Using antifreeze in coolant lines

[Dan Hintz]

Has anyone had any success using some form of antifreeze mix in their coolant lines, or do you stick strictly with distilled water?

[Mike Gillis]

I was wondering the same thing! It is costly to buy distilled every few days. I may just try it.

[Rodne Gold]

The only reason to use antifreeze is that it will raise the temperature to when water boils quite a bit higher than it would naturally boil under pressure in a radiator
IE if it would boil at 220degrees under pressure , the antifreeze would raise that to about 250 degrees , thus allowing the motor to work at much higher temps without overheating. I see no benefit to using it at all.

[Dan Hintz]

The only reason to use antifreeze is that it will raise the temperature to when water boils quite a bit higher than it would naturally boil under pressure in a radiator
IE if it would boil at 220degrees under pressure , the antifreeze would raise that to about 250 degrees , thus allowing the motor to work at much higher temps without overheating. I see no benefit to using it at all.
It would also lower the freezing point of the mix, allowing for a lower cooling point... I would think this would be beneficial for preserving tube life. I could lower the temp setting on my chiller and reduce power degradation during extended use.

[Sandra Force]

Use the antifreeze for RV water lines, this is what is recommended by both my manufacturer and 5 years of running with it. My lasers are in an unheated building and drop to below freezing at times and I have never had a problem. I run with a 50/50 solution and drain and replace the distilled water and RV grade water line antifreeze every fall. Also, check and see if you have filters in you cooler/chiller line and clean those at least 3 times a year. It will solve a lot of problems.:cool:

[Sandra Force]

Reading your post I see that you want to lower the temp on you chiller. Be very careful of doing that. The difference between ambient temperature and the fluid to the laser is very important. If you are running with too large of difference it will cause condensation on the laser tube and shorten the life of the laser. This was one of the biggest problems people running chillers when they firset came out ran into. Check with your laser tube manufacturer at the recommended difference between the air temp and chiller temp.

[Dan Hintz]

Reading your post I see that you want to lower the temp on you chiller. Be very careful of doing that. The difference between ambient temperature and the fluid to the laser is very important. If you are running with too large of difference it will cause condensation on the laser tube and shorten the life of the laser. This was one of the biggest problems people running chillers when they firset came out ran into. Check with your laser tube manufacturer at the recommended difference between the air temp and chiller temp.
Sandra, very good point... the laser will be in an environment where the temp remains in the high-60's year-round. I also have a dehumidifer running on automatic to keep humidity in check, just in case.

[William Johanson]

Just another thought here, I work for a steel rule die maker and we have 4 LMI/Preco laser systems ranging from 100 watt to 2000 watts. We used to use straight distilled water but ran into some issues with the water getting contaminated and so on. So we started adding an additive to the distilled water at LMI/Precos advice which has greatly reduced our problems and lessened how often we change the fluid. As Sandra said we also run filters in line as well. I can't remember the name of the additive but I can look tomorrow if anyone is interested.

Bill

[Dan Hintz]

Was the additive to prevent contaminants such as bacterial growth?

[Mike Gillis]

My thinking on the distilled water requirement was along the lines of conductivity. As pure water is in theory, non-conductive (We measured water contamination in waste water in 'MHO's' which is the opposite of OHMs)and thus safer to use.
Bacteria growth is then a problem if using distilled water. I do not know if Anti-Freeze would therefore be safe to use? I had considered adding a bit of bleach, but again I am not sure if conductivity is a concern.
I just drove a 3 foot length of rebar into the earth outside to ground the laser better (I hope). Bleach does leave a residue, and I have a concern that it may build up in the laser tube, now would A-F do the same?
Interesting...and confused as ever.

Mike

[Sandra Force]

Propylene glycol is the ingredient that is recomended by Coherent and the active ingredient in RV and Marine Antifreeze. As far as I know that is the only thing other than distilled water that Coherent will allow in the coolent lints that will not mess up your warranty. I am assuming that because this is what they recomend it will not build up in the lines as long as you do the yearly drain and replace that they say to. In one of my machines it goes through not only the laser tube but also the power supply and keeps the temp down on that also. Would not even think of running without it under the conditions that my machines work.

