CurtPalme.com Home Theater Forum

alb_qwerti · Joined: 30 Sep 2008 Posts: 41 Location: Italy

Hi,

I want to replace my tubes glycol before ceiling mount it.
Which is the better - easier - safer - cleaner way to go?
Remove the C-Element, fill from there until it spill and then close the flange again?
Or can be made simply filling with a syringe through the draining hole?

Thanks for your advice,
Alberto

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Use the drain hole. Spillage is to be avoided due to the conductive nature of the glycol. If you can't rinse off all the spillage, it can cause future problems.

BUT, if the fluid is visibly contaminated, pulling the C element out and giving everything a good soap and water cleaning is advisable. That contamination will leave a film that has to be removed.

alb_qwerti · Joined: 30 Sep 2008 Posts: 41 Location: Italy

Hi, thanks for your reply!

In these tubes the draining hole is NOT directly over the coolant surface, is on the back side, so the tube should be in a exact position when filling to avoid bubbles.

I think that should be absolutely no bubbles inside when is filled to avoid overheating and reflections.

I can't figure out that position.
Any hints?

Thanks,
Alberto

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

No, you DO want a small bubble. It provides a compressible space for when the coolant heats up, and reduces pressure and stress on the seals and bellows.

**Curt Palme** · Posted: Wed Dec 13, 2017 11:11 pm Post subject:

I always fill the 1209s tubes by removing the C element. The rear fill holes are annoying, I can never fill them up enough to get rid of the air bubble that ends up showing as a reflection through the C element.

BY doing it through the front, you also get spillage as you put the C element on the front, but I am able to get more glycol into the LC chamber than from the back. Wear old jeans while doing it. Smile

km987654 · Posted: Thu Dec 14, 2017 5:23 am Post subject:

Empty the contents of one LC tank into a plastic or glass container. This will show you how much new glycol is required to fill the tank through the C element hole. You should be able to fill it without spilling any if you are carefull.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Pro tip: Get an empty plastic pail like the kind used to hold nails in bulk. Cut a rectangular hole in the cover of it to accept the tube neck and back glass to the frame of the LC hardware. You now have a handy tube filling station that's cheap and easy to make.

This also works with a 10 gallon plastic bucket. The lid may be a bit harder to cut, though.

alb_qwerti · Joined: 30 Sep 2008 Posts: 41 Location: Italy

Great, thanks!

When I'll receive the glycol + glycerine I'll give it a try.

But which are the terrible effects if a little glycol spill out?

In the worst case the paint on alu parts will be damaged!?
Or what else could happen?

Thanks,
Alberto

km987654 · Posted: Tue Dec 19, 2017 1:45 am Post subject:

alb_qwerti · Joined: 30 Sep 2008 Posts: 41 Location: Italy

But really, can eat the glass too ??

Anyway I now have the component.

I saw in varius thread that the final mix of Ethylenglycol and Glycerin should be 80% - 20%

But this is by weight or by volume? Because they have very different specific weight.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Frankly, don't even worry about adding glycerin. It doesn't affect the refractive index of the coolant enough to make any difference.

I worked for a company that is one of the major providers of replacement and refurbished CRT assemblies to the simulator industry and their glycol mix has always been straight glycol. It always works just fine with no complaints over 20 years and tens of thousands of refurbished CRT assemblies sent out, used up, replaced again, returned to the customer, repeat until the projectors are retired.

I also know that VDC never bothered with mixing glycerin into the glycol. They used straight glycol. Again, no issues.

alb_qwerti · Joined: 30 Sep 2008 Posts: 41 Location: Italy

Ok, thanks for your reply.

But could not be different the refraction index with the C element and much more glycol present in a LC setup?

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

The only difference a change in refractive index will make will be the strength of the reflections that occur where materials of different refractive index are in contact with each other. The difference between a "perfect" glycol/glycerin mix with ideal refractive index vs. what you'll get with straight glycol will not make enough difference in the strength of that reflection for you to see it under normal viewing conditions.

It's not worth the effort to make the glycol/glycerin mix. You'll never see the difference.

alb_qwerti · Joined: 30 Sep 2008 Posts: 41 Location: Italy

OK, understood.

Many thanks to everybody for your help!

Alberto

gjaky · Joined: 05 Jun 2010 Posts: 2790 Location: Budapest, Hungary

Glycerin is both cheaper than glycol and less harmfull, so why not use it?

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Because glycerin alone has the wrong refractive index. It's too high. High enough to cause problems if used alone.

Its high viscosity also retards convection flow which is important for transferring heat to the housing.