ASTM D5763-22a

Standard Test Method for Oxidation and Thermal Stability Characteristics of Gear Oils Using Universal Glassware

SIGNIFICANCE AND USE
5.1 Degradation of gear oils by oxidation or thermal breakdown, or both, can result in sludge buildup and render the oil unsuitable for further use as a lubricant.  
5.2 This is the only test method that employs glassware to measure the amount of sludge produced during oxidation and thermal degradation. This test method is a modification of Test Method D2893 which measures the viscosity increase and precipitation number of the oil stressed at 95 °C, but does not measure the amount of sludge formed.  
5.3 This test method can be used to evaluate the oxidation/thermal stability of gear oils. However, the test results may not correlate with the performance of gear oils in field service.
SCOPE
1.1 This test method covers the determination of the oxidation characteristics of extreme pressure and non-extreme pressure gear oils and includes the quantitative determination of total sludge, viscosity change, and oil loss.  
Note 1: While the round-robin tests used ISO VG 220 extreme pressure gear oils for developing precision data, the test method can be extended to other viscosity grades and to non-extreme pressure gear oils. Refer to Classification D2422 for viscosity grades.  
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

• Status: Published
• Publication Date: 31-Oct-2022
• ICS: 75.100 - Lubricants, industrial oils and related products
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.09.0D - Oxidation of Lubricants

Relations

• Refers: ASTM D445-24 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Apr-2024
• Refers: ASTM D4175-23a - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 15-Dec-2023
• Refers: ASTM D445-23 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Nov-2023
• Refers: ASTM D4175-23e1 - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Jul-2023
• Refers: ASTM D2893-19 - Standard Test Methods for Oxidation Characteristics of Extreme-Pressure Lubrication Oils
• Effective Date: 01-Dec-2019
• Refers: ASTM D445-16 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 15-Dec-2016
• Refers: ASTM D445-14e1 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Jul-2014
• Refers: ASTM D445-14 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Jul-2014
• Refers: ASTM D2893-04(2014)e1 - Standard Test Method for Oxidation Characteristics of Extreme-Pressure Lubrication Oils
• Effective Date: 01-Jun-2014
• Refers: ASTM D2422-97(2013) - Standard Classification of Industrial Fluid Lubricants by Viscosity System
• Effective Date: 01-May-2013
• Refers: ASTM D445-12 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 15-Apr-2012
• Refers: ASTM D4871-11 - Standard Guide for Universal Oxidation/Thermal Stability Test Apparatus
• Effective Date: 01-Dec-2011
• Refers: ASTM D4057-06(2011) - Standard Practice for Manual Sampling of Petroleum and Petroleum Products
• Effective Date: 01-Jun-2011
• Refers: ASTM D2893-04(2009) - Standard Test Method for Oxidation Characteristics of Extreme-Pressure Lubrication Oils
• Effective Date: 01-Oct-2009
• Refers: ASTM D2422-97(2007) - Standard Classification of Industrial Fluid Lubricants by Viscosity System
• Effective Date: 01-May-2007

Overview

ASTM D5763-22a: Standard Test Method for Oxidation and Thermal Stability Characteristics of Gear Oils Using Universal Glassware is a key international standard developed by ASTM International. This test method focuses on evaluating the oxidation and thermal stability of both extreme pressure and non-extreme pressure gear oils. Using specifically designed universal glassware, it allows for the quantitative determination of total sludge, viscosity change, and oil loss after subjecting gear oil samples to elevated temperatures in the presence of air.

This standard guides laboratories and industry professionals in understanding how gear oils might degrade due to oxidation and thermal breakdown, which can result in sludge buildup and loss of protective lubrication properties. Maintaining gear oil stability is essential to prolong equipment life, prevent failures, and reduce costly maintenance.

