[pete00]

howdy

I noticed some vendors reccomend using distilled water some dont.
If i remember right if i boil a pot of water and then condense the steam thats distilled water.

As i was emptying a few gallons of water from my dehumidifier i asked my self what is this water....distilled.....filtered.....contaminated from the cooling process.....ahhhh.....can this be used...duh

I had no answer to myself...........
curious pete

[SkipW]

Pete,

Distilled water is pretty cheap here in the US. I buy it at Walmart. Your tube won't develop mineral deposits and will last longer, IMO, if you use distilled.

The dehumidifier water sounds good in theory but it's going to have contaminates from your home air in it, plus maybe copper and other metals from the evaporator lines. If you google dehumidifier water you can find some good discussions on the subject.

I'm going on two years with the original tube and having used only distilled water, with a shot of propylene glycol antifreeze for bacteria control, the inside of the tube still looks like new.

HTH,
Skip

[Mike F]

Pete,

I have just gone through the same process here and dvdlock suggested a trip to the local aquarium dealer to pick up some RO (Reverse Osmosis) water. Very cheap and plentiful.

Mike

[LuAn]

The dehumidifier water sounds good in theory but it's going to have contaminates from your home air in it, plus maybe copper and other metals from the evaporator lines. If you google dehumidifier water you can find some good discussions on the subject.

By "good" you mean "paranoid given the litigious nature of US society"?

Just how much "copper and other metals" do you think are coming off the evaporator lines? If you think it's significant then presumably a dehumidifier only lasts a few weeks before the pipes wear though? As for "contaminated from your home air", what the hell are you doing in your house that makes the air so bad?

Seriously though, the cleaner the water you can use the better, but let's not get paranoid about it. I wouldn't go paying for distilled or OS water if I had a dehumidifier.

[SkipW]

By "good" you mean "paranoid given the litigious nature of US society"?

Just how much "copper and other metals" do you think are coming off the evaporator lines? If you think it's significant then presumably a dehumidifier only lasts a few weeks before the pipes wear though? As for "contaminated from your home air", what the hell are you doing in your house that makes the air so bad?

Seriously though, the cleaner the water you can use the better, but let's not get paranoid about it. I wouldn't go paying for distilled or OS water if I had a dehumidifier.

No, by "good" I meant information that was relevant to the discussion.

The copper and other metals statement came from an aquarium forum where they were questioning if it was safe to use water from a dehumidifier in an aquarium. Tests were done and that's what was found. Sure, it's probably small enough quantities that it would be ok for laser use if that's all that was available. Give it a go, Pete, and let us know how you make out. It's probably better than some of the tap water being used.

I don't give my laser any water that I wouldn't drink myself. And it respects me for that. I do that for my dog too, though.

Just statin' the facts, ma'am.

[cncjunky]

I don't know anything much about lazers but my buddy has a big lazer gantry system he paid like over $100,000 for and he uses liquid nitrogen, for what I don't remember. But it would make sense that it would be for cooling.

[cncjunky]

I'd reccomend if you want distilled water buy or build a still and destill the water yourself, there pretty cheap. Destilled water has a ph level of 6 which is the lowest level I'd use myself for my home water system, I could never get it that low being where I live without using chemicals. Filtered water which normally has a ph of 7.0 - 7.2 is your best bet and would be completely safe. If you start getting a ph of 8+ your going to start seeing scale buildup and things will start to get ate up from the higher ph. Where I live the ph is 9-10 on the scale and my drains show it. Too low of a ph or to high of a ph will be corossive. Hope that helps a wee bit.

[LuAn]

Just statin' the facts, ma'am.

Sure, but when you say

No, by "good" I meant information that was relevant to the discussion.

that's not quite so is it?

(Sorry if this feels like a personal attack. It isn't. I'm attacking your argument, not attacking you. ;-))

You say that the information about metals came from a discussion about whether dehumidifier is safe for aquarium fish. Firstly, there are no fish in my laser cutter so I don't really need to worry about the sensitivity of exotic biological organisms to the chemical content of my coolant water. Oxygen levels and temperatures of water in my laser cutter would be wrong for them too. ;-)

Secondly, an important issue with the aquarium water is that in addition to replacing water that has been removed while cleaning, you're replacing water that has evaporated. When water evaporates, any chemicals in the water are left behind in the main body of water. Thus replacing it with anything less than pure water adds a fresh batch of chemicals and over time the concentration of chemicals in the main body of water increases. The chemicals in a single batch of dehumidifier water, or even tap water (the stuff we drink but which is a big no-no for aquariums), are unlikely to cause problems to even the most sensitive fish. But concentrate the chemicals from 100 refills...

Kettles, irons, and other household gadgets, are also filled with with tap water, used, and emptied, every time we use them. So each time we use them we introduce a fresh batch of things like calcium carbonate to line the surfaces as lime scale.

