I read somewhere (can't remember where), that we can perform a quick-and-dirty qualitative foaming tendency test by shaking samples vigorously for 5 minutes and then watching how long it takes for bubbles to disappear. How long would you think it should take bubbles to disappear for new oil ? For sump oil?

My main question: Does anyone one have any other suggestions, criteria, or references for a quick on-site foaming tendency test ?

Some additional info: I performed my own test today. Here is my procedure:

• Obtain sample of sump oil and new oil in clear (*) bottles approx 50% full.
  
• Take a photograph of the oil samples before initial shaking (*)
  
• Shake all samples vigorously (at the same time) for 5 minutes.
  
• Take photo's at 15 minutes, 30 minutes, 1 hour

* - indicates items I should have done but didn't (my bottles were not clear and I didn't take initial photo).

Attached are photo's of the results.

The oil from the sump has much larger bubbles and there are still large bubbles after an hour. I think that indicates high foaming tendency due to some contaminant... what do you think? (By the way we have sent a similar sample out for lab testing including formal ASTM foaming tendency test, so if you want to take a guess you can compare it to the ASTM results which I'll have in a few days).

Also there is some possibility that the sump sample had entrained air already which affected the test results (although we didn't notice that during sampling and when preparing to shake the samples). I have the samples saved and may repeat the tests after the samples have set over night.

I was a little surprised that small bubbles persisted in the new oil samples even after an hour. I thought they would be gone much earlier based on what I remember reading and previous performance of similar quick test on other oil when it was difficult to create any bubbles at all. What do you think? (maybe I will try it on some other new oil)

This message has been edited. Last edited by: electricpete,

FoamingTendencySmall.ppt (150 KB, 24 downloads)

Pete,

Interesting - do you have the results back yet? Will you share?

My experience is similar to yours on air entrainment - it stays longer than you would suspect and still classified as 'normal'.

Thanks Sam.

Unfortunately, I don't have any results.

We had sent our normal 8 ounce sample for routine analysis. Then as a followup we requested the foaming test. The lab informed us later that the 8 ounces was not enough oil to do both the foaming and the routine analysis so we only got our routine analysis results back (which was sat... no unusual contaminants).

I still have those samples (new and sump oil) saved in our oil locker. The machine foaming problem went away shortly after startup (must have been some air pocket in the oil system I think), so the plant interest has gone away. In other words, I have to convince someone else to spend the money to do the test because I'm interested in the results (he's not yet convinced).

The opinion of our lube oil program guy is that the ASTM foaming test is too unpredictable... too many false alarms on oil that he thinks is good.

UPDATE - We did send the followup samples and just got the results of testing of these samples for foaming tendency per ASTM D892:

Results for the new oil:
Seq. I - 5 minute blowing period . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 mL
Seq. I - 10 minute settling period . . . . . . . . . . . . . . . . . . . . . . . . . . Nil mL
Seq. II - 5 minute blowing period . . . . . . . . . . . . . . . . . . . . . . . . . . 10 mL
Seq. II - 10 minute settling period . . . . . . . . . . . . . . . . . . . . . . . . . . 0 mL
Seq. III - 5 minute blowing period . . . . . . . . . . . . . . . . . . . . . . . . . . 10 mL
Seq. III - 10 minute settling period . . . . . . . . . . . . . . . . . . . . . . . . . Nil mL

Results for the used oil:
Seq. I - 5 minute blowing period . . . . . . . . . . . . . . . . . . . . . . . . . . . 420 mL
Seq. I - 10 minute settling period . . . . . . . . . . . . . . . . . . . . . . . . . . 200 mL
Seq. II - 5 minute blowing period . . . . . . . . . . . . . . . . . . . . . . . . . . 30 mL
Seq. II - 10 minute settling period . . . . . . . . . . . . . . . . . . . . . . . . . . 0 mL
Seq. III - 5 minute blowing period . . . . . . . . . . . . . . . . . . . . . . . . . . 540 mL
Seq. III - 10 minute settling period . . . . . . . . . . . . . . . . . . . . . . . . . 240 mL

So we can see quite a dramatic difference between new oil and used oil, similar to what was suggested by our informal test.

EPRI "Lube Notes" from October 2008 (very timely) suggests sequence 1 limits for used oil of: 450 mL after 5 minute blowing period and 10 mL after 10 minutes settling period. It looks like our used oil met the first limit but not the 2nd.

More info on the scenario:

This happens to be a lube oil sump ( 30 gallons?) with oil system that feeds both pump and motor bearings for a 7000 hp horizontal pump. It has electric driven pump that runs prior to startup and shaft driven pump that runs when the pump starts. There are also some lube oil strainers in the system.

We had seen tremendous foaming during the first startup following a maintenance outage. It filled the siteglass and filled almost the entire air volume of the sump (~6" vertical distance I think) and created difficulties in determining the true oil level. The foam subsided perhaps 12 hours after pump start.

Then the machine was shutdown and started up a day later. On this 2nd startup, there was only slight foam visible in the sightglass.

This message has been edited. Last edited by: electricpete,

There was a thread a few years back that provided a link to a source outling typical oil tets. Go to http://maintenanceforums.com/e...9103451/m/5441097762 to view the previous input.

At the bottom of the referenced link was content about "On-site" tests and it was stated "Foam - After a vigorous shake, foam from the surface should clear within 10 minutes."

Perhaps that is what you are referring to?

John from PA

Thanks John. That is probably what I was remembering.

Interesting that in our case the new oil from the drum still had remnants of bubbles even after an hour, which would suggest a problem with the new oil according to that 10 minute rule. But the new oil passed the ASTM test.

One thing that was clear from the informal test was the difference between the new oil and the sump oil (which did correctly indicate abnormal foaming of the sump oil, as corroborated by the ASTM test).

Maybe the lesson is that this informal test is more valuable as a comparison test (sump oil vs new oil) than as an absolute test.