ASTM D6082 High Temperature Foaming Characteristics of Lubricating Oils
4. Summary of Test Method
4.1 A measured quantity of sample is heated to 49°C for 30 min and allowed to cool to room temperature. The sample is transferred to a 1000 mL graduated cylinder, heated to 150°C, and aerated at 200 mL/min with dry air for 5 min with a metal diffuser. The amount of foam generated before disconnecting the air, the amount of static foam at optional times after disconnecting the air (list of options in Section 10); and the time for the foam to collapse are measured and the percent increase in total volume calculated.
5. Significance and Use
5.1 The tendency of oils to foam at high temperature can be a serious problem in systems such as high-speed gearing, high volume pumping, and splash lubrication. Foaming can cause inadequate lubrication, cavitation, and loss of lubricant due to overflow, and these events can lead to mechanical failure.
5.2 Correlation between the amount of foam created or the time for foam to collapse, or both, and actual lubrication failure has not been established. Such relations should be empirically determined for foam sensitive applications.
