View Full Version : Centrifugal oil filter????

11-30-2005, 09:44 PM
I want to build a centrifugal oil filter to filter hydraulic oil so I can re-use it.I have to work on various machines that carry large volumes of oil.I don't want to pass it through a micron filter untill it's been spun first since there is usually metal flakes,dirt and sludge present that will clog a filter in short order.

I know the basic principals but am wondering about design elements such as materials for the rotating parts,like would I be better with a steel or aluminum rotor and the tolerances involved.

I need to build one because 5 gallons here 100 gallons there adds up to $$$$$$ everywhere,figuring $23.00/5gal pail.

12-01-2005, 02:04 AM
Darin, wish I could help you with your question but don't know much about that subject. When you get one working and have everything working perfectly make a second one and send the old one to me or call and I will come pick it up. Thanks in advance I will put it to good use. http://bbs.homeshopmachinist.net//biggrin.gif


12-01-2005, 02:17 AM
Won't just letting it sit for a month or two do the same thing? If it's heavier than the oil for a spin filter to take out it should drop out on it's own from gravity. Just don't disturb it when "decanting" it.

12-01-2005, 05:02 AM
How about putting some magnets in the bottom of the drum and let it sit for a time.

12-01-2005, 05:47 AM
Run across my first one 15years ago on a Russian farm tractor (Belaiurs) one of the coolest things I ever seen,took off the canister & no element, told the farmer they never put one in,then after some hunting a filter, I was told how it worked, keep me posted on your project.

12-01-2005, 07:08 AM
My father repowered a 4 wheel drive tractor with a V-10 Deutz air cooled diesel which had a centrifuge for engine oil mounted in the hub of the cooling fan. When the cover was removed you would have a solid chunk of carbon shaped like a bunt cake.

I don't know if Deutz used the centrifuge on all of their engines, but it would be worth looking for a junked engine to rob the centrifuge from.


12-01-2005, 08:04 AM
The old 305cc Honda (CL77) used this type of oil filter.


12-01-2005, 08:48 AM
British motorcycle engines used to use a centrifugal seperator in their crankshafts. http://bbs.homeshopmachinist.net//frown.gif

It was located in the same throws that they circulated oil to the rods. BAH!


12-01-2005, 10:30 AM
<font face="Verdana, Arial" size="2">Originally posted by Evan:
Won't just letting it sit for a month or two do the same thing? If it's heavier than the oil for a spin filter to take out it should drop out on it's own from gravity. Just don't disturb it when "decanting" it.</font>

that's about what i do. the oil seems to come out pretty clear after setting for a few days. definitely no chunks or metal filings in it.

andy b.

12-01-2005, 10:58 AM
This is a commercial unit http://www.spinnerii.com/index.cfm

Paul Alciatore
12-01-2005, 11:31 AM
That's the first I have heard of these filters. My question is, how are they powered? Is there a shaft from the engine? But the web site says they can retrofit. How would they add a power takeoff on an existing engine? Or does the oil flow turn them? Or electric?

Paul A.

12-01-2005, 11:39 AM
Zetor (Chech Republic)tractors use them also. Powered by pumping the oil thru nozzles. Slick setup.

12-01-2005, 11:46 AM
On the Spinner II, the larger units are spun with air pressure.

It appears that oil pressure is used for the smaller model 25 unit. http://www.oil-tech.com/md25nstl.htm

[This message has been edited by JPR (edited 12-01-2005).]

12-01-2005, 03:48 PM
<font face="Verdana, Arial" size="2">Originally posted by Evan:
Won't just letting it sit for a month or two do the same thing? If it's heavier than the oil for a spin filter to take out it should drop out on it's own from gravity. Just don't disturb it when "decanting" it.</font>

Sounds to be about the least expensive "filtering" method. I envision a drum with a bung/spigot set some height above the bottom of the drum. Open the spigot to drain the "filtered" oil as necessary.

If that "filtering" method yeilds oil clean enough for your intended use, well only you know the answer to that.

No lubrication expert, nor to get off topic, Is used, filtered, reclaimed, etc. hydraulic oil as "good" as fresh hydraulic oil?

Does hydraulic oil not "break down" as engine oil does?

Just curious.

12-01-2005, 04:26 PM
YEARS ago I worked with/on DeLaval oil seperators in the Navy. Mainly used on old fleet subs but a lot of surface ships employed them.

Maybe you can track one down through old gov't surplus or look for printed info.
Find an old "Engineman 3&2" Navy training manual and iot should have all the info you need.

And, yes, it was the same DeLaval company that made milk parlor equipment.

12-01-2005, 06:21 PM
I have the basic information on both the DeLaval disc type and the tubular type. I can scan them and e-mail them to you if want. Let me know.

12-01-2005, 06:35 PM
KDRed, yes I had 2 of those Honda's and it's amazing the 'mung' you would extract out of those filters.

12-01-2005, 06:45 PM
QSMIDO, also in the FN book. http://bbs.homeshopmachinist.net//biggrin.gif

Turbine oil, water and muck, is all I remember.


