Warning, Distilled Water for ND:YAG

[mixedgas]

Question from ignorance... if DI water is so aggressive/corrosive, why is it used in sensitive electronic/optical equipment? Is there no other/better cooling solution?

DI water is only used to cool lasers where the lamp electrodes must be wet, ie non-conductive water. Other lasers use either water with a oxygen inhibitor cartridge, filtered water, or water plus glycols. In some cases a corrosion inhibiter may be added to anything but deionized water. Much of this depends on the materials used in the baseplate and the plumbing.

I spent three months in a lab once dealing with the effects of a Post-Doc, who added fresh DI water every day to three lasers with aluminum baseplates. I milled new baseplates, remounted/realigned the lasers, and replaced all the chiller pumps. He had a lamp pumped laser in the past and thought that the new diode pumped lasers should also use DI. At least I got paid.

Steve

[buffo]

if DI water is so aggressive/corrosive, why is it used in sensitive electronic/optical equipment?

Only ASTM Type I water (10 meg-ohm or higher) exhibits the aggressive behavior. ASTM Type II does not, and this is what would normally be used for cooling.

As Steve explained above however, there are times when your cooling water MUST be non-conductive. In that case you need ASTM Type I water, and that means continuous recirculation through a DI bed. It also means you need to select your plumbing materials very carefully.

I spent three months in a lab once dealing with the effects of a Post-Doc, who added fresh DI water every day to three lasers with aluminum baseplates.

D'oh! That had to suck. Damned shame too. If only the guy had bothered to ask you first!

Adam

[mixedgas]

D'oh! That had to suck. Damned shame too. If only the guy had bothered to ask you first!

Adam[/QUOTE]


Nah, Guys like that are job security..... Except when the repair bills exceed the available grant money... Then they are a source of grief for both myself and the client.

Steve

[dsli_jon]

...I'm going to nit-pick here. ...One thousand Meg-ohm...

Sorry, typo-fail... That was supposed to be 1000kΩ (on the 2000k DMM-setting..) So, better than 1MΩ - min - to start-with..

..Typically, I find most 'drug-store' distilled to be ~1700-1800kΩ (1.7-1.8M), or better.. Then, yes, into the Sys w/ a fresh DI-cartridge it goes, and circulates for quite some time (..usually, new-new DI-cart, by the time you refil the Res / 'burp' all the air-bubbles out, it'll be fine to light-up.. ) But, if freshly-purchased distilled is below 1000kΩ, I toss it..

..Thanks for the catch..
j

[Eidetic]

I really appreciate all this discussion about DI water, as I prepare to fire up an old Laserscope for my first time. Everything looks clean and well cared-for. It has a huge 50A plug on it I'll have to deal with. Is that really necessary?!? I suppose a new cartridge, to be safe. People who've visited and seen all the lasers around the house ask to see one run. I want this to be one I can turn on and present a beam that makes hair stand up on the back of their necks.

[dsli_jon]

...I suppose a new cartridge, to be safe. ...It has a huge 50A plug on it I'll have to deal with. Is that really necessary?!?

..Well, a 30A plug would be kinda pushin it, since you can-draw better than 35A thru those.. So, with 'proper overhead', ya a 50A is appropriate, if you plan to run it 'full-bore'.. (and a lot of those puppies 'sweet-spot' is right-about 37.7A..

Feel free to gimme a call to chat about yer pup, anytime, Bob.. Happy to help ya learn to scratch her chin..
cheers..
j

[Eidetic]

Thanks Jon. I found a manual online with the service mode modification and instructions, but may have questions.

[mixedgas]

Thanks Jon. I found a manual online with the service mode modification and instructions, but may have questions.

The on line mod sheet is screwy, talk to Jon...

Karl has one working across town from you.

Steve

[Laserman532]

any store bought distilled water, run in time of 30 minutes for a fresh fill prior to lamp ignition, with a DI cartridge replaced every 90 days is totally sufficient.

[kecked]

You can buy a mixed bed resin column for around $30.00 and pass plan old tap through it. the water on the other end is good enough for a reef aquarium and tds is really low. Might be easier and cheaper to simply buy a small RO mixed bed filter and keep it around or dump the store bought DI water through the column once. It will clean it up and the bed will last for a long time. I make water for the reef once a week and make about 10 gallons. The resin lasts about a year for me coming out of an RO unit. It only lasts a short time on tap water.