Reversing Mercury Starvation!

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SuperSix
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Reversing Mercury Starvation!

Postby SuperSix » Sat Jun 25, 2011 11:53 am

This is something I really hate, when an otherwise perfectly good fluorescent tube becomes mercury starved and is useless. I've managed to reverse the process with a GE F18/35 I got from Kev! People have said before hair dryers help when the lamps are just starting to become mercury starved but after that the mercury combines with the phosphor permanently and it did seem that way until now...

Today I thought I might as well get rid of that tube since it's useless, I just thought I'd have another last go at heating it! :P This time it went in in the oven at 225°C for 15 minutes! I thought the tube was gonna crack but somehow it survived. After letting it cool down I popped it in a fitting, hoped for the best and fired it up... instant full brightness! It also seems to have removed the 'permanent' black sputtering around the cathodes as well and the tube looks brand spanking new! :D

I don't have any more mercury starved tubes at the moment, it'd be interesting if someone else could give this a go!

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SuperSix
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Re: Reversing Mercury Starvation!

Postby SuperSix » Sat Jun 25, 2011 12:06 pm

Here's some pics.

Before:
F18W 35 Before.jpg
F18W 35 Before.jpg (28.04 KiB) Viewed 4314 times


After:
F18W After.jpg
F18W After.jpg (24.24 KiB) Viewed 4314 times

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Tom
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Re: Reversing Mercury Starvation!

Postby Tom » Sat Jun 25, 2011 12:14 pm

Nice one!! I wish I'd tried that with a couple of my old tubes in the past!
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Dez
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Re: Reversing Mercury Starvation!

Postby Dez » Sat Jun 25, 2011 12:24 pm

My friend has an almost Mercury Starvd BC TUBE and It has hard time striking :cry: :cry: so how do you reverse Mercury Starvation on a 5ft BC TUBE could I use a heat gun :?: :?:
Last edited by Dez on Sat Jun 25, 2011 12:26 pm, edited 1 time in total.

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sailormoon01uk
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Re: Reversing Mercury Starvation!

Postby sailormoon01uk » Sat Jun 25, 2011 12:25 pm

I can see there is a Big Difference in the Photos Can You!

All the Best

Colin

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SuperSix
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Re: Reversing Mercury Starvation!

Postby SuperSix » Sat Jun 25, 2011 1:28 pm

A heat gun might work, this seemed to take pretty extreme temperature though! I still can't believe this worked, I really wish I'd of kept the other tubes I had which I threw out. :(

What do you mean Colin? The first photo is a snapshot from a video I had of the lamp when it was mercury starved, only one I could find and it's in an LP20, since then the LP20s moved so I used an LP18 and took a proper photo.

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sailormoon01uk
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Re: Reversing Mercury Starvation!

Postby sailormoon01uk » Sat Jun 25, 2011 1:56 pm

In the first photo it shows a T8 Tube and in the Second Photo it shows a T12 Tube, thus it looks like you just swapped the Tubes

All the Best

Colin

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SuperSix
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Re: Reversing Mercury Starvation!

Postby SuperSix » Sat Jun 25, 2011 2:19 pm

LOL they're two different fittings though, first one's a 20W Lightpack for 2' 20W T12 tubes, the second one's an 18W Lightpack for 2' 18W tubes. Same tube though!

DSCF6517.jpg
DSCF6517.jpg (25.74 KiB) Viewed 4300 times

DSCF6515.jpg
DSCF6515.jpg (26.35 KiB) Viewed 4300 times

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Paul
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Re: Reversing Mercury Starvation!

Postby Paul » Sat Jun 25, 2011 2:23 pm

LOL @Colin - deffo same tube that I can see and just the battens on the fittings are different sizes! 8-)

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sailormoon01uk
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Re: Reversing Mercury Starvation!

Postby sailormoon01uk » Sat Jun 25, 2011 2:46 pm

Ahh that explains things, still quite decieving to the untrained eye

All the Best

Colin

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Re: Reversing Mercury Starvation!

Postby James » Wed Jul 06, 2011 6:43 pm

Dez - please don't try heating any BC tubes - it is impossible to get mercury starvation in those and you will only risk cracking it! Old fluorescent tubes are dosed with extremely high mercury weights, typically up to 100mg. A very long life tube will typically absorb only 1 to 3mg of mercury over its lifetime, and the problem of mercury starvation arises only due to modern restrictions which limit how much mercury we can now dose into the tube. Today a typical modern tube may be dosed with as little as 1-2mg of mercury - and this can all be consumed during life. But even if you ran an old BC tube for a century you would never be able to get the glass and phosphor to absorb its huge mercury dose! The same applies for any tube made up to about 1985, even then a typical 4' tube was still being dosed with about 40mg of mercury.

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Dez
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Re: Reversing Mercury Starvation!

Postby Dez » Wed Jul 06, 2011 7:08 pm

I have seen the tube my sellf and its pink in the middle and white at the ends the tube has been used for 40 years if left blinking for abut 10 mins it will strike and if I heat it up with a hair drier it will light normal but when turned off and left off for more than a min it will go back to being MG starved :cry:

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Re: Reversing Mercury Starvation!

Postby Kev » Wed Jul 06, 2011 10:56 pm

Hi James, I actually have a 2, 40W Atlas tube that is mercury starved. It is not pink like Eliots however it has gone a very very dull grey colour. Lee has dated it for me at Jan 1968! Is that just a one off?

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Re: Reversing Mercury Starvation!

Postby James » Thu Jul 07, 2011 9:07 pm

Without seeing these it is very difficult to say what is the problem, but I suspect simply contamination of the gas filling. That can arise either from a slow air leak which lets some air (nitrogen) into the lamp, or another occasional cause is that the electrodes were not activated correctly during production. Then some carbon dioxide gas is produced inside the tube during later service. Both of these phenomena will change the discharge colour as well as making ignition very difficult or impossible.

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Kev
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Re: Reversing Mercury Starvation!

Postby Kev » Thu Jul 07, 2011 9:15 pm

HI James, I will bring this one with me. After i stuck it in the oven it worked perfect! Doesnt seem to have any starting problems, The mercury starved lamps that i have come across do not have starting problems as such but have just simply turned pink, a lot of Fitzgerald branded tubes which i think were the last of the GB made GEs suffered bad from mercury starvation. There is a boiler room in one of the schools i look after where the lamps have gone mercury starved in Fitzgerald BDP270 Weather proof switch start fittings. They all strike up as a normal lamp would however are just pink!!


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