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Matthew Grant
10-03-2015, 8:20 PM
Can anyone come up with a reason that a copper heat exchanger wouldn't be suitable for a laser chiller? I know the aquarium chillers have titanium heat exchangers to tolerate salt water, and I believe the CW series use aluminum.. But I've never heard of one with copper.

What do you guys think?

Clark Miles
10-03-2015, 9:29 PM
Copper has much less of a tolerance for halogens (chlorine). I don't know enough about engravers to know what kind of water is recommended in the exchanger system. I guess it all depends on any other metal in the system (galvanic corrosion).

Dave Sheldrake
10-03-2015, 10:05 PM
One of the issues with the CW5000 is the dissimilar metals problem between the coil and the entry tube, one is aluminium the other stainless steel, add de-ionised water and it causes gas leaks . Down side is there is no refill valve for that model so it's usually game over when the gas leaks :(

I use chlorinated water in mine as a coolant so copper as Clark said would be a non starter :(

Jerome Stanek
10-04-2015, 8:14 AM
most cities add chlorine to their water systems and most people have copper water lines in their homes so where is the problem

Dave Sheldrake
10-04-2015, 11:59 AM
City supplies don't run the same concentrations as you would use in a laser :) ever looked at the inside of a copper water pipe ;)

Matt McCoy
10-04-2015, 12:01 PM
One of the issues with the CW5000 is the dissimilar metals problem between the coil and the entry tube, one is aluminium the other stainless steel, add de-ionised water and it causes gas leaks . Down side is there is no refill valve for that model so it's usually game over when the gas leaks :(

I use chlorinated water in mine as a coolant so copper as Clark said would be a non starter :(

Do those metals have to touch in the CW-5000?

Clark Miles
10-04-2015, 12:05 PM
In a recirculating water system, the metals do not need to be touching for galvanic corrosion to occur.

Jerome Stanek
10-04-2015, 12:59 PM
City supplies don't run the same concentrations as you would use in a laser :) ever looked at the inside of a copper water pipe ;)

Why would you need more than the cities supply both keep the algae from forming. and yes I have seen cooper pipes that have had chlorine run through them. It would take more years than the unit could run to do any damage

Dave Sheldrake
10-04-2015, 2:27 PM
Why would you need more than the cities supply both keep the algae from forming.

The biological reasoning behind it I have no understanding of but even when using tap water in a chiller the algae forms within 2 weeks and totally clogs the system within 6 over here. Hence the reason I add Chlorine crystals to my chillers

Matt McCoy
10-04-2015, 4:10 PM
Are the coils of the CW-5000 copper?

Dave Sheldrake
10-04-2015, 5:42 PM
stainless steel but joined to aluminium

Matthew Grant
10-05-2015, 11:03 AM
The biological reasoning behind it I have no understanding of but even when using tap water in a chiller the algae forms within 2 weeks and totally clogs the system within 6 over here. Hence the reason I add Chlorine crystals to my chillers

Hi Dave,

You may try propylene glycol, aka RV or non toxic antifreeze. It is antimicrobial and antifungal above about 20% concentration.

Just be sure to clean out those chlorine crystals (pool stuff?) before you add it.

Dave Sheldrake
10-05-2015, 11:08 AM
Hi Dave,

You may try propylene glycol, aka RV or non toxic antifreeze. It is antimicrobial and antifungal above about 20% concentration.

Just be sure to clean out those chlorine crystals (pool stuff?) before you add it.

Cheers Matt, only problem would be that it would be conductive :(

I'm good for temp as the factory is humidity and temperature controlled it's just the algae :)

Kev Williams
10-05-2015, 11:32 AM
FWIW I filled my cooler with distilled water when I got it, same water is still in it, never seen a bubble or a hint of algae.

David Somers
10-05-2015, 1:15 PM
Same thing here Kev. Distilled water from the git go and no sign of algae after 6 mos. i do use black hose and fittings so there is little light for any algae. I also do the same thing with the water cooler for the CNC. Also no issues there with algae.

Dave! Take your algae and harvest it! Dry it in sheets and sell to foodies as Nori! Locally sourced and gluten free! Likely its Vegan too! <Grin>

Matthew Grant
10-05-2015, 1:38 PM
Cheers Matt, only problem would be that it would be conductive :(

I'm good for temp as the factory is humidity and temperature controlled it's just the algae :)

Interesting, I did not know that about PG. My setup is temp controlled as well, I just use PG to avoid growth.

Tell me, why is the conductivity a problem? I ask because chlorine seems like it would add conductivity as well. I wonder if there is such a thing as a nonconductive growth inhibitor...

Dave Sheldrake
10-05-2015, 4:16 PM
Interesting, I did not know that about PG. My setup is temp controlled as well, I just use PG to avoid growth.

Tell me, why is the conductivity a problem? I ask because chlorine seems like it would add conductivity as well. I wonder if there is such a thing as a nonconductive growth inhibitor...

It seems to destabilise the plasma if conductive coolant is used. The concentration of Chlorine crystals in mine are tiny, 1 teaspoon in 6 litres of water stops any kind of growth :)

Matthew Grant
10-05-2015, 10:53 PM
It seems to destabilise the plasma if conductive coolant is used. The concentration of Chlorine crystals in mine are tiny, 1 teaspoon in 6 litres of water stops any kind of growth :)

Now I'm thoroughly intrigued. I could see a conductive coolant acting as a capacitor, which could certainly disturb a "nice" power supply. When I switched to PG, I felt that my own generic 60W power supply was working better.

I say this because there were a few power settings (8-10mA, 15-18mA) that would cause the power supply to hiss and give a less clean cut. Visible as little striations in an acrylic edge, as the supply seemed to be oscillating instead of giving a smooth output. Two different supplies did that, at different ranges - but not anymore. I had chalked it up to black magic or phase of the moon or something, but I wonder if the capacitance of the PG/glass/plasma is doing some filtering.

Makes me want to switch to regular distilled water and see if the hiss comes back... Maybe this next weekend.

Dave Sheldrake
10-06-2015, 4:33 AM
Now I'm thoroughly intrigued. I could see a conductive coolant acting as a capacitor, which could certainly disturb a "nice" power supply. When I switched to PG, I felt that my own generic 60W power supply was working better.

I say this because there were a few power settings (8-10mA, 15-18mA) that would cause the power supply to hiss and give a less clean cut. Visible as little striations in an acrylic edge, as the supply seemed to be oscillating instead of giving a smooth output. Two different supplies did that, at different ranges - but not anymore. I had chalked it up to black magic or phase of the moon or something, but I wonder if the capacitance of the PG/glass/plasma is doing some filtering.

Makes me want to switch to regular distilled water and see if the hiss comes back... Maybe this next weekend.

Same Matt, I've had it happen but can't express in testable data exactly what's happening. Always the chance it's observational bias of course but I can't come up with anything that fits better at this point.

Kev Williams
10-06-2015, 11:14 AM
The concentration of Chlorine crystals in mine are tiny, 1 teaspoon in 6 litres of water stops any kind of growth :)
This is interesting-- I've owned a hot tub for 20 years, so when I hear 1 teaspoon of chlorine crystals for 6 liters of water, that sounds massive--!

The Sodium Dichloro-S-Triazinetrione granules used in hot tubs requires just 2 teaspoons per 500 gallons to raise free chlorine levels by 2 parts per million, and 1ppm is acceptable in hot tubs to kill off 20 minutes worth of bacteria left behind by humans soaking in it...

I would think this type of chlorine would work to keep algae at bay? If so, 2 teaspoons would be a lifetime supply! :)

(or not?)