ASTM D4055-04(2019)

Standard Test Method for Pentane Insolubles by Membrane Filtration

SIGNIFICANCE AND USE
5.1 Pentane insolubles above 0.8 μm in size may lead to increased wear. This increased wear can lead to premature equipment failure in critical applications.
SCOPE
1.1 This test method covers the determination of pentane insolubles for particles exceeding 0.8 μm in new and used lubricating oils.  
Note 1: Pentane insolubles with particle sizes less than 0.8 μm may be studied with appropriate size membrane filters. Particle sizes above or below 0.8 μm can be studied. The precision of this test method has been determined only at 0.8 μm.  
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.  For specific warning statements, see 7.1, 8.2.1, and Annex A1.  
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-Dec-2018
• ICS: 75.100 - Lubricants, industrial oils and related products
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.06 - Analysis of Liquid Fuels and Lubricants

Relations

• Replaces: ASTM D4055-04(2013) - Standard Test Method for Pentane Insolubles by Membrane Filtration
• Effective Date: 01-Jan-2019
• Refers: ASTM D4175-23a - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 15-Dec-2023
• Refers: ASTM D4175-23e1 - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Jul-2023
• 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

Overview

ASTM D4055-04(2019) – Standard Test Method for Pentane Insolubles by Membrane Filtration outlines a procedure for determining the pentane-insoluble content in new and used lubricating oils. The method targets particles exceeding 0.8 μm, providing a significant measure of oil cleanliness and potential wear-inducing contaminants. Developed by ASTM International, this test method is recognized for its role in identifying insoluble materials that may contribute to equipment degradation and failure in critical applications such as engines, gearboxes, and turbines.

Key Topics

• Pentane Insolubles Determination: The standard covers a methodology for quantifying particles greater than 0.8 μm in lubricating oils through membrane filtration.
• Size Specificity: Only particles above 0.8 μm are measured for precision; the use of membranes with different pore sizes is possible for other analyses, but is not validated within this method.
• Analytical Procedure:
  • Mixing oil samples with pentane
  • Filtering the solution through a 0.8 μm membrane
  • Washing, drying, and weighing the filter to determine insoluble content
• Result Calculation: Pentane insolubles are reported as a percentage by weight of the oil sample.
• Significance in Equipment Reliability: Insolubles above critical size thresholds can accelerate wear, increasing the risk of premature mechanical failure.

Applications

This standard test method has practical applications across several industries where lubricating oil cleanliness is paramount:

• Condition Monitoring of Lubricating Oils: Routine analysis using ASTM D4055-04(2019) enables maintenance teams to assess levels of contamination and make informed decisions on oil change intervals.
• Equipment Protection: By identifying high levels of pentane insolubles, organizations can preemptively address issues affecting engines, turbines, gearboxes, and hydraulic systems, thereby minimizing downtime and repair costs.
• Quality Control in Lubricant Manufacturing: Oil producers utilize this method to ensure new lubricating oils meet cleanliness and performance specifications before distribution.
• Failure Analysis: The detection of excessive insoluble content aids in investigating causes of wear or mechanical failures.
• Industrial and Power Generation Sectors: Facilities operating high-value, critical machinery benefit from routine application of this test to monitor oil integrity.

Related Standards

For comprehensive oil analysis and petroleum product testing, ASTM D4055-04(2019) is often used alongside other ASTM standards and industry references, including:

• ASTM D4057: Practice for Manual Sampling of Petroleum and Petroleum Products
• ASTM D4175: Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• ASTM D4177: Practice for Automatic Sampling of Petroleum and Petroleum Products

These standards ensure consistency in sample collection, terminology, and procedures, supporting robust oil condition monitoring programs and reliable test results.

Keywords: pentane insolubles, membrane filtration, lubricating oil analysis, ASTM D4055, oil cleanliness, equipment wear, particle contamination, petroleum product testing

By following the ASTM D4055-04(2019) standard, industries can effectively measure and control pentane-insoluble contaminants, safeguarding equipment performance and optimizing maintenance practices.