12-01-2005, 07:26 PM
<font face="Verdana, Arial" size="2">Originally posted by BudB:
Zetor (Chech Republic)tractors use them also. Powered by pumping the oil thru nozzles. Slick setup.</font>

That is one hell of a tractor i think the one we have spends more time in the shop than it does the fields!

12-01-2005, 07:31 PM
what we use is a 55 gallon drum with a stand pipe to keep it off the bottom. just let the oil sit a while to the heavy stuff fall out.

Peter S
12-02-2005, 05:52 AM
More on the "let it settle" idea.

When I was a kid, Dad used to fill one of the smaller oil drums (12 gallon?) with waste oil, fit a tap to the small bung in the end, then lay it on its side in the rack, just as you would a normal oil drum. But instead of having the tap right at the lowest point, the drum was rotated a little so the sediment would settle and never come out.

This oil was then used in the chainsaws for bar oil. Of course no one would do that nowadays, but you did back then! http://bbs.homeshopmachinist.net//smile.gif

There was a thread on centrifugal oil filters recently, maybe on the PM forum.

Simca was another car with this system, I think the front pulley did the job.

12-02-2005, 05:20 PM
There is a version of centrifugal fuel filter for Deisel truck engines. There are centrifugal filters for water systems that work quite well. The Lacos Sand Separator name sp? was separated from the old De Laval co. These can be designed to remove very small particles. The seperators that are designed to clean up flue gases from things like steel mills use this concept. These are all spun by pumping the fluid with particles mixed in into a tangential entrance to a cone or cylinder of some sort. These devices don't seperate things that are soluable in one another.

12-02-2005, 06:42 PM
Hi There,

My cousin had a Fiat Spider (1970?) that had that type of "filter" system. It was built into the crankshaft balancer.

-Blue Chips-

12-02-2005, 07:20 PM
Well first off there is a time factor involved,I don't have hours let alone days or weeks to let the oil settle so that is out.
I have witnessed a commercial built unit operate and they are impressive,.5 micron filtration with no $40 apiece elements,only they aren't cheap. Dirty,nasty,chunky oil goes in ,clean useable oil you can read through comes out.
Hydraulic oil really doesn't have much in the way of additives,mostly anti-foaming etc.Considering that there is no acid combustion residue present it can be reused several times.It does sometimes contain soot from when a pump gets overheated from continous bypassing.
What really impresses me is that a centrifuge will also drive the water out of solution so it can be seperated.

I have seen the inside of a Balarus tractor cleaner,simple as snot,it's just a bobin that has multiple small holes drilled radially at an angle to the axis and they drive soley off oil pressure.I would copy one of them,but sadly the tractors weren't as good as the oil filters and there aren't many around anymore http://bbs.homeshopmachinist.net//biggrin.gif

BTW,from what I have read about the Belarus units they would spun up 6,000 rpm at idle http://bbs.homeshopmachinist.net//eek.gif

[This message has been edited by wierdscience (edited 12-02-2005).]

12-03-2005, 07:22 AM
Where do you live? I have 1 of these sitting in my storage shed I bought when the company I work for changed hydralic systems in the axle forging mill. It uses a stack of dishes that look like an old cream seperater for milk house. Has a heating element and 3 phase pump all on a cart. Probably weighs 200 or 300 lbs.

12-03-2005, 08:17 PM
There is alot involved in designing a centrifuge, the easiest way would be to buy one of the cream separators on ebay and modify it for your use.

The Spinner centrifuges mentioned will not remove water, you need to have separate discharges for separation instead of simple clarification, which these units do not have. You could take the basic design and make it into a separator by providing a discharge for the water. Keep in mind the water is the heavy phase.

As for building one, I would definitely go with steel. You also want to make sure the material is annealed, you will get stress cracks if there are any hard spots on the outer surface of the bowl. The tolerances will depend on what design you go with. You need to keep in mind the bowl will expand due to the centrifugal forces.
If you wnat any kind of throughput, you need to use the conical disks to increase the clarification area. If you use a simple bowl, it will work, but you will need to feed it at a much lower rate.

The reason to go with centrifuges instead of simple decanting is oil recovery and better clarification of fine particles. The centrifuge will recover significantly more oil then decanting due to the ability to concentrate the sludge. During decanting, the sludge drawn off still has a large amount of recoverable oil. If you design your centrifuge right, you will not need a filter.

If you want any drawings of commercial units, let me know, I have a number I can scan. You might also check and see if your local university library has the book "Industrial Centrifugation Technology" by Wallace Leung, it has pretty much everything you will want to know and has many good illustrations of centrifuges that would be a big help in designing your unit.


Peter S
12-03-2005, 08:28 PM
On the other thread about oil centrufuges, I mentioned an oil filter that was briefly popular in NZ back in the 1970's? It looked like an old style by-pass type filter, except it used toilet rolls as the filter.
I think they claimed that your oil never needed changing - just fit another roll!

Have always thought it would have been good for waste oil cleaning.