Keeping Coolant Clean?

[donl517]

I'd like to revisit this subject, I've seen a few suggestions of how some of you are doing this scattered about. Can we put it all in one thread?

What you use?
Applicable part #'s and source?

Thanks,
Don

[Delw]

you can buy one or make one. I have gone through 6 of them store bought in 15 years. Finally said screw it and used a rotisserie motor with the org disc and frame works perfect.
The motors go bad but usually its the gears inside that go bad. so I ended up using rotisserie motors.

BTW its just angle Iron to make one also

[Geof]

Do you mean removing tramp oil?

I am a recent convert to coalescers. I did try skimmers but they could not be fittied on most machines and when they could be put in place they tended to take out coolant as well as tramp oil. Also it was necessary to have the coolant sitting still for over a day to get the tramp oil floating to the surface so the skimmer could get it; skimmers are not effective when the machine is in use.

Coalescers work whether the machine is circulationg coolant or not, although they can be more efficient when the coolant is not circulating. In these the coolant is pumped through a coalescing filter which is a stack of finely grooved plastic discs, into a holding tank. The tramp oil dispersed in the coolant tends to adhere to the plastic and comes out of the filter as micro droplets which float upward in the holding tank while the coolant is returned to the machine from the bottom of the holding tank.


EDIT: I just noticed: Part numbers and source? Keller Products, I forget the part number but we ordered the largest size individual machine units; the one I bought first for testing was the small size portable unit.
I bought a coalescer at half price a few months ago as a test on my home shop machine which had really grungy brown colored 18 month old coolant that developed a skin of tramp oil about 1/8" deep wheneever the machine was not running for a week or so. It took about four weeks of running the coalescer fulltime and the coolant became a creamy white color and there was about 1/2 gallon of tramp oil in the holding tank of the coalescer.

That was so encouraging that at our Christmas cleanup we collected the coolant from all the machines in a 300 gallon tank and instead of getting a disposal company to take it away as we did previous year, we connected the coalescer; I had to monitor it because for the first three days so much oil was being collected it was overflowing the holding tank on the coalescer. Over the eleven days of shutdown the coalescer removed about ten gallons of tramp oil and we returned nice creamy white sweet smelling coolant to the machines when we started up again in January.

Then we ordered fifteen individual machine coalescers so we can keep the coolant clean all the time.

[CNC Viking]

Geof,

That was great development. Any chance to see pictures, connected to machine, opened unit to see the guts, connection scheme?

What about UV light or UV filter sets to kill bacteria with, that many talks about? Anyone with experiences?

Darn!, I just built my own skimmer, mostly from parts I had laying around.
Anyway FWIW, my DIY way oil skimmer:

Completed chassis 1,5 mm steel sheetmetal, easy to weld.


The skimming strips are made of 0,8 mm Teflon, I had laying around, with 3mm steel hold-down strips fastened with 4mm countersunk screws.


I also had this 230VAC geared motor, unfortunately only 2rpm, so I will have to run it for longer periods during nights. The oil will defenitively have time to adhere to the disc LOL. Turned a simple alu housing to protect it.



I also had this 10 x 26 x 8 mm 2RS ball bearing, so I made a housing for that too.


The shaft is made of stainless steel and I had to make it 3-part, so I could slide it in place complete with the disc on it when the skimmer frame is under the machine, on top of the tank. The joins are just usual "jam" pipe joins from the plumbers' industry.


The complete ”moving parts kit”. The disc is made of 3,2 mm Acrylic(plexiglas) with a 300mm dia. Flashy color? This is what I had, why not use it?



Mock-up for testing it before the paint came on. The disk runs very lightly between the teflon lips, even when running it dry. The measured power consumption is only 4W!


This is how it will sit on the coolant tank.


I applied 3mm self adhesive and oil resistant cell rubber strips to cushion against the tank so it stays put.


When installed, the disc runs 25mm above tank floor.


A houshold plastic container acts as my catch tank. A see-through version is preferable, to see when it is getting full. The skimmer is run via an electronic household timer for some hours duty during nights.


To be honest I have not tried it yet, but my first machining will soon take place, and then I will report on the performance.

I have also installed a fish tank aerator to keep the coolant aerated (bacteria hate it). Pics and story next time.

Cheers

[Geof]

Originally Posted by CNC Viking Geof, That was great development. Any chance to see pictures, connected to machine, opened unit to see the guts, connection scheme? What about UV light or UV filter sets to kill bacteria with, that many talks about? Anyone with experiences?.........

Before answering your question I have to ask: How do you keep your place so clean? I have been complimented about how clean our place is but cannot hold a candle to you.