[Walt Nicholson]

I do not own a laser (someday maybe in my next life) and have no idea how the coolant process works but the proplylene glycol caught my attention. A product that has been around for a little while is non-aqueous proplylene glycol sold by Evans cooling www.evanscooling.com (http://www.evanscooling.com) for use in performance cars and bikes. We have used it in several street rods and it is really cool. (pun intended) There is a lot of techinal data on the website. I have no affilation with the company. Just thought it might be worth checking out. It would be cool if it worked in your lasers.:D:D:D

[Mike Gillis]

Sandra, thanks for the information. It seems the RV antifreeze is for plastic pipe only, and non toxic. Two good reasons to use this type I would think.
I am going to mix some up and try it out. Do you keep your fluid cycling all of the time, or just when using your laser?
I only have a 40W laser, and am not set up with filtration of any sort. Maybe I should look into that while I am at it.
Also, does anyone know of a simple way to test the cooling fluids conductivity?

[Rodne Gold]

Generally , the density of a liquid will determine its ability to transfer heat, the lesser space between atoms of a substance will allow the transfer of kinetic energy of the excited atoms (the hot thing) to happen quicker.
In your case , you would have to consider many factors as to whats really effective. I would say there are many other factors other than density that I would consider first. Heat transfer is more a function of the whole system rather than the fluid properties.
The factor I think that would be most effective is flow. Increasing it might or might not be more effrective than anything else including dropping the temp of the coolant.
For example if you drop the temp of the coolant and radically increase flow , you might be WORSE off cos the increased flow might not allow good transfer of heat to the cooler liquid. The transfer of heat is a function of time and increasing flow might not allow the heat to transfer to the cooler medium effectively as it has less time in contact with the coolant.

What I would do in your case , IF overheating is a problem is this.

1) Reduce ambient temp with an aircon or direct cooled air to the vicinity of the tube

2) Increase pump rate and the amount of coolant you flow and use a temp probe or thermometer to see whether this is actually effective.

I have built some seriously powerful motors and have messed a lot with cooling systems and fluids for them and would imagine that like a motor , a laser works best within a set temp range. Overcooling , like in a motor might not be effective. I think your biggest gain in maintaining a very constant operating temp of your tube would be the fact that the tube output would be more predictable and constant. Arent those glass tubes quite cheap anyway (assuming yours is one of the chinese glass ones ), I was quoted $125 as a replacement cost .

[Dan Hintz]

My thinking on the distilled water requirement was along the lines of conductivity. As pure water is in theory, non-conductive (We measured water contamination in waste water in 'MHO's' which is the opposite of OHMs)and thus safer to use. Bacteria growth is then a problem if using distilled water.
Mike

Mike,

I don't have a tube in front of me to say with 100% certainty, but the water should not be in contact with any conductive portion of the tube's power supply. As with lab equipment, distilled water is specified not just for lack of conductivity, but lack of the products that would cause conductivity... the minerals. Without minerals in the water, there will be no residue left in bad places, which could result in localized hot spots. Also, distilled water helps prevent bacterial growth.

Bleach is a mixture of quite a few things, so I would suggest using a high-grade chlorine instead. I will have to check on the purity of that found at local pool supply stores, but pure chlorine should be fine in small quantities. If the water is distilled, there are no salts to combine with the chlorine keeping conductivity low (even pure water has a small amount of conductivity). I'm considering making a sealed 5-gallon container with a window for visual verification of purity and a pH meter to verify chemical/electrical purity.



Rodney, I'll reply to your post separately... I just saw it and there are a few good points I'd like to touch on when I have some more time.

[Sandra Force]

I turn on the cooling systems when I turn on the laser systems and run both all day. If I am not going to be using the lasers for 1 or more hours I turn off the cooling system so that there is no condensation started. The manufacturer recomendation is to only have the cooling system operation when the engravers are turned on and not to leave the engravers turned on without using for long periods of time (i.e. over 1-2 hours).

[Ricky Gore]

...I work for a steel rule die maker and we have 4 LMI/Preco laser systems ranging from 100 watt to 2000 watts.
Bill

2000 Watts? I would love to see that in operation. Is there anything you can't cut with that much power? What about Diamonds? :rolleyes:

I never really thought about it, but what are the most powerful lasers out there?

[Dan Hintz]

I've often heard of 10's of kW, though I imagine there are more powerful out there. Are we considering CW or pulsed?

