1. Scope
1.1 This test method covers quantitative procedures for the evaluation of the compatibility of automotive engine oils with five reference elastomers typical of those used in the sealing materials in contact with these oils. Compatibility is evaluated by determining the changes in volume, Durometer A hardness and tensile properties when the elastomer specimens are immersed in the oil for a specified time and temperature.
1.2 Effective sealing action requires that the physical properties of elastomers used for any seal have a high level of resistance to the liquid or oil in which they are immersed. When such a high level of resistance exists, the elastomer is said to be compatible with the liquid or oil.
NOTE 1 - The user of this test method should be proficient in the use of Test Methods D412 (tensile properties), D471 (effect of rubber immersion in liquids), D2240 (Durometer hardness), and D5662 (gear oil compatibility with typical oil seal elastomers), all ofwhich are involved in the execution of the operations of this test method.
1.3 This test method provides a preliminary or first order evaluation of oil/elastomer compatibility only. Because seals may be subjected to static or dynamic loads, or both, and they may operate over a range of conditions, a complete evaluation of the potential sealing performance of any elastomer-oil combination in any service condition usually requires tests additional to those described in this test method.
1.4 The five reference elastomer formulations specified in this test method were chosen to be representative of those used in heavy-duty diesel engines. The procedures described in this test method can, however, also be used to evaluate the compatibility of automotive engine oils with different elastomer types/formulations or different test durations and temperatures to those employed in this test method.
NOTE 2 - In such cases, the precision and bias statement in Section 12 does not apply. In addition to agreeing acceptable limits of precision, where relevant, the user and supplier should also agree: (1) test temperatures and immersion times to be used; (2) the formulations and typical properties of the elastomers; and (3) the sourcing and quality control of the elastomer sheets.
NOTE 3 - The TMC may also issue Information Letters on this matter.
1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.6 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 and health practices and determine the applicability of regulatory limitations prior to use.
1.7 This test method is arranged as follows:
2. Referenced Documents
2.1 ASTM Standards:
D297 Test Methods for Rubber Products - Chemical Analysis
D412 Test Methods for Vulcanized Rubber and Thermo-plastic Elastomers - Tension
D471 Test Method for Rubber Property - Effect of Liquids
D1193 Specification for Reagent Water
D1566 Terminology Relating to Rubber
D2240 Test Method for Rubber Property - Durometer Hardness
D4175 Terminology Relating to Petroleum, Petroleum Products, and Lubricants
D4485 Specification for Performance of Engine Oils
D5662 Test Method for Determining Automotive Gear Oil Compatibility with Typical Oil Seal Elastomers
E 29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E 178 Practice for Dealing With Outlying Observations
3. Terminology
3.1 Definitions:
3.1.1 automotive, adj - descriptive of equipment associated with self-propelled machinery, usually vehicles driven by internal combustion engines.
3.1.2 candidate oil, n - an oil that is intended to have the performance characteristics necessary to satisfy a specification and is to be tested against that specification.
3.1.3 elastomer, n - a natural or synthetic polymer having the rubber-like property of substantially recovering its size and shape after removal of a deforming force.
3.1.4 engine oil, n - a liquid that reduces friction or wear, or both, between the moving parts within an engine; removes heat particularly from the underside of pistons; and serves as combustion gas sealant for the piston rings.
3.1.4.1 Discussion - It may contain additives to enhance certain properties. Inhibition of engine rusting, deposit formation, valve train wear, oil oxidation and foaming are examples.
3.1.5 formulation, n - the specific chemical composition used in manufacturing a seal elastomer or a reference oil.
3.1.6 hardness, n - of an elastomer, the resistance to deformation or indentation.
3.1.6.1 Discussion - In this test method the hardness of an elastomer is measured with a Shore Durometer A (see Test Method D2240).
3.1.7 heavy-duty engine, n - in internal; combustion engine types, one that is designed to allow operation continuously at or close to its peak output.
3.1.7.1 Discussion - This type of engine is typically installed in large trucks and busses as well as farm, industrial, and construction equipment.
3.1.8 non-reference oil, n - any oil other than a reference oil, such as a research formulation, commercial oil or candidate oil.
3.1.9 reference oil, n - an oil of known performance characteristics, used as a basis for comparison.
3.1.9.1 Discussion - Reference oils are used to calibrate testing facilities, to compare the performance of other oils, or to evaluate other materials (such as seals) that interact with oils.
3.1.10 tensile strength, n - the maximum tensile stress applied in stretching a specimen to rupture.
3.1.11 test oil, n - any oil subjected to evaluation in an established procedure.
3.1.12 ultimate elongation, n - the elongation at which rupture occurs in the application of continued tensile stress.
3.2 Definitions ofTerms Specific to This Standard:
3.2.1 compatibility, n - of an engine oil/elastomer combination, a characteristic that signifies a complete or high-level of resistance of the elastomer to deleterious effects imparted by contact with, or immersion in, the oil.
3.2.1.1 Discussion - The phrase "high compatibility" indicates that after contact or immersion, the elastomer properties are maintained at or near their initial level. The terms "lack of compatibility" and "low compatibility" indicate that after contact or immersion, the elastomer properties are adversely affected to an extent that could be detrimental to sealing performance.
3.2.2 immersion test, n - an operation to evaluate compatibility by determining the effect of a liquid on elastomer test specimens submerged in the liquid for a specified time and at a specified temperature.
3.2.2.1 Discussion - The effect of the liquid is evaluated by the difference in (typical) elastomer physical properties preand post-immersion.
3.2.3 reference elastomer, n - an elastomer compound prepared using a specified formulation; its immersion test properties with selected oils have been well established by the use of recognized and accepted testing and documentation procedures.