ASTM D892

Why is it important to know the foaming characteristics of lubricating oils?

This test method is intended for use in evaluating the foaming characteristics of lubrication oils. Excess foaming can degrade the life of lubrication oil. This can cause damage to the equipment that is being lubricated by the oil, such as high-speed gearing and high-volume pumping gear. Lubricant Serious operational problems can be caused by excess lubricant foaming. The most common are inadequate lubrication, cavitation and loss of lubrication. Also, the foam acts as a thermal insulator, which can cause overheating. Foam is caused by air bubbles in the lubricants. When the fluid can’t release the air efficiently, it accumulates and causes foam. Often, additives are added to lubrication oils to prevent foaming. Two values are of interest when analyzing the foaming characteristics of lubrication oils. The foaming tendency and the foaming stability. The foaming tendency is the amount of foam that is present directly after the flow of air has been stopped. The foaming stability is the amount of foam that is present 10 minutes after the flow of air has been stopped. Both values are analyzed using ASTM D892 

Summary of the test method ASTM D892

A portion of the sample in the foaming cylinder is maintained at a bath temperature of 24°C. This portion of sample is blown with air at a constant rate. After the blowing stops, the amount of foam is recorded. Then the foam is allowed to settle for 10 minutes, then the amount of foam is recorded again. In sequence II, a second portion of the sample follows the same process, but then at a bath temperature of 93.5°C. In sequence III, the same portion of sample as in Sequence II is cooled down in room temperature until the sample is below 43.5°C. Then, the cylinder with the sample is placed in the bath that is maintained at 24°C. The same process of blowing air and recording the foam is repeated. 

Why should you use a Tamson Foaming Dual bath?

The Tamson Foaming Dual bath consists of two visibility baths and a rack with four flow meters. Each bath offers the possibility of four positions. One bath is used as a high temperature (normally 93.5°C) bath and one bath is used as low temperature (normally 24°C) bath. The advantage is that both baths have cooling coils, so that the baths can be used interchangeably. Also, our bath come with a drain, so that the bath content can be emptied easily when the bath needs to be cleaned. The baths have a stirrer with a long shaft for optimal temperature uniformity. The baths have a robust zincor powder coated case with removable outside windows around the glass jar. The apparatus is standard delivered with four foaming cylinders, four flowmeters and four Delrin stoppers. We use Delrin stoppers instead of rubber stoppers, as rubber stoppers can crack over time.

Please contact our sales team (sales@tamson.nl) to get a quotation. Custom made setups of the foaming apparatus are available on request.