Thread: Perhaps a stupid idea (flood coolant)

Originally Posted by Mcgyver

IThe idea was to continually circulating the coolant through it using the pump. I have no idea of the math, but the thought was with enough passes through the UV chamber eventually all the bugs would find themselves momentarily in that thin layer of doom.

They will multiply quicker than they'll be killed.

At one point I studied aquatic UV sterilizers quite intensely. They're constructed exactly as you describe, and that's what I had in mind while answering the question. There is a very definitive relationship between the construction of the chamber, UV power/flowrate (=effective doze), and the volume turnover rate to make sure the pathogens are killed quicker than they're multiplied. With non-transparent fluids, it'll be an exercise in futility.

I am wondering, transparent means transparent to the UV frequency right. I am not sure if it's possible for a fluid to be opaque to visible light, but transparent to UV light of the right frequency (253 nm in the case of the UV cleaner we have).

Ozone has also been suggested. Though I still wonder if heat isn't simpler. My idea is a stainless tower tank with a tight lid, taller than wide to reduce surface area and evaporation. Maybe 50 liters in size is quite enough.

I have checked the ingredients of my current coolant concentrate and none that I can find out are are sensitive to temperatures of below 100C (canola oil, sodium hydroxide and triethanolamine). None of them are near unstable at pasteruization temps.

As a side benefit, once heated up it would act as a heating element for the shop. Could even be fitted with radiators and a fan that turns on once the temperature is high enough.

Originally Posted by DennisCA

I am wondering, transparent means transparent to the UV frequency right. I am not sure if it's possible for a fluid to be opaque to visible light, but transparent to UV light of the right frequency (253 nm in the case of the UV cleaner we have).

UV-C penetrates air quite well, but is attenuated by even clear distilled water very rapidly. The more turbidity or salt/solids water has, the more strongly it blocks short wave UV.

Ozone and other strong oxidizers such as oxygen peroxide or sodium hypochlorite solutions (Clorox) may, in theory, noticeably affect quality of the coolant.

I'd rather try heating. I think your idea may be valid, but it depends on the thermal resistance of the offending bacterial strain(s).

I have a spray can of olive oil and Garlic made by McCormack over 27 years ago. Used some last week it is not rancid.
Bil lD

Originally Posted by MichaelP

UV-C penetrates air quite well, but is attenuated by even clear distilled water very rapidly. The more turbidity or salt/solids water has, the more strongly it blocks short wave UV.

Ozone and other strong oxidizers such as oxygen peroxide or sodium hypochlorite solutions (Clorox) may, in theory, noticeably affect quality of the coolant.

I'd rather try heating. I think your idea may be valid, but it depends on the thermal resistance of the offending bacterial strain(s).

I think I want to try and evaluate the methods one by one, to see what happens with the cutting fluid and which is effective or not. There is a lot of of theories but I think some practical experiments are going to be needed.

I would like to test the following methods

-Oxygen treatment
-Plain old aquarium aerator
-Heating
-Ozone treatment (someone is developing this for machining)

I also remembered we have this interesting stuff which clears liquids by causing small particles and oils to bind and sink to the bottom.

I will probably go through the methods according to how cheap and simple they are to implement. Though I don't expect to begin on it this year.

Originally Posted by DennisCA

I

I have checked the ingredients of my current coolant concentrate and none that I can find out are are sensitive to temperatures of below 100C (canola oil, sodium hydroxide and triethanolamine). None of them are near unstable at pasteruization temps.

As a side benefit, once heated up it would act as a heating element for the shop. Could even be fitted with radiators and a fan that turns on once the temperature is high enough.

Film temp on a large heating element in direct contact with the coolant is probably high enough to scorch the coolant little by little over time. You could mitigate this with a liquid/liquid Hx but that my be expensive.

That said, what about one of those instant water heaters? Surely they have film temp under control or youd have rapid fouling of the Hx (tubes, I assume?).

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just a tight lid won't help with evaporation, you'll need to seal it (and allow pressure to build), or you'll lose couple liters of water from it during a day, that water will condensate somewhere - shop walls, windows or iron in the shop, I wouldn't do that unless I absolutely must, I'd use neat oil, or even pressurized spray bottle with emulsion for this, you don't really need emulsion flood coolant with those machine tools (no production and slow spindles), too many problems for the benefits it may provide for you

https://www.amazon.com/HQUA-OWS-6-Ul...-search&sr=8-4

uv purification for 135 bucks.

