
the case of a liquid having a specific gravity greater than one,
5.2.2 Take a sufficient quantity of liquid as a sample to
some of these impurities are most likely to be found on or near
cover the requirements of the respective tests to be made. Make
the surface. reference to the procedures governing these tests to ascertain
the quantity of liquid for each test specimen and the number of
4. Significance and Use test specimens required.
5.2.3 When samples are to be taken the temperature of the
4.1 Accurate sampling, whether of the complete contents or
liquid should be equal to or greater than the temperature of the
only parts thereof, is extremely important from the standpoint
surrounding air in order to minimize the possibility of con-
of evaluating the quality of the liquid insulant sampled.
densed moisture from the air being absorbed by the liquid
Obviously, examination of a test specimen that, because of
during the sampling process, particularly in a humid atmo-
careless sampling procedure or contamination in sampling
sphere.
equipment, is not directly representative, leads to erroneous
5.2.4 When taking samples of liquid from large storage
conclusions concerning quality and in addition results in a loss
tanks, transformers, oil-circuit breakers, gravity-fed reservoirs
of time, effort, and expense in securing, transporting, and
on oil-filled cable feeders, and other electrical equipment, the
testing the sample.
electrical equipment drain valve is usually adequate. However,
4.2 A study of gases and moisture contained in insulating
when high relative humidity conditions exist and it is desired to
oils from transformers and other electrical power apparatus can
obtain samples through a closed system, the manifold in Fig.
frequently give an early indication of abnormal behavior of the
10 is recommended.
apparatus, and may indicate appropriate action be taken on the
5.3 General Information when Sampling Electrical Appara-
equipment before it suffers greater damage. Specific gas and
tus:
moisture content can be determined from oil sampled for this
5.3.1 All non-hermetically sealed equipment, filled with
purpose.
insulating liquid having a relative density (specific gravity) less
than 1, should be provided with the sampling outlet located at
the bottom of the tank so that bottom samples of the oil may be
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
obtained.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.3.2 All non-hermetically sealed equipment, filled with
Standardsvolume information, refer to the standard’s Document Summary page on
the ASTM website. insulating liquid having a relative density (specific gravity)
D923 − 15 (2023)
greater than 1, should be provided with the sampling outlet de-energized electrical apparatus. This device is especially
located at the top of the tank at the 25 °C (77 °F) liquid level suitable when collecting samples in a glass jar, metal can, or
so that a top sample of the liquid may be obtained. other suitable containers as described in this section.
5.3.3 When make-up liquid is added to any piece of
6.3 Glass Bottle—Used for securing and storing the sample.
electrical equipment or the liquid is filtered, allow sufficient
Amber or clear (see Notes 1 and 2) and may be either
time to lapse to allow for complete mixing before sampling in
glass-stoppered or fitted with screw caps having a pulp-board
order that a representative sample is obtained.
liner faced with tin or aluminum foil, or with a suitable
5.3.4 If samples or test specimens must be taken when the
oil-resistant plastic such as polyethylene, polytetrafluoroethyl-
liquid temperature is below 0 °C (32 °F), high water content
ene (PTFE) or fluoro-elastomers. Do not use any incompatible
may not be detected because of the formation of ice. Ice is a
natural or synthetic rubber materials. Must meet the require-
concern in both energized and de-energized electrical appara-
ments of Section 16. (See Appendix X2.)
tus where insulating oil-filled compartments operate at tem-
NOTE 1—While amber-colored glass bottles are used for storing
peratures below freezing, such as some tap changer compart-
samples as protection against light, clear glass bottles afford better visual
ments and circuit breaker tanks.
inspection of the samples or test specimens for impurities such as water
5.3.5 When retrieving samples from electrical apparatus, and foreign particles. Take samples that are to be subjected to referee tests
in new amber-colored containers that have been cleaned as described in
record the apparatus temperature (°C) along with the identifi-
Section 16.
cation information as required by Section 19. Knowledge of
the apparatus temperature (°C) at the time of sampling aids in 6.4 Other Bottle or Can Containers (Note 2)—Used for
securing and storing the sample. May be constructed from a
the interpretation of results from certain tests (refer to Appen-
dix X1). suitable oil-resistant plastic such as high-density polyethylene
(HDPE) (do not use for long term storage when water content
5.4 General Information when Sampling Liquid-Filled
is to be determined), or metal cans such as those made from
Tanks, Drums, Tank Trucks, Tank Cars and other Similar
aluminum, stainless steel, other appropriate metal, or PTFE
Containers:
lined. Metals cans are to be constructed as fully extruded,
5.4.1 When sampling large outdoor tanks, tank trucks, tank
pressed seams or welded seams. Solder seams may leave a
cars, and de-energized electrical equipment the temperature of
residue that will contaminate the sample. Screw caps and
the liquid to be sampled may be colder than the surrounding
closures must meet the requirements of 6.3. (See Appendix
air. On such an occasion, determine and report the temperature
X2.)
of the liquid and air as well as the relative humidity with the
NOTE 2—It is recommended to retrieve samples for DGA and water
results of tests. It is undesirable to collect samples that are
analysis using only syringes or stainless steel cylinders. If bottles and cans
exposed to the atmosphere when the relative humidity exceeds
are used, gases that are to be measured in the DGA analysis can easily
50 % or under conditions of rain or snow.
escape from these types of containers. Alternatively, environmental gases
5.4.2 Allow containers of new liquid to remain undisturbed can become entrained into the sample. Both situations can alter the results
significantly.
for at least 8 h before samples or test specimens are taken. In
some instances, such as in the case of tank cars, it is not
6.5 Glass Syringe—The device shown in Fig. 1 must be of
practical to wait this prescribed length of time, and samples for
a suitable size terminated with a Luer lock fitting to which is
routine tests may be taken after the liquid has remained
attached a three-way stopcoc
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