Pictures? No I didn't take any but you can see them here;

http://www.kellerproducts.net/tramp_...ngle_pumps.htm

They are really quite simple; a compressed air operated pump, an inlet cartridge filter, the holding tank with the coalescing filter inside and a few pipes. Actually Keller Products calls it "(the) patented Keller all-plastic
separator element ", and I have to give them their due; it works better than other separator systems I have seen. The key with these separators is to give the ultra-micro-scale dispersed oil droplets a chance to contact the plastic surface. Because the oil has a higher affinity for plastic than water does it sticks to the plastic, that is how the skimmers work, the oil sticks to the plastic disc better than the coolant. Once the oil is in contact with the plastic it moves along with the flow and the really tiny droplets bump and fuse into just tiny droplets that ooze out of the end of the grooves I mentioned; then these droplets float up faster than the coolant is flowing down in the holding tank. A pre-filter is necessary of course or the grooves will get clogged with metal fines.

Regarding UV sterilization coolant is opaque so how is the UV going to penentrate to get at the bacteria. Anyway sterilization is pointless because coolant tanks and machines are open to the air so bacterial spores are getting in all the time. Also it is not needed if you keep the tramp oil content very low and keep the coolant aerated. The bacteria that create foul smells are anaerobic and they metabolize sulfur compounds in the oil in the absence of oxygen; remover their food and keep conditions unsuitable for them and they are not a problem.

[donl517]

Geof,

That is certainly a glowing review of the Keller skimmer! You should be getting a commission! I'm definitely going to investigate these.

I had seen some suggestions for simpler filtration (pads, etc). I'd still like to hear other suggestions and what you are using.

Thanks,
Don

[Geof]

A long time ago I tried the pads that were supposed to soak up the tramp oil when you floated them in the tank. They did work but it was necessary to wait for the oil to float to the surface first then put them in. I think they are potentially an economical solution if your machine is used infrequently so there are long periods of time when the coolant is static and the oil can float to the top. But they are messy, oil drips everywhere when you a taking them out, and really they should not be thrown in regular garbage. When the oil is collected as oil you can take it to an oil recycling place, or as we do wait until we have a 45 gallon drum full and then get it picked up.

I am happy to give glowing reviews when a product works for me and I don't need to be "bribed" with a commission.

[donl517]

Geof,

I like what I see in that skimmer, it looks like a good product. Although it is not in the budget at the moment it may be a priority purchase in the near future. I'm glad they didn't have to bribe you, at least I know I'm getting an honest review!

Thanks Again,
Don

[Donkey Hotey]

Wow, thanks for sharing that, Geof. I've been looking for the right solution for my VF-2 and that looks like it.

[Edster]

I'm tesing a zebra sidewinder skimmer.

http://i445.photobucket.com/albums/q...idewinder1.jpg

http://i445.photobucket.com/albums/q...idewinder2.jpg

http://www.zebraskimmers.com/oil_ski...l_skimmer.html

So far it works great! I got the magetic mount so I could move it easily from machine to machine.

The reason I chose this skimmer is that it would fit every machine in my shop from our haas sl-10 and tl-1 tanks to my okuma mcv4020 and captain lathe tanks. The coolant does need time for the oil to build up on the surface then you skim it out. If you leave the skimmer on after it's removed all the oil it will remove some coolant. Usually it only needs to run for an hour or two then I move it to a different machine.

I used to use a keller filter, but I wasn't satisfied with the results. the unit itself is a pita to clean and if you leave it sit for a while the air pump will get stuck. This happened a few times and I had to blow compressed air through the exhaust muffler on the air pump to free it. The skimmer is a better solution in my opinion. It's also much cheaper than the keller filter.

BTW, CNC Viking that is a bad@ss skimmer!!! You definatly have one of the best skimmers I've seen

[donl517]

Edster,

Thanks for the response. A friend of mine just mentioned the Zebra skimmer to me yesterday. You didn't like the Keller, how long did you use it? How long have you used the Zebra? How does the Zebra work? There is not a real clear description about installation and how it picks up the coolant/oil to separate it. Can you give a rough $$$ amount?

Thanks,
Don

Ah, I found a picture that shows how it works.
http://www.oilskimmerstories.com/sto...arkmfctng.html

[DareBee]

The UV systems and other methods of killing bacteria generally are a poor choice. To keep the coolant as it should be, it needs good bacteria, these will die with UV as well.

My machines don't get used enough for a system such as the Keller. Both for money reasons and that they will completely clog while sitting idle for extended periods.
I hated the skimmer/soaker bags as they soaked up the "imulsified" coolant oil as well, creating 2 issues.
1) The bag was saturated (therefore useless) in a couple of hours.
2) The coolant concentration had to be continually checked and adjusted (to no avail due to the bags).

My current mixed bag-o-tricks.
Every machine has a Zebra skimmer - the disc units are better but I have Sidewinders on the machines that the disc wouldn't fit. My skimmers are all on timers or operated by the MCS. The first morning you come to work when you accidentally left the skimmer on all night you will know why.
I have a bubbler system hooked up to the compresser at 5PSI with soft cooper runners in my tanks. Runs 20min on every hour.
I put filter paper on all the return baskets to catch any fines.
Get a refractometer and keep the concentration levels at optimum.

These things have prolonged MY coolant life ten fold.