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Thread: How to check the metal content of laser cooling water

  1. #1

    How to check the metal content of laser cooling water

    New to the group, glad to be here but please bear with me. How do you check the metal content of the cooling water for a Laser. I am currently using a pond fountain pump, not a separate chiller and it works well. Reason I am asking is I was in the middle of a job and my laser started arching to the water inlet. I refreshed the water, cleaned the tube best I could and even put more silicon sealant around the area it looked like the arc was coming from (HV line). No luck, same problem. I was told that it was due to too much metals (contaminants) in the water possibly from the pump . I guess I'm looking for a meter of sorts i can place in the water to monitor its purity. If y'all have any ideas please reply. At the point of ordering a new tube and P/S. Not sure how to put up a video but will try. BTW I am using a Chinese 60W Red/Black. Bought brand new 3 years ago and this is the first major problem.

    Thanks in advance

  2. #2
    First, use distilled water-

    Second, seems to me the water fittings are probably just screwed to the metal cabinet without any isolation and would therefore be a ground source. Even if O-rings are used, that won't isolate the part of the fitting passing thru the hole FROM the hole...

    Anyway, if it is the water, using distilled will fix it...
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  3. #3
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    Is it metal or minerals in the water

  4. #4
    Quote Originally Posted by Jerome Stanek View Post
    Is it metal or minerals in the water
    That's what I'm trying to find out. Water looks clear. Is there a meter or something I can place in the water to determine its purity. Thanks for your replay.

  5. #5
    Quote Originally Posted by Kev Williams View Post
    First, use distilled water-

    Second, seems to me the water fittings are probably just screwed to the metal cabinet without any isolation and would therefore be a ground source. Even if O-rings are used, that won't isolate the part of the fitting passing thru the hole FROM the hole...

    Anyway, if it is the water, using distilled will fix it...
    Sorry for late reply but I am using distilled water. All fittings are a plastic type material. Could not see any metal in the water path, even in the pump. Didn't dismantle the pump to inspect it.

  6. #6
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    Changing the water to new distilled water would be my first step in order to remove any contaminates that were promoting arcing. Even if the current distilled water is new, I would still change it because it might have been contaminated/defective when you bought it. If it was new, I would definitely buy a different brand of distilled water.

    I don't think metal in your pump is the cause of your problem because many of us use chillers without issues where water comes in contact with various metals as it moves through the system.
    Last edited by Doug Fisher; 05-21-2019 at 11:48 AM.
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  7. #7
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    Once you get a carbon path from an electrical arc its pretty much going to keep doing it. Remove the connection, cut back the HV wire a couple inches, clean everything up with acetone or the like no residue solvent. Slip some clear vinyl tubing over the HV cable as far back as you can. Let dry, remake the connection and cover with RTV Silicone sealer. It must be completely cured before you turn the power back on. Or replace the entire HV cable.
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  8. #8
    Quote Originally Posted by Doug Fisher View Post
    Changing the water to new distilled water would be my first step in order to remove any contaminates that were promoting arcing. Even if the current distilled water is new, I would still change it because it might have been contaminated/defective when you bought it. If it was new, I would definitely buy a different brand of distilled water.

    I don't think metal in your pump is the cause of your problem because many of us use chillers without issues where water comes in contact with various metals as it moves through the system.
    Thanks for reply. I'll change the water again (distilled) and see what happens. I really didn't think the pump was the problem but just needed someone else's input.

  9. #9
    Quote Originally Posted by Bill George View Post
    Once you get a carbon path from an electrical arc its pretty much going to keep doing it. Remove the connection, cut back the HV wire a couple inches, clean everything up with acetone or the like no residue solvent. Slip some clear vinyl tubing over the HV cable as far back as you can. Let dry, remake the connection and cover with RTV Silicone sealer. It must be completely cured before you turn the power back on. Or replace the entire HV cable.
    Never thought about using acetone or cutting back the HV line a bit. Gone to try and report back. Thanks again, great help here

  10. This happened to me with my first laser. The cause was a crack in the glass tube, it didn't seem to be leaking until I was taking a video for tech support. Once I replaced the tube the arching never came back. BTW I always used distilled water, and I don't think any metal contained in your cooling water will conduct electricity any differently than the water itself.
    Just my thoughts.

  11. #11
    Quote Originally Posted by Edward L Brown View Post
    This happened to me with my first laser. The cause was a crack in the glass tube, it didn't seem to be leaking until I was taking a video for tech support. Once I replaced the tube the arching never came back. BTW I always used distilled water, and I don't think any metal contained in your cooling water will conduct electricity any differently than the water itself.
    Just my thoughts.
    Thanks, I had my suspicions about the leaking tube. I ordered a new tube and p/s from Lighobject due to arrive this week. I upgraded to an 75w RECI with p/s to handle per their support. Gonna stick out of the frame but thats what extensions are for. Have distilled water, new water lines and pump ready. Might as well replace the lot with better quality while I'm at it. Post back when finished.

  12. #12
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    No, metal in the water wouldn't cause arcing outside the tube. Good to see you are upgrading. Spend the money and get a good chiller CW5000 or higher, cause you'll need it with a 75w tube..... Just say'n. And BTW, I used my tap water which is pretty darn hard in my chiller (closed system) and over 2+ years with no issue.
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  13. #13
    Quote Originally Posted by John Lifer View Post
    No, metal in the water wouldn't cause arcing outside the tube. Good to see you are upgrading. Spend the money and get a good chiller CW5000 or higher, cause you'll need it with a 75w tube..... Just say'n. And BTW, I used my tap water which is pretty darn hard in my chiller (closed system) and over 2+ years with no issue.
    Thanks for the reply. Yea, just received my new tube and p/s but haven't installed yet. Been looking at the CW5000 chillers and will definitely get one. Only do short runs a few times a week for now, CNC does most of the work so hopefully if I watch my temp carefully and pre-chill the distilled water I use it will be OK for now. Update here when installed, thanks

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