[James Jaragosky]

I changed my distilled water yesterday and decided to ad rv anti freeze to the mix as suggested here. I was hoping to keep down an any bacteria growth and hopefully change out the water less often. I do not have a chiller I use a bucket and a pump. I mixed 3 gallons of distilled water to 1 gallon of rv antifreeze. about 1 hour after doing this my laser lost most of it's power.
on my potentiometer's scale I was firing at 30 mg and now i am only firing at 10mg.
question: Is my tube lost or can it be cleaned out. I would lean to lost myself.
Is there a way to test if it is the power supply or the tube?
I don't believe in coincidence, so I really believe it is the tube damaged from the antifreeze. i have a extra tube. but would prefer to hear from you all before changing it out.
thanks for your help jim

[James Jaragosky]

I changed my distilled water yesterday and decided to ad rv anti freeze to the mix as suggested here. I was hoping to keep down an any bacteria growth and hopefully change out the water less often. I do not have a chiller I use a bucket and a pump. I mixed 3 gallons of distilled water to 1 gallon of rv antifreeze. about 1 hour after doing this my laser lost most of it's power.
on my potentiometer's scale I was firing at 30 mg and now i am only firing at 10mg.
question: Is my tube lost or can it be cleaned out. I would lean to lost myself.
Is there a way to test if it is the power supply or the tube?
I don't believe in coincidence, so I really believe it is the tube damaged from the antifreeze. i have a extra tube. but would prefer to hear from you all before changing it out.
thanks for your help jim
it just dawned on me.
do all you guys using antifreeze in your cooling mix have metal tubes?
i have a glass tube could that have caused my failure?
jimj

[Dan Hintz]

Jim,

It may seem to be too much of a coincidence, but I would reserve judgment until we've exhausted all avenues. There should be no connection between the electrodes and the cooling water. If the tube was running fine for an hour after introduction of the coolant, and the drop is power is due directly to the coolant, that leads me to believe there was a crack/leak between the coolant section and the lasing section. If it's not due to the coolant, well, that's what coincidences are all about. Empty the tube and examine it closely... do you see any water or coolant in the lasing section?

[Mike Gillis]

I changed my pure distilled water to a 50:50 mixture using distilled water and the RV AF. I wonder if your pump got gummed up.
I haven't tried using the laser on mine yet. I just am cycling the fluid to see if I run into a pump problem. I hope your tube is ok! I have the glass tube on
my laser.

[James Jaragosky]

After removing the tube I found what appeared to be a crack inside on the second tube that carries the coolant, but upon examining it under a magnifying glass it looks like a hair has fused with the glass between the second and third inner tubes. Is this possible? anyway I am currently replacing that tube now, I just need to get some high voltage electrical tape.

[Dan Hintz]

After removing the tube I found what appeared to be a crack inside on the second tube that carries the coolant, but upon examining it under a magnifying glass it looks like a hair has fused with the glass between the second and third inner tubes. Is this possible? anyway I am currently replacing that tube now, I just need to get some high voltage electrical tape.
As I expected, though its a shame your tube paid the ultimate price. At least you can rest easy knowing it wasn't the anti-freeze, just a coincidence.

Do you have the ability to photograph what you see under the microscope? The "hair" is most likely not actual hair as that would have burned up upon nearing the molten glass during manufacture. A more likely explanation is "fried anti-freeze"... once the water/anti-freeze solution seeped into the crack, the high voltage flowing through the thin tendril dried the mix into a gummy black hair the same shape/size as the crack.

[James Jaragosky]

As I expected, though its a shame your tube paid the ultimate price. At least you can rest easy knowing it wasn't the anti-freeze, just a coincidence.

Do you have the ability to photograph what you see under the microscope? The "hair" is most likely not actual hair as that would have burned up upon nearing the molten glass during manufacture. A more likely explanation is "fried anti-freeze"... once the water/anti-freeze solution seeped into the crack, the high voltage flowing through the thin tendril dried the mix into a gummy black hair the same shape/size as the crack.
right now i am a little agitated that i can not seem to be able to get the wire leads soldered to the tube posts. i have soldered wires by the mile for machine repair and i can braze . i have even soldered 1' thick copper plate. but i cannot seen to get the posts on the tube to hold the solder connection. i am using a 40watt iron. god i wish i could use quick connects. right now i am still not 100% sure it was the tube and not the power supply and i wont be unless i can figure a way to make this connection work.
its like trying to solder copper to wood.
jim j.

[Dan Hintz]

right now i am a little agitated that i can not seem to be able to get the wire leads soldered to the tube posts. i am using a 40watt iron. god i wish i could use quick connects. its like trying to solder copper to wood.
jim j.
I would suggest a higher wattage iron... you want high heat for a short period of time, in and out. Too long and you start to heat up the post farther up into the glass, and that's a crack waiting to happen.

Edit: Oh, and don't forget flux... use some sandpaper on the post to get it nice and clean, apply flux, then solder.

[Skip Weiser]

James,

That RV antifreeze that you used. Does it say on the jug whether it's ethylene glycol or propylene glycol? I've always read to use the propylene glycol for laser coolant applications. Maybe someone can explain to us the difference?

