Foaming? Why?

[TestDriver]

Last night, I was cleaning a 5 gallon batch of my mix with the on-board centrifuge. Everything was going good till I had a minor (1-1.5gal) spill. The oil mix had started foaming faster than the air could come out of it and it foamed over the top of the container.

It did not happen at all when I previously cleaned 10 gallons of straight hydraulic oil. This mix has used motor oil (+-50%), veggie (+-30%), hydraulic (+-10%) and diesel (+-10%). Which of these could be responsible for the foaming? I know diesel foams quite well as I pump it out of the diesel pumps. But, the foam I got was very long lived. I pumped the rest (about 4 gallons) of it out of the circuit through the centrifuge into an open top 5 gallon pail. The foam was quite thick and lived for more than a couple of minutes after pumping. The resulting oil looks good a day after and I might just dump it into the tank. But, I want to know how to prevent this.

One more thing. The mix must have gone through the centrifuge about 4 times before the foaming over happened. I don't think it was necessary for it to go through so much but I thought I could let it go forever before deciding to take it out.

 

[rjjp]

Motor oil, and Diesel, hydraulic has anti foam additives, and so does some motor oil.

 

[RLDSL]

Are you heating this witch's brew to operating temp before running it through that thing? if not, expect foaming. Heavy oils will foam if churned up cold. and a centrifuge by design will churn the stuff up like a blender with whipping cream

. All honest centrifuge manufacturers will state in their literature that it takes a MINIMUM of 5-6 complete passes through one of those things to catch the basics ( many more when teh thing is clean and it hasn't had a chance to build a cake inside yet for things to start catching on)

There are simpler ways to filter, but with a centrifuge it is by design a multipass filtration system

 

[TestDriver]

Heat

Are you heating this witch's brew to operating temp before running it through that thing? if not, expect foaming. Heavy oils will foam if churned up cold. and a centrifuge by design will churn the stuff up like a blender with whipping cream

. All honest centrifuge manufacturers will state in their literature that it takes a MINIMUM of 5-6 complete passes through one of those things to catch the basics ( many more when teh thing is clean and it hasn't had a chance to build a cake inside yet for things to start catching on)

There are simpler ways to filter, but with a centrifuge it is by design a multipass filtration system

Yes, it is heated to engine temperature. I wonder if the veggie oil is to blame?

 

[RLDSL]

Yes, it is heated to engine temperature. I wonder if the veggie oil is to blame?

It's very possible, you realize when you get veg , you wind up getting some cleanser residue with most batches, some places flush a bunch of cleaner out with the veg and even after settling that stuff stays mixed in

 

[TWeatherford]

I've never seen vegetable oil foam at any temperature, and I've seen a fair amount of it, most of it going through a centrifuge.

 

[mariner45]

Could it be that some dishwash detergent (Dawn, Sunlight etc) inadvertently got included with the mix ???