ASTM D91-02(2019)
(Test Method)Standard Test Method for Precipitation Number of Lubricating Oils
General Information
- Abstract
SIGNIFICANCE AND USE
4.1 Fully refined petroleum oils normally contain no naphtha-insoluble material. Semirefined or black oils frequently contain some naphtha-insoluble material (sometimes referred to as asphaltenes). This test measures the amount of naphtha-insoluble material in the oil. This quantity is reported as the precipitation number.
SCOPE
1.1 This test method covers the determination of the precipitation number of steam cylinder stocks and black oils, and can be used for other lubricating oils.
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.
- Status
- Published
- Publication Date
- 30-Apr-2019
- Technical Committee
- D02 - Petroleum Products, Liquid Fuels, and Lubricants
- Drafting Committee
- D02.06 - Analysis of Liquid Fuels and Lubricants
Overview
ASTM D91-02(2019): Standard Test Method for Precipitation Number of Lubricating Oils is an internationally recognized standard published by ASTM International. This test method is essential for determining the precipitation number-the volume of naphtha-insoluble material, often referred to as asphaltenes-in steam cylinder stocks, black oils, and other lubricating oils. By providing a repeatable and reliable procedure for measuring insoluble content, ASTM D91-02(2019) supports quality assurance and process control in the petroleum and lubricants industry.
Understanding the precipitation number is critical for manufacturers and end users, as the presence of insolubles can affect oil performance, equipment longevity, and maintenance requirements.
Key Topics
Significance of Precipitation Number:
The precipitation number reflects the amount of naphtha-insoluble materials present in lubricating oils. While fully refined petroleum oils typically contain minimal or no insolubles, semirefined or black oils can have higher levels, potentially affecting their suitability for various applications.Test Method Overview:
- Oils are mixed with a specified volume of precipitation naphtha.
- The mixture is centrifuged to isolate insoluble materials.
- The volume of resulting sediment is measured to the nearest 0.1 mL.
- The final value, reported as the ASTM precipitation number, provides an empirical indication of the oil’s cleanliness and suitability for service.
Precision and Reproducibility:
The test method details procedures for ensuring repeatability and comparability of results between laboratories. The standard specifies SI units for reporting.Safety and Compliance:
Users must observe appropriate safety, health, and environmental practices, as the test involves flammable reagents and laboratory equipment.
Applications
ASTM D91-02(2019) is widely used in the petroleum, lubricants, and industrial manufacturing sectors for several critical applications:
Quality Control and Specification Compliance:
Refineries, lubricant blenders, and oil reprocessors use this test to ensure products meet required standards for insoluble content before shipment or blending.Equipment Maintenance and Reliability:
Power plants, manufacturing facilities, and marine operators rely on oils with low precipitation numbers to minimize the risk of deposits, wear, and potential equipment downtime.Research and Product Development:
The precipitation number is an important parameter in the development of new oils or additive packages, allowing researchers to compare and refine formulations for improved performance.Field Testing and Diagnostics:
The procedure is useful for monitoring changes in oil condition over time, helping to identify degradation or contamination that may require corrective action.
Related Standards
Professionals referencing ASTM D91-02(2019) should be aware of related ASTM standards that support consistent sampling and evaluation of petroleum products:
- ASTM D4057 - Practice for Manual Sampling of Petroleum and Petroleum Products
- ASTM D4177 - Practice for Automatic Sampling of Petroleum and Petroleum Products
These standards ensure correct sample collection, which is crucial for obtaining accurate precipitation number results.
ASTM D91-02(2019) provides a robust, globally recognized method for determining the precipitation number in lubricating oils. By ensuring thorough measurement and reporting, it helps industries maintain lubricant quality, optimize equipment performance, and uphold safety and regulatory standards. Proper application of this test method supports ongoing reliability and efficiency in lubricated systems.
Relations
- Refers
ASTM D4057-06(2011) - Standard Practice for Manual Sampling of Petroleum and Petroleum Products - Effective Date
- 01-Jun-2011
- Refers
ASTM D4057-95(2000) - Standard Practice for Manual Sampling of Petroleum and Petroleum Products - Effective Date
- 10-Apr-2000
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Frequently Asked Questions
ASTM D91-02(2019) is a standard published by ASTM International. Its full title is "Standard Test Method for Precipitation Number of Lubricating Oils". This standard covers: SIGNIFICANCE AND USE 4.1 Fully refined petroleum oils normally contain no naphtha-insoluble material. Semirefined or black oils frequently contain some naphtha-insoluble material (sometimes referred to as asphaltenes). This test measures the amount of naphtha-insoluble material in the oil. This quantity is reported as the precipitation number. SCOPE 1.1 This test method covers the determination of the precipitation number of steam cylinder stocks and black oils, and can be used for other lubricating oils. 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.
