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Re: small tube filling pressures

Morgan & Jeff,

You'll have to excuse my even lessthan good mastery of physics in general (I 
couldn't hack thermodynamics). This is fascinating stuff and in many ways 
is at the core of what the whole technology is about.  It amazes me that there 
are no commonly known industry and/or laboratory studies on the subject.

Morgan's July 1994 article was an excellent summary of the BSA study.

One question  I have is might it not be worthwhile to investigate these variants 
of the PVk/T relationship with a "low leakage" transformer.  While this would 
not provide the characteristics of 'normal' neon, it would possibly reveal 
additional info on neon's  characteristics - data which is somewhat masked by 
the feedback current in the typical transformer.  

I'm not familiar with the power supply for the brake lights.  But it 
is likely that here we are looking at hf transformers where different 
rules apply.   

My 'experiments' with ne-2 bulbs have cooked many at 60hz, but I have 
barely detected temperature changes with anything between 500 and 30,000hz. 

Kenny



> Jeff,  you'll have to excuse my less than complete mastery of Paschen's Law;
>  I think that it's showing that there is a curve which has a point of max
> light output, and falls down (at different rates) when the pressure is above
> or below this ideal pressure.
> Regardless, we have run several tests in the our shop having to do with
> filling pressures:
> in the firet set of tests we were using identical 10 inch OPEN signs (11 mm).
>  Filling them in pairs we filled the first set to12mm pressure, the second to
> 6 and the last pair were filled to 24 mm of neon.  They all looked the same
> (none brighter than others).  When we found a trans former that gave us as
> close to 80% load as possible with our "normal fill pressure - 12 mm" we put
> the other two pair on to see how it effected the mA meter.  There was
> something like 1 mA total swing from such great filling pressure differences.
>  
> In another series of tests we were doing for some company selling to the auto
> industry,  we were pumping and filling some 6mm tubes (red) and were filling
> between 20 and 200 mm.  There was VERY little difference in operating temp or
> light output.
> In Neon Techniques they talk about underfilling and cleanup (pgs.15-16; 183)
> and how quickly it can shorten the life of the tube.  There are some
> references to overfilling and resultant hotter running tubes and
> "compression" of the arc stream.  Yes it happens: in fact I have a 20 mm 4
> foot tube that was fill by opening the new red gas bottle and letting as much
> in as will go (guessing around 3/4 atm); it runs hot and never stops snaking.
>  It is little different in light output.
> The most enlightening information I  think comes from a study published by
> the British Sign Assn from another study on tube life where they come up with
> Life hours for both neon and argon. (And yes I did do an article for Sign
> Business - July 94)  
>  
> 
> Life (hours)= (Axp^4xV)/ (kxi^2)
> where A= inside surface area of each electrode
>          p=filling pressure of neon
>          V= tube volume
>          i= tube current
>          k= empeical factor based on the coating material
> 
> Note the real killer:  pressure is to the fourth power
>                           
> I'm sorry that Wayne is not on line now, but maybe has co-worker would help
> out in that Wayne has also been involved with the tail light industry and can
> shed some more (red)light here.
> 
> Morgan     
> 
> 
Kenny Greenberg --  Neon - Scenic and Environmental Art  
                    Internet Site Consultant and Author   
KRYPTON NEON 34-43 Vernon Blvd Long Island City, NY 11106
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