Alcohol Based Coolant Question

[Shaun ChurchillParticipant @shaunchurchill54517]

And today’s hot topic is…..😂

I am fortunate enough to have both the flood coolant system and also a compressed air fed Fogbuster misting unit on my Tormach CNC and the question I have is does anyone have experience of using alcohol based liquids in a misting system in the same way that Datron do on their high end machines? My concern is centred around the creation of a potentially explosive atmosphere, which is a subject that I often am required to address in my day job (DSEAR Regulations). I have tried IPA in the Fogbuster unit initially as a flushing fluid and to kill any bacteria that had built up in the system. In doing this it got me thinking about using IPA whilst machining aluminium and of course I had to give it a try. The results were encouraging as it both cools things down and leaves the workpiece (and the machine) nice and clean. I then considered the potential for this to create an explosive atmosphere and have not taken things any further. Any thoughts on this would be welcome.

 

[RobinParticipant @robin]

I was spark eroding a spike out of a 6 pounder cannon using paraffin as the electrolyte. It took forever so I was keenly looking down the bore when I heard it breaking through.

Nearly lost my eyebrows but no real damage done 🙂

Robin

[Shaun ChurchillParticipant @shaunchurchill54517]

I would suggest that paraffin dielectric is vastly less likely to create an explosive atmosphere than alcohol, not least due to paraffin having a higher auto ignition temperature and different LEL and UEL characteristics. The main issue with my scenario is not about the flammability of the raw liquid but the fact its being atomised in compressed air.

[John HaineParticipant @johnhaine32865]

Don’t do it!!!!!

[JasonBModerator @jasonb]

I thought the who idea of a fog buster was that it did not atomize the liquid and therefore little or no fog/mist. So is it a fog buster or a misting system?

You are more likely to fill the workshop with what evaporates off the surface and off the swarf with more volatile liquids which may well build up like a gas rather than fog

I have been using paraffin through my fog buster on aluminium and it dries off in a day or two so swarf can be swept or vacuumed up OK. Just bought some Monos Miko S3G to try as that is synthetic so won’t swell the tube in my peristatic pump but feel it may leave some residue. Same supplier does small bottles of another product that is said to all but evaporate so may try that.

I don’t find the work gets that hot so it’s more the lubricating properties I use it for to stop tip build up rather than cooling.

 

 

 

 

[JAParticipant @ja]

Paraffin is not a good idea.

Atomised paraffin will burn very well indeed (even in a very cold workshop) if an ignition source is present, which cannot be ruled out. From my working days, the spontaneous ignition temperature of paraffin is about 500C which could easily be reached when machining.

In addition, paraffin usually contains water can give major problems like rust (the Myford guide for replacing belts warns you not to clean with paraffin). Bacteria etc also like growing in paraffin.

I cannot see any advantage in using paraffin (which was not part of the original question). I also think alcohol would be very unwise. For my own curiosity, are neat cutting oils suitable with spray systems?

JA

[Shaun ChurchillParticipant @shaunchurchill54517]

According to Fogbuster in the States one of the selling points about their system is that it can accommodate a wide range of liquid coolants and they are aware that some customers have used alcohol based coolants but advise that this will most likely incur O-ring deterioration. I have no intention of using alcohol coolant as a full-time solution it was merely a question that I thought might elicit a response from someone who may have had first hand experience of using it within a commercial engineering setting. The fact that Datron employ an alcohol based coolant in their awesome machines is what had attracted me to this in the first instance. If you havent seen their Neo range of CNC’s in action then would encourage you to look them up. When I win the lottery, I am getting one for my workshop😂

[JasonBModerator @jasonb]

Datron suggest using Ethonl only on metals that are unlikely to spark so can’t be used with steel. Also they have enclosed cabinets which should help keep fumes in.

The Fogbuster and similar systems do not atomize the liquid like a spray action does they are pumped into the flow of air and get carried onto the job with the air. Not seen any rust on my CNC and as the liquid is not being stored and recirculated like a traditional flood system bacteria is unlikely to be a problem.

The liquid that I have just bought is used neat and is fine for MQL systems as is the other one I want to try that is specifically for Aluminium.

Jokisch

Samnos AL

 

 

 

 

[JasonBModerator @jasonb]

Also worth noting that some of these MQL (minimum quantity lubrication) systems only use a very small amount of liquid. 5mls to 20mls per hour is not going to have it dripping off the workshop ceiling.

[John Haine]

On John Haine Said:

Don’t do it!!!!!

I agree.

At least three factors in play: the flash point of the liquid, the explosive range (ie lowest % of liquid to air that goes bang, through to the highest.), and the amount of fuel in the system if it ignites.

Flash point alone is probably enough to suggest IPA is unwise!

• Paraffin has a flash-point of about 50°C, considerably safer than petrol at -40°C, and therefore not completely insane!
• With an FP of about 12°C Propanol is distinctly riskier that paraffin.
• If anyone wants to go out with a bang,  Propane will do the trick – Flash Point about -105°C

A mix of vaporised fuel in compressed air reminds me strongly of the internal combustion engine, the difference being that the IC engine contains the burn and cools it by doing work.  Though the results of it burning produce a lot of power, the amount of fuel in an IC cylinder is rather low.   Quite a small explosion in the wrong place can do lots of damage.

My guess is Datron have put considerable effort into keeping their alcohol coolant system safe, probably only injecting tiny quantities of Ethanol at a time into a large sealed cabinet with forced ventilation.    Wonder why Datron choose Ethanol rather than IPA?  Ethanol being a drug abuse / taxable product makes using it much more complicated than IPA, which is unrestricted.   Must be a good reason.

