Foaming Issues – Identify the Cause
Any circulating or excessive cosmetic foam should be addressed at the first available opportunity by sending a sample of the lubricant to a suitable laboratory to measure the extent of foaming compared to the lubricant’s specification. This will identify the level of tendency to form foam and the stability of the foam once produced.
Tendency of foaming is a measure the amount of foam the lubricant is likely to produce in service if agitated with air. The Foam in this test is likely to and should collapse quickly once the agitation stops. Unless there is an excessive level of tendency to Foam then there should be no observable cosmetic foam problems. Generally, manufacturers quote on their product data sheets the foaming tendency levels to be expected and if there is a cosmetic foam issue, the oil supplier may be able to provide an anti-foam additive solution to the problem.
Stable foam – Stable foam is very serious and unless the lubricant is designed for special applications, even with high detergents lubricants, there should never be any stable foam in a system.
If observing high Foam tendency, the first step should be to check the new oil baseline is for the product in use – available from the manufactures datasheets. If this is not available then it is essential for the operator to send a unused reference sample from an IBC or new oil barrel.
All reputable lubricant brands will have undergone years of test-bed testing to confirm that the new lubricants provide the best lubrication properties to components before going on sale. If the new oil barrel / IBC value for tendency is close to the product datasheet value then it is very unlikely any observed excessive foam in the system is as a result of the lubricant, and is usually caused by contamination. If contamination is suspected a full 1L oil sample should be sent to the laboratory for a system health check analysis to investigate the problem and identify the cause of the foaming.
Note the laboratory may ask for samples of potential contaminants or products on site, which can be discussed by telephone or indeed agree to a site visit to help resolve the problem.
If on the other hand, the value of foam comes out considerably higher on the new barrel/IBC sample than the product datasheet state, then the next step should be to take a second sample to rule out bad sampling of the IBC or barrel. The laboratory can give advice on best practice for sampling to assist the operator if required. Confirmation of high Foam tendency and/or stability should be reported to the lubricant supplier, which will of course wish to carry out further tests.
Foaming Issues – Correcting
Depending on the cause of the foaming the issue may be solvable by filtration to remove contaminants. However, sometimes the issue may be mixing incompatible oil; then the solution could be a full drain, flush and fluid change to remove the contamination, which can be expensive and of course the last resort.
Ideally it may be just the addition of an anti-foam additive to the system help reduce the problem, but under no circumstances should this be done without first consulting the lubricant manufacturer. Over-dosing with antifoam can exasperate the problem of lead to to other issues such as air release issues, which can cause more problems than small amounts of cosmetic foam.
In some cases low level cosmetic foam with a slightly raised tendency, but no stable foam may be something the machinery operator chooses to live with and just closely monitors the machine system for wear. To help with this choice, it is recommended the operator submits oil filters regularly for wear debris analysis to confirm the foam is not leading to any abnormal wear processes within the system.