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: D4055 − 04 (Reapproved 2019)
Standard Test Method for
Pentane Insolubles by Membrane Filtration
This standard is issued under the fixed designation D4055; 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 3. Terminology
3.1 Definitions:
1.1 This test method covers the determination of pentane
3.1.1 pentane insolubles, in used oil analysis, n—separated
insolubles for particles exceeding 0.8 µm in new and used
matter resulting when a used oil is dissolved in pentane.
lubricating oils.
3.1.1.1 Discussion—In this test method, the separation is
NOTE 1—Pentane insolubles with particle sizes less than 0.8 µm may be
effected by filtration through a membrane.
studied with appropriate size membrane filters. Particle sizes above or
3.1.2 used oil, n—any oil that has been in a piece of
below 0.8 µm can be studied. The precision of this test method has been
determined only at 0.8 µm.
equipment (for example, an engine, gearbox, transformer, or
turbine) whether operated or not. D4175
1.2 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
4. Summary of Test Method
standard.
4.1 A sample of new or used lubricating oil is mixed with
1.3 This standard does not purport to address all of the
pentane in a volumetric flask. The oil solution is filtered
safety concerns, if any, associated with its use. It is the
through an 0.8 µm membrane filter.The flask, funnel, and filter
responsibility of the user of this standard to establish appro-
are washed with additional pentane to effect a complete
priate safety, health, and environmental practices and deter-
transfer of particulates onto the filter. The filter and its
mine the applicability of regulatory limitations prior to use.
particulates are dried and weighed to give the pentane in-
For specific warning statements, see 7.1, 8.2.1, and AnnexA1.
solubles.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
5. Significance and Use
ization established in the Decision on Principles for the
5.1 Pentane insolubles above 0.8 µm in size may lead to
Development of International Standards, Guides and Recom-
increased wear. This increased wear can lead to premature
mendations issued by the World Trade Organization Technical
equipment failure in critical applications.
Barriers to Trade (TBT) Committee.
6. Apparatus
2. Referenced Documents
6.1 In the development of this test method, it was noted that
2.1 ASTM Standards:
variations, particularly with respect to glassware and filter
D4057 Practice for Manual Sampling of Petroleum and
media, can affect the test result significantly.
Petroleum Products
D4175 Terminology Relating to Petroleum Products, Liquid 6.2 When the user of this test method uses an alternate
Fuels, and Lubricants
membrane filter, it is incumbent upon them to establish that the
D4177 Practice for Automatic Sampling of Petroleum and alternate filter will give equal results.
Petroleum Products
6.3 Precision data were established using the apparatus
listed and a 0.8 µm filter pore size.
6.4 Membrane Filter.
This test method is under the jurisdiction of ASTM Committee D02 on
6.5 Borosilicate Filter Holder.
Petroleum Products, Liquid Fuels, and Lubricantsand is the direct responsibility of
Subcommittee D02.06 on Analysis of Liquid Fuels and Lubricants.
6.6 Borosilicate Filtering Flask.
Current edition approved Jan. 1, 2019. Published February 2019. Originally
approved in 1992. Last previous edition approved in 2013 as D4055 – 04 (2013).
6.7 Forceps (plain flat tips, not serrated),
DOI: 10.1520/D4055-04R19.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 6.8 Wash Bottle equipped with 0.8 µm membranes.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
6.9 Analytical Balance, capable of weighing with an accu-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. racy of 60.1 mg.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4055 − 04 (2019)
6.10 Vacuum Source, capable of maintaining a vacuum of 8.3 Filtration:
255 mm 6 50 mm Hg. 8.3.1 Remove the membrane filter from the weighing dish
with the flat forceps and center in the filtering apparatus.
6.11 Oven, capable of maintaining 90 °C 6 5 °C.
Assemble the funnel and clamp.
6.12 Oven Thermometer, ASTM Thermometer 1C.
8.3.2 Fill the volumetric flask containing the sample to the
6.13 Aluminum Foil Weighing Dish, about 60 mm in diam- 100 mL mark with filtered pentane. Stopper and shake well.
Immediately filter the mixture using a vacuum of 255 mm 6
eter.
50 mm Hg (see 8.1.3.1). Rinse the flask and stopper twice with
6.14 Desiccator, with calcium chloride.
small amounts of filtered pentane, pouring the washings down
6.15 Mechanical Paint Shaker, three-dimensional.
the sides of the filter funnel. Rinse the walls of the filter funnel
withagentlestreamofpentanedispensedfromthewashbottle.
6.16 Volumetric Flask, 100 mL with ground-glass or TFE-
8.3.3 Carefully, remove the clamp and funnel. Wash any
fluorocarbon stopper.
adhering insolubles from the funnel onto the membrane, using
6.17 Ionizing Unit, insert under or next to balance pan.
the wash bottle with pentane. Wash the membrane gently,
particularly the edges, with pentane from the wash bottle. If
7. Reagent
any sample fails to remain on the membrane, the test must be
7.1 Pentane, reagent grade or bett
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