ASTM D4289 - Elastomer Compatibility of Lubricating Greases and Fluids
Signiﬁcance and Use
5.1 Measurement of the changes in the volume and hardness of an elastomer that occur from immersion in a lubricating grease or ﬂuid provides a means for evaluating relative compatibility. Much of this test method was derived from procedures described in Test Method D471 and Federal Test Method 791C ⁄ 3603.5. In contrast to these two test methods, which emphasize the evaluation of rubber and rubber-like compounds, Test Method D4289 was developed speciﬁcally to evaluate lubricating greases and ﬂuids, especially those used in automotive applications, although the test method can be applied to lubricants used in industrial applications as well. Excepting the Shore Durometer A, this test method requires no specialized, rubber-testing equipment. Virtually all other equipment and supplies speciﬁed in the procedure are stock items in lubricants laboratories.
5.2 The volume and hardness-change values determined by this test method do not duplicate similar changes that occur in elastomeric seals under actual service conditions. However, they can be correlated in many instances. In one such instance, the volume-change values determined by the antecedent of this test method correlated (r2 = 0.99) with those that occurred during a vehicle test.6 Because of wide variations in service conditions and differences in grease and elastomer formulations, correlations between the results obtained with this test method and particular applications should be deter-mined on an individual basis.
5.3 With speciﬁcations requiring elastomers other than Reference Elastomers AMS 3217/2C or AMS 3217/3B, coupons cut from standard sheets (Practice D3182) should be used. When the preparation of such coupons is not feasible, or the lubricant speciﬁcation requires the use of rubber products that do not have a suitable size or conﬁguration for use in preparing coupons for testing (Practice D3183), this test method can be used as a guide for evaluating compatibility.
NOTE 5—Inasmuch as the precision values apply only to the elastomers speciﬁed in Annex A1 of Test Method D4289, when a lubricant speciﬁcation requires some other elastomer, the user and supplier of the lubricant should agree to the values of acceptable precision. Such values may or may not be the same as those of Test Method D4289. It is recommended that the agreed upon precision values be stated in the user’s lubricant speciﬁcation.
5.4 The results of this test method are most applicable to the use of lubricating greases and ﬂuids in contact with elastomeric seals, boots, O-rings, and similar products, where the physical demands on the elastomer are not extreme. In critical applications where the lubricant will be in contact with rubber parts subject to severe ﬂexing, extreme temperatures, or similar stresses, other rubber properties, such as tensile strength and elongation, should also be evaluated as they may be more indicative of the true compatibility characteristics.
1.1 This test method evaluates the compatibility of lubricating greases and ﬂuids with coupons cut from standard elastomer sheets (Practice D3182). Compatibility is evaluated by determining the changes in volume and Durometer A hardness that occur when elastomer coupons are totally immersed in a lubricant sample for 70 h or for a duration as required by the lubricant speciﬁcation at either 100 °C or 150 °C or at a test temperature as required by the lubricant speciﬁcation.
1.1.1 Some lubricant speciﬁcations may require different elastomers or test conditions, such as longer durations or lower or higher temperatures. In such instances, the repeatability and reproducibility values stated in Section 12 do not apply, and the user and supplier should agree on acceptable limits of precision.
NOTE 1—The scope of this test method now includes the evaluation of the elastomer compatibility of both lubricating ﬂuids and greases. Testing of ﬂuids was not included in Test Method D4289–95 and earlier versions.
1.2 This test method can also be used as a guide to evaluate the compatibility of greases with rubber products not in standard sheet form (Practice D3183).
Extracted, with permission, from ASTM D4289-21 - Elastomer Compatibility of Lubricating Greases and Fluids, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard may be purchased from ASTM International, astm.org