On the other hand, with something like a household central heating system, we fill it with tap water, add some chemicals, and the same water goes around the system for years. When the system is first filled/used, air in the water comes out and collects at the top of the radiators which then need bleeding. The problem decreases as the water 'ages' and we get all of the dissolved gasses out of it. Similarly any calcium carbonate in there gets deposited but once it's out of the water, there is no more because we're not refreshing the water.

Unless you are refilling your laser cutter's cooling system on a regular basis, then whatever water you use will 'age' and any 'damage' done by it will be limited to the potential of that single batch of water.


So getting back to the main point i.e. whether or not dehumidifier water is a good thing to use in a laser cutter, we need to consider any facts in relation to the intended purpose. Conclusions relating to it's suitability for other purposes are of little value unless we also understand the parameters of those other requirements.

SkipW, your dog drinks water out of the garden pond and licks it's butt so following your logic... :-)

(Sorry, couldn't resist that one.) ;-)

Seriously though, in my case I opted to use RO water because it was the best I could get without going to A LOT of trouble/expense, and have set up what is pretty much a closed system i.e. my reservoir has a lid to prevent any crud from falling into it, and to limit evaporation and re-oxygenation of the water. I'll be using the same water for years so the damage it can do to my system is VERY limited.

A little more information about my set up plus a picture of my closed reservoir can be found on my personal website:
http://www.andyslater.com/laser-cutting/set-up.html

[SkipW]

Pete asked a question and I was trying to help him with an answer, period. I have not yet attained your level of Zen where everything I say is the indisputably correct answer. I am still learning.

And for the record, I have no garden ponds and my dog is too fat to lick his butt. Sad, but true.

Skip

[LuAn]

I have not yet attained your level of Zen where everything I say is the indisputably correct answer.

Clearly that suggests that I have offended you.

I DIDN'T ever suggest that you were doing anything other than trying to help and I DID say that I wasn't attacking you personally and was merely attacking your argument.

Please don't be offended.

[SkipW]

Clearly that suggests that I have offended you.

I DIDN'T ever suggest that you were doing anything other than trying to help and I DID say that I wasn't attacking you personally and was merely attacking your argument.

Please don't be offended.

Forget about it. Give me a hug...

[LuAn]

Forget about it. Give me a hug...

I can't find a hug smilie so here a :cheers: instead. :-)

[protomate]

Hello Everyone!
I work with high powered lasers for a living, so I thought I might share some of my observation's and thought's with everyone. I have observed that many older coherent tubes tend to arrive with appreciable scale on the lasing tube and outer cooling tube. At some point in time, I do not think they recommended using distilled water. The newer systems I have come across, with similar amount of hours on the laser tube do not exhibit this scale. Having thought back to my heat transfer classes in school, I draw the parallel that the scale, in theory, can act as an insulator. This in turn can increase the lasing chamber temperature, thus reducing laser power potential. The output power of a co2 laser is proportionate to temperature. To go one step further, I have designed systems employing cooling methods to increase the laser output, while holding maintaining the same length.
A note on adding radiator fluid to the cooling water. Great idea! I have worked on numerous systems that use a 40/60 mix of coolant/water blend. They are always spotless, and look like new. With that said, coolant actually does not provide the level of heat transfer as the water does, but by design the flow rate and heat exchanger are sized to provide the correct cooling. (PS:I used to consult the companies that make the radiators, condensers, heater cores, and evaporator systems for almost every automotive company in the world.)
What I have found is that just a shot of the coolant works wonders and I adopted it as a standard process. It is designed to prevent corrosion. Many pumps may suffer from corrosion if subjected to certain contaminates. The other question that comes to mind is that tap water has chlorine in it. This is a salt. Salt water is a great conductor.
Just on a side note, i am an avid jet skier. I made the mistake of touching both terminals of my battery when I was reaching into my engine bay. I have done this 100x in freshwater, no problem. I was on the shore of the Atlantic. Oh boy did I feel the electricity fromthat little battery. really hurt!LOL
Some of the confusion may lie in that YAG laser almost always have water flowing across the anode and cathode spaced maybe 6" apart and carrying 30kv at times. It is critical that the water does not effectively short out the power that is supposed to go into the arc lamp/flash lamp. All reputable manufacturer's employ a de ionizing subsystem to minimize the charge carrying potential. Some CO2 cooling systems I have also have de ionizers as well. I think of it this way, I spend $1000's of dollars to set up a laser. What is $1 to assure it will last as long as possible?

[SkipW]

Greeting protomate,

Thanks for that info. Glad to hear you agree about the anti-freeze use.

What do you think about using dehumidifier water in a glass tube laser?

Skip

[protomate]

Hello Skip,
Now I do not want to step on anyones feet here. Concerning the dehumidifier I am thinking of the ones you put in a damp basement to prevent mold growth, and mildew on your cardboard boxes. In my mind I think about the dust that seems to be present everywhere in my home. Not sure what it is composed of. Dead skin I have read. I would just assume spend $.88, then take a chance. This is my opinion and practice (with a shot of coolant of course).LOL