ASTM D7342-20

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Designation: D7342 − 15 D7342 − 20
Standard Test Method for
Prolonged Worked Stability of Lubricating Grease in
Presence of Water (Water Stability Test)
This standard is issued under the fixed designation D7342; 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 a procedure for determining the shear stability of lubricating grease in the presence of water (wet shear
stability) by a full scale grease worker. This test method is also known as the water stability test.
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 safety, health, and healthenvironmental 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:
D217 Test Methods for Cone Penetration of Lubricating Grease
D1193 Specification for Reagent Water
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
3. Terminology
3.1 Definitions:
3.1.1 consistency, n—of lubricating grease, degree of resistance to movement under stress.
3.1.1.1 Discussion—
The term consistency is used somewhat synonymously with penetration. Generally, consistency refers to the worked penetration
of a grease. D217
3.1.2 lubricating grease, n—semi-fluid to solid product of a dispersion of a thickener in a liquid lubricant.
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.G0.02 on Consistency and Related Rheological Tests.
Current edition approved Dec. 1, 2015June 1, 2020. Published February 2016September 2020. Originally approved in 2007. Last previous edition approved in 20072015
as D7342 – 07.D7342 – 15. DOI: 10.1520/D7342-15.10.1520/D7342-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 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 the ASTM website.
*A Summary of Changes section appears at the end of this standard
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D7342 − 20
3.1.2.1 Discussion—
The dispersion of the thickener forms a two-phase system and immobilizes the liquid lubricant by surface tension and other
physical forces. Other ingredients are commonly included to impart special properties. D217
3.1.3 penetration, n—of lubricating grease, depth that the standard cone, when released to fall under its own weight for 5 s, enters
the sample. D217
3.1.4 prolonged worked penetration, n—of lubricating grease, the penetration of a sample after it has been worked more than 60
double strokes in a standard grease worker at a temperature of 15 °C to 30 °C (59 °F to 86 °F).
3.1.4.1 Discussion—
After the prescribed number of double strokes, the worker and contents are brought to 25 °C (77 °F), worked an additional 60
double strokes, and penetrated without delay.
3.1.5 thickener, n—in lubricating grease, substance composed of finely divided particles dispersed in a liquid lubricant to form
the product’s structure.
3.1.5.1 Discussion—
The thickener can be fibers (such as various metallic soaps) or plates or spheres (such as certain non-soap thickener) which are
insoluble or, at most, only very slightly soluble in liquid lubricant. The general requirements are that the solid particles to be be
extremely small, uniformly dispersed, and capable of forming a relatively stable, gel-like structure with the liquid lubricant. D217
3.1.5 wet shear stability, n—of lubricating grease, change in consistency of a mixture of sample and small amount of water after
a specified amount of working in a grease worker.
3.1.6 worked penetration, n—of lubricating grease, the penetration at 25 °C, without delay, of a sample after 60 double strokes
in a standard grease worker. D217
3.1.7 working, n—of lubricating grease, subjection of a sample to the shearing action of the standard grease worker. D217
3.2 Definitions of Terms Specific to This Standard:
3.2.1 wet shear stability, n—of lubricating grease, change in consistency of a mixture of sample and small amount of water after
a specified amount of working in a grease worker.
4. Summary of Test Method
4.1 A grease sample mixed with a small amount of water is subjected to low shear at 20 °C to 35 °C for a specified time or strokes
in a standard grease worker. The difference between the cone penetration before working and the cone penetration after is used
as a measure of the wet shear stability of the grease.
5. Significance and Use
5.1 It is known that contamination by water can affect the shear stability of some greases in service. This test method is widely
used to determine the wet shear stability of greases in service. Many grease specifications require these procedures as a wet shear
stability test. No accurate correlation is established between the test results and wet shear stability of grease in actual service.
6. Apparatus
6.1 Motorized Grease Worker, as specified in Test Methods D217.
6.2 Penetrometer, as specified in Test Methods D217.
6.3 Electric Kitchen-type mixer, Low speed of 500 r ⁄min.
6.4 Suitable Mixing Bowl.
6.5 Spatula.
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