Key Topics

• Oxidation and Thermal Degradation: The method reveals the susceptibility of gear oils to chemical changes when exposed to heat and air.
• Sludge Measurement: Unlike other methods, ASTM D5763-22a specifically measures both filterable and adherent sludge produced during aging.
• Viscosity Change and Oil Loss: Monitors the alteration in viscosity and mass loss, which are critical indicators of lubricant stability.
• Universal Glassware: The standardized test setup ensures reproducibility and comparability across laboratories.
• Applicability to Various Gear Oils: Although originally validated for ISO VG 220 extreme pressure gear oils, the procedure can be applied to a range of viscosity grades and oil types.

Applications

ASTM D5763-22a is widely used in several practical contexts:

• Quality Control in Lubricant Manufacturing: Oil formulators and manufacturers use this method to compare thermal-oxidative resistance among gear oil formulations, ensuring product reliability before marketplace release.
• Research and Development: Product developers employ this test to assess new additives or base oils for improved oxidation stability and reduced sludge formation.
• In-Service Oil Monitoring: Although field performance correlations may vary, the method provides a controlled baseline for interpreting used oil analyses and predicting relative oil life under thermal stress.
• Equipment Maintenance Planning: Insights from sludge and viscosity data support the development of maintenance schedules, oil change intervals, and troubleshooting alerts in heavy industry and automotive applications.

Related Standards

ASTM D5763-22a references and aligns with several important standards in gear oil testing and classification:

• ASTM D445: Test Method for Kinematic Viscosity of Transparent and Opaque Liquids
• ASTM D2422: Classification of Industrial Fluid Lubricants by Viscosity System
• ASTM D2893: Test Methods for Oxidation Characteristics of Extreme-Pressure Lubrication Oils
• ASTM D4057: Practice for Manual Sampling of Petroleum and Petroleum Products
• ASTM D4175: Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• ASTM D4871: Guide for Universal Oxidation/Thermal Stability Test Apparatus

These referenced documents ensure that ASTM D5763-22a is part of a comprehensive framework for lubricant evaluation, supporting consistent methodology and terminology in the industry.

Summary

By providing a reproducible measure of oxidation and thermal stability using universal glassware, ASTM D5763-22a supports lubricant manufacturers, researchers, and maintenance professionals in maintaining the integrity and performance of gear oils. Its focus on real, measurable degradation byproducts like sludge makes it a valuable tool for ensuring the reliability and efficiency of mechanical systems that rely on gear lubrication. For organizations committed to quality lubrication and equipment longevity, adherence to ASTM D5763-22a and related standards is essential.

