Centrifuge issues

[The FNG]

Has anyone had issues with or warn out a pressure driven centrifuge?

I have a 55gph fuge (OC-20) from Dieselcraft. I'm pretty sure it is exactly the same as the PA Biodiesel fuge. I bought it second hand from a veggie guy who I am assuming put some good use on it. He made 2 sight holes in the cover to see what was happening inside, which is actually really nice. Since I bought it, I have run 600+ gallons of WMO through it problem free.

The last batch I made is when I began having issues. Everything starts out fine, the fuge begins to operate at 40 psi and steadily speeds up as the pressure rises to 80 psi. About a minute after the fuge reaches speed, the entire thing floods with oil and the fuge stops spinning.

After calling Dieselcraft, it was determined that there were three things that could cause this:
1) The drain is restricted
2) The jets are flowing too much
3) The brass bushing (in the center of the rotor) is warn an oil is flowing past it

I checked the drain. It's a 1.5" pipe, restriction is non-existent. I also checked the jets. They look the same as they always have. If my oil is abrasive enough to wear the jets, then I'm in trouble... So really, the only option here is that the brass bushing in the center is warn. It makes sense since it rotates on the shaft.

Anyway, a new rotor is almost as much as a new centrifuge. Looks like I'm getting a new centrifuge...unless anyone has any bright ideas.

 

[Josh Carmack]

Take a picture of the rotor, and mic the fuge shaft post, and if you can mic the center hole, it's possible it is the same unit, and a replacement rotor from PA is only 45 bucks. What temperature are you running at? My rotor won't spin well if the oil is too thick. The rotor bushing and shaft post is the seal, so if the bushing wears out enough to pass a lot of oil around it, that could definitely be the issue.

As my rotors get deformed I notice they don't perform well, how is the seal between the rotor nut and dome. If my rotors deform and the seal between the nut and rotor is bad they will flood with oil and barely spin, or not at all. They typically will leak more at speed due to the g forces on the oil at the seal making the pressure many hundreds of PSI higher than what they are actually being fed. In other words, the lower rubber seal may be worn, causing them to leak at speed, but not before.

 

[The FNG]

Well, everything you mentioned seems to be working fine. The o-rings seem to be ok, the nut gets nice and tight, and I was trying to fuge at 160*f. In fact, thicker oil seems to be working better.

I checked the pa biodiesel site for a new rotor. The 60gph model is $45 and the 55gph model is $70 (plus $15 in shipping)... Makes no sense. I need the 55gph model for mine (I'm 99% sure they are the same). Anyway, I figured for $129 I could order a 60gph model brand new on ebay, so that's what I did. I'll try to recoup some cash and sell the dieselcraft one online for parts...