Laser Chiller

[puffernutter]

You will laugh at this, but some will sympathise as it was a bargain!

As some will know I recently bought a laser/engraver from here. It was without a chiller and various people and sites warned me against buying a chiller from China as they were just a fan in front of a radiator and relied on a low ambient temperature to work (although to be fair, some were happy with them).

I did some hunting on the internet and found a secondhand Laserpure20 chiller local to me. Now I (will have) a 50W laser, the Laserpure 20 is designed for 20kW, so I have a little headroom there! Unfortunately I cannot find a manual for it! I have been in touch with the manufacturer in the states and they don't have one. It is fairly basic and some connections are obvious, but there is "water - laser in" and "water - laser out" (I can cope with that). There is also a "water in" (it has an inboard tank, so that makes sense). But there is also a "water out". All I can assume is that is a drain? There is an internal valve, I know not what it does! (I have studied the plumbing, but I probably need to draw it out!) Finally there is a strange connection on the back that I am not sure if it is electrical or fluid!

So, you seem to have a tremendous "reach" has anyone come across a manual for a Laserpure 20? (There is one you can find quickly by Googling, but that is to do with the water you use to cool it, not the cooler itself - I found that and it has some odd bits of use, but it isn't an operating manual.

Cheers

Peter

 

[hotponyshoes]

Is it actually a Chiller?
Or a heat exchanger?

If it's a chiller it will have a fridge type compressor in that will clunk slightly when you first turn it on.

Yours sounds more like it's a heat exchanger. The funny connection will probably be a fill point for an internal tank that you fill with coolant or distilled water or something. Laser in/out to the laser. Water in/out from the dirty tap water to the drain. The valve will be to set the flow rate of the water to the laseI would guess.

 

[Agroshield]

Everything I can see on it says it is a water-to-water chiller, so it circulates water in one loop through the laser (which needs to be a certain specification/quality) and dumps the heat in that water into the other water loop - that is the mains water in and out.

If you own a reservoir in Wales, make it open loop and exhaust to the drain; if not, maybe rig up a pump and sell it to the Missus as a way to reduce your energy bills by not using the immersion to heat the bathwater.

You may have seen it already, but the machine comes as a 40 and 60 in addition to the 20 you have, so including these in your search might help. Sometimes you might have to write it as 'laser pure' (two words). Try 'LP20' as sometimes they are seen thus.

York Scientific offer repairs, so for the price of an email you might get something: http://www.yorkscientific.com/store/product/coherent-laserpure20-refurbished

These people have one in their lab. so tell them you are an impoverished mad scientist trying to ensure/prevent DT returning to power and they may help further your worthy scientific cause: http://www.physics.umd.edu/drew/peo...um recovery system - Liquefier Room - v31.htm

Small description of how one works here: https://www.iitk.ac.in/dordoldn/data/care_funding/2008-09/Arun_K_ME.pdf

Increasingly irrelevant: https://lists.purdue.edu/pipermail/cytometry/2004-September/027342.html

 

[puffernutter]

Thank you, another good plan down the drain (pun intended) by me not knowing what I am buying!

Cheers

Peter

 

[puffernutter]

Is it actually a Chiller?
Or a heat exchanger?

Looking inside - it's a heat exchanger! I really must read the specs first!

 

[hotponyshoes]

You could dump the outgoing water to a waterbutt in the garden.
For a 50w laser, unless it's running 24/7 you would probably be fine raising the drain pipe up so the plate is always full of water and just running it at a slow trickle.
You could always monitor the temp of the drain water on a test run to see what sort of flow you need or even fit a temp sensor/alarm to the laser loop and if you wanted to get fancy, a solonide on the tap line.

You might even find that the funny connector is electricrical and is for temperature or some sort of over-temp alarm or lockout anyway.

I don't think it will take much to get it working for what you want. You could make up a 2nd tank with a pump in to pump water in/out of it.
I bet a 25l tank would last you all day.
Or, Fit a small radiator and a fan, basically a tig water cooler setup but without the expensive pump as a cheap one would be fine.