Dave

 

[JasonBModerator @jasonb]

The cabinet is not sealed on the Datron so nothing is really under any pressure. Infact thay advise against blocking the vent.

They also advise not to use extraction when the Ethanol is in use as the gasses going through the fan motor may ignite things.

A lot more Ethanol is used than with other MQL systems. Gallon of Ethonol a day vs 1us oz of lube.

[Shaun ChurchillParticipant @shaunchurchill54517]

That makes sense Jason as in my job an Atex rated axial fan and similarly rated intrinsically safe electrical components would be employed dependent on the hazardous area classification under the DSEAR Regs which effectively relates to the likelihood of an explosive atmosphere occurring. The mere fact Datron dont spec this in their enclosed machines would suggest the explosive atmosphere mix of air and ethanol is above the UEL or in other words the atmosphere is too saturated with ethanol for it to be ignited. I somehow doubt its below the UEL without forced ventilation. As my Tormach is only partially enclosed then my experiment with IPA ends here and the only time I ever use paraffin is when I occasionally mix it with light oil to spray on my mag chucks when resurfacing them on my two manual surface grinders. As they are both dry grinders the paraffin / oil mix just keeps the heat out of the mag chucks.

[Shaun ChurchillParticipant @shaunchurchill54517]

And of course the other nasty characteristic of a lot of industrial alcohols is they burn with a fairly invisible flame. In fact they used to instruct fire crew with methanol fires to use a rolled up newspaper when approaching such a fire and when the end of the paper roll started to go brown then you were getting close to the seat of the fire! Cant say I would want to put that to the test!

[JasonBModerator @jasonb]

I think several CFM of compressed air being pumped in will tend to keep the saturation level down. You are just forcing the air in which will carry fumes out with it rather than forcefully removing the fumes

[Mark RandParticipant @markrand96270]

For any who don’t frequent the ‘other place’, the subject came up recently:- https://www.practicalmachinist.com/forum/threads/better-misting-coolant-for-aluminum-than-99-isopropanol.428909/

[RobinParticipant @robin]

My biggest problem with paraffin and spark erosion was moving it with a peristaltic pump. I could not find a silicone rubber tube that didn’t harden and then burst when faced with the stuff.

Paraffin was suggested as cutting oil for cast iron. That Gotteswinter bloke uses IPA for a cutting lube and he hasn’t blown up yet 🙂

Robin

[JasonBModerator @jasonb]

Thats why I wanted to try the other fluids they swelled my tubes too. I think Tygon do a resistant one but could not find it easily available. All the google results are for their more common model engine tubing.

The S3G is fully synthetic so does not affect silicon like oil based ones do.

[mike TParticipant @miket56243]

Tygon fuel tube is compatible with hydrocarbon fuels; paraffin, petrol, oils etc. Unfortunately you will find the tube material too hard for use with a peristaltic pump. It’s soft silicon or nothing, I’m afraid to say.

Mike

[JasonBModerator @jasonb]

Mike, I did look on the Tygon site before and they make a whole range of much softer ones than the usual fuel tube for peri pumps. Some food safe, some solvent resistant, etc This sort of thing

[JasonBModerator @jasonb]

Found it, this one resists hydrocarbons and is for Peri pumps. No cheap though.

[mike TParticipant @miket56243]

My mistake, I did not know they also made Peri-pump grade tube. As you say, neither are cheap.

You could no doubt play around with the internal diameter to alter the flow rate. Expensive experiment!!!!

[SillyOldDuffer]

On SillyOldDuffer Said:

On John Haine Said:

Don’t do it!!!!!

…    Wonder why Datron choose Ethanol rather than IPA?  Ethanol being a drug abuse / taxable product makes using it much more complicated than IPA, which is unrestricted.   Must be a good reason.

Dave

 

Trying to answer my own question:

Ethanol boils at 78.5°C and Propanol at 97°C.   As a coolant, Ethanol starts absorbing the heat needed to change from a liquid to a gas sooner,  keeping the work cooler than Propanol does.

Industrial Ethanol not taxed as a beverage is about half the price of Propanol,   it’s cheaper.

The minimum amount of Ethanol needed to ignite when mixed with air is 3.28%, whereas Propanol will go at 2%.   Ethanol is safer than Propanol provided the mix is kept weak.    But a Ethanol/air mix will still burn all the way up to 18.95% alcohol, making it more dangerous if the mix is rich.   In comparison, Propanol won’t burn if the mix is richer than 11% making it safer in other conditions.  Conversely this also means that Ethanol is a better fuel for a carburated internal combustion engine than Propanol.   On a system where Alcohol is  intended to cool as opposed to go bang, it would be wise to control the mix.  Not too difficult by metering the flow.

Unfortunately this is point at which the amateur machinist gets stiffed!  It’s difficult and expensive for Joe Public to buy industrial ethanol.   To get it at reasonable price requires us to buy in bulk, requiring a licence, and immediately attracting the darkest suspicions of the authorities, who know Joe Public buying industrial alcohol is usually a crook wanting to water it down and sell it to boozers!   The potential profit is enormous – a ton of industrial Ethanol costs less than £500, and can be converted into say 3000 bottles of Duffer Vodka selling for a tenner each, tax free!   And it would take me forever to use a 50 gallon drum of ethanol legitimately.

Dave

 

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