Cooling Water

[Bill Howie]

Hi Just ordered a machine so waiting for them to come in
What I need to know can you use tap water for the cooling and if not where can I get the correct water in west yorkshire.
I paid an ad hock visit to the Halifax works on friday and was very imprest with the demonstration
Any tips or advice is welcome as I have never seen a laser machine untill last friday.
Many thanks
Bill

[Spooky]

Heya Bill,

nonononono not good to use tap water for the same reasons as its not good to use in steam irons / boilers etc.

Deionised from pretty much anywhere that sells the stuff for steam irons or car batteries will be fine. Tescos do it, as do many BP garages etc...

Chris will fill it on delivery I would think (not sure so better ask him) so that will give you 6 to 8 weeks before you need to change it (depending on use)

hope that helps

Best wishes

Dave

[HPCLaser]

Hi Daft as it may seem De ionised doesnt conduct electricity -sounds stupid but a Physisist told me this good for lasers though...

[Spooky]

Hiya Chris,

Not daft at all (hehhe as it happens I am a qualified Physicist) and absolutly true. Pure 100% H2O doesn't conduct electricity at all, at Porton Down they can get to 99.99997% pure but to remove the last 0.00003% would cost more than 10 times what the previous operation has cost. It's the impurities that conduct the current

best wishes

Dave

[David]

Hi Bill

We've had ours in school for nearly two years, changed the water on principle about a year ago, it still looks ok - no obvious particles or things growing in it, and hasn't needed topping up. We used deionised water from the science department still (given the size of the cooling water tank the Halfords option would have been expensive!) and the tank itself is in a dark corner with a close fitting lid, reducing evaporation contamination etc. I'll probably change it again this summer, but it doesn't appear to be necessary.

Hope this is of use / interest

David

ps just a thought - have you tried talking to your local secondary school science technician? I bribe ours with favours such as engraving 2mm square grids on the bottom of PS petri dishes to help measure culture growth areas...

[Bill Howie]

Hi All
Thanks for the info all sorted tub box with lid from Staples and 6 x 5ltr water from halfords.
Next question what is a good glue for perspex
Cheers (Chris can you ask the boat to put more coal on the fire )

[johnb80]

I'm a little confused with all of this....

The water is circulated around the outside of the laser tube and thus has no electrical connection so why is conductivity important?

The water sole purpose is one of cooling so again why does it have to be distilled etc?

The fact that it's exposed to UV light should kill of anything growing in it.

Why can't antifreeze or bleach be added to kill off anything growing and prevent freezing in winter?

Maybe I've got it wrong but can somebody please answer the questions which to me seem obvious ones.

Thanks in advance - John

[Spooky]

The minerals and ions in tap water can be corrosive to small components as well as causing sedimentary deposition into the tube glass (thats going to affect cooling as you will end up with a microfine insulation layer in the tube coils) also those impurities will carry and hold heat more efficiently than clean water (basic material density issues) in simplistic terms dirty water stays hotter for longer
Where I live (middle of nowhere) the water sometimes looks like liquid chalk comming from the tap so I hate to think what it would do to the inside of my lasers cooling tubes.

hope that makes some sense

best wishes

Dave

[johnb80]

Yes it does make sense to a point.... Many people will look at the insides of a kettle and consider the calcium build up that occurs, the situation with the laser will be very different because the same water is being circulated. I also wonder about automotive antifreeze, this will have corrosion inhibitors built in which should also alleviate some potential problems.

What would your views be of antifreeze (just in case) and distilled water?

J

[Spooky]

No idea to be honest John, Chris will be the man for this one