SIGNIFICANCE AND USE 4.1 Fully refined petroleum oils normally contain no naphtha-insoluble material. Semirefined or black oils frequently contain some naphtha-insoluble material (sometimes referred to as asphaltenes). This test measures the amount of naphtha-insoluble material in the oil. This quantity is reported as the precipitation number. SCOPE 1.1 This test method covers the determination of the precipitation number of steam cylinder stocks and black oils, and can be used for other lubricating oils. 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.
ASTM D91-02(2019) is classified under the following ICS (International Classification for Standards) categories: 75.100 - Lubricants, industrial oils and related products. The ICS classification helps identify the subject area and facilitates finding related standards.
ASTM D91-02(2019) has the following relationships with other standards: It is inter standard links to ASTM D4057-06(2011), ASTM D4057-95(2000). Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ASTM D91-02(2019) is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
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: D91 − 02 (Reapproved 2019)
Standard Test Method for
1,2
Precipitation Number of Lubricating Oils
This standard is issued under the fixed designation D91; 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.Asuperscript
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 lubricating oil are mixed with 90 mL of ASTM precipitation
naphtha, and centrifuged under the conditions of the test.
1.1 This test method covers the determination of the pre-
cipitation number of steam cylinder stocks and black oils, and
4. Significance and Use
can be used for other lubricating oils.
4.1 Fully refined petroleum oils normally contain no
1.2 The values stated in SI units are to be regarded as
naphtha-insoluble material. Semirefined or black oils fre-
standard. No other units of measurement are included in this
quently contain some naphtha-insoluble material (sometimes
standard.
referred to as asphaltenes). This test measures the amount of
1.3 This standard does not purport to address all of the
naphtha-insoluble material in the oil. This quantity is reported
safety concerns, if any, associated with its use. It is the
as the precipitation number.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
5. Apparatus
mine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accor- 5.1 Centrifuge Tube, cone-shaped, conforming to the di-
dance with internationally recognized principles on standard- mensions given in Fig. 1, and made of thoroughly annealed
ization established in the Decision on Principles for the glass. The graduations, numbered as shown in Fig. 1, shall be
Development of International Standards, Guides and Recom- clearanddistinct,andthemouthshallbeconstructedinashape
mendations issued by the World Trade Organization Technical suitable for closure with a cork. Scale-error tolerances and
Barriers to Trade (TBT) Committee. smallest graduations between various calibration marks are
given in Table 1 and apply to calibrations made with air-free
2. Referenced Documents
water at 20 °C.
2.1 ASTM Standards:
5.2 Centrifuge, meeting all the safety requirements for
D4057 Practice for Manual Sampling of Petroleum and
normal use and capable of whirling two or more filled
Petroleum Products
centrifuge tubes at a speed which can be controlled to give a
D4177 Practice for Automatic Sampling of Petroleum and
relative centrifugal force (rcf) between 600 and 700 at the tips
Petroleum Products
of the tubes. The revolving head, trunnion rings, and trunnion
cups, including the rubber cushion, shall be soundly con-
3. Terminology
structed to withstand the maximum centrifugal force capable of
3.1 Definitions of Terms Specific to This Standard: being delivered by the power source. The trunnion cups and
3.1.1 ASTM precipitation number, of lubricating oils, n—the cushions shall firmly support the tubes when the centrifuge is
number of millilitres of precipitate formed when 10 mL of in motion.The centrifuge shall be enclosed by a metal shield or
case strong enough to eliminate danger if any breakage occurs.
Calculate the speed of the rotating head by means of the
This test method is under the jurisdiction of ASTM Committee D02 on
following equation:
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.06 on Analysis of Liquid Fuels and Lubricants.
speed, r/min 5 1337 =rcf/d (1)
CurrenteditionapprovedMay1,2019.PublishedJuly2019.Originallyapproved
in 1921. Last previous edition approved in 2017 as D91 – 02 (2017). DOI: where:
10.1520/D0091-02R19.
rcf = relative centrifugal force, and
This test method has been adopted for use by government agencies to replace
d = diameter of swing, in mm, measured between tips of
Method 3101 of Federal Test Method Standard No. 791b.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or opposite tubes when in rotating position.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Table 2 shows the relationship between diameter swing, rcf,
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. and revolutions per minute.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D91 − 02 (2019)
to the 100 mL mark with hexanes and close tightly with a
softened cork (not a rubber stopper). T
...