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: D5763 − 22a
Standard Test Method for
Oxidation and Thermal Stability Characteristics of Gear Oils
Using Universal Glassware
This standard is issued under the fixed designation D5763; 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* Extreme-Pressure Lubrication Oils
D4057 Practice for Manual Sampling of Petroleum and
1.1 This test method covers the determination of the oxida-
Petroleum Products
tion characteristics of extreme pressure and non-extreme pres-
D4175 Terminology Relating to Petroleum Products, Liquid
sure gear oils and includes the quantitative determination of
Fuels, and Lubricants
total sludge, viscosity change, and oil loss.
D4871 Guide for Universal Oxidation/Thermal Stability
NOTE 1—While the round-robin tests used ISO VG 220 extreme
Test Apparatus
pressure gear oils for developing precision data, the test method can be
extended to other viscosity grades and to non-extreme pressure gear oils.
3. Terminology
Refer to Classification D2422 for viscosity grades.
3.1 Definitions:
1.2 The values stated in SI units are to be regarded as
3.1.1 See Terminology D4175 for a list of terms relating to
standard. No other units of measurement are included in this
petroleum products, liquid fuels, and lubricants.
standard.
3.2 Definitions of Terms Specific to This Standard:
1.3 This standard does not purport to address all of the
3.2.1 adherent sludge, n—sludge that is formed on the walls
safety concerns, if any, associated with its use. It is the
of a container and is not easily removed.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter- 3.2.2 aliquot, n—portion of sample being tested that is a
representative portion of the whole.
mine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accor-
3.2.3 extreme pressure gear oil, n—a fluid for the lubrica-
dance with internationally recognized principles on standard-
tion of gears that contains chemical additives, such as sulfur
ization established in the Decision on Principles for the
and phosphorus compounds, which produce a protective film
Development of International Standards, Guides and Recom-
on the metal surface to provide enhanced load carrying
mendations issued by the World Trade Organization Technical
capability.
Barriers to Trade (TBT) Committee.
3.2.4 filterable sludge, n—sludge that is formed in the oil.
2. Referenced Documents 3.2.5 non-extreme pressure gear oil, n—a fluid for the
2 lubrication of gears that contains no chemical additives that
2.1 ASTM Standards:
produce a protective film on the metal surface to provide
D445 Test Method for Kinematic Viscosity of Transparent
enhanced load carrying capability.
and Opaque Liquids (and Calculation of Dynamic Viscos-
3.2.6 oxidation,n—theprocessbywhichoxygenchemically
ity)
reacts with materials.
D2422 Classification of Industrial Fluid Lubricants by Vis-
cosity System
3.2.7 sludge, n—in gear oils, a precipitate that sometimes
D2893 Test Methods for Oxidation Characteristics of
forms as the oil ages or oxidizes that is insoluble in n-heptane.
3.2.8 universal glassware, n—the glassware that is de-
scribed in the universal oxidation thermal stability test. Refer
This test method is under the jurisdiction of ASTM Committee D02 on
to Guide D4871.
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.09.0D on Oxidation of Lubricants.
Current edition approved Nov. 1, 2022. Published November 2022. Originally
4. Summary of Test Method
approved in 1995. Last previous edition approved in 2022 as D5763 – 22. DOI:
10.1520/D5763-22A.
4.1 The viscosity of the gear oil being tested is determined.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
A 100 g aliquot of the oil in a weighed apparatus is subjected
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
to a temperature of 120 °C for 312 h while dry air is passed
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. through the aliquot at 3 L⁄h.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5763 − 22a
4.2 At the end of the stress period, the aliquot is cooled to 6.5 Air Dryer—Before being supplied to the flowmeters, the
room temperature.The apparatus is reweighed to determine oil air shall be passed through a drying tower packed with
loss. Filterable sludge is recovered by vacuum filtration using indicating grade anhydrous calcium sulfate or equivalent. The
a 2.8 µm glass fiber filter medium. The viscosity of the filtered quantity of desiccant should be sufficient to last for the entire
oil is determined. Sludge adhering to the oxidation cell and test. It is recommended that the drying tower be filled with
associated glassware is rinsed with n-heptane and the washings fresh desiccant prior to the test.
passed through the same filter used to filter the filterable
6.6 Filter, glass fiber, 2.8 µm porosity, 47 mm in diameter.
sludge. The filter is dried in an oven to a constant weight to