Or, I could probably sort you out with a beer Chiller but that's probably overkill for 50w.
I might have a suitable pump though..

 

[hotponyshoes]

Aside from being able to pump clean coolant around the laser the coolant in the exchanger should be at room temperature which should help stop any condensation in the laser head.

Plenty of other uses for heat exchangers anyway, 20kw might just be enough for a small hard anodizing bath

 

[MattH]

Not all the Chinese units are just heat exchangers. I have 3 x 5000 series and these are definitely refrigerated chillers. The 3000 series are just heat exchangers.

 

[8ob]

Pipes to and from a chiller would dissipate more than 50w of heat, I would have thought a pumped closed circuit through a coil of soft roll copper would keep up with that.

Bob

 

[hotponyshoes]

Pipes to and from a chiller would dissipate more than 50w of heat, I would have thought a pumped closed circuit through a coil of soft roll copper would keep up with that.

Bob

That would be my thinking.
If you had the specs for the laser (ie min and max temp of the cooling water) and the size of the tank in the cooler you could workout how long it would run for without even having the secondary side connected.

I bet you could extend that time considerably just by mounting a tank up on the wall behind and plumbing it to the in/out and just let it work by convection.

If you had some sort of temp alarm you could start off with that. Them swap the tank for a radiator if needed.Then if needed, add a pump, then if needed add a fan.

For 50w which I'm guessing is the peak power of the laser not all of that 50w will be heat. Plus if its engraving on wood it will be running less than 50w for the lighter areas.
Oughtright guess but you might find that over an hour of engraving the average power is 25w for example.

 

[hotponyshoes]

Although I should point out I've got no idea how laser power is classified.

If it's 50w then it's 50w.
If the strength of the light beam is 50w and its actually using 5kw of power to make that then that's a different solution to what I proposed and you might want a beer chiller!

 

[rcx132]

If it's 50W then it sounds like a CO2 laser, in which case the 50W is the light output.
Laser diode engravers are often quoted using their input power, but CO2 engravers continue to use the more informative output power.
As others have said, the 5000 series chillers are the real deal, they have a compressor inside which cools the liquid coolant. The cheaper 3000 series are just a fan and radiator.

 

[hotponyshoes]

Ignoring the environmental aspect,
I wonder what's cheaper..
Running an electric chiller or pouring tap water down the drain?

Edit, the water company probably use electricity to pump the water to you so which ever is financially cheaper is probably better for the planet as well..

 

[voipio]

You could try contacting Coherent directly (email, phone), or there's an option on their website to raise a support ticket.

Support Services | Coherent

Get all the customer support tools and resources you need to make sure you get the most out of your Coherent lasers, laser systems, and laser components.

www.coherent.com

 

[puffernutter]

All, thank you. Whilst on the dog walk this morning (brain in neutral) I realised all was not lost and a variation on @hotponyshoes could work! I have a small car radiator (mini I think) and all I'll do is have a second closed circuit on the water in/out side of the heat exchanger, mount the radiator outside (another heat exchanger!), I have a 12v Kenlow equivalent to give a bit of a blow if required.

I reckon that's a cunning plan - I've been in touch with Coherent, they do not have a copy of the manual in their archive. But there were some good search options earlier I'll try!

Thanks all - a great resource as ever!

Peter

 

[Newlands]

I’ve got a 5000 on my 100w co2 laser and it’s overkill - while it’s nice to have a proper refrigeration unit I could easily have just used a cheaper 3000 chiller, even in the hot temperatures we had this summer.

 

[hotponyshoes]

The input power of the laser minus the 50w output power will give you the amount of cooling required with a decent safety margin

 

[rcx132]

I’ve got a 5000 on my 100w co2 laser and it’s overkill - while it’s nice to have a proper refrigeration unit I could easily have just used a cheaper 3000 chiller, even in the hot temperatures we had this summer.

The 3000 will never get the temperature below ambient. CO2 lasers have much shorter lifespan at higher temperatures. So the 5000 may be over kill but the 3000 doesn't really solve the cooling issue because it uses the wrong technology.