3 ball valves

done

betcha 1/2 an hour once a week

Why not just use a UV sterilizer like what’s used in aquariums?


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Because it doesn't seem likely to work. At least based on earlier comments in this thread anyway.

I think it might as the recirculating will kill a bunch on the surface over and over

most of them are meant for single time through and I think you are correct that would be ineffective in less than clear liquid

they do use them for sewage treatment and while it is 3rd stage, it is not bound to be 'clear'

I think heating it is difficult, expensive, and probably smelly, and if poorly done, worse than nothing

I did some googling and apparently the UV idea is not that far fetched after all.
UV disinfection of soluble oil metalworking fluids. - PubMed - NCBI

Abstract
The efficacy of a new high-intensity germicidal ultraviolet (UV) lamp for disinfection of opaque metalworking fluids (MWF) was investigated under laboratory conditions. Three dilutions of "soluble oil" MWF and water controls in a circulating system were inoculated with suspensions of Pseudomonas fluorescens to an initial concentration of about 10(7) colony forming units (CFU) per milliliter and irradiated with a submerged nonglass UV lamp.

Aliquots of the circulating fluid were withdrawn before irradiation and at 10-sec intervals in the water control and 10-min intervals in the MWF. The samples were diluted with sterile water, plated, and counted after 18-24 hours' incubation. The UV-C radiation output of the lamp was estimated by irradiance measurements using a research radiometer.

The concentration of CFU decreased by at least 2 logs (>99% reduction in culturability) in 30 sec in irradiated water. In all three dilutions of MWF, a 2-log decrease was obtained within 60 min. The UV-C output of the lamp was estimated at about 6 W. The disinfection appeared to follow a first order rate law both in MWF and in water. The CFU concentration was stable over time in unirradiated controls.

These results demonstrate that UV disinfection is feasible in MWF opaque to both visible and UV wavelengths of light.

Wondering is all this effort and speculation is easier than just doing the conventional maintenance routine....(skim, bubble, annual change coupled with constant monitoring and adjustment of the concentration)

Also, remember heating the coolant, while that is going on the machine will not have coolant available....(hot coolant is pretty useless)
Cheers Ross

I don't know it's easier, but for me it scratches an itch... I like to speculate and ponder things like these and to experiment a bit. We're probably coming at it from different angles, to you it's a means to an end (making things for profit), to me it's the process is the purpose of itself. I'm thinking it will be educational no matter how it turns out.

I’m definitely interested in your results.

I’d be wondering about some kind of oily crud build up on whatever the heater element is.

And I get these horrible (possibly unrealistic) visions of a warm fog condensing on all my tools.
I have used a crockpot full of degreaser or soapy water on nasty parts and had to do it outside. My temps were a bit higher 200F ish


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So since a BTU is the energy required to raise the temp of a pint of water 1 degree F, how many does it take to raise 50 gallons of coolant[ or whatever] 100 degrees

and then there is heat loss

Put it this way, how long would your water heater take to return from room temp to full hot, and it is well insulated

heating it in the sump is probably impractical and the electricity would be expensive

the UV solution would be cheap to buy and run

as a note if anyone plays with the UV, the bulb is apparently like staring at the sun, neighbor was doing some kind of project years ago and looking at the bulb for a very short time sent him to the hospital

The heater could be in a separate smaller tank and recirculated to the big tank


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I think I will try the UV first after reading the results in the study, I feel it has the most evidence behind it and it can be found quite cheap online, we also sell our own UV version but it would be overkill to run it on this, it's meant for much larger volumes.

Don't know if they continue to use it or not, but several years ago a tier one auto parts mfgr here had a large tank for used coolant and another one for new. They contracted with some company that brought in a big trailer every so often for processing the used coolant. Hooked up to a couple valves on the side of the building, pumped the coolant thru a heated pressure vessel, filtered it, and returned it to the new coolant tank.

A friend who worked there said it saved them about 2/3 as compared to previous coolant disposal costs, and they saw no difference in the performance of the recycled stuff versus new coolant. They still used a lot of new coolant as evidenced by the fact that there were always 10 to 15 of the 200 gallon or so totes of new coolant sitting in the coolant area which they used to maintain concentration, and I assume that makeup coolant adequately replenished any used up components like EP additives, etc.

IIRC, the sump on each machine was pumped out and replaced with the recycled/new mix every 6 months. He said they decided it was cheaper to do everything on a standardized schedule than to pay for the manpower to track each machine and fine tune the pumpout schedule for each one individually.