6.7 Balance, electronic, top-loading, capable of weighing to
determine the total filterable sludge.
thenearestcentigram(0.01 g)andhavingthecapacitytoweigh
4.3 The apparatus is dried and weighed to determine the
up to 2000 g.
amountofadherentsludge.Thesumofthefilterablesludgeand
6.8 Filter Holder, 47 mm, consisting of a borosilicate glass
adherent sludge is reported as total sludge. The percentage
funnel and a funnel base with a coarse-grade fritted glass filter
change in viscosity and percent oil loss are also reported.
support or stainless steel screen support such that the filter can
be clamped between the ground glass sealing surfaces of the
5. Significance and Use
funnel and its base by means of a metal clamp.
5.1 Degradation of gear oils by oxidation or thermal
6.9 Oven, explosive-proof, capable of heating from 50 °C to
breakdown,orboth,canresultinsludgebuildupandrenderthe
60 °C and of a sufficient size to hold oxidation cells.
oil unsuitable for further use as a lubricant.
6.10 Thermometer, ASTM solvent distillation thermometer
5.2 This is the only test method that employs glassware to
having a range from 98 °C to 152 °C or equivalent digital
measure the amount of sludge produced during oxidation and
contact thermometer.
thermal degradation. This test method is a modification of Test
Method D2893 which measures the viscosity increase and
6.11 Vacuum Source, to provide pressure reduction to
precipitation number of the oil stressed at 95 °C, but does not
100 mm 6 5 mm Hg absolute pressure.
measure the amount of sludge formed.
7. Reagents and Materials
5.3 This test method can be used to evaluate the oxidation/
thermal stability of gear oils. However, the test results may not
7.1 Air Supply, dried air, oil free, at constant pressure to
correlate with the performance of gear oils in field service.
permit 3 L⁄h air flow through the system. House air supply or
pressurized air cylinders can be used.
6. Apparatus
7.2 Calcium Sulfate Desiccant,Anhydrous,indicatinggrade
6.1 Heating Bath or Block, thermostatically controlled,
(desiccant that changes color when it nears saturation with
capable of maintaining the oil sample in the oxidation cell at a
water). Desiccants equivalent to calcium sulfate can be used.
uniform temperature of 120 °C 6 1 °C and large enough to
7.3 n-Heptane—minimum purity, 99.75 %. (Warning—n-
hold a minimum of two oxidation cells and sufficiently deep to
Heptane is flammable and a health hazard.)
allow approximately 120 mm of the test tubes to extend above
the heating liquid or block. The heating block is further
8. Sampling
described in Test Method D4871.
8.1 Samples for this test method can come from tanks,
6.2 Oxidation Cell, consists of borosilicate glass; a 38 mm
drums, small containers, or operating equipment. Therefore,
inside diameter and a 300 mm 6 5 mm length is required.
use the applicable apparatus and techniques described in
NOTE 2—While the round-robin test used the oxidation cell from a
Practice D4057 to obtain suitable samples.
specific equipment manufacturer in determining the precision statement,
8.2 Special precautions to preserve the integrity of a sample
the test method permits the use of other oxidation cells that meet the
requirements of 6.2.
will not normally be required. It is good practice to avoid
undue exposure of samples to heat, sunlight, or strong direct
6.3 Air Delivery Tube, a borosilicate glass tube having an
light. Visibly heterogeneous samples should not be used.
inside diameter of 5 mm and a minimum length of 320 mm,
with the lower tip cut at a 45° angle.
8.3 It is recommended that a 200 mL representative be
obtained.To ensure the aliquot being tested is representative of
NOTE 3—The oxidation cell and delivery tube are further described in
Test Method D4871. thesample,agitation;forexample,stirringorshakingoftheoil
3 prior to obtaining an aliquot, is recommended.
6.4 Flowmeters, one for each oxidation cell, capable of
measuring an air flow of 3 L⁄h 6 0.5 L⁄h.
9. Preparation of Apparatus
9.1 Cleaning Glassware:
9.1.1 Clean new glassware by washing with a hot detergent
The sole source of supply of the apparatus (universal glassware and heating
bath with flowmeters as a complete unit) known to the committee at this time is
solution (using a bristle brush) and rinse thoroughly with tap
Falex Corporation, 1020 Airpark Drive, Sugar Grove, IL 60554-9452. If you are
water. When any visible deposits remain, soaking with a hot
aware of alternative suppliers, please provide this information to ASTM Interna-
detergent solution can be helpful. After final cleaning by
tional Headquarters.Your comments will receive careful consideration at a meeting
of the responsible technical committee, which you may attend. soaking with a suitable cleaning solution rinse thoroughly with
D5763 − 22a
days can give variable test results.
tap water and then distilled water, and
...

