CurtPalme.com Home Theater Forum

[km987654]

There is a plastic pipe coiled around the back of each tube running from the top of the tank to the bottom. Is this an attempt to cool the fluid or to allow expansion or both. If it allows expansion should the tanks be absolutley full?

[papalek]

That is for expansion. I have some Barco tubes with air in the lines but the tanks are full.

[AnalogRocks]

You know there's probably a convection colling effect in there as well. I wonder if you could apply this to other projectors?

[AnalogRocks]

You know there's probably a convection colling effect in there as well. I wonder if you could apply this to other projectors?

[km987654]

My thoughts were something to do with convection. Curt says the tanks must have an air gap at the top to prevent tube damage. Not sure how convection will work with an air gap.

[Dave Lister]

Does it need an air gap in the tank or will an air gap in the hose be enough to compensate for expansion?

[AnalogRocks]

You could have the air bubble at the top of the tank and feed the tubes at say 11 o'clock and 1 o'clock. Leaving the air buble at 12 o'clock.

[AnalogRocks]

You could have the air bubble at the top of the tank and feed the tubes at say 11 o'clock and 1 o'clock. Leaving the air buble at 12 o'clock.

[km987654]

Interesting thought but the plastic pipe connections are fixed to the tanks at 12 and 6 oclock. It seems to me though that the tanks would have to be full for convection and therefore cooling to be effective.

Thanks Dave. Perhaps expansion of the plastic pipes will deal with pressure build up??

Curt says he has seen a number of tubes implode as a result of pressure build up so I am a little concerned. On the other hand tube failure could result from heat causing the face of the tube to crack and then implode.

[Dave Lister]

I had originally thought that the hoses were for expansion but what I meant about the air bubble was that it may be ok if the air bubble is in the hose as it should still be able to be compressed whether it is in the LC chamber or in the hose.

My retroblock G808s has LC chambers and the hoses connect at the corners, say at 2 and 7 o'clock which should still allow convection currents in the glycol.

I was considering changing the hoses when I replace the seal between the CRT and LC chambers with hoses that would be compatible with glycol and allow more elasticity to allow expansion without having an air bubble, but I am unsure if this is possible.
I was also considering making them much longer to give more surface area for expansion and cooling, if the hose is about half a metre now I was considering going to 1 metre or maybe 1.5 to 2 metre but that would mean more glycol which is expensive.

[Ile]

With bubbles in hose there is no proper convection and without bubbles there is too much pressure.
No convection at all would be smaller problem, since bellow model LC hardwares and AC tubes don't have similar cooling tube at all.

I think I build one common expansion/cooler tank to my BG1200, so I get both problems solved...

[Dave Lister]

Not a bad idea.

Have all hoses connected to a main tank, at the bottom of the tank, with the tank above the height of the LC chambers so the glycol can circulate from convection currents and have an air bubble at the top of that tank to allow for expansion.
Add a heatsink to the tank or inline with the hoses for extra cooling effect, maybe a peltier cooler too although that may make the glycol too cold.
The CRT PJ version of a liquid cooling system for a PC.

A better version of what I originally had in mind for the retroblock G808s, was thinking of just a radiator on the back of the PJ with hoses going to the LC chambers, maybe a fan for extra cooling but the bubble problem would still prevent the convection currents.

If I could run Autodesk Inventor on this old P3 500MHz (oveclocked to 598MHz) then I would draw up a model of this.

[Ile]

I had something similar in minds.

Tank would be filled to half full, so there should be more than enough room for expansion. There is still going to be pressure in lc champers when tubes get hot, but because of big air space it would be much smaller.

One option is not to seal tank, but then glycol would draw moisture from air...

Stainless steel tank with one wall of glass would be cool.

Edit. That would be easiest to make from stainless pocket flask, just weld six pipes to bottom.

[AnalogRocks]

You know on that retro block you could extend the hoses. Car's use Glycol based antifreeze for cooling. The hot rodders have all sorts of inline bilit and extruded aluminium tanks to act as tranny/brake or power steering coolers. The one precaution I would make is to paint the insides of the tank(s) with a high quality paint so you don't end up with tainted glycol.

Here's the coolers I'm talking about:

http://www.streetrodstuff.com/Products/100/

[AnalogRocks]

You know on that retro block you could extend the hoses. Car's use Glycol based antifreeze for cooling. The hot rodders have all sorts of inline bilit and extruded aluminium tanks to act as tranny/brake or power steering coolers. The one precaution I would make is to paint the insides of the tank(s) with a high quality paint so you don't end up with tainted glycol.

Here's the coolers I'm talking about:

http://www.streetrodstuff.com/Products/100/

[km987654]

I had a similar idea(s) about cooling. I would not use a single tank though. If a tube does implode you will effect every other tube. You need separate tanks for each tube. Of course you probably will not be able to invert the PJ with such an installation.

Does anyone know how hot glycol gets?

[Dave Lister]

Ile:
That's virtually what I was thinking but I would use a very large pocket flask and do as AnalogRocks suggests and paint the inside.

Glass sided would be cool for checking the level hasn't changed.

Maybe a plastic tank to solve both problems of corrosion and seeing the glycol level, like a surge tank from a car cooling system.

AnalogRocks:
They are the radiators I was originally thinking of although I had only seen the flat type in local auto parts catalogs, the tyep you linked to would look cool though.

Even though car coolant has glycol in it painting the inside would be a good idea as car coolant doesn't have the same percentage of glycol as it is mostly water so would be less corrosive.

km987654:
If there is enough of an airgap then there should be no way for the tubes to crack from overpressure, use a plastic tank as I suggested above and it can expand a little to compensate a bit more.

The tank could be re-oriented for ceiling mount, not an issue for me though as with the retroblock it would be set up for 0 degree projection, lenses level with the centre of the screen as that is what it is made for.

[Ile]

I just got new easy idea to make expansion "tanks", I'm going to chance plastic tube to boat gasoline tube that have rubber ball pump installed, tube diameter match straight.
http://www.biltema.fi/osteri/osteri.cgi?sivu=skriptisivut/index_kauppa.htm&linkki=25704.htm&tuote=25704

When I fill tubes I squeeze that rubber and connect tubes. Squeezed rubber ball allow lot of heat and air humidity expansion and it's easy to check when there is need to drain tubes again. This kind system should allow convection, because there is no air bubles in tube.

[Dave Lister]

You know, that just might work, depending on whether there would be any chemical reaction between the hose/rubber bulb and the glycol.

Oh no, that would mean your CRT PJ would have bulbs in it.

[AnalogRocks]

Just remember NOT to pump the BULBs before trying to pull start the projector. No need to prime the glycol before HV startup.

[AnalogRocks]

Just remember NOT to pump the BULBs before trying to pull start the projector. No need to prime the glycol before HV startup.

[Dave Lister]

[Ile]

I think those gasoline pumps need back-pressure valve to work properly. Have to buy one next week and see if it's possible to remove that valve.