When I was shopping for the propylene antifreeze at local stores, the hardware store had RV antifreeze but it was ethylene based. I ended up with a gallon of Sierra brand propylene glycol antifreeze.

Since the cold weather started I've been mixing about 3 cups with 2 1/2 gal. of distilled water in my chiller. I just wanted to drop the freezing temperature of the distilled water down another 10 degrees or so. I have a glass laser tube also and I've encountered no problems so far.

Regarding soldering the wires onto your tube, I've heard from others that it's a big PIA. The laser that I have uses heavy duty alligator clips on the tube power wires. They just clip onto the tube metal posts and you're done. I don't know why you couldn't do something similar.

Good luck,
Skip

[James Jaragosky]

James,
Good luck,
Skip
Well I had a job some years back that required to look into this for a piece of equipment that used a lot of antifreeze, we wanted to cut our waste antifreeze disposal charges. as well as avoid EPA issues.
The sierra brand was the only propylene glycol based product on the market at the time. I remember the two types are interchangeable for most applications, but you should not mix them, so use one or the other. the propylene glycol is more environment friendly product, in fact I had some salesman tell me you could drink the stuff without it killing you ( i do not suggest anyone trying this. we all know sales man have a propensity to stretch the truth). As far as differences in their ability do conduct electricity i haven't got a supportable answer for you on that but i would think that both product would work.

[Sandra Force]

The antifreeze that I use ispropylene glycol based. As I said it is what my manufacturer recommends. I have poly tubing on my lasers.

[Dan Hintz]

Forgot to reply...

Ethylene/Propylene glycol has a resistivity of about 1Mohm/cm^3... that should be more than adequate for the voltages we're dealing with.

[Rodne Gold]

Surely your cooling fluid doesnt touch or go thru electronics or comes into contact with anything that carries power?
Are the mnfgrs concerned that the tube will fail and liquid will be introduced and thus it must NOT conduct electricity?

The only thing I can think of that caused a crack is over rapid or inconsistent cooling over the inner tube. Perhaps there was a hotspot and the coolant evaporated over that hotspot and then when the coolant came into contact with it , it rapidly cooled and thus stressed and cracked? Or the tube was real hot at the time and the coolant was introduced when it was hot and thus caused a crack?

How hot does the inner tube get?

[Mike Gillis]

When I went to get some laser instruction from the salesman who sold me the laser, I was told to ONLY use distilled water. I asked it this was required because of the minerals in the water, and he said no, it is because of the high electricity. Now this was spoken in Chinese/English, and I may have misunderstood, but Sandra posted that she was told a mixture of a specific type of AF was fine. I figure if a company would give that kind of approval, then it would be safe.
I would like to know, why exactly, distilled water is recommended. For safety
reasons, or another reason. Because someone just might get hurt here. We are talking very high voltages, and with water...

[Dan Hintz]

I would like to know, why exactly, distilled water is recommended.
Why must companies put a sticker on the side of the lawnmower telling people not to pick it up with their hands? Because they're protecting their own butts. (Maybe a bad example as in that case it is still a safety issue).

All it takes is for some local yokel to put some odd chemical in the tube, kill it, then blame it on the manufacturer. Most of the Chinese manufacturers are just that, manufacturers... they don't understand the actual lasing process, nor do they understand the connections being made, only that it needs to be done "X, Y, and Z".

There's a nice blog from the maker of Chumbys (think a Gremlins-style mogwai with an LCD tummy) where he discusses at length the issues involved while working with Chinese manufacturers. They were very quick to pick up new ideas, suggest alternate manufacturing methods to resolve problems, etc., but almost none of them had even been on the internet or even owned a computer... they could put together an MP3 player form parts like there was no tomorrow, but they had exactly ZERO concept of what the product in their hand did.

So, if Mr. Li down the street doesn't allow anything but pure water in his tube, there's no harm in saying the same. It most likely comes out of the fact that if there is a leak, pure water won't fry the tube, but any cooling solution with impurities in it would. The thing is, propylene/ethylene glycol has such a high resistivity, you would do more damage to the water's purity by sticking your hand in it (sweat/salt) than dumping in coolant.

Rodne's rapid cooling theory has some merit, but I don't believe the thermal conductivity of the coolant is large enough to cause that kind of thermal shock... though I admit with a cheaply replicated tube much might be possible.

[Sandra Force]

The explination that I have received from laser and other equipment makers for the use of distilled only water is that the distilling process removes the salts and mineral content in the water and makes it less corrosive. Most tap and well water will leave deposits of one kind or another in time, even filtered water.