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: D5763 − 22 D5763 − 22a
Standard Test Method for
Oxidation and Thermal Stability Characteristics of Gear Oils
Using Universal Glassware
This standard is issued under the fixed designation D5763; 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*
1.1 This test method covers the determination of the oxidation characteristics of extreme pressure and non-extreme pressure gear
oils and includes the quantitative determination of total sludge, viscosity change, and oil loss.
NOTE 1—While the round-robin tests used ISO VG 220 extreme pressure gear oils for developing precision data, the test method can be extended to other
viscosity grades and to non-extreme pressure gear oils. Refer to Classification D2422 for viscosity grades.
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.
2. Referenced Documents
2.1 ASTM Standards:
D445 Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
D2422 Classification of Industrial Fluid Lubricants by Viscosity System
D2893 Test Methods for Oxidation Characteristics of Extreme-Pressure Lubrication Oils
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D4871 Guide for Universal Oxidation/Thermal Stability Test Apparatus
3. Terminology
3.1 Definitions:
3.1.1 See Terminology D4175 for a list of terms relating to petroleum products, liquid fuels, and lubricants.
3.2 Definitions of Terms Specific to This Standard:
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.09.0D on Oxidation of Lubricants.
Current edition approved July 1, 2022Nov. 1, 2022. Published July 2022November 2022. Originally approved in 1995. Last previous edition approved in 20162022 as
D5763 – 11 (2016).D5763 – 22. DOI: 10.1520/D5763-22.10.1520/D5763-22A.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5763 − 22a
3.2.1 adherent sludge, n—sludge that is formed on the walls of a container and is not easily removed.
3.2.2 aliquot, n—portion of sample being tested that is a representative portion of the whole.
3.2.3 extreme pressure gear oil, n—a fluid for the lubrication of gears that contains chemical additives, such as sulfur and
phosphorus compounds, which produce a protective film on the metal surface to provide enhanced load carrying capability.
3.2.4 filterable sludge, n—sludge that is formed in the oil.
3.2.5 non-extreme pressure gear oil, n—a fluid for the lubrication of gears that contains no chemical additives that produce a
protective film on the metal surface to provide enhanced load carrying capability.
3.2.6 oxidation, n—the process by which oxygen chemically reacts with materials.
3.2.7 sludge, n—in gear oils, a precipitate that sometimes forms as the oil ages or oxidizes that is insoluble in n-heptane.
3.2.8 universal glassware, n—the glassware that is described in the universal oxidation thermal stability test. Refer to Guide
D4871.
4. Summary of Test Method
4.1 The viscosity of the gear oil being tested is determined. A 100 g aliquot of the oil in a weighed apparatus is subjected to a
temperature of 120 °C for 312 h while dry air is passed through the aliquot at 3 L ⁄h.
4.2 At the end of the stress period, the aliquot is cooled to room temperature. The apparatus is reweighed to determine oil loss.
Filterable sludge is recovered by vacuum filtration using a 2.8 μm glass fiber filter medium. The viscosity of the filtered oil is
determined. Sludge adhering to the oxidation cell and associated glassware is rinsed with n-heptane and the washings passed
through the same filter used to filter the filterable sludge. The filter is dried in an oven to a constant weight to determine the total
filterable sludge.
4.3 The apparatus is dried and weighed to determine the amount of adherent sludge. The sum of the filterable sludge and adherent
sludge is reported as total sludge. The percentage change in viscosity and percent oil loss are also reported.
5. Significance and Use
5.1 Degradation of gear oils by oxidation or thermal breakdown, or both, can result in sludge buildup and render the oil unsuitable
for further use as a lubricant.
5.2 This is the only test method that employs glassware to measure the amount of sludge produced during oxidation and thermal
degradation. This test method is a modification of Test Method D2893 which measures the viscosity increase and precipitation
number of the oil stressed at 95 °C, but does not measure the amount of sludge formed.
