Originally Posted by CNR Glen
That I wouldn't know. I have the book Canadian national in the west Volume 3 that shows a Mikado that's stained almost completly white from the foaming problem. The text states that engines were equiped with a 'skimmer device' inside their boiler to extract the foam and ejected it from a pipe just ahead of the cab.
I might be speculating but your oil skimmer might be to combat this problem before the water gets to the boiler. Most of the foaming problems seemed to happen on the prairie provinces where the water was of questionable quality. And people wonder why the railways were so eager to dieselize!
Makes sense to me.
I was looking at some Vanderbilt tenders that come with and without oil separators so there must be something on them, which can be seen to distinguish them apart, but I can't seem to find images of it.
I'm still searching the net.