5.3 This test method can be used to evaluate the oxidation/thermal stability of gear oils. However, the test results may not correlate
with the performance of gear oils in field service.
6. Apparatus
6.1 Heating Bath or Block, thermostatically controlled, capable of maintaining the oil sample in the oxidation cell at a uniform
temperature of 120 °C 6 1 °C and large enough to hold a minimum of two oxidation cells and sufficiently deep to allow
approximately 120 mm of the test tubes to extend above the heating liquid or block. The heating block is further described in Test
Method D4871.
The sole source of supply of the apparatus (universal glassware and heating bath with flowmeters as a complete unit) known to the committee at this time is Falex
Corporation, 1020 Airpark Drive, Sugar Grove, IL 60554-9452. If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters.
Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend.
D5763 − 22a
6.2 Oxidation Cell, consists of borosilicate glass; a 38 mm inside diameter and a 300 mm 6 5 mm length is required.
NOTE 2—While the round-robin test used the oxidation cell from a specific equipment manufacturer in determining the precision statement, the test
method permits the use of other oxidation cells that meet the requirements of 6.2.
6.3 Air Delivery Tube, a borosilicate glass tube having an inside diameter of 5 mm and a minimum length of 320 mm, with the
lower tip cut at a 45° angle.
NOTE 3—The oxidation cell and delivery tube are further described in Test Method D4871.
6.4 Flowmeters, one for each oxidation cell, capable of measuring an air flow of 3 L ⁄h 6 0.5 L ⁄h.
6.5 Air Dryer—Before being supplied to the flowmeters, the air shall be passed through a drying tower packed with indicating
grade anhydrous calcium sulfate or equivalent. The quantity of desiccant should be sufficient to last for the entire test. It is
recommended that the drying tower be filled with fresh desiccant prior to the test.
6.6 Filter, glass fiber, 2.8 μm porosity, 47 mm in diameter.
6.7 Balance, electronic, top-loading, capable of weighing to the nearest centigram (0.01 g) and having the capacity to weigh up
to 2000 g.
6.8 Filter Holder, 47 mm, consisting of a borosilicate glass funnel and a funnel base with a coarse-grade fritted glass filter support
or stainless steel screen support such that the filter can be clamped between the ground glass sealing surfaces of the funnel and
its base by means of a metal clamp.
6.9 Oven, explosive-proof, capable of heating from 50 °C to 60 °C and of a sufficient size to hold oxidation cells.
6.10 Thermometer, ASTM solvent distillation thermometer having a range from 98 °C to 152 °C or equivalent digital contact
thermometer.
6.11 Vacuum Source, to provide pressure reduction to 100 mm 6 5 mm Hg absolute pressure.
7. Reagents and Materials
7.1 Air Supply, dried air, oil free, at constant pressure to permit 3 L ⁄h air flow through the system. House air supply or pressurized
air cylinders can be used.
7.2 Calcium Sulfate Desiccant, Anhydrous, indicating grade (desiccant that changes color when it nears saturation with water).
Desiccants equivalent to calcium sulfate can be used.
7.3 n-Heptane—minimum purity, 99.75 %. (Warning—n-Heptane is flammable and a health hazard.)
8. Sampling
8.1 Samples for this test method can come from tanks, drums, small containers, or operating equipment. Therefore, use the
applicable apparatus and techniques described in Practice D4057 to obtain suitable samples.
8.2 Special precautions to preserve the integrity of a sample will not normally be required. It is good practice to avoid undue
exposure of samples to heat, sunlight, or strong direct light. Visibly heterogeneous samples should not be used.
8.3 It is recommended that a 200 mL representative be obtained. To ensure the aliquot being tested is representative of the sample,
agitation; for example, stirring or shaking of the oil prior to obtaining an aliquot, is recommended.
D5763 − 22a
9. Preparation of Apparatus
9.1 Cleaning Glassware:
9.1.1 Clean new glassware by washing with a hot detergent solution (using a bristle brush) and rinse thoroughly with tap water.
When any visible deposits remain, soaking with a hot detergent solution can be helpful. After final cleaning by soaking with a
suitable cleaning solution rinse thoroughly with tap water and then distilled water, and allow to dry at ro
...